AU654038B2 - Well shut-in testing tool - Google Patents

Description

i-.

r~ lit i I Regulation 3.2

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT 8 ORIGINAL W FIILaDUITC- PTl D- HiE~nh~uiEIT PTY bTBI-n Name of Applicant: Actual Inventor: MARK HILDER Address for Service: R K MADDERN ASSOCIATES, 345 William Street, Adelaide, South Australia, Australia King Invention title: "WELL SHUT-IN TESTING TOOL" 4- Details of Associated Provisional Application No: PK 8175 filed 4th September 1991 The following statement is a full description of this invention, including the best method of performing it known to us.

~U ~i-I This invention relates to a well shut-in testing tool, and method of using such a tool, and in particular relates to a tool which is more easily located within a well, and more easily recovered after testing is completed.

Oil and gas formations are frequently tested under what is known as shut-in and flowing conditions. Various formation characteristics indicate future well production, and the existence of such formations can be determined in part from shut-in and flow rate testing procedures. Among the information which is obtained from such tests are the rates at which formation pressures build up under snut-in conditions, and the rates of pressure reduction under flowing conditions.

v Such information is obtained by alternately flowing and then shutting the wells. It is desirable that such information be obtained or measured in the well formation rather than at the well head. This avoids the requirement of building the full length of the well up to formation pressure. In conducting such downhole shut-in testing, a "".valve, commonly a barrel type valve, is located at the base of the well. Such valves normally comprise an inner cylindrical sleeve or barrel which is located within an outer 25 tube. Apertures within the outer tube and inner sleeve align, Fllor low flow through the valve. A spring is used to urge the barrel into this open position. The valve is closed by raising the barrel which in turn brings a lower portion of the barrel, which has no apertures, over the openings of the outer tube.

With such barrel valves, it is necessary to have pressure sensing devices on the well side of the valve.

Therefore, it is common to lower a probe which comprises among other thing.3 pressure sensing equipment, which is incorporated with some form of locking mechanism which connects the probe to the barrel valve. The locking mechanism b. rrr- r -1 is designed so that it can operate the valve, by raising and lowering the barrel sleeve, and also is designed to release the probe from the valve once testing is complete.

In the past, such arrangements have normally comprised a probe having a male member which locates within a female member within the barrel of the valve. The male member may be provided with an annular groove and the barrel valve is provided with spring loaded locking dogs which release the probe upon a set upward force being applied.

Such wells are normally operated using a wire line, and involve the steps of inserting the barrel valve, and subsequently inserting the probe, or inserting a combination valve and probe element within the dual spring at well formation depth.

A major problem with such arrangements are that the barrel valves are normally positioned so that the well fluid flow is into the outer tubular element, through the barrel valve and exiting the apertures in the internal barrel and external tubular member. Although the well will not be flowing during the stage of introducing the probe into the barrel valve, the lower portion of the barrel valve may be full of fluid or water, and there will be resistance to insertion of the probe through the valve. In fact, a hydraulic lock may bR formed which prevents the locking mechanism from engaging.

A further problem with such arrangements is the possibility of debris such as corrosion scale or sand falling from above the probe and settling above the locking mechanism -once it is engaged. Upon attempting to disengage the locking mechanism, the debris above causes the two components to jam thereby preventing a free release.

3 il~ Therefore, it is an object of this invention to provide a well shut-in testing tool which overcomes the abovementioned problems, and in particular to provide a testing tool which has an improved locking mechanism.

In its broadest form, the invention comprises a locking mechanism for engagement with the sliding barrel valve element of a downhole shut-in barrel valve, the sliding barrel valve element having a throat portion of reduced diameter, said locking mechanism comprising, an elongate tubular member, a releasable lock positioned intermediate of the ends of said elongate tubular member, the lower end of said elongate tubular member arranged to pass freely through the internal bore of said sliding barrel valve element to enable engagement of the lock with said sliding barrel valve element about said throat portion so that upon said tubular member being raised, said engaged lock abuts against said throat portion thereby raising said sliding barrel valve element, said lock further arranged such that it disengages and moves past said throat portion upon a predetermined 2Q. upward force being applied to said tubular member.

