NO341190B1

NO341190B1 - Drill pipe string conveyed pressure integrity test tool and method for testing the pressure integrity of a casing

Info

Publication number: NO341190B1
Application number: NO20151699A
Authority: NO
Inventors: Atle Johnny Sørhus
Original assignee: Archer Oiltools As
Priority date: 2015-12-11
Filing date: 2015-12-11
Publication date: 2017-09-04
Also published as: NO20151699A1

Description

Drill pipe string conveyed pressure integrity test tool and method for testing the pressure integrity of a casing

Introduction and prior art

The present invention is a drill pipe string conveyed tool and a method for testing the pressure integrity of a casing. The tool is used in combination with a drilling or milling bit before dressing and tagging a cement plug in order to verify the pressure integrity of the casing above the tagging tool before dressing and tagging for testing a plug. It may also be used without the drilling or milling bit, or without tagging.

Cement plugs are formed for several reasons in a casing pipe. One purpose is to form a plug for separating zones, or for temporary or permanent abandonment. The formation of a cement plug within a casing is sometimes combined with a cementing also of the annulus about the casing. The cement plug quality must be tested, both with regard to mechanical integrity and pressure integrity. However, if a leakage is detected when testing for pressure integrity of the plug, one must be certain that the casing above the plug has pressure integrity.

US4482013 describes a downward directed swab cup-like device for being extended downwardly from a drill string and used to test a formation below the swab cup. It has an expandable funnel-shaped downward-facing packer which is possible to move out of and retracted into the drilling bit.

US2012/0175108A1 defines a downhole tool with a throughbore for use in a tubular in the wellbore, with a sealing element for sealing an annulus between the tool and the inner wall of the tubular, and håving a flo w path formed in the tool to allow flow past the sealing element when the sealing element is in an otherwise sealed position. The sealing element is actuated to engage with the inner wall of the tubular.

US2691418 which forms background art to the invention describes a combination of a packing cup with slips engaging with the bore wall when the packing cup is expanded under pressure.

US patent application 2001/0015277 "Packer" describes a packer for use inside a casing in a well and comprises a resilient element, a housing and a rupturing dise. This resilient element seals off an annulus when compressed.

Brief Figure captions

The invention is illustrated in the attached drawing Figures.

The context of the invention is testing of testing the integrity of a casing from a given point of depth and all the way to surface. The context is also, when testing as above, further conducting dressing and tagging of a cement plug formed in the casing.

Fig. 1 is a section and elevation view of a well casing portion within which is arranged a test tool of the invention comprising, from bottom and up, a milling or drilling bit, the test tool of the invention comprising an upward-annulus flow opening valve body, here embodied as a swab cup sliding between a lower closed and an upper open position on the tool stem. Axial-parallel grooves allow upward flow when the valve element is in the upper position shown in Figs. 1 and 3. Further, above the valve body, there is arranged a bore-open radial inlet valve which is closed by a sleeve in Figs. 1-2-3, and open in Fig. 4. Fig. 1 illustrates what the skilled person would call RIH (run into hole). When running the drill pipe string with the tool into the well, i.e. down into the casing, then the counter-pressure below the valve element, i.e. the swab cup will lift the cup upwardly on the stem so as for opening up the passage on the surface of the stem so that fluid may move to above the cup. This avoids build-up of excess pressure below the tool. Fig. 2 is an illustration of the situation of the testing occurring when the tool has arrived at a given desired or "target" depth, i.e. a short distance above a cement plug to be tested in the next sequence. The tool is halted. The drill pipe is closed at the surface, and pressure is increased in the annulus, i.e. in the drill string annulus within the casing in order to check the pressure integrity of the casing. Fig. 3 illustrates what the well engineer calls "Dress and Tag the cement."

