Wireline control system and method

Abstract

A wireline control system and method for moving a wireline into or out of a well including multiple wireline control units mounted on the well for alternately gripping and moving said wireline, each of the wireline control units being synchronized by a common fluid power system for continuously moving the wireline into or out of the well.

Description

BACKGROUND OF THE INVENTION

The field of this invention is control systems for moving a wireline or the like into or out of a well.

The use of wirelines for performing operations downhole in an oil well is well known. Typically, a tool is connected to the wireline at the well head and the wireline is then fed downhole. After completion of the operation, the wireline and tool are retrieved.

In wells having high pressures, it is difficult to inject a wireline through a sealing means into a well. This is due to the pressure in the well which tends to force the wireline upwardly as it is fed downhole through a sealing means. High well pressures also make it difficult to control retrieval of a wireline from a well.

One known apparatus for injecting a wireline into a well uses a series of sinker bars to weight the wireline sufficiently to overcome the thrust due to well pressure tending to push the wireline through the usual seal near the surface. The use of sinkers or other weight has become more difficult due to the excessively long lubricators and related equipment required when higher pressures are encountered in the deeper wells drilled today. "Snubbers" are gripping units that are used to move tubing into or out of a well, an example of which is disclosed in U.S. Pat. No. Re: 25,860, which snubber opertes externally of the well to force the tubing into the well through a seal, whereby the tubing is placed in compression due to the well pressure. If a wireline were to be fed into a well with such apparatus, the wireline would birdcage or otherwise tend to expand or buckle, thereby making it difficult or impossible to feed the wireline into the well.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a new and improved wireline control system for continuously feeding a wireline into a well or retrieving a wireline therefrom, even if the well is under substantially high pressures. The wireline control system of the preferred embodiment of this invention includes one or more wireline control units mounted in longitudinal alignment on a well head and adapted to receive the wireline for sequentially operating to alternately grip, move and release the wireline in order to move the wireline into or out of the well.

The system for continuously moving the wireline into or out of the well includes a first gripper unit mounted on the well for firstly gripping and moving the wireline through a first stroke and a second gripper unit mounted with the first gripper unit for secondary moving the wireline through a second stroke, the first gripper unit releasing the wireline after the second gripper unit has gripped the wireline. In the preferred embodiment of this invention, a third gripper unit is mounted with the first and second gripper units in longitudinal alignment for thirdly gripping and moving the wireline, the second gripper unit releasing the wireline after the third gripper unit has moved into gripping engagement with the wireline.

The second gripper unit includes means for gripping and initially moving the wireline at a higher velocity than the first gripper unit and the first gripper unit includes means allowing the wireline to disengage from the first gripper unit prior to release from the wireline so that the wireline can be moved at the initially higher velocity of the second gripping unit. Similarly, the third gripper unit includes means for overtaking the gripping of the second gripper unit so that the wireline can be moved at the higher initial velocity of the third gripper unit.

Movement of the gripper units are synchronized such that the first, second and third units operate 120.degree. out of phase with each other based upon a 360.degree. cycle. Syncronization is provided by a fluid control system which either provides power or controls the distribution of power to each of the gripper units.

a wireline gripper unit in the preferred embodiment of this invention includes a housing adapted for mounting on a well tubing which extends downhole in a well. Means are provided for maintaining the housing and the wireline positioned therein at a pressure equal to or greater than well pressures. An actuator assembly is mounted in the housing for longitudinal movement between first and second positions. A gripping means for grippingly engaging the wireline is mounted on the actuator assembly for movement with the actuator assembly between the first and second positions, and further for relative movement into and outwardly of the wireline for alternately gripping and releasing the wireline. A fluid system is connected with the actuator assembly for movement thereof for feeding the wireline longitudinally into the well or for braking movement of the wireline when the wireline is coming out of the well.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partly schematic side view of the wireline control system of the preferred embodiment of this invention in position on a well;

FIG. 2A is a sectional view of the outlet for the grease injector system utilized to maintain the wireline control system at a substantially high operating pressure with respect to well pressure;

FIG. 2B is a sectional view of the inlet for the grease injector system;

FIG. 3 is a schematic view illustrating the fluid power system for operating a wireline control unit;

FIGS. 4A and 4B illustrate in top and bottom sectional views, respectively, the actual structure of the gripping mechanism of a wireline control unit;

FIG. 5 is a sectional view taken along line 5--5 of FIG. 4B;

FIG. 6A is a sectional view of the connection between the inlet for the grease injector system and the bottom of one of the wireline control units; and

FIG. 6B illustrates the connection between the top of one of the wireline control units and the outlet for the grease injector system; and

FIG. 7 is a graph illustrating the gripping stroke for the actuator sleeve and gripping element of a wireline control unit; and

FIG. 8 is a graph illustrating the sequential operation of the three gripping units of the wireline control system of the preferred embodiment of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings, the letter W generally designates the wireline control system of the preferred embodiment of this invention. The wireline control system W is mounted on the well head H for feeding the wireline L into or out of a well such as an oil well.

Referring in particular to FIG. 1, the wireline control system W includes in the preferred embodiment of this invention three wireline control units C-1, C-2 and C-3 which are mounted in longitudinal alignment onto the well head H. The well head H is of known construction and includes a series of three blowout preventers 10a, 10b, and 10c mounted onto well tubing 11 which extends downhole into the well. A lubricator assembly generally designated as 12 may include a tool trap 12a mounted onto the top of the blowout preventers 10a - 10c. The lubricator assembly 12 further includes a quick-disconnect coupling 12b which allows in a known manner for the attachment and removal of tools from the wireline L.

A grease injector system generally designated as 14 includes a grease inlet 14a mounted above the lubricator assembly 12. The wireline control unit C-3 (sometimes referred to herein as the third wireline control unit) is mounted onto the grease injector unit 14a and, the wireline control unit C-2 (sometimes referred to herein as the second wireline control unit) is mounted onto unit C-3. Finally the wireline control unit C-1 (sometimes referred to as the first wireline control unit) is mounted onto the second wireline control unit C-2.

Grease outlet unit 14b of the grease injector system is mounted onto the top of the first wireline control unit C-1 and a stuffing box 15 is mounted onto the top thereof. The wireline L extends through the tubing 11, the blowout preventers 10a-10c, the lubricator system 12, grease inlet unit 11a, the wireline control units C-1, C-2 and C-3, the grease outlet unit 14b and upwardly through the stuffing box 15 and about a sheave assembly 16. The sheave assembly 16 is supported by a suitable bracket 16a and is utilized for directing the wireline L directly downwardly into the stuffing box 15. The wireline L can be attached to any suitable winding or reel device (not shown) for winding or unwinding the wireline L as it is fed into or retrieved from the oil well by means of the wireline control system W of this invention.

It is well known in the art to use a lubricator assembly 12 in conjunction with some kind of wireline movememt device to move wireline tools into and outwardly of an oil well. Typically, a tool is mounted onto the wireline L after the quick-disconnect coupling 12b has been disconnected from the wireline. After insertion of the connected tool into the lubricator 12, the quick-disconnect coupling 12b is again connected and some type of wireline movement device is used to lower the wireline L and the tool mounted thereon into the well. After operation of the tool downhole, the wireline L and the tool are retrieved from the well.

