Fluid Sampler

Abstract

A retrievable tool arranged to be moved through a well bore and adapted for taking a sample of fluid contained in the well bore at any selected depth therein. The tool includes a first chamber containing a compressible gas at a pressure lower than the ambient pressure in the well bore where the sample is to be taken, a second chamber that has a piston slidingly positioned therein and containing a liquid relatively above the piston, a first valve for controlling the flow of the liquid from the second chamber into the first chamber, and a second valve for controlling the flow of the sample into the second chamber below the piston. The body of the tool is separable whereby the portion thereof containing the second chamber, that is the chamber containing the sample, can be readily separated and sent to the laboratory for tests. A latching device is provided that retains the second valve in the closed position after the sample is obtained so that the sample is maintained at substantially the ambient pressure where the sample was obtained.

Description

Generally, this invention relates to improved sampling apparatus for use in well bores. More particularly, but not by way of limitation, this invention relates to an improved retrievable sampling tool for obtaining a sample of well bore fluids during a production test and maintaining the sample substantially uncontaminated and at substantially the pressure in the well bore at the depth where the sample is obtained.

During the initial production of oil and gas and the like, and at intervals throughout the producing life of an oil-bearing formation, it is desirable to acquire data on the physical characteristics of the producing reservoir. The desired data includes bottom hole pressure, pressure drawdown or change at various production rates, the amount of dissolved gas in the fluid, viscosity of the fluid, and other characteristics under environmental or ambient conditions at the formation depth. The data is valuable in determining the production yield to be expected from the well and in determining the most efficient method of producing the well.

In the past, fluid samples have been taken from well bores, but the samples were not maintained under the ambient conditions of the well bore wherein the samples were obtained. Some of the desired characteristics can be derived by calculation, but others, such as the amount of gas in solution, cannot be determined because the gas comes out of solution as the pressure decreases upon retrieving the sample.

This invention provides an improved retrievable tool for use in obtaining a sample of fluid from a well bore or the like. The improved tool includes a tool body containing first and second chambers, first valve means between the first and second chambers for controlling the flow therebetween, and second valve means for controlling the flow from the well bore into the second chamber. A piston is positioned in the second chamber and a liquid substantially fills the second chamber between the upper end of the piston and the first valve means. The first chamber contains a compressible gas at a pressure lower than the pressure of the sample to be obtained. Opening the first valve means permits the liquid to flow from the second chamber into the first chamber and the sample fluid to enter the second chamber below the piston. The second valve means is actuated to close the second chamber thereby trapping the sample in the second chamber at the ambient well bore pressure.

An object of the invention is to provide an improved retrievable sample tool that is capable of obtaining a sample of well bore fluid at any desired depth in the well bore.

Another object of the invention is to provide an improved retrievable sample tool for obtaining a sample of fluid in the well bore and maintaining the sample at substantially well bore pressure when retrieved.

Still another object of the invention is to provide an improved retrievable sample tool for obtaining a sample of well bore fluid and maintaining the sample uncontaminated when retrieved.

A further object of the invention is to provide a retrievable sample tool which includes a separable sample chamber which can be easily removed from the remainder of the tool and sent to the laboratory for analysis.

The foregoing and additional objects and advantages will become more apparent as the following detailed description is read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIGS. 1A, 1B, and 1C, taken together, comprise a cross-sectional view of a fluid sampler constructed in accordance with the invention.

FIGS. 2A and 2B, taken together, comprise a cross-sectional view of a portion of the fluid sampler, but showing parts of the sampler arranged in another operating position.

FIG. 3 is a cross-sectional view of a modification of the lower portion of the fluid sampler.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawing and to FIGS. 1A, 1B, and 1C in particular, shown therein and generally designated by the reference character 10 is a fluid sampler constructed in accordance with the invention. The fluid sampler 10 includes an elongated body 12 comprising an upper section 14 that is releasably connected with a lower section 16 by threads 18.

