GB2429722A

GB2429722A - Crossover tool for injection and production fluids

Info

Publication number: GB2429722A
Application number: GB0518101A
Authority: GB
Inventors: Neil Andrew Abercrombi Simpson; Kenneth Fraser; Iain Adams
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-09-06
Filing date: 2005-09-06
Publication date: 2007-03-07
Also published as: GB0518101D0

Abstract

A production string includes a crossover tool or crossover sub 31 which allows returning produced fluids to be directed from their route up the casing annulus 24 into the main production bore 35. The production fluids are able to exit the Christmas tree at the standard main production bore. The crossover arrangement allows for directing power fluids which are injected or pumped into and down the tubing casing annulus 32 to be redirected into the main tubing bore 26 where they can be used to aid in lifting the production fluid by powering a jet pump 34 or by co-mingling gas as artificial gas lift (figure 5). A crossover tool (figure 1) has overlapping cross flow ports (2, 3) and a landing nipple (7) for a wireline removable bridging plug; removal of the plug allows full access to the wellbore below the crossover tool. The tool can be placed at the wellhead or within the borehole.

Description

Cross Flow Apparatus for use in well bores S Background of the Invention

and description of related art In the area of oilfield production many producing oil wells need to employ artificial means to lift the oil from the producing zone to the surface. This may be achieved in a number of ways. By mechanical pumping means, using reciprocating or rotary type pumps driven from surthec or powered downhole by electric or hydraulic motors- By gas lift using the introduction of gas downhole normally via the tubing casing annulus, to gas cut the production fluids (mainly oil) and lift them through the production tubing to the surläce.

Or by hydraulic power fluids pumped or injected front surface down the tubing to be utilised downhole to drive jet pumps in which the power fluid creates a high velocity jet or jets which entrain and co-mingle with the downhole production fluids, carrying them to the surface., normally via the tubing casing arinulus.

In the ease of artificial lift utilising hydraulic jet pump systerm, the power fluid applied from surthce is effectively pumping the oil to the surface and if interrupted or stopped will cause the well to stop flowing. There are therefore less stringent requirements in land- based operations for complex production weilbeads or downhole safety mechanisms.

This is however 1w less of an acceptable situation olThhore where it is normally a mandatory requirement to have an ( SSSV) and or other safety valves set in the casing and tubing below seabed, even in the case of wells driven by jet pump artificial lift systems. In the offshore environment a real risk does exist of catastrophic damage to weliheads from

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fishing activity in the case of subsea completions, or the possibility of ship collision, storm damage or problems from other wells on multi-well platforms. In artificial lift situations where gas injection is utilised, the use of downhole and sub surface valves becomes especially important in view of the large volumes of high pressure gas injected, normally down the casing tubing annulus, to provide the drive fluid, in this case gas, required to gas cut and lift the production fluids to the surface via the production tubing.

In recent development of a subsea production well using jet pumps for artificial lift, it is planned to reverse the normal process by introducing the power fluid down the annulus and produce the co-mingled power and production fluids up the production tubing as in conventional pressurised wells. The advantages of this approach are that conventional subsea wellheads and Christmas trees can be used reducing cost of installation in this area of the well completion and the more reliable SSSV in the tubing is now operating on the producing side of the system. The disadvantages are that the power fluid applies higher pressure to the casing and liner and in addition collapse pressure to the tubing and its * : :* connections, which will lead to the requirement to upgrade these components with respect **** * . to their pressure rating, significantly increasing cost. **** * * * S

* 45 The proposed invention seeks to address the above disadvantages by retaining the lower * : e cost of conventional downhole tubulars while still being able to produce up the tubing as it * enters the subsea wellhead thereby maintaining the benefit of utilising conventional subsea completion equipment. As well as providing additional safety features, which apply in particular to artificial lift systems where gas is the preferred power fluid.

Summary of the Invention

The invention consists of a method of, or apparatus for directing fluid or fluids injected or pumped into the tubing casing annulus or injected or pumped through the welihead, into the tubing string, whilst at the same time directing fluids returning up the tubing casing annulus back into the tubing bore or main bore of the production Christmas tree.

In one aspect a method comprises a sub based fluid crossover system installed and externally sealed within the standard subsea welihead housing located in the lower part of the wellhead assembly and below the subsea Christmas tree. This fluid crossover has two sets of transfer ports located within the body of the tool. The set located in the lower portion of the sub allow power fluid introduced from the annular space at the top of the sub between the sub body and the internal bore of the welihead housing to enter the bore of the tubulars hanging below the sub. The transfer ports at the top of the sub allow produced * : fluids passing up the tubing casing annulus to enter the sub bore to be produced through I...