The wireline control system W of the preferred embodiment of this invention is utilized to feed the wireline L into the well with a suitable tool thereon and to thereafter retrieve the wireline L and the tool even if the well is at a substantially high pressure.

The wireline control system W of this invention operates at pressures greater than the pressure in the well. This is accomplished by the grease injector system 14 which provides for a continuous flow of grease through the wireline control units C-3, C-2 and C-1, respectively, at a pressure higher than the pressure actually in the well. The use of grease in such an oil field operations is known and it should be understood that any suitable fluid can be used to maintain the pressures in the wireline unit W.

The inlet unit 14a for the grease injector system 14 is illustrated in detail in FIG. 2B. An inlet line 14c extends from a suitable high pressure pump into a coupling housing 14d having a bore 14e therethrough. Grease lines 14f are mounted at either end of the housing 14d for guiding the wireline L therethrough. Each of the grease lines 14f include an outer sleeve 14g and an inner guide sleeve 14h which actually receives and guides the wireline L. The inner diameter of the guide sleeve 14h is slightly greater than the diameter of the wireline L such that the grease at high pressure passes through the housing bore 14e and upwardly between the wireline L and the guide sleeve 14h into the bottom of the third wireline control unit C-3.

FIG. 6A illustrates the connection between the grease line 14f and the wireline control unit C-3. The outer grease sleeve 14f includes a threaded outer end 14i which is threadedly connected to the bottom end 14j of the third wireline control unit C-3. The threaded connection between the grease line 14f and the wireline control unit C-3 is sealed by a suitable means such as seal ring 14k. Thus, grease at high pressure is pumped through the grease inlet unit 14a and along the wireline L through the wireline guide sleeve 14h and into the third wireline control unit C-3.

A series of passageways (generally designated by the number 15 in FIG. 3) are provided in each of the wireline control units C-3, C-2 and C-1 such that the grease can be pumped along the wireline L and through the units themselves upwardly into the grease line 15a connected to the top of the first wireline control unit c-1 as illustrated in FIG. 6B. The upper grease line 15a includes an inner guide sleeve 15b similar to the guide sleeve 14h and an outer guide sleeve 15c. Connection between the upper guide sleeve 15a and the top end 15d of the wireline control unit C-1 is a threaded connection which is sealed by seal ring 15e positioned between the top end 15e of the wireline control unit C-1 and the outer guide sleeve 15c.

Therefore, high pressure grease or other suitable fluid moves upwardly through each of the wireline control units C-3, C-2 and C-1, respectively, and through the upper guide sleeve 15a and finally into the grease outlet unit 14b, which is illustrated in section in FIG. 2A. The grease outlet unit 14b includes a cylindrical housing 16 having a bore 16a therein. An outlet line 16b is connected into the bore so that the grease can pass outwardly from the bore 16a and into the outlet line 16 b, which is exposed to atmosphere. In this manner, fluid circulation of grease or other suitable fluid is provided at a pressure equal to or higher than well pressure throughout the wireline control units C-1, C-2 and C-3. The specific series of passageways 15 provided in each of the wireline control units will be discussed hereinafter.

WIRELINE CONTROL UNIT C-2

The structure for the wireline control unti C-2 is illustrated in detail in FIGS 4A and 4B, and is further illustrated schematically in FIG. 3. The structure of the wireline control unit C-2 is identical with the structure of the wireline control units C-1 and C-3; therefore, only the particular structure of the wireline control unit C-2 will be discussed. The same numbers and letters will be used to describe the same parts in each of the units C-1, C-2, and C-3.

The only difference between the wireline control unit C-2 and the control units C-1 and C-3 is in the joint structure used for mounting the units in longitudinal alignment. The mounting of the bottom end 14j of the wireline control unit C-3 onto the grease line 14f has been described with reference to FIG, 6A. The connection between the top 15d of the unit C-1 and the upper grease line 15a has been described in FIG. 6B. The connections between the top of the unit C-3 and the bottom of the unit C-2, and further between the top of the unit C-2 and the bottom of the unit C-1 are simple threaded connections which need not be disclosed in any detail.

The wireline control unit C-2 includes an outer cylindrical housing generally designated as 20. The outer cylindrical housing 20 consists of three cylindrical sections 20a, 20b and 20 c which are threadedly interconnected. Each of the cylindrical sections are hollow and cooperate to provide a substantially continuous, cylindrically-shaped inside wall 21 to define an internal operating chamber 22. A top guide tube 23 is threadedly mounted at 23a into a bore portion 20d in the top housing section 20a. The top guide tube 23 includes an internal bore 23b having an internal diameter slightly larger than the diameter of the wireline. The top guide tube 23 further includes a series of longitudinal grooves 23c which allow for the passage of grease or other suitable fluid from the bore 23b into the internal operating chamber 22.

A bottom guide tube 24 is threadedly mounted at 24a into the bottom of the third housing section 20c. The bottom guide tube 24 includes an internal bore 24b having a diameter slightly larger than the diameter of the wireline L. The top and bottom guide tubes 23 and 24 serve to guide the wireline L through the wireline control unit C-2. The guide tube 24 further includes a series of longitudinal grooves 24c which allow for the passage of grease or other suitable fluid from the bore 24b into the internal operating chamber 22.

The wireline control unit C-2 includes an actuator assembly generally designed as 25 mounted in the housing 20 for movement longitudinally thereof between top and bottom positions for feeding the wireline L into the well or for controlling the movement of the wireline L as it is removed from the well. Gripping means generally designated as 26 are mounted with the actuator assembly 25 for longitudinal movement therewith and for relative movement with respect thereto for alternately gripping and releasing the wireline L. And, a fluid system generally designed as F in FIG. 3 is provided for operating the actuator assembly 25 for movement thereof while moving the wireline into or out of the well. The fluid system F, a hydraulic power system to be described in detail hereinafter, also provides fluid power to the hydraulic control units C-1 and C-3 for synchronizing the movement of the actuator assemblies 25 and the gripping means 26 in each of the units whereby the wireline L can be moved substantially continuously into or out of the well. A slip release means generally designated as 28 is mounted with the actuator assembly 25 for holding the gripping means 26 in a released position out of engagement with the wireline L; operation of the slip release means 28 is controlled by the fluid power system F.

The actuator assembly 25 includes an actuator sleeve sections 30, 31, 32 and 33 which provide a unitary sleeve or piston 25a for movement within the internal operating chamber 22 of the housing 20. The sleeve sections for the actuator sleeve 25 include a cylindrical sleeve section 30 which is mounted for slidable movement with respect to the inside housing wall 21. The main outer sleeve section 30 extends longitudinally substantially the length of the entire internal operating chamber 22 less the length of stroke of actuator assembly 25 relative to stationary housing 20. The sleeve section 30 is mounted for slidable movement between an UP position and a DOWN position. The up position for the sleeve section 30 is the position wherein upper sleeve end 30a thereof abuts top 22a of the internal housing chamber 22. The down position for the sleeve section 30 is illustrated in FIGS. 4A and 4B. In the down position, the bottom end 30b of the sleeve section 30 abuts the lower end 22b of the internal housing chamber 22.