For reasons primarily dictated by manufacturing, the upper section 14 and lower section 16 are each constructed from a plurality of threadedly interconnected portions. As shown in FIG. 1A, the uppermost portion 20 of the upper body section 14 includes a thread 22 for attaching the fluid sampler 10 to a wireline or cablehead (not shown) whereby the fluid sampler 10 may be lowered into a well bore (not shown). Also contained within the uppermost portion 20 is an electrical connection member 24 that cooperates with the cablehead (not shown) and an electrical conductor in the wireline (not shown) for conducting electrical current to the fluid sampler 10. The uppermost portion 20 is connected by a spacer member 26 to a relief valve body member 28.

The relief valve body member 28 has a passageway 30 extending therethrough to accommodate an electrical conductor 32. Each end of the passageway 30 is sealed by a pressure-tight electrical connector 34. A valve passageway 36 also extends through the member 28 and has one end thereof extending through the sidewall of the body member 28 and the opposite end extending into a first or upper chamber 38. A relief valve 40 is threaded into the member 28 whereby the passageway 36 can be opened and closed as desired.

The upper chamber 38 is formed by the lower end of the body member 28, a tubular member 42 that is connected to the body member 28 and the upper end of an operating valve body 44. It will be noted that the operating valve body 44 is threadedly attached to the chamber forming, tubular member 42 and is the lowermost portion of the upper body section 14.

An electrical conductor 46 has its upper end connected with the lower connecter member 34 and its lower end connected with an igniter 48 that is mounted in the upper end of the valve body 44. The igniter member 48 closes the upper end of a valve bore 50 formed in the valve body 44. A propellant charge 52, located in the upper end of the bore 50, is in electrical communication with the igniter 48 whereby detonation of the charge 52 can be accomplished.

A piston valve member 54 is slidingly positioned in the bore 50 below the charge 52 and is movable therein in response to detonation of the charge 52. As illustrated in solid lines in FIG. 1A, the piston valve member 54 carries spaced seals 56 and 58 that are arranged to prevent communication between a passageway 60 and a passageway 62. Each of the passageways are formed in the valve body 44. The passageway 60 extends between the bore 50 and the chamber 38 and the passageway 62 extends from the bore 50 downwardly through the valve body 44.

In addition to the seals 56 and 58, the piston 54 also carries an O-ring or resilient lock ring 64 that is located between the seals 56 and 58. The lock ring 64, when the piston 54 is in a position closing the passageway 62, is located in an annular recess 66 in the valve body 44, retaining the piston 54 in the position preventing flow from the passageway 62 to the passageway 60.

The lower body section 16 includes a latch housing 68 that is threadedly connected with a tubular member 70 to form a second or lower chamber 72. The latch housing 68 includes a passageway 74 that extends from the upper end thereof in communication with the passageway 62 in the valve body 44 into communication, at its lower end, with the lower chamber 72. A removable orifice member 76 mounted in the housing 68 has an orifice 78 therein that is positioned in the passageway 74 to restrict the velocity of fluid flowing through the passageway 74. The orifice member 76 is removable so that the desired size of orifice can be inserted therein as needed.

In the preferred form, the orifice member 76 also functions as a relief valve to relieve the pressure in the upper chamber 38 if it exceeds a predetermined value. To perform this function, a passageway 75 extends from the orifice 78 outwardly through the member 76 and a spring-loaded valve ball 77 is located in the passageway 75 engaging the member 76, closing the passageway 75. The spring load is designed to prevent the ball 77 from moving to a position opening the passageway 75 until the pressure in the chamber 38 reaches a predetermined value.

A valve 80 is located below the orifice member 76 in the latch housing 68. The valve 80 is provided so that the passageway 74 can be closed after a fluid sample has been obtained.

A counterbore 82 extends upwardly into the latch housing 68 from the lower end thereof and is sized to receive the upper end of a latch rod 84. As illustrated, the upper end of the latch rod 84 provides a first downwardly facing shoulder 86 and, spaced therefrom, a second downwardly facing shoulder 88. A spring-biased plunger 90 carried by the latch housing 68 engages the shoulder 86, retaining the latch rod 84 in the position illustrated in FIG. 1B.