* the Christmas tree. A retrievable bridge plug is located between the two sets of ports during normal operation of the tool thereby creating the fluid crossover. In this way it now 70 becomes possible to provide power fluid introduced via the annulus or wellhead to be : transmitted down the tubing to power a jet pump providing artificial lift, while producing *. * the co-mingled power and production fluids up the annulus transferring them into the central bore of the sub above the bridge plug to be produced through the Christmas tree in the normal manner. The benefits provided by this system approach are to be able to use standard tubulars in the completion while maintaining the use of conventional subsea welihead and Christmas tree layouts.

It should be noted that it would also be possible to introduce the fluid crossover sub lower in the well, set in the casing tubular annulus, where it could be utilised in gas lifi systems.

In this application it would reverse the normal approach placing the bulk of the high- pressure gas inventory within the production tubing and below the standard SSSV as well as providing the additional possibility of the combined tubing bore and casing tubing annulus shut off.

In workover situations such as removal of the production jet pump the bridge plug may be removed to allow full bore access to the well. In the case of permanent or temporary abandonment the well may be additionally secured by installing a purpose-built bridge plug that not only shuts off the weilbore but also both sets of transfer ports thereby sealing the well.

The sub based fluid crossover tool has a built in hydraulic transfer port to allow for the use : of conventional SSSV's located in the tubing. The possibility exists within the concept to : : : :* provide for annular and tubing bore shut off at the crossover sub in addition to the * . : conventional * 95 SSSV system by utilising the hydraulic pressure within the SSSV control line to trigger a : * sliding sleeve valve or valves, located within the sub body or as part of the retrievable bridge plug, to shut off both sets of transfer ports

Brief description of the Drawings

So that the manner in which the above-summarised features of the present invention can be understood in detail a more particular description of the invention may be had by reference to embodiments, some of which are illustrated in the appended drawings. It should be noted, however that these drawings illustrate only the typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

FIGURE 1 is a sectional view of the sub based cross flow tool.

FIGURE 2 is a schematic isometric of a retrievable bridge plug.

FIGURE 3 is sectional view of the sub based cross flow tool installed in a subsea * : production wellhead assembly.

* a *e * ...

FIGURE 4 is a sectional schematic view of an oil well using jet pump based artificial lift *: 120 showing the one possible positioning of the sub based cross flow tool. * I * * I*. S.

*.: FIGURE 5 is a sectional schematic view fn oil well using gas lift showing one possible position the sub based cross flow tool.

Detailed description of the preferred embodiment.

In general the present invention consists of a method of, or apparatus for directing fluid or fluids injected or pumped into the tubing casing annulus or injected or pumped through the welihead, into the tubing string, whilst at the same time directing fluids returning up the tubing casing annulus back into the tubing bore or main bore of the production Christmas tree. To achieve this it is necessary have overlapping fluid paths between the tubing bore and tubing casing annulus with some barrier between the inlet and outlets of these flow paths. One way of achieving this is by a sub based cross flow tool as described in the preferred embodiment below.

Figure i is a sectional view of the cross flow sub main body 1 which will be described as it relates to the present invention. The main body 1 is cylindrical in form and as shown in this view designed to nest in the standard subsea welihead housing. The reduced outer diameter below the upper transfer ports 2 provide for a large flow area fluid path between *11 * the tool body and the wellhead housing for the co-mingled power and production fluids a,.

passing up the well into the transfer ports 2. The lower transfer ports 3 connect to a number

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* 145 of galleries 4 within the body of the tool 1 to communicate with the power fluid injection galleries 25 in the christmas tree body 19 At the lower end of the main body central bore * 12 a threaded connection 5 has been provided for the attachment of the tubing string hanging below the cross flow sub and at the upper end a seal area 6 for connection to the production christmas tree main bore.

A profile groove 7 for the installation of a retrievable bridge plug is located in the main body bore 12 between the upper and lower transfer ports 2 and 3. At the top of the main body within the large bore 8 profiles grooves 9 are located for running and retrieving the cross flow sub main body and on the outside diameter of the main body 1 an upset 10 is provided to lock the cross flow sub into the wellhead housing 18. Below this upset diameter 10 a seal section 11 is located to provide a seal between the cross flow sub main body I and the wellhead housing 18.