The main outer sleeve 30 has welded thereto an intermediate sleeve 31 which is mounted onto inside, cylindrical wall 30c of the main outer sleeve 30 for movement therewith. A top, inside actuator sleeve section 32 is threadedly connected at 32a to upper end 31a of the intermediate sleeve section 31. The top actuator sleeve section 32 has an internal, cylindrical bore 32b positioned in alignment with the bottom portion of the top guide sleeve 23 in order to slidably move with respect thereto. A seal ring 32c serves to prevent the passage of fluid between the upper intermediate sleeve section portion 31a and the top sleeve section 32. A supporting bottom sleeve 33 is threadedly connected to lower end 31b of the intermediate sleeve section 31 and a guide sleeve section 34 is threadedly connected at 34a to inside bore wall 33b of the support sleeve 33. The guide sleeve section 34 includes an internal bore 34b which is slidably mounted over the upper portion of the bottom guide sleeve 24. In this manner, the top and bottom sleeve sections 32 and 34 of piston 25a are mounted over the top guide sleeve 23 and the bottom guide sleeve 24, respectively, to further support the entire actuator piston 25a for slidable movement within the internal operating chamber 22.

The intermediate sleeve section 31 includes a radially inwardly extending collar portion 31d which is defined by an upwardly facing shoulder 31e and a downwardly facing shoulder 31f. A substantially cylindrical wedging element 35 is mounted onto inside cylindrical wall 31g of the intermediate sleeve section 31 between the downwardly facing shoulder 31f and upper end 33c of the support sleeve section 33. The wedging element 35 further includes opposed inside wedging surfaces 35b which are positioned at an incline with respect to the longitudinal axis L' of the wireline L extending through the unit C-2. The wedging surfaces 35b are inclined radially inwardly from bottom to top of the wedging element 35. The wedging surfaces 35b are substantially flat when viewed in section as in FIG. 5.

The gripping means 26 includes two slips or shoes 26a mounted opposite each other against the inclined wedging surfaces 35b of the wedge element 35. Each of the slips 26a has a semi-cylindrical internal face or bore 26b for receiving the wireline L. The semi-cylindrical bores 26b of the slips 26a cooperate to provide a cylindrical bore for receiving and gripping the wireline L. Each of the slip elements 26a further include outer, flat, wedging surfaces 26c which are inclined at an angle complimentary to the angle of incline of the wedging surfaces 35b of the wedging element 35. A series of steel rollers 26d are suitable mounted onto the outside wedging surfaces 26c of the slips 26a to mount the slips 26a for relatively frictionless movement along the wedging surfaces 35b. In this manner, movement of the slip elements 26a upwardly and downwardly along the wedging surfaces 35b of the wedge element 35 moves the slips 26a radially inwardly and outwardly, respectively, with respect to the wireline L. Separating spring assemblies 26e mounted in aligned bores in the shoes 26a continuously urge the shoes 26a apart.

A resilient means such as coil spring 37 is mounted between the support sleeve section 33 and the bottom sleeve section 34 and extends upwardly into resilient engagement with the two slips 26a in order to urge the slips upwardly and thus radially inwardly into engagement with the wireline L.

The slip release means 28 includes a slip release member 28a mounted for slidable movement with respect to the top sleeve section 32 and the intermediate sleeve section 31. The slip release member 28a is mounted for slidable, sealable movement by seal ring 28b with respect to the bore 32b of the top sleeve section 31. The slip release member is further slidable, sealable movement with respect to inside wall portion 31h of the intermediate sleeve section 31 by means of seal ring 28c. Further, the slip release member 28a is mounted for slidable, sealable movement with respect to the intermediate sleeve section collar 31d by the seal ring 28d. The slip release member 28a has a bore 28e with a diameter slightly larger than the wireline L so that the wireline L is free to move with respect thereto. A coil spring 38 is mounted onto the upwardly facing shoulder 31e of the intermediate sleeve collar 31d and extends into engagement with an outwardly extending collar portion 28f on the slip release member 28a. The coil spring 38 serves to continually urge the slip release member 28a upwardly such that the slip release member 28a is out of engagement with the two slips 26a. When the slip release sleeve 28a is moved downwardly, it engages the slips 26a and moves the slips 26a downwardly and thus radially outwardly away from gripping engagement with the wireline L.

Each of the wireline control units C-1, C-2 and C-3 includes a series of interconnected passageways 15 for allowing the flow of the high pressure grease or other fluid from the grease inlet unit 14a upwardly and out through the grease outlet unit 14b. First, the cylindrical housing 20 for the wireline control unit C-2 includes top and bottom ports 40a and 40b for allowing the passage of the high pressure grease through the internal operating chamber 22. In a similar manner, the cylindrical housing 20 for the unit C-3 at the top thereof include ports to allow the passage of the grease from its internal operating chamber 22 upwardly through the inlet ports 40b and into the wireline control unit C-2. Further, the bottom of the housing for the wireline control unit C-1 includes an inlet port similar to 40b for receiving the grease flowing upwardly from the outlet port 40a of the wireline control unit C-2. The flow of the high pressure grease along the wireline L inwardly into the housing for the wireline control unit C-3 and outwardly from the top of the housing for the wireline control unit C-1 has been previously described with respect to FIGS. 6A and 6B.

In addition, with respect to each of the wireline control units C-1, C-2 and C-3, the actuator assembly 25, the gripping means 26 and the slip release means 28 includes a series of passages and/or ports for allowing the high pressure grease to pass through the entire mechanism which operates within the internal operating chambers 22. The bottom tube guide 24 includes grooves 24c to allow the passage of grease between the bottom guide tube 24 and the bottom sleeve section 34. Ports 31l and 31m and 31n extend through collar portions of the intermediate sleeve section 31 of the actuator piston 25a in order to allow the passage of high pressure grease between intermediate sleeve section 31 and the main outer sleeve 30. Finally, each of the wireline control units C-1, C-2 and C-3 includes the grooves 23c for top guide sleeve 23 to allow the passage of the grease between the top sleeve section 32 and the top guide sleeve, itself. In this manner, the actuator assembly 25, the gripping means 26 and the slip release means 28 are mounted for movement within the internal operating chamber of the wireline control unit C-2 even though the entire internal operating chamber 22 and the wireline L is filled with grease or other fluid at a pressure equal to or higher than well pressure.

FLUID POWER SYSTEM F

The fluid power system F includes three fluid networks 41, 42 and 43 for sequentially operating the actuator assemblies 25, the gripping means 26 and the slip release means 28 within each control unit C-1, C-2 and C-3 in order to sequentially move the wireline L into a well and/or to control the movement thereof out of a well. Hydraulic networks 41, 42 and 43 are basically identical and are operated from a common piston pump 44 and are supplied by a common hydraulic control means 45. Since each of the hydraulic control networks 41, 42 and 43 are basically identical, only the hydraulic control network 41 for the wireline control unit C-2 will be described in detail FIG. 3). It should be understood that like numbers and letters will be referred to throughout in order to describe like parts for each of the hydraulic control networks just as such like numbers and letters are utilized throughout to describe identical structure for each of the wireline control units C-1, C-2 and C-3.