I

-4 Preferably, the throat portion of the barrel valve has tapered portions either side of the throat to allow the locking mechanism to pass freely through either side of the St In a further aspect of this invention, the locking mechanism may further comprise the elongate tubular member having a shaft with a smaller diameter than the tubular member and an upper and lower locking projection which are spaced along the shaft so as to divide the shaft into an 30 upper, intermediate and lower portion. A slider assembly is mounted on the upper section of the upper shaft portion and comprises a collar having at least one resilient member depending from the collar. The free end of the resilient member is provided with an outwardly directed projection. The collar is slidably located on the upper section of the shaft 4 0 portion between the coupling and the upper locking member, and the collar and resilient member may be connected to one another by a sheer pin.

The slider assembly has two primary working positions, the first being at the upper end of the shaft portion wherein the free end of the resilient member is between the upper and lower locking projections such that the free end of the resilient member may bend inwardly and allow the projection on the free end to pass through the throat of the barrel valve. The second working position is where the slider is in its lowest position against the upper locking projection where the free end of the resilient member is positioned over the lower locking projection so as to prevent the resi ient member from bending inwardly, whereupon the projections engage the throat which enables the sliding element of the barrel valve to be raised.

In order to disengage the locking mechanism, sufficient upward force is applied to the elongate tubular member such that the sheer pin connecting the resilient member to the collar fractures thereby freeing the collar from the o resilient member. The resilient member falls to the lower end of the shaft, such that the free end of the resilient member is below the lower locking projection, whereupon the free end Sof the r~silient member is able to bend inwardly anid allow the projection to pass upwardly and through the throat of the barrel thereby freeing the elongate tubular member from the barrel valve.

In order for the invention to be fully understood, a preferred embodiment will now be described, but it will be realised that the invention is not to be construed as being restricted or confined to the precise details of this embodiment.

This embodiment is illustrated in the accompanying drawings in which: i:t-A F~L~ ~(n Fig 1 shows an elongate tubular member with a releasable lock in position; Fig 2 shows the locking mechanism prior to engagement with a barrel valve; Fig 3 shows a locking mechanism engaged with the barrel valve; and Fig 4 shows the locking mechanism being disengaged from a barrel valve.

In this embodiment, the locking mechanism comprises an elongate tubular member 11 having a coupling 12 for the 15 attachment of measuring means 13. In this embodiment, the measurinS means 13 comprises a pressure sensor, but obviously may comprise other measuring equipment such as temperature or flow rate measuring devices. The coupling 12 is provided with sealing means so as to provide fluid communication along the elongate tubular member 11 to the measuring means 13. In addition, the measuring means 13 is connected to the coupling o 12 by a brass sheer pin. Should the locking mechanism jam, then the measuring means 13 may at least be retrieved.

The releasable lock 16 comprises a shaft 17 which is of reduced diameter by comparison to the tubular member 11.

Positioned along the shaft 17 are an upper and lower locking projections 18 and 19, respectively which divide the shaft into an upper, intermediate and lower portion.

The releasable lock 16 further comprises a slider assembly 20 having a resilient member which in this embodiment comprises a tube 22 having a plurality of fingers 23 depending therefrom. In this embodiment, the fingers are formed by cutting longitudinal slots in a tube so as to form six radially spaceuL fingers 23.

The ends of the fingers are formed with projections 24 which have tapered portions 25 either side.

L. The slider assembly 20 further comprises a collar 27 which is secured to the tube 22 via an aluminium sheer pin 28. The collar 27 is slidably located to the upper portion of the shaft portion 17 and slides between an upper position adjacent the coupling 12 and a lower position adjacent the upper locking projection 18.

The inner diameter of the tube 22 and fingers 23 is larger than the overall diameter of the upper and lower locking projections 18 and 19.

As shown in Fig 2, the locking mechanism 16 is designed to engage with the sliding element of a barrel valve 30. The barrel valve 30 is positioned at a well head in a separate operation, and is secured by locking dogs which engage a nipple that is prepositioned in the drill stem. The locking dogs (not drawn) and associated operating mechanisms are secured to the barrel valve at its upper end, and securely S. locate the barrel valve 30 in the desired position until testing is complete.