Dressing the cement means drilling away the upper layer or portion of the cement as this upper portion usually is of inferior quality, as illustrated in Fig. 3. When cementing, usually the upper metres will be a mixture of mud and cement so there is no proper foundation. So one drills until håving solid cement to test. One may use a drilling bit or a milling head (as in the drawing) to drill out the top of the cement. Then the dressed cement plug may be "tagged", i.e. then one weight loads the cement to check whether one has a proper foundation or whether it yields. Subsequently or alternatively one may pressure test the cement plug in the ordinary way by closing the annulus and setting pressure in the drill pipe string. Any leakage detected upon the second pressure testing of the plug itself will then be due to a leakage through the plug or between the plug and the position of the swab cup during the first test; all leakage problems above the test tool are eliminated. Fig. 4 illustrates what the well engineer skilled in the art calls a POOH (pull out of the hole, i.e. the well). When håving finished the test, one opens a radial inlet port valve so as for obtaining radial flow communication channels between the drill pipe string bore and the drill pipe string annulus so as for allowing well liquid to move from above to below the otherwise closed swab cup. The valve in this case is one in which one releases a ball or dart from surface, through the drill pipe string and moves a sleeve. There are several types of valves available. Fig. 5 is an elevation view of the pressure integrity test tool of the invention. There are illustrated centralizers (lc) on the short drill pipe string sections above and below the test tool (30) itself. Here, the valve element (31v) is embodied as a moving swab cup (31) facing upward, shown in its lower, closed position, similar to the situation in Fig. 2 above. Fig. 6 is a vertical section view and part elevation view of the same, wherein we have subdivided the pressure integrity test tool into a lower shoulder section (30c), a central valve or swab cup section (30b), and an upper radial port valve section (30a). Fig. 6b is an enlarged view of part of Fig. 6 and shows the central sleeve 31s of the swab cup (31) in its closing position on the lower slide stopper (33). There may be arranged seals between the stem and the central sleeve near above the lower slide stopper (33), please see seal grooves forO-rings in Fig. 8. Fig. 7 is a cross-section view of part of the central valve or swab cup section from Fig. 6, showing the valve element or swab cup (31v, 31) in its upper, opened position held back by the upper slide stopper (33). Fig. 7b is an enlargement of the same, showing the axial-parallel bypass grooves ( 34) arranged on the tool stem (30) which are now open. Fig. 8 is a view of the tool stem (30), more specifically the central stem portion (30b) with the upper slide stopper (33) and the axial-parallel grooves (34).

Brief summary of the invention

The invention solving the above problems is a A drill pipe string (l)-conveyed pressure integrity test tool section (3) for a casing (100), comprising

- a cylindrical tool stem (30) håving an axial bore (35) and

upper and lower tool joints (11,12) to said drill pipe string (1) and a drilling or milling bit (2); - an annulus check valve for closing downward annulus flow relative to the check valve (31v) comprising a check valve body (31) on said tool stem (30),

characterized in thatsaid check valve (31v) comprises

- an upwardly directed swab cup body (31) with an axial cylindrical bore (310) tightly fitting and sliding on said tool stem (30) between a lower and an upper slide stopper (32, 33); - axial-parallel bypass grooves (34) arranged on said tool stem (30) extending across said upper slide stopper (33) for allowing annulus flow upwardly when the swab cup is at the upper slide stopper (33); - said swab cup (31) blocking tool annulus flow in the downward direction when stopping at said lower slide stopper (32) away from said bypass grooves on the tool stem (30)..

The invention is also a method of testing the pressure integrity of a casing (100) using the pressure integrity test tool section (3) of any of claims 1-4,

characterized in

- running said pressure integrity test tool section (3) to a target depth in said casing (100) with said swab cup body (31) displaced to an open position by pressure from below,

- halting the pressure integrity test tool section (3) at target depth,

- closing the central bore (35);

- increasing pressure in the casing bore to displace the swab cup (31) to its lower, closing position,

- verifying pressure integrity of said casing (100) above the swab cup (31).

Those definitions of the invention are given in the independent claims attached. Further features of the invention are defined in the dependent claims.

Components

drill pipe string (1)

drilling or milling bit (2)

casing (100) (not part of the invention)

cement (200) (not part of the invention)

pressure test tool section (3)

tool stem (30)

swab cup (31) sliding on tool stem, upward facing

lower slide stopper (32) for swab cup (31)

upper slide stopper (33) for swab cup (31)

axial-parallel passage grooves (34) in stem, passing under upper slide stopper (33) with lower ends above said lower slide stopper (32).

axial bore (35) through pressure tool section (3) to connect to drilling or milling bit (2).

valve sleeve (50)

valve sleeve seat (51)

valve sleeve bypass bore (52)

valve release ball (53)

valve radial inlet channels (54)

Description of an embodiment of the invention

The invention is a drill pipe string (1) conveyed pressure integrity test tool section (3) for a casing (100). The integrity test tool section (3) comprises the following main components: - a cylindrical tool stem (30) håving an axial bore (35) and upper and lower tool joints (11,12) to said drill pipe string (1) and a drilling or milling bit (2); - a relative downward annulus flow closing check valve (31v) comprising a check valve body (31v) on said tool stem (30).

In an embodiment of the invention the check valve body (31v) comprises a sliding swab cup (31).

The check valve (31v) is thus relative upward annulus flow opening, and relative downward annulus flow closing.