The hydraulic control network 41 is operably connected to the hydraulic control unit C-2 through four hydraulic lines 41a, 41b, 41c and 41d. Referring to FIGS. 3, 4A and 4B, entry of hydraulic fluid under pressure through line 41a will move the entire actuator piston 25a to the down position of FIGS. 4A and 4B. Line 41a is attached to the housing section 20bthrough a port 20b' therein such that hydraulic fluid under pressure can enter through the housing 20b and into the annular space between the inside housing wall 21 and the main outer sleeve 30 of the actuator piston 25a. The annular space between the housing section 20b and the main outer sleeve 30 is sealed off to provide a downstroke chamber 48a by seal assemblies 47a and 47b which are mounted with the housing sections 20a and 20b and extend into sealed engagement with the outer wall of the main outer sleeve 30 of the actuator piston 25a. Thus entry of hydraulic fluid under pressure into the downstroke chamber 48a causes the piston 25a to move downwardly to the down position illustrated in FIGS. 4A and 4B.

Entry of hydraulic fluid under pressure through the line 41d moves the actuator piston 25a upwardly to the up position previously described. The hydraulic line 41d is mounted in a port 20e in the bottom part of the housing section 20b. The port 20e is in fluid communication with a sealed, annular upstroke chamber 48b, which is formed by the inside wall portions 21 of the housing sections 20b and 20c and the outside wall of the main outer sleeve 30. Seal assemblies 49a and 49b mounted in the housing sections 20c and 20b, respectively, serve to seal off the upstroke chamber 48b such that the entry of hydraulic fluid therein will move the actuator sleeve unit upwardly from the down position of FIGS. 4A and 4B to the up position.

Entry of hydraulic fluid under pressure through line 41b into the wireline control unit C-2 will cause movement of the slip release sleeve 28a downwardly into engagement with the slips 26a thereby moving the slips 26a radially outwardly along wedging surfaces 35b to a position out of gripping engagement with wireline L. The hydraulic line 41b is connected to the housing section 20b through a port 20f therein. The port 20f is aligned with an annular chamber 49 formed in the annular space between the housing section 20b and the main outer sleeve 30 and sealed off by the seal assemblies 47b and 50. The annular chamber 49 is in fluid communication with port 51 which extends through the main outer sleeve section 30 and the intermediate sleeve section 31 into a chamber 52. The chamber 52 is an annular sealed chamber basically formed between the intermediate sleeve section 31 and the slip release sleeve 28a and sealed off by seal rings 28b and 28c. Thus, hydraulic fluid under pressure may enter through hydraulic line 41b into the annular chamber 49, through the port 51 and into the inside, slip release chamber 52 thereby moving the slip release member 28a downwardly into engagement with the slip elements 26a.

Hydraulic line 41c is connected into the housing section 20b through port 20g. A port 53 extends from the annular space in which the coil spring 38 is mounted into an annular space 54 between the main outer sleeve section 30 and the housing section 20 such that fluid communication is provided between the annular space wherein the spring 38 is mounted and the hydraulic line 41c. As will be described in further detail hereinafter, hydraulic line 41c provides a means for venting hydraulic fluid outwardly from the annular space about the slip release member 28a and outwardly through the sleeve sections 30 and 31 and the hydraulic line 41c.

The hydraulic network 41, which includes the hydraulic actuating lines 41a - 41d, is connected to one of the three power cylinders 44a of the piston pump 44. The piston pump 44 includes three power cylinders having pistons 44b slidably mounted therein. The pistons 44b are connected to piston rods 44c, which are driven by driving rods 44d. As schematically illustrated in FIG. 3, the driving rods 44d are eccentrically mounted onto the power shaft 44e of the piston pump 44 and it will be understood that they are suitably mounted to pass each other during rotation of the shaft 44e.

The hydraulic line 41a is connected to the left side or bottom dead center side 44f for the piston 44b. The hydraulic line 41d is connected to the right side or top dead center side 44g for the piston 44b. The eccentric drive shaft 44e, which is connected to a suitable motor (not shown), operates to synchronize each of the three hydraulic networks 41, 42, and 43 in order to synchronize the operation of the hydraulic control units C-2, C-1 and C-3, respectively. The eccentric mounting of the drive rods 44d pivotally connected to each of the piston rods 44c provides for a particular velocity pattern for the travel of a piston 44b between bottom dead center and top dead center. The velocity pattern is such that the velocity of the piston travelling between bottom dead center side 44f and top dead center side 44g for the piston is such that the velocity of the piston is a maximum intermediate between sides 44f and 44g (in the middle of the piston stroke). The velocity of the piston is zero at bottom dead center side 44f as well as top dead center side 44g and a maximum at a point intermediate thereof. The variable velocity feature of the pistons 44b will be described in further detail hereinafter with respect to the synchronizing of the sequential gripping of the wireline L by the control units C-1, C-2 and C-3.

Referring again to the particular hydraulic fluid network 41, the hydraulic control means 45 includes a supply tank 45a connected through a strainer 45b to the hydraulic pump 45g used to replenish the system. The outlet line 45c of the pump 45g is connected to a safety relief valve 45d, and pressure-reducing valve 61, and is further connected along line 45e to the control valve 60.

The control valve 60, has two positions 60a and 60b. In the normal position 60a, the pressure line 45e is blocked, and the outlet line 45f is vented to the tank 45a. When it is desired to release the slips of all three control units C-4, C-2, and C-3 simultaneously to permit free movement of the wireline L therethrough, the valve 60 is placed in the "slip release" position 60b. In this position the pressure line 45e is connected to the line 45f, and through check valve 65a and line 41b to the slip release port of the control unit C-2 to actuate the slip release means as hereinbefore described. Hydraulic line 45f extends also from the valve 60 to the hydraulic networks 42 and 43.

A pressure reducing valve 61 is also mounted in line 45c which further extends to line 41e in the hydraulic network 41 and also to hydraulic networks 42 and 43. Check valves 62a and 62b cooperate with the pressure reducing valve 61 to replenish the hydraulic network 41 with hydraulic fluid whenever the pressure in lines 41a and/or 41d drops below a certain minimum level such as 100 psi.

Criss-cross pressure relief valves 63a and 63b are interconnected between the lines 41a and 41d by lines 64a and 64b in order to redistribute the hydraulic fluid within the network 41 and the cylinder 44a at the beginning of operation of the system. The criss-cross valves 63a and 63b are set to pass fluid over a certain pressure, such as 1,000 psi. Another safety relief valve 65 is connected between the supply tank 45a and safety line 41f having check valves 66a and 66b therein. The purpose of the safety relief valve 65 is to provide relief to the supply tank whenever the pressure within either line 41a or 41d exceeds a certain desired limit.

The hydraulic line 41b is also connected through line 41h to a sequence valve 67 and to operating valve 68. The operating valve 68 includes a GOING INTO THE HOLE (G.I.T.H.) position 68a and a COMING OUT OF THE HOLE (C.O.T.H.) position 68b.

