Well Circulation Tool

Abstract

A tool for use with a well string to improve circulation of fluid pumped to a well hole. The tubular body section of the tool has a channel for fluid which extends through the side wall to the outside. Inside the body section there is a previously set operable member which covers over the channel and thus blocks the flow of fluid and which can be operated by an action taken at the surface to uncover the channel and permit flow of fluid from the tool into the well hole. Among other uses, the tool can be employed to restore adequate circulation to a bore hole when a bit plugs, or to increase and/or control circulation during the drilling, fishing, or servicing of a hole.

Description

BACKGROUND OF THE INVENTION

This invention pertains to apparatus used in the drilling or servicing of wells, more particularly deep wells, and especially petroleum wells.

In either drilling or fishing operations it is conventional practice to circulate a fluid such as drilling mud in the bore hole to cool the drill bit, flush away drill cuttings, and lubricate the string as it runs in the hole. This is accomplished by pumping the fluid down the drill string and out of discharge orifices in the drilling bit. Should the orifices of the bit become even partially plugged, adequate circulation of fluid to the hole can be lost. As a consequence, the beneficial functions of fluid circulation are also lost or else seriously impaired. Plugging of the bit can also be dangerous, especially in the event of an unexpected pressure kick which occurs when a high pressure zone is penetrated, or when attempting to kill a kick which has already occurred, since the ability to control pressure at the bottom of the hole is lost if pumping of drilling fluid cannot be adequately maintained.

Full or partial plugging of the bit, with concomitant impariment or loss of circulation, can also occur during fishing operations wherein junk or debris must be cleared from the hole before drilling can be effectively continued.

Prior methods of restoring adequate circulation of drilling fluid after plugging of the bit include making a round trip to replace the bit and perforating the drilling string about the bit by shooting. Since it is not practical to trip the string out of the hole upon encountering a kick, it has been necessary to perforate the string while it remains in the hole, but this requires preparation and lowering of a shot. Valuable time is consumed in an emergency situation and affords little control over the degree of perforation and, hence, the resulting pressure which will be required to restore adequate circulation. As a consequence, a need was recognized for a method for restoring adequate circulation of drilling fluid to a well hole after plugging of the bit, and preferably, to restore adequate circulation without substantial increase or decrease in the pumping pressure required.

SUMMARY OF THE INVENTION

It is therefore an object of this invention to maintain or improve circulation of fluid to a well hole during drilling or servicing of a well.

Another object of this invention is to provide a method for quickly restoring adequate circulation of drilling fluid to a bore hole after the drilling bit has become plugged.

Still another object is to maintain or increase the rate at which drilling fluid is pumped to a bore hole without substantial increase or decrease in the pressure required to achieve the circulation.

Even another object is to improve safety of the drilling operation when a kick is encountered.

Other objects and advantages of the invention will become apparent from the following description and the appended claims.

The present invention is a drilling tool which can be used in combination with other members of a drilling string to restore, improve, or enable control over circulation of fluid being pumped to the well hole. The tool comprises a tubular body section having threads at each end which are connectible to members of a well drilling string. A longitudinal passageway extends through the body section for conveying fluid received from the string. At least one channel extends through the side wall of the body section of the tool from the passageway therein to the outside. There is a previously set operable member inside the body section which normally covers the channel through the wall, and which uncovers the channel when operated. The purpose of the preexisting but normally covered channel in the wall of the tool body is to provide a duct through which fluid being pumped can be diverted to the well hole in the event that greater or improved circulation is needed which cannot be accomplished by pumping through an attached drill bit or the like, or in the event that adequate circulation cannot be maintained due to partial or total plugging of a drilling bit. For instance, a plugged bit can be by-passed by diverting fluid from the drilling string to the well hole through the uncovered channel; or, the flow of fluid to the well hole can be increased while still pumping fluid through an unplugged bit. One or more preexisting channels can be used and all can be kept covered when there is no need for restoring or improving circulation of the fluid, and uncovered by an action taken at the surface when a need for improving or restoring circulation arises.

In addition to the channels and the operable member for the covering and uncovering thereof, the passageway in the body section of the tool can be provided with a seat having a sealing surface which receives a matching sealing surface of a flow obstructing member emplaced in the passageway. Accordingly, flow of fluid through the passageway beyond the one or more uncovered channels can be shut off, thus preventing flow of the fluid beyond the tool and thus diverting all of the fluid through the one or more channels in the wall of the body section. Means can also be employed for covering the channels again with the operable member after they have been uncovered, and for unseating the flow obstructing member in the passageway should it again become desirable to pump all or part of the fluid beyond the tool.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view, partly in section, of one embodiment of the tool of the present invention.

FIG. 2 is a side view of a weighted dart, or plunger, which can be used to operate a slidable sleeve which covers the channels in the wall of the body section of the tool, and also to obstruct flow of fluid beyond the tool.

FIG. 3 is a side view, partly in section, of a slidable sleeve which can be used as the preset operable member in the tool of FIG. 1 for covering and uncovering the channels in the wall of the body section of the tool.

