SELECTIVE MULTI-STAGE CEMENTING OF CASING

Abstract

An apparatus and a method for cementing a casing in various elevations is disclosed. A casing string having at least one cementing valve is lowered into a borehole. In the closed position, the valve prevents fluid communication between the interior and exterior of the casing. In the opened position, the valve allows fluid communication between the interior and the exterior of the casing so that cement is pumped therethrough to cement the borehole adjacent the valve at the borehole elevation where the valve is located. Opening of the valve is effected by landing on the valve an opening dart having a unique profile corresponding to the valve and applying pressure on the dart to move a sleeve in the valve to a first position exposing radial ports in the casing. The valve is closed by landing a dart on the opening dart and applying pressure thereon to move the sleeve to a second position to close the ports.

Description

RELATED PRIORITY DATE APPLICATION

This application claims the benefit under 35 U.S.C. 119(e) of the U.S. provisional application No. 62/561,114 filed on Sep. 20, 2017.

FIELD OF THE INVENTION

The field of the invention relates to the field of casing cementing and, more particularly, an apparatus and a method of cementing the casing in various zones in different elevations in a random order with sleeve valves having unique profiles that can be selectively opened and then closed without well intervention.

BACKGROUND OF THE INVENTION

It is well known that cementing operations are done in a bottom up orientation where stage tools are opened and closed as the operations are moved up the hole by the use of cement wiper plugs. Selective placement of cement is possible with the use of a shifting tool on drill pipe. Casing inflation packers are required, however, to prevent the cementing hydrostatic head from breaking down the formation. Casing inflation packers can also be used to relieve excessive hydrostatics pressure or to isolate an area of the wellbore where cement is not desired. When cementing wiper plugs are used this is a bottom up operation and the plugs have to be drilled out to open the casing passage for completion or further drilling operations. Stage tools that require the use of shifting tools require the use of drill pipe whereby a substantial amount of time is required to run and retrieve the drill pipe.

The disadvantages of the prior art cementing methods and apparatus used therein is overcome by the present invention wherein an apparatus and a method are disclosed to cement in any desired sequence without the use of well intervention. The method is accomplished with sliding sleeve valves with unique profiles to accept darts with matching profiles. A selected valve receives a dart with a predetermined profile matching the unique valve profile to allow subsequent pressure buildup to shift the sleeve to an opened position wherein ports in the casing provide fluid communication between the interior and the exterior of the casing. After the well cementing operation through the opened ports is completed, a second dart lands on the first dart to effectively seal the valve to allow a second pressure buildup on the sleeve to shift the sleeve so that the ports are then closed. Thereafter both darts are blown through the sleeve to hole bottom.

Additional valves having unique profiles may be opened by darts having conforming profiles and closed by darts as described above to cement at different elevations. The method allows a random order of cementing without well intervention.

Another advantage of the tool used according to the present invention is that it may accommodate cementing operations either with the use of the darts, as described below, or with shifting tools.

These and other advantages of the present invention will become apparent from the following description and drawings. Those skilled in the art will further appreciate other aspects of the invention from a review of the detailed description of the preferred embodiment and the associated drawings while understanding that the full scope of the invention can be determined by the appended claims.

SUMMARY OF THE INVENTION

A casing string having at least one cementing valve that includes a slidable sleeve that closes and opens radial casing ports in the casing is lowered into a borehole. In the closed position, the sleeve closes the radial casing ports and prevents fluid communication therethrough. In the opened position, the sleeve opens the radial casing ports to allow fluid communication between the interior and the exterior of the casing.

The valve has a unique profile so that it can be sealingly engaged by an opening dart having a unique profile corresponding to the valve profile. The first dart is dropped into the valve and sealingly engages the valve. Pressure is applied on the opening dart to move the slidable sleeve to expose the radial casing ports to allow for the fluid communication between the interior and exterior of the casing. After the valve is opened, cement is pumped through the casing ports to the exterior of the casing at the borehole elevation where the valve is located. Following the completion of the cementing operation through the valve, a second dart lands on the opening dart to seal the valve. Pressure is applied on the second dart to move the sleeve to a second position to close the casing ports.