Line 41i is connected through check valves 69a, 69b and 69c to lines 41a, 41b and 41d. Another safety relief valve 70 is connected to the line 41i. The purpose of the relief valve 70 is to provide safety relief to atmosphere through the vent line 70a whenever the pressure within any of the lines 41a, 41b or 41d exceeds a certain desired limit.

The vent line 41c is connected through check valve 71 to the vent line 70a such that any air or hydraulic fluid which may accumulate in the spring chamber 38 of the slip release means 28a is vented to atmosphere.

OPERATION OF WIRELINE CONTROL UNIT C-2

The operation and use of the wireline control unit C-2 will now be described in conjunction with the operation of the hydraulic network 41 including the piston pump 44. The actuator piston 25a has been previously described as being movable within the internal operating chamber 22 of the housing 20 between an up position and a down position. This movement of the actuator piston, with the slip release member 28a and the slips 26a mounted therewith, between an up and a down position may be defined as a stroke. More specifically, movement of the actuator piston 25a, the slip release member 28a and slips 26a from the up position to the down position is called a downstroke; and, movement of the actuator sleeve unit 25a, the slip release sleeve and the slip elements 26a from the down position to the up position is called an upstroke.

GOING INTO THE HOLE (G.I.T.H.)

In order to operate the wireline control unit C-2 for feeding or pulling the wireline L into the hole, or downhole into the well, the operating valve 68 is first moved to the G.I.T.H. position 68a. For simplicity in explanation, we will assume that the pump piston 44b is initially in the top dead center position 44g, the actuator piston 25a thus being in the up position. When the actuator piston 25a is in the up position, the slip release member 28a is actually depressed a certain distance by engagement with the top guide tube 23. This depression occurs against the urging of the slip release spring 38. Depression of the slip release member 28a with the actuator sleeve in the up position causes a depression of the slips 26a against the urging of the slip coil spring 37. This depression of the slip release member 28a and of the slips 26a downwardly causes the slips to be positioned radially outwardly against the wedging surfaces 35b of the wedge element 35. Thus, with the actuator piston 25a in the up position, the slips 26a are held out of engagement with the wireline L.

Rotation of the eccentric shaft 44e of the pump 44 moves the piston 44b from the top dead center position 44g toward the bottom dead center position 44f (in the direction of arrow 72). During the pump piston stroke, fluid is pumped through line 41a into downstroke chamber 48a, thus moving the actuator piston 25a downwardly in a downstroke.

During the movement of the actuator piston 25a through a certain initial or lag distance (which may be 0.2 inches for a full downstroke of 4 inches, for example), the actuator piston 25a does not engage the slip release member 28a. During this initial movement of the actuator sleeve unit 25a downwardly, the slip release spring 38 is actually moving the slip release member upwardly with respect to the actuator piston 25a. Movement of the actuator sleeve member 28a upwardly with respect to piston 25a allows slip spring 37 to move the slips 26a upwardly and thus radially inwardly into gripping engagement with the wireline L.

Therefore, after movement of the actuator piston 25a through this initial distance of 0.2 inches, the slips 26a are released into gripping engagement with the wireline L; and, the entry of further hydraulic fluid pressure into the downstroke chamber 46 will move the actuator piston 25a, the slip release member 28a and the slips 26a downwardly through the downstroke to the down position. Movement of the slips 26a in gripping engagement with the wireline L through this downstroke causes the wireline L to be fed into the hole a distance equal to the entire downstroke distance of the actuator piston (4.0 inches in the embodiment here) minus the initial distance moved by the piston 25a (0.2 inches) prior to movement of the slip elements into gripping engagement with the wireline L, which is a total distance of 3.8 inches in this particular embodiment. It should be understood that the total downstroke distance of 4.0 inches and the initial released distance of 0.2 inches are examples only and that various combinations of such distances can be utilized as desired.

When the actuator piston 25a reaches the down position, the pump piston 44b is on the bottom dead center position 44f in the cylinder 44a.

With the actuator sleeve unit in the down position, some type of gripping device (such as C-1 and C-3) is utilized to hold the wireline L so that the actuator piston 25a can return to the up position. In the preferred embodiment of this invention, the wireline control units C-1 and C-3 are utilized in conjunction with the wireline control unit C-2. The wireline is continually gripped and released in sequence and, thus, continually fed into the hole. The sequential operation of the three wireline control units C-1, C-2 and C-3 together will be described hereinafter.

At this point, we will assume that the wireline L is held in its new position further downhole by some gripping device. the pump piston 44b is then moved in the direction of arrow 73 from the bottom dead center side 44f of the cylinder to the top dead center side 44g. Movement of the piston in the direction of arrow 73 causes the injection of hydraulic fluid under pressure into the line 41d and thus into the upstroke chamber 48 thereby moving the actuator piston 25a upwardly to the up position. During movement of the actuator sleeve unit 25a to the up position, the wireline L is either stationary or moving downwardly with respect to the upwardly moving slip elements 26a. The downward frictional force exerted continually by the wireline L as the slips 26a move upwardly with respect to the wireline L continually urges the slips 26a downwardly and thus radially outwardly against the urging of spring 37. Therefore, the slips 26a do not grip the wireline L as the actuator sleeve unit 25a is moved from the down position to the up position.

With the actuator piston 25a returned to the up position, the wireline control unit C-2 is in position for another complete cycle of the actuator sleeve unit 25a, the eccentric shaft 44e for the pump 44b having rotated one revolution or 360.degree..

Thus, when going into the hole, the actuator piston 25a is driven downwardly with the slip elements 26a in gripping engagement with the wireline L after the initial release of the slips 26a; thereafter, the actuator sleeve unit 25a is returned to the up position with the slip elements being urged out of gripping engagement with the wireline L. The number of cycles or revolutions of the actuator sleeve unit 25a will be dependent upon the number of revolutions of the eccentrically mounted shaft 44e.

COMING OUT OF THE HOLE (C.O.T.H.)

When it is desired to utilize the wireline control unit C-2 for coming out of the hole, the operating valve 68 is moved to the C.O.T.H. position 68b. In one type of service to which the wireline control unit C-2 will be exposed, the downhole well pressure is substantially great. As previously mentioned, this requires that the entire wireline control unit C-2 be subject to a grease system pressure which is equal to or higher than the well pressure. The use of the grease supply system 14 prevents the entry of any of the well fluid into the tools. However, the very high downhole well pressure and the grease system pressure does have another effect upon the operation of the wireline control unit C-2. The high well pressure tends to push the wireline L out of the well; therefore, an upward force is continually exerted on the wireline L as it is moved upwardly. Hence, the actuator piston 25a being urged upwardly by the pressure thrust on the wireline and/or the upward pull exerted on the wireline by the wireline reel, acts as a pump itself to drive the pump piston 44b, tending to drive the pump 44 as a motor. Thus, during the coming out of the hole operation of the wireline control unit C-2, the motor for the pump 44 acts as a braking means, and by regulating the rotational speed thereof the rate of travel of the actuator piston 25a is also regulated. The system operates in the manner and sequence to be described.