In an embodiment of the invention, the check valve (31v) comprises a well-known swab cup element but mounted in an unconventional manner: I this embodiment of the integrity test tool section (3), the check valve body (31v) comprises: - an upwardly directed swab cup body (31) with a cylindrical bore (310) tightly fitting and sliding between a lower and an upper slide stopper (32, 33), and - axial-parallel bypass grooves (34) arranged on the tool stem (30) extending under and past said upper slide stopper (33) for allowing tool annulus flow in the upward direction, and - said swab cup (31) blockingtool annulus flow in the relative downward direction when stopping at said lower slide stopper (32). The lower slide stopper is in the embodiment shown in Fig. 6b the shoulder of the lower shoulder section (30c).

The purpose of the swab cup body (31) is to prevent downward relative flow in the stem annulus, and allow relative upward flow, such as when running in with the tool assembly as shown in Fig. 1. Simply, the swab cup (31) acts as a downward closing check valve (31v) for the stem annulus within the casing, please see Fig. 2 and Fig. 6. Thus, if pressure is set in the annulus above the swab cup, i.e. within the casing, the casing may be pressure tested above the swab cup. During such a pressure test one pumps fluid into the casing. If the drill pipe string with the stem is run into the hole as in Fig. 1, the swab cup will be retained or dragging by its friction against the casing inner wall, and will be kept open, held back by the upper slide stopper (33) as long as there is upward relative flow in the stem annulus or if the drill pipe string is moving downwardly. If the drill pipe string is pulled only a short distance (corresponding to the distance between the lower and upper slide stoppers (32, 33)) the swab cup will close. Likewise, if the drill pipe string movement downward is stopped, and the annulus pressure increases, the swab cup will close.

The purpose of the pressure integrity tool section (3) is, when mounted on a drill pipe string and run into a desired depth in a casing, is for the operator to increase the pressure above the swab cup, in the tool's annulus, to test the pressure integrity of the casing above the swab cup, please see Fig. 2. In order to achieve this the central bore in the tool's inlet port (54) must be held closed in the initial phase, as shown in Figs. 1,2, and 3. The integrity of the swab cups may be tested beforehand by observing a return through the central bore. Then the integrity of the casing above the swab cups may be tested to the desired pressure. Then, when the pressure integrity of the casing above the swab cup has been confirmed, a cement plug formed below the test tool may be "dressed", i.e. the upper, non-homogenous parts of the cement plug milled or drilled away until proper cement is reached, please see Fig. 3, and then "tagged", i.e. mechanically tested and pressure tested. During the "dressing" drilling or milling, normal circulation will be applicable so as for transporting away excess material, which will pass via the axial-parallel bypass grooves (34) on the stem under the swab cup (31). Any deficiency in the pressure testing of the cement plug must then at least belong to the cement plug or in rare occasions be related to a casing leakage in the range from the position of the swab cup during the initial pressure testing, and the top of the cement plug.

In an embodiment of the invention, the tool section (3) comprises a ball-releasable valve sleeve (5) in said axial bore (35) allowing axial flow in a radially closed positon, and allowing influx from radial inlet channels (54) to said axial bore (35) in an open position. This feature allows, please see Fig. 4, to retract the drill string with the swab cup (31) in its lower, closing position as the annulus mud will be able to enter the inlet channels (54) above the swab cup, and the mud will subsequently pass downward through the central bore (35) and exit via the milling or drilling bit to the casing below the milling or drilling bit and above the dressed cement plug. The tool may then be pulled out of the hole, so-called

"POOH".

In the embodiment shown in Figs, 1, 2,3, and 4, please also see details in Fig. 6c, the tool section (3, 30a) comprises a ball-releasable valve sleeve (50) in said axial bore (35) allowing axial flow in a radially closed positon, and allowing influx from radial inlet channels (54) to said axial bore (35) in an open position. The inlet ports are arranged above said swab cup's (31) upper position. The inlet port valve mechanism may comprise a ball (53)-releasable valve sleeve (50) in a valve cylinder seat (51) blocking radial channels (54) from said valve cylinder seat (51) in its closed position, and a bypass chamber (52) in the central bore (35). When the valve sleeve 50) is in the bypass chamber (52), fluid will pass in radially, then out axially, even with the ball present.

In an embodiment of the invention shown in Figs. 5, 6, and 7, the swab cup body (31) is provided with a cylindrical bore (310) comprising a sleeve stem (31s) slidable on the tool stem (3, 30b) onto which said swab cup (31) body is mounted. in the lower position of the swab cup body (31) the sleeve stem (31s) doses about the lower, groove-free portion of stem (30b) by landing onto the shoulder of the lower slide stop (32). Seals may be arranged in ring grooves on the lower slide stop (32). In the upper position of the swab cup body (31) there is no need for seals at the upper slide stop (33) as the fluid shall pass through the axial-parallel grooves (34), please see Fig. 8. The sleeve stem (31s) of the swab cup body (31) may have a radial bearing, e.g. comprising an inner liner layer of brass for reducing friction between the stem portion (30b) when sliding or when the drill string is rotated during the dressing of the cement plug. Further, the swab cup may be provided with an axial bearing against the upper slide stopper (33) for avoiding the swab cup being rotated by the rotating drill string.