Additional similar valves having their own corresponding unique profiles may be located at various elevations above the valve to perform additional cementing at the corresponding elevation by being opened with darts having their own unique profiles corresponding to the unique profile of a specific valve being opened. Each of those valves is closed with a dart that lands on the opening dart to effect the closing of the specific valve, as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of the preferred embodiment of the invention, reference will now be made to the accompanying drawings wherein:

FIG. 1 shows the basic system components;

FIG. 2 is a detailed view of a cementing valve that is part of the system;

FIG. 3 is the view of FIG. 2 with the first dart landed in a matching profile;

FIG. 4 is the view of FIG. 3 with the valve shifted to the open cementing position;

FIG. 5 is the view of FIG. 4 with a second dart landed and ready to further shift the valve in the same direction for closure;

FIG. 6 is the view of FIG. 5 with the valve shifted closed;

FIG. 7 is a view of a first zone furthest uphole being treated first;

FIG. 8 is schematic of the initial step of the present invention showing the lowering of the apparatus of the present invention in a borehole prior to the primary cementing operation;

FIG. 9 is a schematic showing the system of FIG. 8 following the primary cementing operation;

FIG. 10 is a schematic showing the system of FIG. 9 with an opening dart lowered therein;

FIG. 11 is a schematic showing the system of FIG. 10 with pressure being applied to open the valve;

FIG. 12 is a schematic showing the system of FIG. 11 in the cementing operation;

FIG. 13 is a schematic showing the system of FIG. 11 after the completion of the cementing operation with a closing dart lowered therein;

FIG. 14 is a schematic showing the system of FIG. 11 after the completion of the cementing operation with a closing dart landed on the opening dart;

FIG. 15 is a schematic showing the system of FIG. 14 with pressure applied on the closing dart to close the valve;

FIG. 16 is a schematic showing the system of FIG. 15 with increased pressure applied on the closing dart to shear out the opening dart and allow both darts to fall into the bottom; and

FIG. 17 is a schematic showing the system of FIG. 15 with both opening and closing darts resting at the bottom of the system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

According to the present invention, a casing string having at least one cementing valve that includes a slidable sleeve that closes and opens radial casing ports in the casing is lowered into a borehole. In the closed position, the valve closes the radial casing ports and prevents fluid communication therethrough. In the opened position, the valve opens the radial casing ports to allow fluid communication between the interior and the exterior of the casing. The valve has a unique profile so that it can be sealingly engaged by a first dart having a profile corresponding to the valve profile to effect opening of the valve as hereinafter described. A second dart lands on the first dart to seal the valve and effect closing of the valve. The valve is opened to pump cement through the casing ports to the exterior of the casing at the borehole elevation where the valve is located. Additional similar valves having their own corresponding unique profiles may be located at various elevations above the valve to perform additional cementing at the corresponding elevation by being opened with darts having their own unique profiles corresponding to the unique profile of a specific valve being opened. Each of those valves is closed with a dart that lands on the opening dart to effect the closing of the specific valve.

Referring now to FIG. 1, a schematic of the bottom portion of a casing 20 comprised of casing tubes connected in series and having a cementing valve 22 disposed therein. Similar cementing valves (not shown) are disposed and strategically placed in casing 20 above the shown portion of casing 20 for cementing respective adjacent borehole sections at different elevations. The bottom of casing 20 includes a bottom hole assembly 10 having a known float guide shoe 12 with a pair of flapper valves 14 and 16 to prevent pumped cement from u-tubing back out of the annulus and into bottom hole assembly 10 during the primary cementing operation.

