WO2016060570A1

WO2016060570A1 - Cementing method allowing initial liner top pressure integrity confirmation

Info

Publication number: WO2016060570A1
Application number: PCT/NO2015/050190
Authority: WO
Inventors: Barton Sponchia; Lars Norheim; Brett Hrabovsky
Original assignee: Archer Oiltools AS
Current assignee: Archer Oiltools AS
Priority date: 2014-10-14
Filing date: 2015-10-14
Publication date: 2016-04-21
Anticipated expiration: 2017-04-14

Abstract

Cementing takes place after a hanger (38) and seal (39) are set to first insure the pressure integrity of the connection between the string to be cemented and the existing tubular. Cementing top down or bottom up is envisioned with either displaced fluid returning toward the surface in a crossover tool (25-29) or with the displaced fluid squeezed into the formation. A work string manipulates the crossover for reversing out after cementing. For running in a valve assembly (1, 2) is held open to permit circulation. Work string manipulation allows at least one valve that keeps the cement in the annulus to close and at least one other valve to close that keeps the reverse fluid from leaving the cemented tubular to allow such flow to return to the crossover and out to the surface. Valve release can be done with a pressure responsive sleeve instead of a stinger (100) on the running string.

Description

Cementing Method Allowing Initial Liner Top Pressure Integrity Confirmation

FIELD OF THE INVENTION

The field of the invention is cementing and more specifically a method allowing setting a liner hanger seal to determine pressure integrity of the connection before cementing bottom up or top down or with returns or by squeezing the formation.

BACKGROUND OF THE INVENTION

Typically in a cementing operation the tubular string being cemented is hung off an existing tubular with an anchor portion of a hanger while leaving the seal unset so that the delivered cement can displace fluid around the set anchor. When the cement is properly placed the hanger seal is set. However, the pressure integrity of the connection to the existing tubular cannot be determined before the cement is pumped. The displaced fluid that flows past the hanger seal can hav e debris including particles of the cement that would later foul the seal area thus preventing an adequate seal. In some instances when this happens another seal can be run in and set above the seal that did not properly seal off pressure. This is an expensive and time consuming process. It is more advantageous to be able to determine the integrity of the connection before cementing begins and one of the objectives of the present invention is to provide equipment that facilitates a method to accomplish this goal.

Many times when a cement job is done in a top to bottom direction the displaced fluid is simply pushed into the formation. This is called squeeze cementing and is commonly done because typical cement shoes, which are the one way valv e assemblies at the bottom of a string being cemented allow cement out of the string in a conv entional cement job (bottom up) but block return flow. If doing a top down cement job a standard shoe would block displaced fluid trying to come back into the string. As a result top down cementing is done with squeezing displaced fluid into the formation. Squeezing the formation can adversely affect subsequent production. ON THE TECHNICAL SOLUTION

The method of the present invention allows for fluid displacement into a work string during cementing as well as preventing fluid from the surface coming down the work string from getting out of the tubular string lower end to facilitate a reversing out of excess cement after a cement job.

With the equipment provided, a cement job can be run in the standard way of bottom up or it can be done in a reverse direction of top down while taking displaced fluid or with a squeeze configuration, all with the liner hanger seal already set so that the pressure integrity of the connection to the existing tubular can be confirmed before cement is pumped.

This flexibility is provided with a sub that has a stack of valves, preferably full opening flappers. One or more lowermost valves are held open when running in with a stinger connected to a running string or a pressure actuated sleeve. At least one uppermost valve is initially held open for running in but when released to operate prevents cement flow into the tubular string. The lowermost flappers permit displaced fluid into the tubular string when pumping cement top down and hold against a reversing out fluid stream coming down the liner to remove excess cement. A cement crossover allows the cement to exit to the annulus near the top of the string and below the tubular hanger and seal. Isolators are provided for the running string that can be dart activated as a backup to close the return path from the crossover in the event the flappers are not properly released. In the alternative with no inner string extending to the flappers a packer is alternatively provided on the stinger assembly for the flappers that can be dart actuated to close off the liner in an emergency if the flappers fail to actuate.