S: The barrel valve 30 comprises an outer tubular member 31 and an inner sliding element or tubular barrel 32. The outer tubular member 31 has a series of apertures 33 spaced around its diameter, and the inner tubular barrel also has a series of apertures 34 spaced around its diameter. A spring 37 holds the tubular barrel 32 in the position shown in Fig 3, and sealing means 38 operates to close the valve when the tubular barrel 32 is raised. Stops are provided at either end of the barrel valve 32 to limits its travel in respect of its open and closed position.

The tubular barrel 32 is provided with a throat 35 which has tapered portions at either side.

Finally, sealing means 39 are provided at the ends of the outer tubular member 31 which provides sealing engagement with the elongate tubular member 11. When the elongate 7

A

tubular member 11 is in position, the well head can be fully closed off by raising the tubular barrel 32, and the measuring means 13 remains fluid communication with the well via the end of the elongate tubular member 11.

Once the barrel valve 30 is in location, the measuring means 13 and elongate tubular member 11 are lowered into the well. The lower portion of the elongate tubular member 11 passes freely through the throat 35. However, the overall diameter of the projections 24 are larger than the throat diameter, and thereby push the slider assembly 20 into the uppermost position as is shown in Fig 2. In this position, the collar 27 bears against the coupling 12 and the ends of the fingers 23 are positioned over the intermediate poriton of the shaft that is between the upper and lower locking projections 18 and 19. The fingers 23 are sufficiently resilient such that the weight of the measuring means 13 and locking mechanism 16 cause the fingers 23 to bend inwardly thereby allowing the projections 24 to pass through the throat 35. The tapered portions 25 on the projections 24 together with the upper tapered portion of the throat assist the inward movement of the fingers 23. This thereby allows the releasable lock 16 to engage the throat 35 of the tubular barrel 32.

As shown in Fig 3, when the locking mechanism 10 is raised, the slider assembly 20 moves to a second working position as shown in Fig 3. In this position, the collar 27 bears against the upper locking projection 18 thereby preventing any further downward movement of the slider assembly 20. In this position the lower end of the fingers 23 are positioned over the lower locking projection 19. As the elongate tubular member 11 is raised the projections 24 engage the throat 35 and continued lifting of the elongate tubular member 11 will cause the tubular barrel 32 to lift thereby closing the barrel valve 30. This then enables various shut-in testing procedures to be performed.

When testing is complete, and the elongate tubular member 11 and measuring means 13 is to be removed from the barrel valve 30, a predetermined upward force is applied to the locking mechanism 10 which sheers the aluminium sheer pin 28. The force of sheering can be determined on the basis of the diameter and material specifications of the sheer pin 28.

Once the pin 28 is sheered, the collar 27 separates from the tube 22. As the elongate tubular member 11 continues to be raised, the lower locking projection 19 moves upwardly past the projections 24. The ends of the fingers 23 are then positioned over the lower portion of the shaft 17 which is below the lower locked projection 19. In this position, the fingers 23 are able to bend inwardly, and in a position shown in Fig 4, the projections 24 are able to pass through the throat 35. The tapered portions 25 of the projections 24 together with the tapered portion below the throat 35 assist in the inward movement of the fingers 23.

The measuring means 13 and an elongate tubular member 11 can then be withdrawn from the barrel valve 30 and returned to the surface.

As can be seen from this embodiment, the introduction of the elongate member 11 into the barrel valve 30 through the throat 35 at all times provides fluid flow around the elongate member 11 and through the throat 35. This avoids any hydraulic lock being formed as the elongate tubuler member 11 is being introduced into the barrel valve member 30. Further, any debris which falls into the tubular barrel 32 is able to fall freely past the releasable lock 16 and through the throat 35. This prevents scale deposits and other debris from packing around the top of the releasable lock 16, and thereby preventing removal of the locking mecha-ism 16.

A brief consideration of the invention described above will reveal that the invention provides a simple and reliable means of operating a barrel valve.

