COMPLETION ASSEMBLY AND A METHOD FOR STIMULATING, SEGMENTING AND CONTROLLING ERD WELLS

Abstract

The invention relates to an assembly to be run with a well tubular having openings provided in the wall and for being arranged in a well bore and thereby forming a space between said tubing and the well bore surface. The assembly comprising: first fluid control means and second fluid control means being provided in another opening in said well tubular. The assembly further having a set of packers for sealing of the space between said tubing and the well bore surface, said set of packers being positioned such that a part the tubular having both first and second fluid control means is located between the set of packers. The first fluid control means is adapted such that it is capable of blocking fluid flow from the interior of said well tubular to said space between said tubing and the well bore surface. The second fluid control means is adapted such that it is capable of blocking fluid flow from said space between said tubing and the well bore surface to the interior of said well tubular.

Description

TECHNICAL FIELD

The present invention relates to an assembly to be run with a well tubular having openings provided in the wall and for being arranged in a well bore and thereby forming a space between said tubing and the well bore surface, said assembly comprising; first fluid control means being provided in one opening in said well tubular; second fluid control means being provided in another opening in said well tubular and; a set of packers for sealing of the space between said tubing and the well bore surface, said set of packers being positioned such that a part of the tubular having both first and second fluid control means is located between the set of packers. Thereby the packers divide the spacing between the well bore and the tubing into separate sections.

The present description includes both a drilled production well intended for the actual production of oil or gas, or it may be a drilled well intended for injection of water or other substances into the formation with a view to displacing oil or gas in a direction towards a drilled production well.

RELATED PRIOR ART

Before the injection of water into the formation can be initiated, it is necessary to stimulate a well bore by pumping down acid that decomposes the compacted layer of drilling mud on the wall of the well bore and a part of the formation. The acid is conveyed into the well bore by means of a supply pipe with a nozzle head that is, while acid is being pumped down, withdrawn slowly from the bottom of the well bore. The described process is labour-intensive, costly and delays the time of onset of production.

OBJECT OF THE INVENTION

The invention aims to remedy the problems and limitations that are associated with conventional techniques for stimulating a drilled well and to provide a new assembly, wherein the invention enables subsequent control of the stimulated well. The system will allow for stimulation and zonal isolation (or segmenting the reservoir), in a quick and efficient manner.

SUMMARY OF THE INVENTION

The object of the invention is obtained by an assembly where the first fluid control means is adapted such that it is capable of blocking fluid flow from the interior of said well tubular to said space between said tubing and the well bore surface and that the second fluid control means is adapted such that it is capable of blocking fluid flow from said space between said tubing and the well bore surface to the interior of said well tubular.

In one embodiment of the invention the first fluid control means comprises a sliding sleeve door (ssd) arranged on the tubular. The sliding sleeve door comprises an aperture in the tubular through which the oil or gas will enter the tubing. The sliding sleeve door can be closed or opened during operation of the well. Sliding sleeve doors are well known to the person skilled in the art and there functionality will therefore not be described in greater details.

In another embodiment screens for the removing of sand particles from the fluid of oil and gas are arranged on the outside of the sliding sleeve door. Such a screen can be manufactured from the material Boron Carbide, which offers the advantage that it can only be eroded by pure diamonds. Furthermore, Boron Carbide ceramic material has a good resistance against acids, such that cleaning of the filter can be done by an acid treatment.

In another embodiment the second fluid control means comprise a check valve, which will allow fluid to flow from the interior of said well tubular to said space between the tubular and the well bore. By use of check valve the stimulation treatment can flow out and into the formation through the non-return valves, while production flow can enter the tubular through the first fluid control means.

Other embodiment of the invention are recited in the independent claims

A method of use of the assembly are recited in claims 17-19

The invention will now be described in further detail with reference to the preferred embodiment shown in the drawing.

FIG. 1 shows an assembly according to an embodiment of the invention,

FIG. 1 shows a tubing 12 of the type which is usually used in the context of oil extraction is arranged in an oil well. In the shown embodiment means are arranged for establishing a number of external packers 10, 11 to the effect that it is possible to produce gas or oil from selected areas of the oil reservoir. The tubing has openings 3, 4 provided in the wall. Between the tubing and the well bore surface is formed a space, tubular space or annulus. In conventional tubing are these opening regular holes which allows fluid flow to run both from the interior of the tubing 12 and to annular space 5 and from the annular space to the interior of the tubing.