FIG. 4 is a partially fragmentary and partially sectional side view of another embodiment of the invention wherein the sleeve arrangement and the method of operating the sleeve are different from that shown in FIG. 1.

FIG. 5 is a sectional view of slidable sleeve as in FIGS. 1 and 3 which is held in position by means of a tensioned spring.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIG. 1, the tool is generally represented at 1, and is connected by threads to a drill pipe 2 and a drill bit 3. The tool is thus made up with the drilling string at the time the bit is to be lowered in the hole, and does not perform any special function until there is need to restore or improve circulation of fluid being pumped through the string. The tubular body section 4 of the tool is attached at the upper end to a coupling 5 on a drill pipe, and the rotary bit 3 is screwed into the lower end of the body section. A passageway 6 for drilling fluid runs through the body section 4 and interconnects at the upper and lower ends with fluid passageways 6a and 6b which lead, respectively, from the drill string 2 and into the drilling bit 3.

Channels 7 are drilled ducts which extend through the wall 8 of the body section from the passageway 6 to the outside. When the string is lowered into the bore hole these channels are normally covered over by an impervious slidable sleeve 9 axially aligned and frictionally held in place in the passageway 6 by means of O-rings 10 attached to the sleeve in recessed grooves. As drilling or fishing, for instance proceeds with an unplugged bit, drilling fluid passes through the central passageway 6c of the sleeve which is aligned with the other passageways 6, 6a and 6b, thus maintaining a flow of drilling fluid to the bit since the channels 7 are blocked off by the sleeve which has been preset in position over the openings of the channels.

In FIG. 1, the sleeve 9 is thus shown in the preset position whereby the channels 7 are covered over. The passageway 6 in the vicinity of the sleeve is recessed for a distance in excess of the sleeve length to permit the sliding thereof when operated and to provide a chamber which accomodates the thickness of the sleeve wall, the latter feature tending to preserve the diameter of the fluid passageway 6 while also forming a shoulder 11 at the top of the chamber which serves as an upper stop for the sleeve. The upper edge 3a of the drill bit 3 serves as a lower stop for the sleeve.

Should the drill bit become wholly or partially plugged, circulation of drilling fluid to the well hole is adequately restored by uncovering channels 7 in order to divert flow from the bit and into the hole through the wall 8 of the body section. This can be accomplished in various ways, and two apparatus arrangements intended for this purpose are shown in the drawings. FIGS. 1-3 illustrate use of a weighted dart, or plunger, which is dropped into the drilling string for displacing the sleeve downwardly to uncover the channels 7, and FIG. 4 illustrates use of a sleeve which normally covers the channels 7 when the sleeve is bottomed, and which can be lifted by wire line to uncover the channels.

Referring to FIGS. 1-3, the dart 12 is dropped into the drilling string from the surface when circulation of drilling fluid must be restored or improved, e. g. following partial or total plugging of the bit. AS soon as the dart is dropped, pressurization of the drilling fluid can be resumed. The momentum of the falling dart may in itself be sufficient to drive the sleeve downward below the channels 7, but in any event both dart and sleeve are constructed so as to form a piston which can be driven downward by pumping pressure when engaged as shown in the drawing.

More specifically, the sleeve 9 comprises an attached or integral ring 13 which projects into the central passageway and is axially aligned therewith. With the sleeve shown, the ring is machine beveled to provide an upper tapered sealing surface 13b. The upper part of the dart 12 is provided with a matched bevel 14, so that when the dart and the sleeve are engaged as in FIG. 1, flow of fluid past the sleeve is effectively obstructed. Therefore, elevation of pumping pressure in the drilling fluid will displace the dart and sleeve downwardly and thus uncover the channels 7 when dart and sleeve are mated as in FIG. 1.

FIG. 4 illustrates a different arrangement wherein the sleeve is normally bottomed against the lower stop 22a for covering of the channels 7. When there is a need to improve or restore fluid circulation to the well hole, a wire line tool is lowered which engages a latch 15 on a rod 16 which extends inside the sleeve from one side to the other. The sleeve is then raised against the upper stop 11 by means of a wire line tool. A snap ring 17 which extends around the sleeve and is attached thereto in a groove engages a latching groove 18 in the wall of the passageway and thus holds the sleeve in an elevated position. The wire line is then pulled loose from the sleeve and the latter remains in place by engagement of the snap ring with the latching groove.

Should it become desirable to again cover up channels 7 once the sleeve has been shifted to uncover them, e. g. when a need is recognized to circulate more fluid at a point below the tool, the sleeve can be relocated over the channels by an action taken at the surface. When using a sleeve and dart arrangement as shown in FIGS. 1-3, the lower spindle 19 of the dart is provided with a snap ring 20 attached thereto in a groove so that upon entry of the dart into the sleeve the snap ring is compressed by the ring 13 into its recess, thus permitting the bevel 14 on the dart to abut the ring bevel 13b. However, when the dart is pulled upward through the sleeve, sufficient resistance is provided by the flat under surface of the ring to effect upward sliding of the sleeve before the ring 20 is compressed. Once the sleeve is topped against the upper stop 11, the snap ring can then be compressed by upward tugging and the dart withdrawn from the sleeve. Alternatively, a tensioned spring can be placed beneath the sleeve in the recess so that it is automatically moved upward once the dart is removed.