Cementing valve 22 is opened by virtue of an opening dart 28 that is directed downhole by free fall to engage cementing valve 22. Alternatively, dart 28 may be pumped downhole. Dart 28 has a unique profile which is shown in more detail in FIG. 7 that registers with a mating profile unique to a sliding sleeve that is part of cementing valve 22. Cementing valve 22 is closed by a second pumpable dart 36 that lands on dart 28 and with applied pressure shifts the sleeve a second time in the same direction as the initial movement of the sleeve to the closed position. After closing cementing valve 22, additional pressure buildup releases both darts 28 and 36 to the bottom.

FIG. 2 shows cementing valve 22 attached to casing 20 in more detail. Cementing valve 22 includes a sliding sleeve 34 which is rotationally locked to casing 20 by virtue of a pin 50 on casing 20 extending into a longitudinal slot 52. Casing 20 has casing ports 54 that are shown misaligned from sleeve ports 56 on sliding sleeve 34. When those ports align, the fully open position of the cementing valve 22 is achieved for performing the cementing operation. This configuration allows dart 28 to open a specific valve 22 followed by dart 36 landing on the dart 28 to reclose the valve by moving it in the same direction. Alternatively, these two movements in the same direction can be effected to open and then close the valve 22 with borehole intervention using a shifting tool on slickline, drill pipe, coiled tubing and/or a tractor device on electric line. That, for example, is shown schematically as 66 that can be used to register with at least one specific cementing valve 22 to put that valve in a desired position. Item 68 is a schematic representation of a detent device that bumps sleeve 34 progressively into different positions. This can be a biased collet that finds grooves in succession, a snap ring that progressively finds different grooves, a stepper motor that drives sleeve 34 in increments or a spring loaded j-slot responsive to pressure cycles on landed darts 28 and 36 to name a few examples.

FIGS. 3 through 6 show the sequence of the operation. In FIG. 3, dart 28 with a unique profile 30 lands into a matching profile 32 in sliding sleeve 34. Then, as shown in FIG. 4, pressure is applied from the surface or other location to slide sleeve 34 to open ports 54 for cementing when ports 56 are moved into alignment with ports 54. When the cementing is concluded, dart 36 lands on dart 28 and further pressure is applied, as shown in FIG. 5. This is made possible because dart 36 when landed on dart 28 covers ports 56, 54 so that the sleeve 34 can be moved a second time in the same direction as the initial movement that opened ports 54. Closed portion 64 lines up with ports 54 to close them as shown in FIG. 6. Continued pressure buildup blows both darts 36 and 28 into the bottom. This happens because the profile 30 on the dart 28 has a shear release that allows the profile 30 to retract into an adjacent slot (not shown) on the dart 28 body so that dart 28 with dart 36 that has landed on it can both be blown through the sleeve 34 to which dart 28 had been previously engaged.

FIG. 7 shows three cementing valves 22, 22′ and 22″. Because of the unique profile at each of these cementing valves the order of operation can be 22, 22″ then 22′ as shown in FIG. 7 or may be changed depending on the profiles of the corresponding darts 28, 28′ and 28″. The second dart 36 that would land on each dart 28 at the various valves 22 is omitted from these figures for greater clarity in illustrating that any order of sleeve 22 operation is possible when each of the sleeves have a unique latch profile including bottom up, top down or random. As mentioned before, cementing valves 22 corresponding to the various elevations can be opened and closed with or without borehole intervention as explained above. As mentioned before an index mechanism allows movement from closed to open and again to closed during the cementing phase.

Referring now to FIGS. 8 through 17 there are shown schematics representing the operations relating to the cementing valve and method of the present invention. FIG. 8 shows a casing 20 being run into a well. Casing 20 having attached thereto a closed cementing valve 22, a float collar 25 and a float shoe 27 is lowered into a borehole 21. The interior of casing 20, the space between the exterior of casing 20 and borehole 21 and the space below float shoe 27 are filled with mud 23.

Referring now to FIG. 9, there is shown the system of FIG. 8 following the primary cementing operation and the lowering of a top wiper plug 29 to float collar 25. There is shown the portion of casing 20 below float collar 25 and the exterior space between the bottom portion of casing 20 and float shoe 27, and borehole 21 being filled with cement 31. The interior of casing 20 above top wiper plug 29 and the exterior space between casing 20 and borehole 21 above cement 31 are filled with mud 23. Cementing valve 22 is closed.