The upward force exerted against the wireline L causes the wireline L to exert an upward frictional force upon the slips 26a thereby holding the slips into gripping engagement with the wireline L. The actuator piston 25a, the slip release member 28a and the slips 26a are forced upwardly toward the up position under the thrust exerted on the wireline L. Movement of the actuator piston 25a upwardly causes a displacement of fluid outwardly of tool chamber 48a, through hydraulic line 41a and into the left side of the pump cylinder 44a thereby moving the pump piston in the direction of arrow 73. As the slip release member 28a approaches the guide tube 23 in this upstroke, the guide tube 23 engages and depresses the slip release member 28a against the spring 38, thus causing a relative movement of the slips 26a downwardly with respect to the actuator piston 25a, and the springs 26e push the slip elements 26a radially outwardly out of gripping engagement with the wireline L as the actuator sleeve unit 25a comes to rest in the up position. This release of the slips 26a by movement radially outwardly occurs in the last 0.2 inches of the 4 upstroke in the embodiment herein.

The actuator piston 25a is then returned from the up position to the bottom position in the following manner. Movement of the piston 44b from the top dead center 44g to the bottom dead center 44f is caused by rotation of the eccentric shaft 44e (which may be caused by pressure exerted upon another wireline control unit, such as C-1 or C-3, or by the pump motor). The movement of the piston from top dead center side 44g to bottom dead center 44f causes hydraulic fluid under pressure to enter through line 41a into the downstroke chamber 48a. This results in a displacement of fluid under pressure from the upstroke chamber 48b into the line 41d. The fluid displaced from upstroke chamber 48b moves through line 41d and through the C.O.T.H. valve 68b into line 41h.

The sequence valve 67, of known construction, functions to hold the pressure in line 41h at a present pressure such as 200 psi while permitting the flow of fluid through the valve 67 into the line 67a and thence through line 41d to the pump 44a.

The valve 67 causes the passage of fluid at the certain design pressure, such as 200 psi, into the line 41h and thus into the line 41b and into chamber 49. The fluid entering chamber 49 passes through ports 51 to move and/or hold the slip release member in a down position against the urging of the spring 38. This holding of the slip member 28a downwardly thus holds the slip element 26a downwardly and radially outwardly of engagement with the wireline L. The actuator piston 25a is moved from the up position to the down position with the slip release member 28a holding the slips 26a released and out of engagement with the wireline L.

A full revolution of the pump shaft 44e having been completed, the actuator piston 25a is again in the initial, down position. In this position, the piston 44b is at bottom dead center side 44f. The pump piston 44b is then moved in the direction of arrow 73 under the power received from the eccentric shaft 44e, which can be provided by wireline thrust on other wireline controls, such as C-1, or C-3, or by the pump motor. In either event, fluid is directed outwardly of the cylinder 44a into the line 41d, through the check valve by-pass route 75 and into the upstroke chamber 48b in the housing 20. As the actuator piston 25a begins upward movement, the slip springs 37 and the slip release spring 38 act to urge fluid in slip release chamber 52 into chamber 49 and into line 41b. The fluid which held the slip release sleeve 28a down is then vented outwardly through the line 41b and into line 41h and finally through C.O.T.H. valve 68b back into line 41d. The slips 26a are released and urged upward by spring 37, are moved radially inwardly into gripping engagement again with the wireline L. The actuator piston 25a is then moved through the remainder of the upstroke as previously described, thereby controlling the movement (by a braking action) of the wireline L further outwardly of the hole.

OPERATION AND USE OF THE WIRELINE CONTROL SYSTEM W INCLUDING SEQUENTIAL OPERATION UNITS C-1, C-2 and C-3

Going Into The Hole (G.I.T.H.)

The structure and operation for the wireline control units C-1 and C-3 is basically identical to the operation and structure of the wireline control unit C-2. The movement of the wireline control C-2 is controlled through the hydraulic network 41, which is in turn controlled by one power cylinder 44a of the pump piston 44. The wireline control units C-1 and C-3 are also operatively connected to power cylinders 44a of the piston pump 44 through hydraulic control networks 42 and 43, which are basically identical to the hydraulic control network 41. In this manner, the piston pump 44 serves to synchronize the movement of the three wireline control units C-1, C-2 and C-3 so that the wireline L can be substantially continuously fed or injected into the well or removed therefrom.

FIGS. 7 and 8 are directed to graphs which describe the stroke of the actuator pistons 25a in each of the wireline control units C-1, C-2, and C-3 and the interaction of the wireline control units C-1, C-2 and C-3 in gripping the wireline L. Before proceeding to a discussion of FIGS. 7 and 8, it is necessary to briefly relate the velocity pattern of the pistons 44b for the piston pump 44 to the velocity pattern to the tool actuator piston 25a for the units C-1, C-2 and C-3.

As previously mentioned, the piston 44b has a velocity of zero at the bottom dead center side 44f and, due to the eccentric mounting through drive shaft 44d, approaches a maximum velocity intermediately of the cylinder and decreases to zero at the top dead center side 44g.

The hydraulic displacement of piston pump 44 is essentially equal to the hydraulic displacement of the actuator piston 25a of the control unit C-2.

Since incompressible hydraulic fluid is pumped through lines 41a and 41b, the tool actuator piston 25a has a similar velocity pattern.

Thus, the actuator piston 25a moves from a zero velocity in the up position to a maximum velocity intermediate of the up and down positions and then to a zero velocity in the down position. This occurs as the pump piston 44b moves from the top dead center side 44g of the cylinder to the bottom dead center side 44f. In a similar manner, during movement of the actuator piston 25a from the down position to the up position, the maximum velocity occurs intermediate between the up and down positions. The eccentric drive of shaft 44e of the piston pump provides each of the tool actuator pistons 25a or each of the wireline units C-1, C-2 and C-3 with the same velocity characteristics for movement between up and down positions. However, at any given time, the velocity of each of the actuator pistons 25a in each of the wireline control units C-1, C-2 and C-3 is different due to the differences in speed of the pistons connected to the common eccentric drive shaft 44e.

Therefore, the piston pump 44 cooperates with the hydraulic networks 41, 42 and 43 to synchronize the gripping and movement action of the wireline control units C-1, C-2 and C-3.

The graphs of FIG. 7 and 8 illustrate the synchronized movement of the three longitudinally aligned wireline control units C-1, C-2 and C-3. FIG. 7 illustrates the travel curve for the actuator piston 25a for the unit C-2. The travel curves for actuator pistons 25a for units C-1 and C-3 are identical except that the abscissas are displaced 120.degree. out of phase with the travel curve for unit C-1, leading and lagging, respectively. The total distance of a stroke, either downstroke or upstroke, is 4.0 inches in the embodiment described herein.

The abscissa in the graph of FIG. 8 represents one revolution of eccentric shaft 44e of the pump piston 44. The ordinate is divided up into two parts about a zero line. The solid line above the zero line represent velocity patterns of the tool actuator pistons for the three wireline control units C-1, C-2 and C-3 during downstroke. Conversely, the dashed lines below the zero line represent the velocity patterns of the three wireline control units during the upstroke.

The coordinated downstroke velocity patterns of the wireline control units indicate that the wireline control units alternately grip and engage the wireline L at 120.degree. intervals to thereby continuously feed the wireline L into the well. The C-1 line is clearly marked and begins for the purposes of this discussion, at a maximum velocity when the eccentric shaft is in the 0.degree. position, which is substantially the position of the pump 44 in FIG. 3.