The latch rod 84 extends downwardly through the lower chamber 72 and is threadedly connected at its lower end with a valve member 92. An enlargement 94 on the latch rod 84 is located in the chamber 72. The enlargement 94 is sized to be received within a bore 96 in a piston 98 that is also positioned within the chamber 72. The enlargement 94 fits relatively close within the bore 96 so that as the piston 98 moves over the enlargement 94 fluid trapped therebetween will reduce the relative velocity between the piston 98 and the enlargement 94.

As may be clearly seen in FIG. 1C, the piston 98 carries a pair of O-ring seals 100 on the exterior thereof so that the piston 98 is in sliding and sealing engagement with the tubular member 70. An O-ring seal 102 mounted on the interior of the piston 98 is in sliding and sealing engagement with the latch rod 84.

A plurality of relatively large ports 104 extend through the tubular member 70 near the lower end thereof. When the fluid sampler 10 is in the position illustrated, the lower seal 100 on the piston 98 is located just above the ports 104 and a seal 106 carried by the valve member 92 is located in sealing engagement with the interior wall of the tubular member 70 just below the ports 104. The ports 104 are preferably of relatively large size so that as the sample enters the chamber 72 below the piston 98, there will be very little drop in pressure due to the velocity change as the sample flows through the ports 104.

A passageway 108 extends downwardly through the valve body 92 providing communication from the lower chamber 72 below the piston 98 and a pressure indicating assembly 110 that is mounted in a counterbore 112 in the lower end of the valve member 92. A valve 114 is positioned in the passageway 108 and is movable from the open position illustrated in FIG. 1C to a position closing the passageway 108.

The pressure indicating assembly 110 includes a body portion 116 that is threadedly attached to the valve member 92, and indicating member or rod 118 that extends through the housing 116 in sliding and sealing engagement therewith, a spring retainer 120, and a coil spring 122 that is positioned between the spring retainer member 120 and the indicating rod 118. The spring 122 biases the indicating member 118 relatively upwardly against pressure in the passageway 108.

A protective cap 124 is threadedly attached to the lower end of the valve member 92. The cap 124 is provided with a removable plug 126 in the lower end thereof. The plug 126 can be removed for observation of the lower end of the indicator rod 118 to ascertain whether there is pressure in the passageway 108 and chamber 72. In fact, and if desired, the rod 118 can be graduated along the lower end thereof so that a fairly accurate indication of the magnitude of the pressure in the passageway 108 can be determined.

OPERATION OF THE PREFERRED EMBODIMENT

When it is desired to obtain a sample from a well bore, the threads 22 are engaged with mating threads on a cablehead which is attached to a wireline for moving the fluid sampler 10 through the well bore. Connecting the cablehead also completes an electrical circuit through the connection member 24 to the igniter 48 and charge 52.

Prior to connecting the cablehead, the upper chamber 38 has been sealed by closing the relief valve 40 and by positioning the piston valve member 54 in the position shown in solid lines in FIG. 1A. The chamber 38 contains a compressible gas, usually air, which is at atmospheric pressure or at a pressure lower than the pressure in the well bore wherein the sample is to be obtained.

The lower chamber 72, above the piston 98, and the passageways 62 and 74 up to the piston valve member 54 are filled with a substantially incompressible fluid, such as oil or water. Filling the chamber 72 with the incompressible fluid maintains the piston 98, which is free to move in the tubular member 70 on the latch rod 84, in the position illustrated in FIG. 1C as the fluid sampler 10 is lowered into the well bore even though the pressure in the well bore is constantly increasing.

Upon reaching the desired location in the well bore for taking the fluid sample, the electrical circuit is completed to the igniter 48 to detonate the charge 52. Upon detonation of the charge 52, the piston 54 is driven downwardly into the position illustrated by dash lines in FIG. 1A. When the piston 54 is in this position, the passageways 60 and 62 are in communication.

Since the pressure in the well bore is greater than the pressure in the chamber 38, well bore fluid flowing through the ports 104 into the chamber 72 below the piston 98, drives the piston 98 upwardly. As the piston 98 moves upwardly, the incompressible fluid in the chamber 72 above the piston 98 is forced through the passageway 74, the orifice 78, and through the passageways 62 and 60 into the upper chamber 38.