Claims (9)

1. A locking mechanism for engagement with the sliding barrel valve element of a downhole shut-in barrel valve, the sliding barrel valve element having a throat portion of reduced diameter, said locking mechanism comprising, an elongate tubular member, a releasable lock positioned intermediate of the ends of said elongate tubular member, the lower end of said elongate tubular member arranged to pass freely through the internal bore of said sliding barrel valve element to enable engagement of the lock with said sliding barrel valve element about said throat portion so that upon said tubular member being raised, said engaged lock abuts against said throat portion thereby raising said sliding barrel valve element, said lock further arranged such that it disengages and moves past said throat portion upon a predetermined upward force being applied to said tubular member.

2. A locking mechanism according to claim 1 wherein the elongate tubular member further comprises a shaft having I upper and lower locking projections which are spaced apart on said shaft so as to divide said shaft into three portions, an upper, intermediate and lower portion, a slider assembly comprising a collar journalled on the upper portion of said shaft, and a resilient member depending from said collar, having an outwardly directed projection at its free end, said slider assembly having two working positions, the first being at the upper end of the upper portion of the shaft where the free end of the resilient member is between the upper and lower locking projections which allows the resilient m.ember to bend inwardly, thereby allowing said projection to pass through said throat portion, and the second being at the lownr end of the upper portion of the shaft, the free end of the resilient meiber being positioned over the lower locking projection which prevents inward deflection of said resilient member whereupon said projection engages the throat portion of said sliding barrel valve element when said tubular member is raised.

3. A locking mechanism according to claim 2 wherein said resilient member is releasably secured to said collar such that when the projection of the resilient member is engaged against said throat portion, a predetermined force will cause the resilient member to separate from the collar, whereupon the resilient member moves downwardly with respect to the shaft such that the free end of the resilient member is below the lower locking projection and over the lower shaft portion which allows the resilient member to bend rn inwardly, thereby allowing said projection to pass upwardly through said throat portion.

4. A locking mechanism according to either claim 2 or 3 wherein said resilient member further comprises a plurality of radially spaced fingers, each having a projection on each free end.

A locking mechanism according to any one of claims 2 to 4 whereir. said resilient member is secured to said collar by a sheer pin, said pin being designed to sheer at a predetermined load.

6. A method of conducting well shut-in and flow rate tests using a locking mechanism in accordance with any one of the preceding claims, wherein said elongate tube is connected to sensors to measure downhole conditions such as pressure, and is lowered into a well for engagement with a barrel valve 11 .r by the locking mechanism, such that when the locking mechanism is engaged, the barrel valve can be closed to measure shut-in conditions, and opened to measure flow conditions by lifting and lowering the elongate tubular member, and upon completion of the tests, the elongate tube and attached sensors may be removed from the well by applying a predetermined upward force to the elongate tube.

7. A method according to claim 6 wherer, the sensor comprises a pressure sensor and digital data storage means.

8. A locking mechanism substantially as described hereinbefore and in accordance with and as illustrated in the accompanying drawings.

9. A method of conducting well shut-in and flow rate tests using a locking mechanism substantially as described hereinbefore and in accordance with and as illustrated in the accompanying drawings. Dated this 4th day of September 1992. 0. IILDADUILT PTY-TD r c By its Patent Attorneys SR K MADDERN ASSOCIATES *i 6 mwl,,T ABSTRACT This invention relates to a tool for use when conducting well shut-in and flow rate testing. Commonly, such testing is conducted "downhole", with a barrel type valve located the well formation. An engagement mechanism controlled by a wire line from the surface is used to engage the valve and to alternately close and open the valve. Conveniently, sensors such as pressure transducers and data logging equipment are located down the hole with the attachment mechanism. Problems associated with such attachment mechanisms are positively engaging the barrel valve, and at the completion of the testing having a convenient means to disengage the barrel valve so as to recover the testing equipment. In order to overcome this problem, the present invention comprises an attachment means or locking member having an elongate tubular member (11) with an upper end coupling for attachment to a measuring means A releasable lock (16) is positioned intermediate of the ends of the elongate 20 tubular member the lower end of the elongate tubular member (11) and lock (16) being arranged to freely pass through the internal bore of a sliding element (32) of a barrel valve but arranged such that upon the tubular member (11) being raised, the lock (16) is unable to pass, and engages the throat portion (35) thereby raising the sliding element After testing, the lozk (16) is further arranged such that it disengages and moves past the throat portion (35) upon a predetermined upward force being applied to the tubular membrr (11).