These and other aspects of the present invention will become more readily apparent from a review of the description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention can be determined from the appended claims.

SHORT SUMMARY OF THE INVENTION

The invention is a well completion method for supporting and cementing a tubular string from an existing tubular and a well liner cementing assembly comprising

More specific, the invention is a petroleum well completion method for supporting and cementing a tubular string from an existing tubular comprising running in, on a running string, said tubular string with a hanger and seal assembly to position said hanger and seal assembly by the desired location on the existing tubular, setting the hanger and seal, pressure testing the integrity of the connection between the string and the existing tubular after said setting, then after said setting and said pressure testing, cementing said tubular string .

The invention is also a petroleum well l iner cementing assembly comprising a dri l l pipe string w ith a tubular string release tool arranged for holding a liner hanger setting sleeve of a liner string said liner string provided w ith a l iner hanger and seal assembly, said l iner string provided w ith an annulus cementing port operated by a crossover tool assembly arranged on said dri ll pipe string below said tubular string release tool, said liner string provided w ith low er valves held open during running in by a cementing stinger arranged below said crossover tool assembly, and said seal assembly al low ing pressure testing when said liner hanger is set in a casing.

Cementing takes place after a hanger and seal are set to first insure the pressure integrity of the connection between the string to be cemented and the existing tubular. Cementing top dow n or bottom up is envisioned with either displaced fluid returning tow ard the surface in a crossover tool or with the displaced fluid squeezed into the formation. A work string manipulates the crossover for reversing out after cementing. For running in a valv e assembly is held open to perm it circulation. Work string manipulation allows at least one v alve that keeps the cement in the annulus to close and at least one other valv e to close that keeps the reverse fluid from leav ing the cemented tubular to allow such flow to return to the crossover and out to the surface. Valve release can be done with a pressure responsive sleev e instead of a stinger on the running string.

BRIEF DESCRIPTION OF THE DRAWINGS

The attached figures i l l ustrate some em bodi ments of the clai med i nvention .

FIG. 0 is a simpl ified sketch il lustrating a wel l bore with a wellhead, casing, with casing shoe, extending from the sea bed surface, a tubular string (35) and a running string (43 ).

FIGS, l a- l e is a combined partial elevation view and partial section view of a l iner string and a tool string. The figure show the flow scheme for fluid circulation when running in with an inner string stinger (100) at a lower end. The casing extends from the surface, and the l iner ( 35 ) extends from the casing. A tubular string release tool (42 ) is show n at the top of the new tubular string ( 35 ). FIGS. 2 a- 2c is a combined partial elevation view and partial section view of a l iner string and a tool string and showing the inner string l ifted for the cementing position with flappers released that allow displaced fluid into the string from the annulus being cemented.

FIGS 3a-3c are the same as 2a-2c with the flow direction reversed after release of a valve to hold fluid in the string to allow for removal of excess cement.

FIG. 4 is a detailed combined partial elevation view and partial section view of the valve assembly when circulating during running in and with no stinger in the work string.

1 IG. 5 is the view of FIG. 4 during cementing with the two lower flappers (2) released to operate.

1 IG. 6 is the view of FIG. 5 with the top flapper (1 ) released to operate.

I IG. 7 is the view of FIG. 6 showing the reverse out flow for removing excess cement.

I IG. 8 shows the stinger v ariation holding valves open to allow circulation when running in. FIGS. 9 and 1 0 show the stinger lifted to allow the lower two flappers (2) to operate with a top down cementing flow.

FIGS. 1 1 and 12 are the view of FIGS. 9 and 10 with the top flapper released to accommodate reversing out excess cement.

DESCRIPTION OF THE INVENTION

The inv ention will in the following be described and embodiments of the invention will be explained with reference to the accompanying drawings.

Before a detailed discussion of the components that facilitate the method are discussed, a general review of the method will serve as an introduction.