In this position of maximum velocity, the actuator sleeve unit C-1 is substantially half-way through its downstroke which is illustrated at point 80a in FIG. 7.

For the remainder of the downstroke, piston 25a for unit C-1 is decreasing in velocity. At the 30.degree. position for the eccentric shaft, the second control unit C-2 begins to move through a downstroke and at the 60.degree. shaft position (after 0.2 inches initial movement of piston 25a for unit C-2), the slips 26a for unit C-2 are released into gripping engagement with the wireline L. At this very same point, the velocity of C-2 unit piston 25a exceeds the velocity of the C-1 unit piston 25a and overtakes control of movement of the wireline. The 0.2 inch lag distance prior to release of the slip elements 26a of the piston 25a for C-2 unit is illustrated at 80b in FIG. 7.

Thus the downward movement of the wireline is controlled by the unit C-2 from the 60.degree. crank position to the 180.degree. crank position.

From the 60.degree. to the 90.degree. crank position, the C-2 piston has control movement of the wireline L because the smooth gripping faces 26b of the slips 26a of unit C-1 allow the wireline to slide therethrough at the higher velocity of Unit C-2. The movement of C-1 unit piston 25a during the 60.degree. to 90.degree. rotation of shaft 44e is 0.2 inches as illustrated at 80c . Therefore, the effective gripping and moving distance of C-2 unit piston occurs during 60.degree. to 180.degree. shaft rotation, which is a distance of 3.6 inches. During the rotation of the eccentric shaft 44e from 60.degree. to 180.degree., the C-2 unit piston approaches maximum velocity at 120.degree.. Thereafter the C-2 piston decelerates to the position of zero velocity at 210.degree. in the shaft rotational position. At the 180.degree. position, the slips 26a for the unit C-3 are released into gripping engagement with the wireline L and the increasing velocity of the unit C-3 overtakes the decreasing velocity of the unit C-2.

The unit C-3 then controls movement of the wireline from the eccentric shaft position of 180.degree. to the eccentric shaft position of 300.degree.. At the eccentric shaft position of 270.degree., the C-1 unit piston begins another downstroke and, at the 300.degree. shaft position, the C-1 unit piston is released into gripping engagement with the wireline L and overtakes and controls the movement of the wireline L until the end of the 360.degree. shaft position.

Thus, during one revolution of the eccentric shaft 44e, each of the slips 26a for the wireline control units C-1, C-2 and C-3 control movement of the wireline.

Coming Out of The Hole (C.O.T.H.)

The bottom portion of the graph of FIG. 8 is used to describe the retrieval of the wireline L from downhole in a well. As previously mentioned, the dashed lines indicate upstroke velocity curves of the pistons 25a for each of the units C-1, C-2 and C-3. Beginning at the eccentric shaft position of 0.degree. , the velocity for the accelerating C-3 piston has just equaled the velocity for the decelerating C-2 piston. Simultaneously, the slip release member 28a of unit C-2 has come into engagement with the top guide 23, which upon further travel of the piston 25a causes depression of the slips 26a, holding the slips 26a out of engagement with the wireline L. The C-3 piston overtakes control of the upward movement of the wireline L from that point forward until the 120.degree. crank position. Similarly, at this point, the slips 26a of unit C-3 are forced out of engagement with the wireline L, and the C-1 piston overtakes control of the upward movement of the wireline L from that point forward until the 240.degree. crank position. Similarly, at the 240.degree. crank position, the slips 26a of the C-1 are forced out of engagement with the wireline L, and the C-2 piston overtakes control of the upward movement of the wireline L from that point forward to the 360.degree. crank position, completing one cycle of operation.

We have referred previously to the fact that the pressure downhole tends to push the wireline L out of the well. Therefore, the pressure downhole on the wireline serves to cause the wireline L tp actually displace upwardly the actuator pistons 25a for each of the units when in gripping engagement with the wireline L. However, the relative velocities of each of the actuator pistons 25a provide the velocity patterns during the upstroke identical to the velocity patterns during the downstroke when the tool is being used to feed wireline into the well. This is due to the interconnection between the three units C-1, C-2 and C-3 by the eccentric pump shaft 44e.

Therefore, the C-3 piston will control the movement of the wireline L in a velocity pattern which increases to a maximum at 60.degree. in the crank rotation, and thereafter decreases to the change-over point at 120.degree. in the crank rotation. At this point, the slips 26a for the piston 25a of the unit C-1 have been released into engagement with the wireline L and the velocity of the accelerating C-1 unit piston is equal to the velocity of the decelerating C-3 piston. Therefore, the C-1 piston overtakes control of movement of the wireline upwardly out of the well from a shaft position of 120.degree. to a shaft position of 240.degree.. At this point, the C-2 unit piston overtakes control of movement of the wireline upwardly from 240.degree. to 360.degree. of crank rotation. Therefore, the wireline units C-1, C-2 and C-3 operate in phases of 120.degree. out of a 360.degree. pump shaft revolution or cycle to alternately grippingly engage and apply a braking action to control the movement of the wireline L out of high pressure oil well.

It should be reiterated here that during the downstroke of the pistons 25a of the units C-1, C-2 and C-3, the slips 26a are held out of arrangement with the wireline L by means of hydraulic pressure acting on the slip release means 28a as hereinbefore described under "Fluid Power System F."

The foregoing disclosure and description thereof of the invention are illustrative and explanatory thereof, and various changes in the size, shape, and materials as well as in the details of the illustrated construction may be made without departing from the spirit of the invention.

Claims

What is claimed is:

1. A wireline control unit for moving a wireline in a well, comprising:

a housing adapted for mounting on a well tubing extending downhole in a well and pressure control means for maintaining said housing substantially at well pressure;

an actuator assembly mounted in said housing for movement longitudinally thereof between first and second positions;

gripping means for grippingly engaging said wireline, said gripping means being mounted for longitudinal movement with said actuator assembly and for relative movement with respect thereto for alternately gripping and releasing said wireline; and

a fluid system connected with said actuator assembly for movement thereof for feeding said wireline longitudinally into the well with said gripping means or for braking movement of said wireline when the wireline is coming out of the well.

2. The structure set forth in claim 1, wherein:

said first position is an up position and said second position is a down position such that movement of said wireline from said up position to said down position feeds said wireline longitudinally into said well;

said actuator assembly includes means moving said gripping means into gripping engagement with said wireline with said assembly in substantially said up position; and

said fluid system including means moving said actuator assembly from said up position to said down position to feed said wireline into said well.

3. The structure set forth in claim 2, including:

said fluid system including means for returning said actuator assembly from said down position to said up position; and

resilient means mounting said gripping means for resilient movement outwardly from said wireline whereby said gripping means is released from gripping engagement with said wireline during movement of said gripping means to said up position.

4. The structure set forth in claim 1, wherein:

said first position is a down position and said second position is an up position such that movement of said wireline from said down position to said up position moves said wireline out of said well;

said actuator assembly includes means moving said gripping means into gripping engagement with said wireline in response to the upward force exerted by said wireline; and

said fluid system including means moving said actuator assembly and said gripping means from said down to said up position thereby moving said wireline out of the well.