Figure 2 is an isometric schematic view of a retrievable bridge plug 13 showing the releasable lock down lugs 14 around the mid section and the running and retrieving neck 15 at the top of the plug. This running and retrieving neck 15 releases the lock down lugs 14 when pulled and locks them out when pushed. Upper and lower seal grooves 16 and 17 are provided for the installation of seals (not shown) to seal the bridge plug 13 when locked into the profile groove 7 in the cross flow sub main bore 12. It should be noted that bridge plugs may take a number of forms and include many more features than shown in this schematic.

: Figure 3 is a sectional view of part of a subsea welihead assembly with the sub based cross flow tool installed in the welihead housing 18 which is attached to the subsea christmas :: :: tree main body 19 by means of the welihead connector package 20. The tubing string 21 *:. 170 can be seen attached to the treaded connection 5 at the lower end of the cross flow sub * * main body I central bore 12. Outside the tubing string 21 can be seen the last casing 22 11 ê 1* hung off and sealed in the welihead housing 18 by means of a hanger 23 creating the annular space 24 between the tubing 2land casing 22. In the christmas tree main body 19 a number of power fluid injection galleries 25 can be seen which connect to the fluid galleries 4 within the cross flow sub main body I directing fluid through the lower transfer ports 3 into the tubing bore 26. The cross flow sub main body is held in place within the welihead housing 18 by means of hold-down latches 27 bearing on the upset diameter 10 and sealed by means of the seals 28 sealing between the wellhead housing 18 and the seal surface 11 on the cross flow sub main body 1. It should be noted that there is an hydraulic gallery within the christmas tree main body 19 which connects via a simiiar gallery in the cross flow sub main body 1 which in turn connects to the hydraulic control line to the SSSV and other safety valve systems, all of which are not shown. An annular space 29 between the welihead housing 18 and the cross flow sub main body 1 permits the flow of fluids up the annulus 24 to enter the top transfer ports 2 passing into the central bore 30 of - the christmas tree main body 19. The retrievable bridge plug 13 is sealed and locked in place within the cross flow sub main body 1 central bore 12 to create a barrier between the upper and lower transfer ports 2 and 3 thereby creating the cross flow required to allow power fluids injected through the galleries 25 in this embodiment or via the upper annular space 32 in other embodiments to enter the tubing bore 26 and pass down the well past the SSSV to the jet pump or gas lift valves to create artificial lift of downhole production fluids. These now co- mingled power and production fluids passing up through the lower annular space 24 to pass through the upper transfer ports 2 and then on through the christmas tree central bore 30 to be produced in the normal manner. *1Sl

Note that the retrievable bridge plug 13 can be removed to enable full bore access to the tubing string 21 and may be replaced by a fixed or hydraulically operated transfer port tubing bore shut off device (not shown). It would also be possible to install a sliding sleeve *i *s *. a transfer port shut off (not shown) within the crossover sub main body 1.

Figures 4 and 5 are schematic views of other embodiments of the same concept.

Figure 4 shows the cross flow sub based tool 31 in slightly different form, set in the casing tubing annulus 24 with power fluid being provided down the upper casing tubing annulus 32 and entering the tubing bore 26 via the lower transfer ports 3 to pass through the SSSV 33 and on down to the jet pump 34 creating artificial lift of the production fluids which co- 205 mingled with power fluid pass up the lower annulus 24 through into the bottom of the cross flow sub main body 1 and through the upper transfer ports 2 to the upper tubing bore 35 to be produced through the christmas tree in the normal manner.

- Figure 5 shows the same configuration but using gas lift where the power fluid is gas 210 supplied to the gas lift valves 36 which provide artificial lift of the production fluids and co-mingled gas power fluid up the lower annulus 24 and crossing over into the upper tubing bore 35 to be produced through the Christmas tree in the normal manner. * *. * I pie * S... * . Si.. *55* * * S S. * Ge. * * S * S... S. *

S S S , S.

Claims

Claims 230 Claim 1.

A method of, or apparatus for, directing fluid or fluids injected or pumped into the tubing casing annulus, or injected or pumped through the wellhead, into the tubing string, whilst at the same time directing fluids returning up the tubing casing annulus back into the tubing bore or main bore of the production Christmas tree.

Claim 2.

A sub based tool installed in weilhead or borehole casing to direct the crossover of power fluids from surface and co-mingled power and production fluids produced up the annulus such that the power fluids travel down the tubing below the sub based tools and the 240 produced co-mingled power and production fluids travelling up the annulus to be directed into the tubing bore or main bore of the Christmas tree above the sub based tool. * S.

:.: . CIaim3. S..