A tubular string to be cemented is delivered through an existing string so that a hanger/seal of the string to be cemented is positioned near the lower end of the existing tubular. Unlike prior cementing methods, both the anchor and the seal are actuated from the string to be cemented against the existing string so that the pressure integrity of the connection is tested before cementing begins. During running in for proper position of the hanger/seal, also commonly referred to as a l iner hanger when the string to be hung and sealed is a liner string, circulation is enabled through a lower valve sub as the valves are al l open. References hereafter to "liner hanger" are intended to include structures that support and seal a l iner or a casing string. Return flow comes up the annu lus outside the string being run in. After the l iner hanger is ful ly deployed and the pressure integrity test is completed, the cementing can begin. The work string is released from the now set liner hanger and raised up to pull a stinger from at least one flapper that opens when displaced fluids from the annulus in a top down cementing operation are pushed into the tubular string. After the cement is placed another flapper is released that prevents cement from leaving the annulus and flowing into the string just cemented. The flow direction is reversed from the cementing step through a crossover where the flow is now inside the string but around the running string. The initial flapper that was allowed to operate when picking up now blocks the flow within the string and around the running string forcing the flow with the excess cement back up through the running string and to the surface through the crossover. The inner string is then removed and the top down cementing job done with taking displaced fluid returns toward the surface is complete. As an alternative to releasing the valves in the valve sub to be functional using a stinger lifted out of them as described above, another way is to use pressure sensitive sleeves that shear at different pressures to first release the valve or valves that allow displaced returns into the string being cemented and following the cement placement in a top down direction to release another valve that keeps fluid from leaving the tubular so that a reversing out of excess cement can be accomplished. In this variation a backup is made available if the flappers fail to close to hold the cement in the annulus by closing off inside the string using a dart dropped in a bushing. After the cement sets the inside of the string can be milled to remove any cement with up to the bushing.

With the above as an introduction the assembly with the removable stinger 100 extends from connection 16 in FIG. le down to debris sub and sleeve catcher 4 at a lower end. Fig. le shows the full IH circulation path continued. In between are a quick connect coupling 11, 12; a no go and shear up locator 7 and a float valve 8. For running in, the stinger 100 holds open the shear flapper valve 1, also considered the second flapper valve, and the reverse flapper valves 2, also considered the first flapper valve, of which there are two illustrated with one to back up the other. The shear flapper valve 1 prevents flow into the guide shoe 6 from the annulus 102 when the cement is delivered there, preferably from a top down direction. The reverse flapper valves 2 allow fluid displaced by the delivered cement to pass into the shoe 6 and the debris baffle plate 5. Holes 104 are sealed off by seal 9 in the running in position. Flow into the stinger 100 during running in is represented by arrows 106 with arrows 108 representing return flow in annulus 102 toward the surface as will be explained below with regard to FIGS. 1 a- 1 d showing the remainder of the assembly above FIG. le.

Referring to FIG. l a shows the running string 43 supporting the tubular string release tool 42 in suspending the liner hanger 38 that has a seal 39. Tool 42 is connected to liner hanger setting sleeve 40 in a re leasable manner. Fig. l a shows a full R I H path contiuned. In FIG. l b the packoff bushing 37 is fitted into polished bore receptacle 36 to close off annular space 110 to direct circulation flow along the path delineated by arrows 106 and 108. The liner or casing is 35 and the cement ports are 34. Items 32 and 33 collets used in location of the crossover tool assembly 25-29 shown in FIG. l c for cement delivery out ports 34. Fig. 1 c shows a full RIH path continued. Expansion joints 30 can also b used adjacent the crossover tool assembly 25-29. The crossover tool assembly 25-29 continues to connection 8 in FIG. I d and includes standard features such as a ball seat 19, a back flow check valve 20, a shroud for a dart catcher 21 and a dart catcher with no flow through 22. Operations at surface are done in an order which is common to the industry so no retraining is required. Fig. I d shows a full R I H circulation path continued. The shrouded bypass port and dart catcher permit a continuous flow in the direction desired.

As seen in 1 IG. l c the circulation flow down is reflected by arrows 106 is forced through the crossover tool assembly 25-29 down past connection 18 and through the stinger 100 with holes 104 isolated until an exit through the guide shoe 6 followed by return to the surface as indicated by arrows 108 around the outside of the liner or casing string 35. Fig. l c shows the full RI H circulation path continued.