These openings can e.g. be distributed as described in European patent application NO EP1184537A.

In the assembly according to the invention these openings are provided with fluid control means (not shown in FIG. 1) which in the following is called “second fluid control means”. These second fluid control means are according to invention capable of limiting the fluid flow such that the fluid can only run from the interior of the tubing and to the annular space. However as described later, the second fluid control means might even be of the type which is capable of blocking the fluid flow in both directions.

In the shown embodiment is the assembly also provided with another opening 6 which is equipped with first fluid control means 4. The first fluid control means is, in the shown embodiment, a device called a “sliding sleeve” which is a well known piece of equipment on the E&P industry. Such a device normally comprises a “standard” inner sleeve which allows for opening or closing (or choking) of the device. Opening or closing of a “sliding sleeve” is normally achieved by use of known intervention tools run on a wireline or a coiled tubing. However the opening and closing of the opening 6 can be achieved in many other ways known to the person skilled in the art and the activation of the first fluid control means can even be made such that it is controllable from the surface.

The packers 10, 11 are positioned such that a part the tubular having both first 4 and second fluid control means 3 is located between the set of packers 10, 11. Normally, the first fluid control means is adapted such that it is capable of selectively opening or blocking fluid flow from the interior of said well tubular to said space 5 between the formation and the well tubular 2 and the second fluid control means is adapted such that it is capable of blocking fluid flow from said space to the interior of said well tubular. Such a configuration entails that the inflow of fluid from the annular space situated between the packers 11, 12 and to the interior of the tubing is controllable by activation (opening or closing) of the first fluid control means 4. By establishing of several independent assemblies having both first and second fluid control means in a well as described above it is thus possible to stimulate and open up or close off production from selected parts of the well. Opening and/or closing off such a part is normally done on order to isolate e.g. a water producing part of the well to ingress of water, or to delimit a part of the well.

In one embodiment of the invention the assembly comprises an inflatable packer section or a “mechanical” packer that does not rely on inflation with fluids. Such packers are known in the industry and comprises e.g. packers that needs to be triggered with a timer and then it sets by squeezing a steel enforced rubber membrane that then creates the seal.

The inflatable packer section might be equipped with one or more packers which can be inflated by fluid. Such inflatable packers are well known to the person skilled in the art and normally they may be used on the outside of a well tubular. In order to control the inflation (or deflation) of the inflatable packer section is the section normally provided with one or more valves for opening and closing of fluid communication into (or out of) the inflatable packer section.

The energy required for delivering of fluid into the inflatable packer section might be delivered by any suitable energy source, as e.g. one or more batteries contained in an energy section. In order to control the expanding of the inflatable packers the assembly might further comprises a triggering section. The triggering section is capable of controlling the energy source and/or controlling of the valve means. Thereby is the triggering section capable of controlling the delivery of fluid into the inflatable packer section.

The triggering section is thus a “trigger/detect function” that is capable of controlling the flow of inflation fluid to the packer. It will either release the flow of fluid by opening of valve(s) to the packer. Or it will turn on e.g. an electrical pump that will transfer the fluid into the packer.

In one embodiment of the invention is the triggering section also capable of controlling the opening and/or closing of the first fluid control means.

The triggering system can be activated either by a timing mechanism, RFID detection, seismic, or other kinds of sonic, electric signal or optical.

One method of use of an embodiment of the invention will now be described.

Turning to FIG. 1 there is shown a horizontal well drilled into the formation. In FIG. 1 the well has been drilled and a well tubular 12 is introduced into the well. Such a well tubular can be a casing or a liner. The outside diameter of the casing is smaller than the inside diameter of the wellbore, providing thereby an annular space 5, or annulus, between the tubular and the wellbore. The well tubular is perforated 3 at one or more zones. In order to stimulate the well fluid as e.g acid is discharged into the annular space through these openings configured in the wall of the tubular.

The openings 3 can have a shape and location that comply with particular, pre-defined specifications, as e.g. described in patent application NO EP 1184537A.

After stimulating of the well is at least two packers expanded in order to seal off a part of said annular space. However the packers could also be expanded prior to pumping of acid.