5. The structure set forth in claim 4, including:

release means releasing said gripping means from gripping engagement with said wireline with said actuator assembly in substantially said up position.

6. The structure set forth in claim 5, including:

said fluid system including means moving said actuator assembly downwardly from said up position to said down position with said gripping means released.

7. The structure set forth in claim 1, including:

said actuator assembly including means moving said gripping means into gripping engagement with said wireline in response to longitudinal movement of said actuator assembly.

8. The structure set forth in claim 1, wherein said pressure control means includes:

means for operating said wireline control unit at a pressure greater than well pressure.

9. The structure set forth in claim 1, wherein said pressure control means includes:

a grease control unit for maintaining said wireline control unit at a pressure equal to or greater than said well pressure.

10. The structure set forth in claim 9, wherein said grease control unit includes:

a grease pumping means for pumping grease into said wireline control unit at a pressure greater than said well pressure, said grease pumping means being attached to said one end of said wireline control unit.

11. The structure set forth in claim 10, including:

a grease return means attached to said other end of said wireline control unit for receiving grease pumped from said grease pumping means through said wireline control unit.

12. The structure set forth in claim 10, including:

said wireline control unit including a series of passages for allowing said grease to flow through said unit.

13. The structure set forth in claim 1, including:

said actuator assembly including an actuator piston mounted in said housing for longitudinal movement between said first and second positions;

said gripping means including a slip element mounted with said actuator piston for movement substantially into and out of gripping engagement with said wireline; and

a slip release member mounted with said actuator piston for holding said slip element substantially out of engagement with said wireline.

14. The structure set forth in claim 13, including:

resilient means resiliently urging said slip element into gripping engagement with said wireline.

15. The structure set forth in claim 13, including:

resilient means resiliently holding said slip release member out of engagement with said slip element.

16. The structure set forth in claim 13, including:

said fluid system including means moving said slip release member into engagement with said slip element.

17. The structure set forth in claim 13, including:

said housing, actuator piston, slip element and slip release members cooperating to provide passages through said housing for high pressure fluid.

18. The structure set forth in claim 13, including:

said slip element having a substantially smooth gripping face which allows said wireline to become disengaged from said gripping face.

19. The structure set forth in claim 1, including:

A second gripping unit for gripping said wireline whenever said wireline control unit gripping means is substantially out of gripping engagement with said wireline.

20. A method for sequentially moving a wireline into and out of a well, comprising the steps of:

gripping said wireline with a first gripping means and moving said wireline through a first stroke portion;

gripping said wireline with a second gripping means and moving said wireline through a second stroke portion;

releasing said first gripping means from said wireline after said wireline is gripped by said second gripping means whereby said wireline is sequentially gripped and released to move said wireline into or out of said well;

gripping said wireline with a third gripping means and moving said wireline through a third stroke portion; and

releasing said second gripping means for said wireline after said wireline is gripped by said third gripping means.

21. The method set forth in claim 20, including:

accelerating said third gripping means to a higher longitudinal velocity then said second gripping means as said third gripping means grips said wireline; and

allowing said wireline to disengage from said second gripping means to free said wireline for movement at the higher velocity of said third gripping means.

22. The method set forth in claim 20, including the step of:

synchronizing the gripping action of said first, second and third gripping means for sequential operation of each gripping means at 120.degree. phase intervals based on a 360.degree. cycle such that said movement of said wireline into or out of the well is substantially continuous.

23. The method set forth in claim 20, including the steps of:

gripping said wireline with said first gripping means for again moving said wireline through said first stroke; and

releasing said third gripping means from said wireline after said wireline is gripped by said first gripping means.

24. The method set forth in claim 20, including the step of:

returning said first gripping means to its original position for again gripping said wireline and moving said wireline through a first stroke portion.

25. The method set forth in claim 20, including the step of:

returning said second gripping means to its original position for again gripping said wireline and moving said wireline through a second stroke portion.

26. A system for continuously moving a wireline into or out of a well, comprising:

a first gripper means mounted on said well for firstly gripping and moving said wireline;

a second gripper means mounted with said first gripper means for secondly gripping and moving said wireline;

said first gripper means including first release means for releasing said wireline after said second gripper means has gripped said wireline;

a third gripper means mounted with said first and second gripper means for thirdly gripping and moving said wireline; and

said second gripper means including second release means for releasing said wireline after said third gripper means has gripped said wireline.

27. The system set forth in claim 26, including:

said first gripper means gripping and moving said wireline subsequent to gripping by said third gripper means; and

said third gripper means including third release means for releasing said wireline after said wireline is gripped by said first gripper means.

28. The system set forth in claim 26, comprising:

said second gripper means including second means overtaking control of movement of said wireline prior to said first release means of said first gripper means releasing said wireline.

29. The system set forth in claim 26, including:

said third gripper means including third means overtaking control of movement of said wireline prior to said second release means of said second wireline releasing said wireline.

30. The system set forth in claim 26, including:

said third gripper means including means for gripping and initially moving said wireline at a velocity higher than said second gripper means; and

said second gripper means including means allowing said wireline to disengage from said second gripper means prior to the release thereof from said wireline.

31. The structure set forth in claim 26, including

synchronizing means for sequentially operating said first, second and third gripper means for continuously moving said wireline.

32. A method for sequentially moving a wireline into and out of a well, comprising the steps of:

gripping said wireline with a first gripping means and moving said wireline through a first stroke portion;

gripping said wireline with a second gripping means and moving said wireline through a second stroke portion;

releasing said first gripping means from said wireline after said wireline is gripped by said second gripping means whereby said wireline is sequentially gripped and released to move said wireline into or out of said well;

accelerating said second gripping means to a higher longitudinal velocity than said first gripping means as said second gripping means grips said wireline; and

allowing said wireline to disengage from said gripping with said first gripping means to free said wireline for movement at the higher velocity of said second gripping means.

33. A method for sequentially moving a wireline into and out of a well, comprising the steps of:

gripping said wireline with a first gripping means and moving said wireline through a first stroke portion;

gripping said wireline with a second gripping means and moving said wireline through a second stroke portion;

releasing said first gripping means from said wireline after said wireline is gripped by said second gripping means whereby said wireline is sequentially gripped and released to move said wireline into or out of said well;

allowing said wireline to slide past said first gripping means at the speed of movement of said second gripping means after said second gripping means has gripped said wireline such that the movement of said wireline is controlled by said second gripping means; and

releasing said first gripping means from said wireline after the movement of said wireline is controlled by said second gripping means.

34. A system for continuously moving a wireline into or out of a well, comprising:

a first gripper means mounted on said well for firstly gripping and moving said wireline;

a second gripper means mounted with said first gripper means for secondly gripping and moving said wireline;

said first gripper means including first release means for releasing said wireline after said second gripper means has gripped said wireline;

said second gripper means including means for gripping and initially moving said wireline at a higher velocity than said first gripping means; and

said first gripper means includes means allowing said wireline to disengage from said first gripper means prior to release thereof from said wireline.