When the liner hanger 38 is properly located, its anchor assembly and seal 39 are set with sleeve 40 and the running tool 42 can release. A pressure integrity test can be run on the seal 39. In Fig. 2a the return flow is shown via the work string annulus within the casing. The running string is picked up as shown in FIGS. 2a-2c. Doing so lifts the bushing 37 out of the polished bore receptacle 36 as also shown in FIG. 2a. It also aligns the crossover assembly 25-29 with the cement ports 34 as shown in FIG. 2b. In flow crosses from internal to external in the crossover tool. Ports 104 in stinger 100 are now open and the stinger has come ful l out of the reverse flapper valves 2 and the shear flapper valve 1. However, sleeve 112 is still holding shear flapper valve 1 open in I IG. 2c. As a result when cement is pumped down the running string 43 as indicated by arrows 113, the flow crosses over in I IG. 2b to outside the string 35 at ports 34 and continues down the annulus 102 into guide shoe 6 that can have uniquely configured flow ports to accommodate the cement. Ahead of the cement flow represented by arrows 113 fluid is displaced as indicated by arrows 114 through the valves 1 and 2, w ith valve 1 held open at this stage and valves 2 being pushed open by the displaced fluid. Valves 2 allow one way flow into guide shoe 6 but stop flow in the direction for getting out of the string 35 through guide shoe 6.

When the cement is delivered to the annulus 102, pressure is bui lt up to put a force on sleeve 112 to break a shear pin that is not shown that w ill then al low the sleeve 112 to shift downward away from flapper 1 to release it to operate. Flapper 1 is oriented to prevent flow into string 35 but opens when reversing out the excess cement as shown in FIG. 3. However, valves 2 are operational to cause the flow direction to reverse from incoming flow indicated by arrows

116 to return flow indicated by arrows 118 as the reverse flow passes through holes 104. The top down cementing done after setting a liner hanger seal and pressure testing the connection to the existing tubular is now complete. The top down cementing occurs with displaced fluid going toward the surface through the crossover as illustrated but the operation can also be done as a squeeze into the formation if the return path through the crossover is closed off.

There is an alternative way to operate the flappers 1 and 2 without the stinger 00. In FIG. 4 sleeve 3 holds open flappers 2 for running in w ith holes 120 sealed off so that circulation flow for running in indicated by arrow 22 passes through the sleeve 3 as well as flappers 1 and 2 and then through guide shoe 6 and back to the surface in the annulus 102 through the crossover assembly that is not shown in 1 IG. 4. As before sleeve 112 keeps flapper 1 open during running in. In I IG. 5 sleeve 3 is shifted w ith applied pressure to release valves 2 to operate in the manner described before. Cement comes top down as indicated by arrows 124 displacing well fluid through holes 120 and valves 1 and 2. Valves 2 are pushed open by the displaced fluid while valv e 1 is still held open. Returning flow represented by arrows 126 goes to the surface through the crossover assembly that is not shown in FIG. 5. In FIG. 6 applied pressure has put a force on sleev e 112 to allow valve 1 the freedom to operate to keep cement from leaving the surrounding annulus 102. Once v alve 1 is operational, reverse flow represented by arrow 128 comes down and opens valve 1 but is stopped by valves 2 and returns uphole to the surface through the crossover. In this embodiment seal 37' can be used in addition to seal 37 but in a lower location as show n in FIG. le with the idea that if valve 1 fails the cement can be retained in the annulus 102 dropping a dart into seal 37' while that seal is positioned in a respective polished bore receptacle or is otherwise in sealing contact with the string 35.

FIG. 8 shows an enlarged view of the stinger 100 running through the valves 1 and 2 for running in to allow circulation out through guide shoe 6 and back to the surface as illustrated with arrows 130. FIGS. 9 and 10 shows valves 2 operative after the stinger 100 is raised and arrows 132 being the top down cementing while well fluids are displaced ahead of the cement as indicated by arrows 134. FIGS. 1 1 and 12 show the valve 1 operative after cementing due to sleeve 112 movement so that cement is prevented from u-tubing back into the string 35. The reverse out flow indicated by arrow 136 can push valve 1 open but valves 2 block flow in the direction out of string 35 so that the excess cement can flow through the crossover that is not shown and toward the surface for removal.