Method:

Pressure Integrity testing

In an embodiment of the invention it is also a method of testing the pressure integrity of a casing (100) using the testing tool section (3) of the invention. - running said testing tool section (3) to a target depth in said casing (100) with said valve cylinder seat closed and said swab cup body (31) displaced to an open position by pressure from below,

- halting the test tool section (3) at target depth,

- optionally, closing the central bore (35) either by closing the drill pipe string at surface or keeping valve (5) closed

- verifying pressure integrity of said casing (100) above the swab cup (31).

At this stage, we have only verified the pressure integrity using the swab cup of the invention, we have not yet arrived at the dressing and tagging, this is just pressure testing so far.

Dressing and tagging

In an embodiment of the invention, after håving verified the pressure integrity, one may dress and tag as follows: - using a drilling or milling bit (2) mounted below said testing tool section (3) to drill away an upper part of the top of a cement plug to uncover proper cement,

- tag test said dressed cement plug and verify its integrity,

- pull said testing tool section (3) and the drilling bit out of hole.

The tagging can be done by mechanical loading using the drilling or milling bit itself to transfer weight onto the top of the cement.

After the pressure integrity testing, or after the dressing and tagging procedure, one may open the valve (5, 54) to allow radial influx flow from the casing bore above the swab cup (31) into the central bore (35), for allowing pulling the tool out of hole.

Claims

1. A drill pipe string (l)-conveyed pressure integrity test tool section (3) for a casing (100), comprising - a cylindrical tool stem (30) håving an axial bore (35) and upper and lower tool joints (11,12) to said drill pipe string (1) and a drilling or milling bit (2); - an annulus check valve for closing downward annulus flow relative to the check valve (31v) comprising a check valve body (31) on said tool stem (30), characterized in thatsaid check valve (31v) comprises - an upwardly directed swab cup body (31) with an axial cylindrical bore (310) tightly fitting and sliding on said tool stem (30) between a lower and an upper slide stopper (32, 33); - axial-parallel bypass grooves (34) arranged on said tool stem (30) extending across said upper slide stopper (33) for allowing annulus flow upwardly when the swab cup is at the upper slide stopper (33); - said swab cup (31) blocking tool annulus flow in the downward direction when stopping at said lower slide stopper (32) away from said bypass grooves on the tool stem (30).

2. The pressure integrity test tool section (3) of claim 1, comprising a ball-releasable valve sleeve (50) in said axial bore (35) allowing axial flow in a radially closed positon, and allowing influx from radial inlet channels (54) to said axial bore (35) in an open position.

3. The pressure integrity test tool section (3) of claim 2, comprising a ball (53)-releasable valve sleeve (50) in a valve cylinder seat (51) blocking radial channels (54) from said valve cylinder seat (51) in its closed position.

4. The pressure integrity test tool section (3) of any of claims 1-3, said swab cup body (31) provided with a cylindrical axial bore (310) constituted by a sleeve stem (31s) onto which said swab cup (31) body is mounted slidable on said tool stem (30).

5. A method of testing the pressure integrity of a casing (100) using the pressure integrity test tool section (3) of any of claims 1-4, characterized in- running said pressure integrity test tool section (3) to a target depth in said casing (100) with said swab cup body (31) displaced to an open position by pressure from below, - halting the pressure integrity test tool section (3) at target depth, - closing the central bore (35); - increasing pressure in the casing bore to displace the swab cup (31) to its lower, closing position, - verifying pressure integrity of said casing (100) above the swab cup (31).

6. The method of claim 5, running to said target depth with a valve cylinder seat (51) in said bore (35) closed and opening said valve (5) to allow radial influx flow from the casing bore above the swab cup (31) into the central bore (35), and pulling the tool out of hole.

7. The method of claim 5 or 6, closing the central bore (35) either by closing the drill pipe string at surface or keeping valve (5) closed.

8. The method of claim 5, 6 or 7 - after håving verified the pressure integrity, - using a drilling or milling bit (2) mounted below said testing tool section (3) to drill away an upper part of the top of a cement plug to uncover proper cement, - tag test said dressed cement plug and verifying its integrity, - pull said testing tool section (3) out of hole.