A sub based fluid crossover tool as in claim 1-2 wherein the central bore is large enough to . : 245 permit the passage of wire line tools for removal of down hole jet pumps and to carry out other well remediation work. * S * S S S 555

IS S

* Claim4.

A sub based fluid crossover tool as in claim 1-3 in which a retrievable bridge plug allows 250 full bore access to the tubulars below the tool.

Claim 5.

A sub based tool as in claims 1-4 wherein there is an hydraulic bypass gallary to permit the 255 installation and use of conventional subsurface safety valves below the crossover system.

Claim 6.

A sub based fluid crossover tool as in claims 1-5 wherein a tapping may be made in the - hydraulic gallery within the tool body to use the hydraulic pressure to lock open and in 260 emergency bring about the closure of sliding sleeve valves within the sub based crossover tool body or as part of the retrievable bridge plug and thereby bring about closure of tubing bore and annulus.

Claim 7.

265 A sub based fluid crossover tool as in 1-6, which is externally sealed and mounted within the wellhead housing or bore hole casing.

Claim 8. S...

A sub based fluid crossover tool as in 1-7, which forms a tubing hanger within the * SS * : 270 wellhead. * S* * S :::

A sub based fluid crossover tool as in 1-7, which is run into the hole as part of the tubing string then locked and sealed in casing below the wellhead housing.

Claim 10 A method of, or apparatus for, directing power fluid or fluids injected or pumped into the 280 tubing casing annulus, or injected or pumped through the christmas tree or wellhead, into the tubing bore, whilst at the same time directing fluids returning up the tubing casing annulus back into the tubing bore or main bore of the production Christmas tree above the apparatus.

285 Claim 11 A method of, or apparatus for, directing power fluid or fluids as in claim 10 where the power fluid is a gas.

Claiml2 290 A sub based tool installed in wellhead or borehole casing as in claims 2 -9 where the power fluid is gas. * .. * * * **. * S... * S " 295 * *5S * S

IS S *SS * . * . S * a.. S. S

S S S.

Amendments to the claims have been filed as follows Claim 1.

A method of, or apparatus for, directing fluid or fluids injected or pumped into the tubing casing annulus, or injected or pumped through the welihead, into the tubing string, whilst at the same time directing fluids returning up the tubing casing annulus back into the 235 tubing bore or main bore of the production Christmas tree.

Claim 2.

A sub based tool installed in welihead or borehole casing to direct the crossover of power fluids from surface and co-mingled power and production fluids produced up the annulus 0*S*S* * 240 such that the power fluids travel down the tubing below the sub based tools and the produced co-mingled power and production fluids travelling up the annulus to be directed into the tubing bore or main bore of the Christmas tree above the sub based tool.

Claim 3.

245 A sub based fluid crossover tool as in claim 1-2 wherein the central bore is large enough to permit the passage of wire line tools for removal of down hole jet pumps and to carry out other well remediation work.

Claim 4.

A sub based fluid crossover tool as in claim 1-3 in which a retrievable bridge plug allows full bore access to the tubulars below the tool.

Claim 5.

A sub based tool as in claims 1-4 wherein there is an hydraulic bypass gallary to permit the installation and use of conventional subsurface safety valves below the crossover system.

260 Claim 6.

A sub based fluid crossover tool as in claims 1-5 wherein a tapping may be made in the hydraulic gallery within the tool body to use the hydraulic pressure to lock open and in emergency bring about the closure of sliding sleeve valves within the sub based crossover tool body or as part of the retrievable bridge plug and thereby bring about closure of tubing I.....

* . 265 bore and annulus.

Claim 7.

A sub based fluid crossover tool as in 1-6, which is externally sealed and mounted within the wellhead housing or bore hole casing.

Claim 8.

A sub based fluid crossover tool as in 1-7, which forms a tubing hanger within the welihead. L4

Claim 9 A sub based fluid crossover tool as in 1-7, which is run into the hole as part of the tubing string then locked and sealed in casing below the welihead housing.

Claim 10 A method of, or apparatus for, directing power fluid or fluids injected or pumped into the tubing casing annulus, or injected or pumped through the christmas tree or welihead, into 285 the tubing bore, whilst at the same time directing fluids returning up the tubing casing annulus back into the tubing bore or main bore of the production Christmas tree above the apparatus.

Claim 11 * 290 A method of, or apparatus for, directing power fluid or fluids as in claim 10 where the power fluid is a gas.

Claiml2 A sub based tool installed in wellhead or borehole casing as in claims 2 -9 where the 295 power fluid is gas. Is