Those skilled in the art will appreciate that while flappers are shown for valves 1 and 2 that other types of valves are contemplated that can be selectively operated with ways other than string manipulation or applying pressure to create a net force to move a sleeve. Valves 1 and 2 can have redundant backup or not as deemed necessary by the operator or by cost considerations. The term "cement" is intended to include any and all known sealing materials. Some of the components have just been mentioned with regard to their function such as the crossover tool or various collet systems used for its positioning. These components have been generally described because they are components well known to those skilled in the art. The position, placement and operation of the valves such as flappers 1 and 2 and how they are integrated into the described method is the actual focus of the claimed method.

The system allows the liner hanger and its seal to be set so that the pressure integrity of the connection to the existing tubular can be determined ahead of the start of cementing.

Cementing can then be done top down with fluid displaced towards the surface or squeezed into the formation. A standard cement job from bottom up can also be undertaken.

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 well completion method for supporting and cementing a tubular string (35) from an existing tubular comprising:

running in, on a running string (43), said tubular string (35 ) with a hanger (38) and seal assembly (39) to position said hanger (38 ) and seal assembly (39) by the desired location on the existing tubular:

setting the hanger ( 38 ) and seal (39);

pressure testing the integrity of the connection between the string (43, 38, 39, 35 ) and the existing tubular after said setting;

cementing said tubular string (35 ) after said setting and said pressure testing.

2. The method of claim 1, comprising:

performing said cementing of said tubular string (35 ) top down.

3. The method of claim 2, comprising:

allowing fluid displaced by said cementing into the tubular string (35 ).

4. The method of claim 2, comprising:

squeezing fluid displaced by said cementing of said tubular string ( 35 ) into a surrounding geological formation.

5. The method of claim 1, comprising:

performing said cementing of said tubular string (35 ) bottom up.

6. The method of claim 1, comprising:

circulating fluid through said tubular running string (43 ) and said tubular string (35 ) when running in, through a plurality of open valves (1 , 2) located near a lower end of the tubular string (35).

7. The method of claim 6. comprising:

initially holding open said valves (1, 2) for circulating fluid .

8. The method of claim 6, comprising:

providing at least one of said valves (1, 2) as a selectively operable first check valve (2) allowing flow into said lower end of said tubular string (35) when operable and another of said valves (1,2) as a selectively operable second one way valve (1) preventing flow into said tubular string (35) when operable.

9. The method of claim 8, comprising:

locating said second check valve (1) closer to a surface location than said first check valve (2).

10. The method of claim 9, comprising:

making said first and second check valves (1,2) flapper valves.

1 1. The method of claim 10, comprising:

holding said first flapper valve (2) open with a stinger (100) connected to a running string (43); allowing said flapper valve (2) to operate by raising said stinger (100) with a running string (43).

12. The method of claim 10, comprising:

holding said second flapper valve (1) open with a second flapper sliding sleeve (112);

using applied pressure in the tubular string (35) to shift said second flapper sliding sleeve (1 12) to enable said second flapper (1) to operate.

13. The method of claim 10, comprising:

holding said second flapper (1) open with a sliding sleeve;

using applied pressure in the tubular string (35) to shift said sleeve (1 12) to enable said another flapper valve associated with said sleeve (112) to operate.

14. The method of claim 12, comprising:

performing said raising of said stinger (100) after said fluid circulating and before said reverse cementing circulation.

15. The method of claim 14, comprising:

performing shifting said sliding sleeve (1 12) after said cementing to enable said second flapper valve (1) to keep cement in a surrounding annulus (102).

16. The method of claim 15, comprising:

using said first flapper valve (2) to redirect reversing flow in said tubular string (35) to take out excess cement.