Using an arrangement as shown in FIG. 4, the sleeve can be lowered again to cover the channels by bumping it downward with a weight on a wire line.

Since one object of the present invention is restore adequate recirculation to a well hole without any substantial change in the pressure required to pump the drilling fluid, the body section 4 of the tool can be provided with at least one channel in the wall of the body which, preferably, has an open area at least equivalent to the total open area of the fluid discharge orifices of any other member of the string carried below it, e. g. a drilling bit. However, more than one channel can be employed to accomplish this effect, and one or more channels can be equipped with threaded, replaceable nozzles 21 so that in any event the open area of the channels can be set to equal that of the bit orifices. Naturally, when more than one channel 7 is employed, as is shown in the drawing, the inlet of each from the passageway 6 should be located so as to be covered over when the sleeve is in the normal position, and each should be uncoverable when the sleeve is shifted to restore circulation to the bore hole.

FIG. 1 represents a case where the tool 1 is located in the drill string just above a drilling bit. Thus arranged, circulation can be restored to the well hole at a point very near its bottom, but it will be understood that the tool can be located still higher up in the hole, e. g. as represented by FIG. 4 wherein a coupling 22 on a drilling pipe is threaded onto the lower end of the tool instead of a drilling bit.

In FIGS. 1 and 4, the sleeve 9 is shown held in a preset position over the channels 7 by frictional means, i. e. O-rings. FIG. 5 illustrates use of a tensioned spring to hold the sleeve in the preset position. Using such an arrangement, the sleeve is held up by spring 23 until displaced by the dart 12. With the dart in place the sleeve can be held down and channels 7 kept open until the dart is removed with a wire line.

It will be appreciated that devices other than a sleeve could be employed as a covering member which could be previously set over the channels 7 and later operated by an action taken at the surface to uncover the members, e. g. valves can be installed which automatically open when pumping pressure is raised above a certain level. In addition, obstructing members other than a dart or plunger could be used for shutting off flow of fluid through the passageway below the channels, e.g. a normally unseated disc or valve associated with the sleeve which is moved to an open or closed condition depending upon the position of the sleeve in the passageway.

Although the present invention has been described with reference to specific apparatus components and arrangements thereof, it will nonetheless be understood that still other embodiments will become apparent which are within the spirit and scope of the invention defined in the following claims.

Claims

Therefore what is claimed is:

1. A well drilling tool comprising:

a. a tubular body section having threads at each end which are connectible to members of a drilling string,

b. a longitudinal passageway through the body section,

c. a channel which extends through the side wall of the body section from the passageway therein to the outside, and

d. a previously set operable sleeve member inside the body section which normally covers the channel through the wall of the body section and which uncovers the channel when operated, said sleeve member being contiguous with the wall of the passageway in the body section, and slidable in the passageway over and beyond the opening of the channel,

e. an integral ring member which projects from the inner surface of the sleeve, is axially aligned therewith, and has a sealing surface which receives a matching sealing surface on a flow obstructing plunger emplaced in the sleeve, and further comprising a snap latch which couples said plunger and said ring when the plunger is emplaced within said sleeve.

2. Apparatus as in claim 1 and further comprising a recess in the passageway of the body section of the tool and the sleeve is located in the recess.

3. Apparatus as in claim 1 wherein the plunger is gravity actuated into the sleeve.

4. Apparatus as in claim 1 and further comprising means for retrieving the plunger by wire line.

5. Apparatus as in claim 1 wherein the channel in the wall of the body section has a removable nozzle inserted therein.

6. Apparatus as in claim 1 wherein said ring member also has a second surface for engaging said snap latch and whereupon withdrawing the emplaced plunger from said sleeve member the sleeve member first travels upwardly and covers said channel and the snap latch is adapted for disengagement from said ring member upon further upward movement of the plunger.

7. Apparatus as in claim 1 and further comprising at least one other channel which extends through the wall of the body section of the tool, said other channel being covered by the operable member when preset and uncovered upon operation of the member.

8. Apparatus as in claim 3 wherein at least one of the channels is projected at an inclined angle with respect to the wall of the body section.

9. Apparatus as in claim 1 and further comprising a drilling string having a central passageway for fluid affixed to one end of the body section of the tool.

10. Apparatus as in claim 9 and further comprising another component of a drilling string attached to the other end of the body section of the tool, said other component having discharge orifices for fluid which passes through the string, and wherein the total open channel area is at least equivalent to the total open area of the discharge orifices in the other component.

11. Apparatus as in claim 1 and including securing means for holding the sleeve in a normal position over the channel in the wall of the body section of the tool.

12. Apparatus as in claim 11 wherein the securing means comprises at least one O-ring fitted into a groove around the outer circumference of the sleeve.

13. Apparatus as in claim 11 wherein the securing means is a tensioned spring which urges the sleeve in an axial direction.