Patent Application
20160273298
The present invention relates to an annular barrier to be expanded in an annulus between a well tubular structure and an inside wall of a borehole downhole for providing zone isolation between a first zone and a second zone of the borehole. Furthermore, the invention relates to a downhole system and a method of expanding an annular barrier.
When completing a well, production zones are provided by submerging a casing string having annular barriers into a borehole or a casing of the well. When the casing string is in the right position in the borehole, the annular barriers are expanded or inflated. The annular barriers are in some completions expanded by pressurised fluid, which requires a certain amount of additional energy.
In other completions, a compound inside the annular barrier is heated so that the compound becomes gaseous, hence increasing its volume and thus expanding the expandable sleeve. However, the diameter of a borehole or a casing may vary, and when the sleeve is expanded, the sleeve may damage the formation or collapse the casing if the diameter of the borehole is smaller than expected, i.e. an excess of expansion energy occurs. Furthermore, the sleeve of the known annular barriers may also fracture if the expansion energy is higher than required.
It is an object of the present invention to wholly or partly overcome the above disadvantages and drawbacks of the prior art. More specifically, it is an object to provide an improved annular barrier comprising a compound in an expandable space, where said annular barrier is capable of fitting a range of inner diameters of the borehole in which it is arranged, without the sleeve fracturing.
The above objects, together with numerous other objects, advantages and features, which will become evident from the below description, are accomplished by a solution in accordance with the present invention by an annular barrier to be expanded in an annulus between a well tubular structure and a wall of a borehole downhole for providing zone isolation between a first zone and a second zone of the borehole, the annular barrier comprising:
The compound may be adapted to expand the annular space when subjected to heat.
When having an expandable sleeve with a first inner diameter which is smaller than a second inner diameter or a first thickness which may be larger than a second thickness of the second section, the pressure for expanding the sleeve section having the first inner diameter or the first thickness is higher than the pressure required for expanding the section with the second inner diameter or second thickness. The compound in the annular space generates a certain amount of expansion energy, and if the inner diameter of the borehole is smaller than expected at a location where the annular barrier is to be expanded, there we will be an excess of expansion energy. This excess of expansion energy can then be used to also expand the section of the sleeve with the smaller inner diameter or the smaller thickness. Thus, the first sections of the sleeve function as a passive pressure compensation function since expansion of this section occurs when there is an excess of expansion energy.
The first sections may have an increasing thickness.
Moreover, the second inner diameter may at least 0.5 mm larger than the first inner diameter, preferably at least 1 mm larger than the first inner diameter, more preferably at least 2 mm larger than the first inner diameter.
The compound may comprise at least one thermally decomposable compound adapted to generate gas or super-critical fluid upon decomposition, the thermally decomposable compound decomposing at a temperature below 400° C.
Further, the ends of the expandable sleeve may be welded to the tubular part.
Thus, the risk of leaks is further diminished.
The ends mentioned of the expandable sleeve mentioned above may be connected to the tubular part by means of connection parts.
Additionally, the ends of the expandable sleeve may be crimped onto the tubular part.
Moreover, the first thickness may be at least 15% larger than the second thickness, preferably 25% larger than the second thickness, more preferably 50% larger than the second thickness.
Furthermore, the expandable sleeve may comprise a transition section between the first section and the second section, the transition section having an increasing thickness from the second section to the first section.
The expandable sleeve may also comprise a third section between the first section and the second section, the third section having a third thickness which may be smaller than the first thickness and larger than the second thickness.
Further, the expandable sleeve may comprise a transition section between the second section and the third section and a transition section between the third section and the first section.
All sections of the expandable sleeve may be made of the same material.
Also, the sections of the expandable sleeve may be made when making the expandable sleeve.
In addition, the sections of the expandable sleeve may further be fabricated as one piece.
Sealing elements may be arranged on the outer face of the expandable sleeve.
Moreover, the ends of the expandable sleeve may be sandwiched between the connection parts and the tubular part.