17. The method of claim 16, comprising:

using a crossover tool (25-29) in said running string (43);

directing reversing out excess cement flow to outside said running string (43) at said crossover tool (25-29) and taking returns with the excess cement through said crossover tool (25 - 29) and out to a surface location via an annular space (1 10) between said running string (43) and said tubular string (35).

18. The method of claim 17, comprising:

providing redundant first or second flapper valves (1,2).

19. The method of claim 12, comprising:

holding said first flapper valve (2) open with a first flapper sliding sleeve (3);

using applied pressure in the tubular string to shift said first flapper sliding sleeve (3) to enable said first flapper v alve (2) to operate.

20. The method of claim 19, comprising:

moving said first flapper sliding sleeve (3) before said second flapper sliding sleeve (1 12).

2 1 . The method of claim 20, comprising: cementing after moving said first sliding sleeve (3);

using said first flapper valve (2) when made operable by said mov ing said first flapper sliding sleeve (3) to allow fluid displaced by cement to enter said tubular string (35).

22. The method of claim 2 1 , comprising:

moving said second flapper valve (1) sliding sleeve (1 12) after delivering the cement;

using said second flapper valve (1) made operable by moving said second flapper sliding sleeve (1 12) to prevent cement in the annular space (102) around said tubular string from entering the tubular string (35).

23. The method of claim 2 1 , comprising:

deflecting open said second flapper valve (1) with reverse flow into said tubular string (35)from a surface location after said cementing;

redirecting said reverse flow in said tubular string w ith said first flapper valve (2) to remove excess cement toward a surface location.

24. The method of claim 19, comprising:

providing a selectively operable seal in an annular space (1 10) between said running string (43) and said tubular string (35);

positioning said seal(37') in a sealing position and blocking said running string (43) adjacent said seal (37') to retain cement in the surrounding annulus (102) should said second flapper valve (1) fail to operate.

25. A petroleum well liner cementing assembly comprising

- a drill pipe string (43) with a tubular string release tool (42 ) arranged for holding a liner hanger setting sleeve (40) of a liner string (35);

- said liner string (35) prov ided with a liner hanger (38) and seal (39) assembly;

- said liner string (35) provided with an annulus cementing port (34) operated by a crossover tool assembly ( 25 -29) arranged on said drill pipe string (43) below said tubular string release tool (42 ):- said liner string provided with lover valves (1, 2) held open during running in by a cementing stinger (100) arranged below said crossover tool assembly (25 - 29);

- said seal assembly (39) allowing pressure testing when said l iner hanger (38) is set in a casing.

26. The liner cementing assembly of claim 25, said crossover tool assembly ( 25 - 29) arranged for shifting a cementing section's v alve sleeve (34b ) to open cementing ports (34) w hile said cementing stinger (100) is shifted upwards out of said lover valves (1, 2), allowing reverse circulating in of cement from said cement ports (34) to the liner annulus and back through said lower valves (1, 2) of said liner string (35).

27. The liner cementing assembly of claim 26, said valves (1, 2) arranged for being shut after reverse circulating in of cement, so as for allowing normal circulation washing out of excess cement within said liner below said crossover tool (25 - 29) having shut said cement ports (34).

28. The liner cementing assembly of claim 26, said running string (43) arranged for normal circulating down of cement above said crossover tool assembly (25 - 29).

29. The liner cementing assembly of claim 27, the running string (43) arranged for reverse circulating down the running string's (43) annulus within the existing tubing and set liner (35) during excess cement wash-out.

NARROW CLAIMS

Method

30. A well completion method for supporting and cementing a liner string (35) on a running string (43), from an existing casing,

comprising :

- providing said running string (43) with a packoff bushing (37) fitted into a polished bore receptacle (36) of said liner string (35) below a liner hanger (38) and seal assembly (39),

- said liner string (35) provided with a cementing section valve sleeve (34b) initially holding closed an annulus cementing port (34) operated by a crossover tool assembly (25-29) arranged on said drill pipe string (43) below said tubular string release tool (42) ;

- running in, on said running string (43), said liner string

(35) with a hanger (38) and seal assembly (39) to position said hanger (38) and seal assembly (39) by the desired location on the existing casing;