As the liquid flows through the orifice 78, the restriction imposed by the orifice 78 reduces the velocity of the liquid flowing and consequently reduces the velocity of upward movement of the piston 98 in the chamber 72. It is desirable to reduce the velocity of the liquid flow into the chamber 38 because the sudden mixture of a liquid such as oil at a relatively high pressure with air in the chamber 38 could result in an explosion.

Also, reducing the upward velocity of the piston 98 restricts the velocity of the sample fluid flowing through the ports 104 and thereby prevents pressure changes due to velocity flow through the ports 104 which could result in the gases contained in the sample being forced out of the mixture. If this occurs, the sample obtained would not be in the same condition as it is in the well bore and valuable information will be lost.

When the piston 98 engages the abutment 94, the latch rod 84 and the attached valve member 92 are moved upwardly relative to the tubular member 70. The upward movement of the valve member 92 moves the seals 106 thereon past the ports 104 in the lower end of the tubular member 70 into the position shown in FIG. 2B. In this position, the ports 104 are closed and the lower chamber 72 containing the sample is closed and sealed.

The upward movement of the latch rod 84 with the piston 98 depresses the plunger 90 until the lower shoulder 88 has moved above the plunger 90. The plunger 90 then moves into engagement with the shoulder 88, latching the valve member 94, in the closed position illustrated in FIG. 2B.

At this time, the fluid sample has been collected and is trapped in the lower chamber 72 below the piston 98 and above the upper end of the valve member 94. The sample is maintained under the same pressure conditions and with the same gas entrainment as it was at the location in the well bore where the sample was obtained.

Since the gas in the chamber 38 is compressed, a relatively small temperature increase could result in a fairly high force being exerted downwardly on the piston 98 and possible shearing the plunger 90. To avoid this possibility, it is preferred that the spring load on the valve ball 77 be adjusted so that the relief valve portion of the orifice member 76 will open relieving the pressure in the chamber 38.

The fluid sampler 10 is then retrieved from the well bore. Upon reaching the surface, the valve 80 is closed manually to positively assure against leakage of the sample through passageway 74.

The cap 104 or the plug 126 can be removed so that the indicating member 118 is exposed and can be observed to determine if the pressure of the sample in the chamber 72 is being maintained. The position of the rod 118 is noted from time to time to be certain that the fluid in the chamber 72 is not leaking and permitting a reduction of pressure therein. As a further precaution against leakage, the valve 114 can be closed manually to block the passageway 108.

After the valves 80 and 114 have been closed, the threaded connection 18 between the upper section 14 and the lower section 16 of the body 12 is unscrewed and the lower section 16 of the fluid sampler 10 is sent to the laboratory for analysis. If desired, a cap can be placed over the upper end of the lower section 16.

Additional samples can be obtained by replacing the charge 52, by repositioning the piston valve member 54 and connecting another lower section 16 to the upper section 14. Thus, as many samples as desired can be obtained from the well bore. It should also be pointed out that the use of the electrically fired charge 52 permits the samples to be obtained at any desired location in the oil bore.

DESCRIPTION OF THE MODIFICATION OF FIG. 3

FIG. 3 illustrates a modification to the lower portion of the fluid sampler 10 and relates to the provision of a different type of apparatus for indicating the pressure in the chamber 72. The same reference characters are utilized in describing FIG. 3 wherein the parts are substantially the same as previously described.

As shown in FIG. 3, a piston 150 is located in the counterbore 112 in the lower end of the valve member 94. The piston 150 is in sliding and sealing engagement with the valve member 94.

The lower end of the counterbore 112 is closed by an adapter 152 that is threaded into the valve member 94 defining a relatively small chamber in which the piston 150 operates. A passageway 154 extends through the adapter member 152 and is in fluid communication at its lower end with a pressure gauge 156.

The pressure gauge 156 may be of any suitable type. In fact, and if desired, the pressure gauge 156 could be replaced by a commercially available Bourdon tube pressure recording device.

The passageway 154 and counterbore 112 below the piston 150 are filled with a liquid 158. The liquid 156 transmits the pressure exerted on the upper end of the piston 150 to the gauge 156. The purpose of the piston 150 and fluid 156 is to prevent well fluids, which in some instances may be harmful to the gauge 156, from entering the gauge.