Furthermore, the second section may be adapted to expand at a first pressure above 300 bar, preferably above 325 bar, more preferably at a pressure of approximately 345 bar, and the first sections may be adapted to expand at a second pressure which may be higher than the first pressure.
Thus, the first pressure may be at least 65 bar, preferably at least 100 bar, more preferably at least 150 bar, most preferably at least 250 bar.
The second pressure mentioned above may be at least 100 bar, more preferably at least 250 bar, most preferably at least 350 bar.
The third section may be adapted to expand at a third pressure which may be higher than the first pressure and smaller than the second pressure.
Also, a one-way valve may be arranged in the tubular part.
Further, the tubular part may not have any openings, holes or apertures into the annular space.
Additionally, the tubular part may comprise an outer face, the outer face being continuous.
Furthermore, the compound may comprise nitrogen.
The compound may be selected from a group consisting of: ammonium dichromate, ammonium nitrate, ammonium nitrite, barium azide, sodium nitrate, or a combination thereof.
Moreover, the compound may decompose at temperatures above 100° C., preferably above 180° C.
Also, the annular space may be pre-pressurised to a pressure above 5 bar, preferably above 50 bar and more preferably above 100 bar, even more preferably above 250 bar.
The compound described above may be present in the form of a powder, a powder dispersed in a liquid or a powder dissolved in a liquid.
The annular barrier according to the invention may further comprise a heating wire arranged in the tubular metal part or in an abutment to the tubular metal part.
Also, the annular barrier may comprise a pressure compensation unit fluidly connected with the space.
The pressure compensation unit may be a hollow tube closed in one end and arranged along the tubular part and connected with the connection part.
Additionally, the annular barrier may comprise an anti-collapsing element arranged in the space.
The anti-collapsing element may be coiled around the tubular part.
The anti-collapsing element mentioned above may be a helical spring.
The invention also relates to a downhole system comprising:
The downhole system mentioned above may further comprise a plurality of annular barriers.
Moreover, the well tubular structure may be filled with a fluid having a temperature above 110° C., preferably a temperature above 180° C., and more preferably a temperature above 250° C.
The downhole system as described above may further comprise a tool comprising a heating unit for heating the tubular metal part of the annular barrier from within the well tubular structure.
Further, the tool may comprise isolation means for isolating a zone in the well tubular structure opposite the expandable space of the annular barrier.
Additionally, the heating unit of the tool may comprise a heating wire adapted to be arranged in abutment to the tubular metal part.
Furthermore, the tool may comprise a positioning device, such as a magnetic profiler or a casing collar locator.
Also, the tool may be adapted to abut the one-way valve in the tubular metal part to provide heat to the annular space through the one-way valve.
The well tubular structure may be connected with a heating device at surface or seabed.
Moreover, the well tubular structure may be connected to a tubing, such as a drill pipe, for submerging the well tubular structure, the tubing being connected with a heating device at surface or seabed.
The invention further relates to a method of expanding an annular barrier according to the invention comprising the steps of:
Said step of activating the compound may comprise the steps of providing heat to the annular space, decomposing the thermally decomposable compound present in the annular space, and generating gas or super-critical fluid.
The method of expanding an annular barrier as described above may further comprise the step of filling the expandable space with at least one thermally decomposable compound, which compound is thermally decomposable below 400° C.
Also, the method as described above may further comprise the step of mounting the tubular metal part as part of the well tubular structure.
Said method may further comprise the step of isolating a zone opposite the opening of the annular barrier by means of a tool.
Moreover, the method of expanding an annular barrier as described above may further comprise the step of heating the pressurising fluid with the zone.
Further, the tool may comprise a pump for pressurising the fluid.
Finally, the tool may be connected by tubing to a pump arranged at surface or seabed.
Finally, the present invention relates to a method of compensating for a varying borehole diameter when expanding an annular barrier as described above, comprising the steps of:
The invention and its many advantages will be described in more detail below with reference to the accompanying schematic drawings, which for the purpose of illustration show some non-limiting embodiments and in which
All the figures are highly schematic and not necessarily to scale, and they show only those parts which are necessary in order to elucidate the invention, other parts being omitted or merely suggested.