As described above, acid stimulation of the well takes place through the second fluid control means. During this process, the first fluid control means are usually closed. Since the second fluid control means do not allow fluid to flow into the production pipe, it is therefore necessary to subsequently open the first fluid control means to allow the production flow to run into the production pipe. The second fluid control means usually comprise one-way valves that allow fluid to flow from the interior of the well tubing and into the formation via the annular space, while the flow of fluid is blocked in the opposite direction. As mentioned above, this was described in particular for use in conventional production wells, and in that context the advantage obtained was that of achieving a higher degree of control of the valve, all production in the individual sections of the well (between two packers) taking place through the controllable first fluid control means. By that configuration it is thus obtained that it is possible to close off each of the sections by means of the first fluid control means, which may be convenient eg in the context of water breakthroughs.

However, the second fluid control means may also be constituted by valves that are provided with a mechanism which is capable of closing off the valves completely.

The embodiments of the invention described above relates mainly to conventional oil producing wells. However the invention can also be implemented in a well into which water or pressurized gas is pumped in order to push petroleum resources out of underground reservoirs toward a production wells so as to increase its production. Such a well is commonly known as a injection well. By using valves equipped with a (self-closing) mechanism which is capable of completely closing off the valves, it is accomplished that also “injector wells” can be stimulated with acid prior to being used. According to one embodiment for use in those wells “the second fluid control means” may thus be equipped with a closure mechanism that does not close until a given period of time has elapsed. The second fluid control means may also be equipped with a closure mechanism that does not close until the closure mechanism is activated by some kind of activation means, as e.g described below in connection with injection wells. Thereby it is obtained that (when the well is a recently established one) acid stimulation may take place through the second fluid control means while in their open state. When the second fluid control means are subsequently closed, the subsequent injection of water will take place via the first fluid control means in the individual sections of the well (between two packers) and thereby an increased control of that type of well is also accomplished since the individual sections can thereby be closed down by means of the first fluid control means.

According to the invention, the openings are provided with second fluid control means 3 which allows fluid to flow from the tubing and into the annular space 5. The second fluid control means might comprises a check valve, a one-way valve or it might even be made as self closing valves that are activated after pumping of acid into the well. This can be accomplished by use of e.g. by “an acid-activated valve” as described below.

In injection wells, a special non-return valve will be installed with an “acid detection” mechanism or a “delayed closing” mechanism. The mechanism is that the valve will have some of its components made of a material that is acid solvable (e.g. zinc, aluminium etc.). This acid solvable material is used to protect a “hold-open” mechanism. Once the stimulation job is performed, this hold-open mechanism is dissolved, and the non-return valve will shut off flow from both directions, effectively turning into a plug.

A delayed closing valve can be made with a water swellable elastomer compound that slowly swells during injection of water and thereby slowly closes the valve, permanently.

This will facilitate that subsequent injection is directed through the opening sleeves (first fluid control means) and not through the second fluid control means (second fluid control means) inserts.

Claims

1. An assembly to be run with a well tubular having openings provided in a wall and for being arranged in a well bore and thereby forming a space between said tubing and the well bore surface, said assembly comprising:

first fluid control means being provided in an opening in said well tubular,

second fluid control means being provided in another opening in said well tubular and a set of packers for sealing off the space between said tubing and the well bore surface, said set of packers being positioned such that a part of the tubular having both first and second fluid control means is located between the set of packers, wherein said first fluid control means is capable of blocking fluid flow from the interior of said well tubular to said space between said tubing and the well bore surface and that the second fluid control means is capable of blocking fluid flow from said space between said tubing and the well bore surface to the interior of said well tubular, said second fluid control means comprises a check valve, which will allow fluid to flow from the interior of said well tubular to said space between the tubular and the well bore.

2. An assembly to be run with a well tubular having openings provided in a wall and for being arranged in a well bore and thereby forming a space between said tubing and the well bore surface, said assembly comprising:

first fluid control means being provided in an opening in said well tubular,

second fluid control means being provided in another opening in said well tubular and

a set of packers for sealing off the space between said tubing and the well bore surface, said set of packers being positioned such that a part of the tubular having both first and second fluid control means is located between the set of packers, wherein said first fluid control means is capable of blocking fluid flow from the interior of said well tubular to said space between said tubing and the well bore surface and that the second fluid control means is capable of blocking fluid flow from said space between said tubing and the well bore surface to the interior of said well tubular, said second fluid control means comprises a valve equipped with a self-closing mechanism which is capable of completely closing off the valve, said self-closing mechanism being adapted such that acid stimulation may take place through the second fluid control means while in their open state.

3. An assembly according to claim 1 wherein the first fluid control means comprises a closable opening being operable from the surface.