A protective cap 160 is threadedly connected with the lower end of the valve member 94. The cap 160 can be removed when desired to permit observation of the gauge 156.

Claims

1. A retrievable tool for obtaining a sample of well bore fluid or the like, said tool comprising: an elongated tool body movable through the well bore, said body having first and second chambers therein, a passageway connecting said chambers, and at least one inlet port providing communication between said second chamber and the well bore, said tool body including: an upper member containing said first chamber; a lower member containing second valve means, a piston, and said second chamber; and said lower member being releasably connected with said upper member whereby said lower member containing said sample can be readily separated from said upper member; first valve means located in said body, said first valve means being movable between positions opening and closing said passageway; said piston located in said second chamber in sliding and sealing engagement with said body, said piston having an upper end and a lower end, said lower end being subjected to well fluid through said port; said first chamber having a gas therein at a pressure below the well bore pressure; said second chamber having a liquid therein between the upper end of said piston and said first valve means; and second valve means carried by said body for opening and closing said port, said second valve means closing said second port after the well bore fluid has entered said second chamber below said piston whereby said sample is maintained at substantially well bore pressure when said tool is

2. The retrievable tool of claim 1 wherein said second valve means includes: a valve member movable in said body to open and close said port; and a valve operator connected with said valve member and engageable with said piston to move said valve member to a position closing said port when the sample fluid has substantially filled said second chamber below said

3. The retrievable tool of claim 2 and also including latch means carried by said body and engageable with said valve operator for holding said

4. The retrievable tool of claim 3 wherein: said latch means includes a plunger movable in said body and a spring resiliently biasing said plunger into engagement with said valve operator; and, said valve operator has a first shoulder engaging said plunger when said valve member is in the position wherein said port is open and a second shoulder engaging said plunger when said valve member is in the position

5. The retrievable tool of claim 4 wherein: said piston slidingly and sealingly encircles said valve operator and has a cavity formed in said upper end; and said valve member has an abutment thereon sized to fit into said cavity and engage said piston at the lower end of said cavity, said cavity and abutment cooperating to reduce the relative velocity between said piston

6. The retrievable tool of claim 1 and also including relief valve means for releasing the pressure in said first chamber when said pressure

7. The retrievable tool of claim 1 wherein said first valve means includes: an explosive charge in said body; means for detonating said charge; and a valve member slidingly located in said body, said member being initially disposed in a position closing said passageway and movable upon detonation of said charge to a position opening said passageway, whereby said liquid

8. The retrievable tool of claim 7 wherein said first valve means also includes a flow control member extending into said passageway reducing the flow area of said passageway to control the rate of liquid flow

9. The retrievable tool of claim 8 and also including means for indicating

10. The retrievable tool of claim 1 wherein: said first valve means includes: an explosive charge in said body; means for detonating said charge; a first valve member slidingly located in said body, said member being initially disposed in a position closing said passageway and movable upon detonation of said charge to a position opening said passageway, whereby said liquid flows from said second chamber to said first chamber; and a flow control member extending into said passageway reducing the flow area of said passageway to control the rate of liquid flow therethrough when said first valve member is in the open position; said second valve means includes; a second valve member movable in said body to open and close said port; and a valve operator connected with said second valve member and extending through said piston in sliding and sealing engagement therewith, said valve operator having a first shoulder and a second shoulder and having an abutment thereon engageable with said piston, whereby said piston moves said second valve member to a position closing said port when the sample fluid has substantially filled said second chamber below said piston; said piston having a cavity is said upper end receiving said abutment to reduce the relative velocity between said piston and abutment prior to engagement therebetween; latching means carried by said body, said latching means including: a spring in said body; a plunger biased by said spring into engagement with said valve operator, said plunger engaging said first shoulder when said second valve member is in a position wherein said port is open and engaging said second shoulder when said second valve member is in the position closing said port; and said body includes: an upper member containing said first chamber, first valve member, charge, and detonating means; and a lower member containing said second chamber, flow control member, said second valve means, and latching means, said lower member being releasably connected with said upper member whereby said lower member containing said sample fluid can be readily separated from said upper member.