- while running in, circulating fluid through said tubular running string (43) and said liner string (35) through one or more open valves (1, 2) located near a lower end of said liner string (35), said valves (1, 2) held open by a lower stinger (100) of said running string (43);

- setting the hanger (38) and seal (39);

- pressure testing the integrity of the connection between the string (43, 38, 39, 35 ) and the existing casing after said setting;

- elevating said running string (43) so as for releasing said liner string (35), releasing said packoff bushing (37) from said polished bore receptacle (36), shifting said annulus cementing port (34) open by said crossover tool assembly (25 - 29), and releasing said stinger (100) from said lower valves (2, 1 ) ;

- reverse circulating top down cementing said liner string (35) annulus via said annulus cementing port (34) and allowing return fluids back via said lower valves (2, 1) and said stinger (100) within said liner string (35) .

31. The method of claim 30, comprising:

providing at least one of said valves (1, 2) as a selectively operable first check valve (2) allowing flow into said lower end of said liner string (35) when operable and another of said valves (1,2) as a selectively operable second one way valve (1) preventing flow into said tubular string (35) when operable.

32. The method of claim 30 or 31, comprising:

locating said second check valve (1) closer to a surface location than said first check valve (2) .

33. The method of claim 30 - 32, comprising:

making said first and second check valves (1,2) flapper valves.

34. The method of any of claim 30 - 33, comprising:

using applied pressure in the liner string (35) to shift said second flapper sliding sleeve (112) to enable said second flapper (1) to operate.

35. The method of any of claim 30 - 33, comprising:

holding said second flapper (1) open with a sliding sleeve;

using applied pressure in the tubular string (35) to shift said sleeve (112) to enable said another flapper valve associated with said sleeve (112) to operate.

36. The method of any of claim 30 - 35, comprising:

37. The method of any of claim 30 - 36, comprising:

performing shifting said sliding sleeve (112) after said cementing to enable said second flapper valve (1) to keep cement in a surrounding annulus (102) .

38. The method of any of claim 30 - 37, comprising:

39. The method of any of claim 30 - 38, comprising:

using said crossover tool (25-29) in said running string (43); directing reversing out excess cement flow to outside said running string (43) at said crossover tool (25-29) and taking returns with the excess cement through said crossover tool (25 - 29) and out to a surface location via an annular space (110) between said running string (43) and said tubular string (35) .

40. The method of any of claim 30 - 39, comprising:

providing redundant first or second flapper valves (1,2) .

Narrow Device claims

41. A petroleum well liner cementing assembly comprising

- a drill pipe running string (43) with a tubular string release tool (42) arranged for holding a liner hanger setting sleeve (40) of a liner string (35);

- said liner string (35) provided with a liner hanger (38) and seal (39) assembly;

- said running string (43), provided with a packoff bushing (37) fitted into a polished bore receptacle (36) of said liner string (35) below said hanger (38) and seal assembly (39),

- said seal assembly (39) and said packoff bushing (37) together allowing pressure testing when said liner hanger (38) is set in a casing,

- said liner string (35) provided with lower valves (1, 2) arranged for being held open during running in by a stinger (100) arranged below said crossover tool assembly (25 - 29) on said running string (43);

- said crossover tool assembly (25 - 29) on said running string (43) arranged for shifting said cementing section's valve sleeve (34b) to open said cementing ports (34) while said cementing stinger (100) is shifted upwards out of said lower valves (1, 2), allowing top down reverse circulating in of cement from said cement ports (34) to the liner annulus and with return back through said lower valves (1, 2) of said liner string (35) .

42. The liner cementing assembly of claim 41, said valves (1, 2) arranged for being shut after reverse circulating in of cement, so as for allowing normal circulation washing out of excess cement within said liner below said crossover tool (25 - 29) having shut said cement ports (34) .

43. The liner cementing assembly of any of claim 41 - 42, said running string (43) arranged for normal circulating down of cement above said crossover tool assembly (25 - 29) .

44. The liner cementing assembly of any of claim 41 - 43, the running string (43) arranged for reverse circulating down the running string's (43) annulus within the existing tubing and set liner (35) during excess cement wash-out.