4. An assembly according to claim 1 wherein the check valve is a one-way valve.

5. An assembly according to claim 3 comprising a triggering section for controlling of an energy source for controlling said closable opening, said triggering section further being provided with means for communication with a triggering device for initiating the opening or closing of said closable opening.

6. An assembly according to claim 1 wherein the first fluid control means comprises a sliding sleeve door (ssd) arranged on the tubular.

7. An assembly according to claim 6 wherein screens for the removing of sand particles from the fluid of oil and gas are arranged on the outside of the sliding sleeve door.

8. An assembly according to claim 7 wherein said screen is manufactured from the material Boron Carbide.

9. An assembly according to claim 1 comprising an inflatable or mechanical set packer section prepared for being expanded by fluid, and being provided with valve means for opening and closing of fluid communication into the inflatable packer section

10. An assembly according to claim 1 comprising two inflatable packers each of the prepared for being expanded by fluid and being provided with valve means for opening and closing of fluid communication into the inflatable packers.

11. An assembly according to claim 1 comprising an energy section comprising an energy source for the delivering of fluid into the inflatable packer section.

12. An assembly according to claim 5 wherein the triggering section further comprising means for controlling of said energy source and/or for controlling of said valve means thereby being capable of controlling the delivery of said fluid into said inflatable packer section, said triggering section further being provided with means for communication with a triggering device for initiating the expansion of said inflatable packer section.

13. Assembly according to claim 5, wherein the triggering device is capable of being pumped through the well tubular.

14. Assembly according to any one claim 5, wherein the triggering by said trigger section can be set by a time delay.

15. Assembly according to claim 1, wherein said trigger section triggers with a certain time delay after a pre selected pressure is monitored by said means for monitoring of the well pressure.

16. Assembly according to claim 5, wherein said trigger section triggers when a pre selected radio frequency identification chip is passing through said trigger section.

17. A method for sealing a part of an annulus between a well tubular and a well bore, comprising:

providing one or more assemblies that each include: first fluid control means being provided in an opening in said well tubular, second fluid control means being provided in another opening in said well tubular and a set of packers for sealing off the space between said tubing and the well bore surface, said set of packers being positioned such that a part of the tubular having both first and second fluid control means is located between the set of packers, where said first fluid control means is capable of blocking fluid flow from the interior of said well tubular to said space between said tubing and the well bore surface and that the second fluid control means is capable of blocking fluid flow from said space between said tubing and the well bore surface to the interior of said well tubular, said second fluid control means comprise a check valve, which will allow fluid to flow from the interior of said well tubular to said space between the tubular and the well bore

drilling a well into a formation;

introducing into the well the one or more assemblies, said assemblies partake as elements inserted between a conventional tubular, thereby providing an annular space, or annulus, between said tubular and the formation surrounding said tubular;

pumping of acid through said tubular and further through said second fluid control means into the formation in order to stimulate said well;

triggering of at least two assemblies in order to expand two packers to seal off a part of said annular space and to open the first fluid control means, allowing production to flow into the tubular through first fluid control means.

18. A method for sealing a part of an annulus between a well tubular and a well bore, comprising:

providing one or more assemblies that each include: first fluid control means being provided in an opening in said well tubular, second fluid control means being provided in another opening in said well tubular and a set of packers for sealing off the space between said tubing and the well bore surface, said set of packers being positioned such that a part of the tubular having both first and second fluid control means is located between the set of packers, where said first fluid control means is capable of blocking fluid flow from the interior of said well tubular to said space between said tubing and the well bore surface and that the second fluid control means is capable of blocking fluid flow from said space between said tubing and the well bore surface to the interior of said well tubular said second fluid control means comprise a check valve, which will allow fluid to flow from the interior of said well tubular to said space between the tubular and the well bore

drilling a well into a formation;

introducing into the well the one or more assemblies, said assemblies partake as elements inserted between a conventional tubular, thereby providing an annular space, or annulus, between said tubular and the formation surrounding said tubular;

closing of said first fluid control means;

pumping of acid through said tubular and further through said second fluid control means into the formation in order to stimulate said well;

triggering of at least two assemblies in order to expand two packers to seal off a part of said annular space;

opening of said first fluid control means and blocking of said second fluid control means, thereby allowing production to flow into the tubular or injection of fluids to flow through the first fluid control means into the wellbore.

19. The method of claim 18 further comprising opening or closing of said opening in order to establish or shut off the fluid communication between said inner tube and said sealed off part of the annular space.