Referring now to FIG. 10 there is shown the lowering of dart 28 in the system shown in FIG. 9 on cementing valve 22 and to sealingly engage it due to the unique profile correlation between the two. Cementing valve 22 is still closed.

As shown in FIG. 11, pressure is applied from above on dart 28 through mud 23 and the sleeve in cementing valve 22 is moved downwards to open cementing valve 22 and to establish communication between the interior and exterior of casing 20.

Referring now to FIG. 12, cement 41 is pumped down the interior of casing 20 above dart 28 and flows through open cementing valve 22 to the exterior of casing 20 to cement the adjacent location 43. Referring now to FIG. 13, following the cementing operation of FIG. 12, dart 36 is lowered in casing 20 to displace cement 41 from the interior of casing 20 through open cementing valve 22 while advancing towards cementing valve 22 below.

Then, as shown in FIG. 14, dart 36 lands on dart 28 and sealingly engages cementing valve 22. Thereafter, as shown in FIG. 15, pressure is applied from above on dart 36 through mud 23 to move the sliding sleeve of cementing valve 22 to close cementing valve 22.

Referring now to FIG. 16, increased pressure is applied on dart 36 to shear out dart 28 and allow both darts 28 and 36 to fall into the bottom. Cementing valve 22 is closed.

FIG. 17 shows darts 28 and 36 resting at the bottom on float collar 25. The portion of casing 20 below float collar 25 and its exterior space between the bottom portion of casing 20 and float shoe 27 and borehole 21 are filled with cement 41a. The interior of casing 20 above dart 36 is filled with mud 23 and the exterior space between casing 20 and borehole 21 above cement 41a are filled with mud 23a. Cementing valve 22 is closed. The space between casing 20 and borehole 21 above mud 23a and adjacent to cementing valve 22 is filled with cement 41b.

After cementing is completed, and the cementing valve or valves 22 are closed, the tools included to the downhole string may be locked in the closed position with a locking device such as a snap ring. The locking device may be appropriately designed so that it may unlocked by applying on it a force that is sufficiently high to unlock it and to allow for the further use of cementing valve 22 for further cementing operations. After the cementing operations, the tool may be locked again.

The tool described above may be used to perform cementing operations by either with the use of the darts, as described below, or with the use shifting tools, at the operators option.

Those skilled in the art will appreciate that the present invention enables cementing of the casing art different elevations in any needed order using objects with unique profiles that register in a specific location of a cementing valve that has the mating profile. The cementing can be done without intervention using pressurized darts.

The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below:

Claims

1. A method for selectively cementing a casing, comprising:

locating a first valve having a first valve unique profile in the casing;

delivering a first object having a matching profile to the first valve unique profile for sealingly landing on the first valve;

moving the first valve with said first object with pressure to open a first casing port through the casing, the first casing port extending from the interior of the casing to the exterior of the casing;

flowing cement from the interior of the casing to the exterior of the casing through the first casing port; and

closing the first casing port.

2. The method according to claim 1 wherein the step of closing the first casing port includes the steps of:

delivering a second object for sealingly landing on the first valve; and

moving the first valve with the second object with pressure to close the first casing port.

3. The method according to claim 1 further including the steps of:

locating a second valve having a second valve unique profile in the casing;

delivering a third object having a matching profile to the second valve unique profile for sealingly landing on the second valve;

moving the second valve with the second object with pressure to open a second casing port through the casing, the second casing port extending from the interior of the casing to the exterior of the casing;

flowing cement from the interior of the casing to the exterior of the casing through the second casing port; and

closing the second casing port.

4. The method according to claim 3 wherein the step of closing the second casing port includes the steps of:

delivering a fourth object for sealingly landing on the second valve; and

moving the second valve with the fourth object with pressure to close the first casing port.