In
In
When the compound entrapped in the expandable space chemically reacts or thermally decomposes, generating gas or super-critical fluid, the expandable sleeve 8 is expanded until the outer face 10 of the sleeve presses towards the inner face 5 of the borehole 6, as shown in
When using an enclosed compound 16 in the space 15 and an expandable sleeve 8 made of metal, the expandable sleeve 8 may be welded or in another way fixedly connected to the tubular metal part 7 without connection parts as shown in
One way of expanding the sleeve is when the compound 16 decomposes when heated to above a certain temperature. The compound is then decomposed into gas or super-critical fluid and e.g. water, and as the compound generates gas or super-critical fluid, the volume of the compound increases. In this way, the volume of the space increases, and the expandable sleeve 8 is expanded, as shown in
The compound 16 comprised in the space may comprise nitrogen, such as in the form of ammonium, nitrite, azide, or nitrate, and may be selected from a group of ammonium dichromate, ammonium nitrate, ammonium nitrite, barium azide, sodium nitrate, or a combination thereof. These nitrogen-containing compounds decompose when heated, e.g. by flushing the casing with hot steam or a heated fluid which heats the compound 16 by heating the tubular metal part 7. At many well sites, hot steam is available as it is used for bringing up the hydrocarbon-containing fluid from the reservoir and hot steam can therefore also be used for expanding the annular barriers.
The compound 16 in the space may be present in the form of a powder, a powder dispersed in a liquid or a powder dissolved in a liquid. Thus, the compound 16 may be in a solid or liquid state, e.g. dispersed or dissolved in a liquid, which may be water, mud or well fluid. As the compound 16 is heated, the compound decomposes into gas or super-critical fluid and water, and the expandable sleeve 8 is expanded. Whether it is gas or super-critical fluid depends on the pressure and temperature present downhole. The amount of compound in the space is determined according to the expected pressure downhole and if the pressure is higher than expected, the decomposition could create a super-critical fluid instead of a gas.
As shown in
In
Furthermore, the connection parts overlap the expandable sleeve 8, squeezing the sleeve in between the connection parts and the tubular part. The connection part has a groove in which a sealing means, such as an O-ring, is arranged.
As can be seen from the figures, all sections 21, 22 of the expandable sleeve are made of the same material. Thus, the sections of the expandable sleeve are made when making the expandable sleeve. The sections 21, 22 of the expandable sleeve 8 may be moulded in one piece or machined from one piece. As shown in
In
When expanding the annular barrier 1, the second section 22 is adapted to expand at a first pressure above 65 bar, preferably at least 100 bar, more preferably at least 150 bar, most preferably at least 250 bar, or approximately 345 bar, and the first sections are adapted to expand at a second pressure higher than the first pressure. The second pressure may be at least 100 bar, more preferably at least 250 bar, even preferably at least 350 bar, and most preferably at least 414 bar.
The third section of the annular barrier 1 of
In
In the annular barrier of
In
In order to easily fill the compound in the annular space, the annular barrier of
In another embodiment, the first sections of the sleeve have an increasing thickness from the sleeve ends towards the second section of the sleeve. In this way, the first sections have a combination of an increased thickness and inner diameter compared to the second section of the sleeve.
In
In
The compound 16 decomposes when heated to above a certain temperature in a temperature range of 100-400° C. and is then decomposed into gas or super-critical fluid and e.g. water, and as the compound generates gas or super-critical fluid, the volume of the compound increases. In this way, the annular space increases and the expandable sleeve 8 is expanded. The injected steam or heated fluid has a temperature around 250° C. which is sufficient to heat the compound 16 arranged in the space of the annular barrier 1 to above 200° C. Furthermore, the heat can be provided by locally heating the tubular metal part 7 and/or the fluid in the well tubular structure opposite the tubular metal part.
The compound may comprise a catalyst, and by having such a catalyst, the temperature at which the compound decomposes can be increased or decreased depending on the temperature conditions in the borehole. In this way, the annular barrier can be designed for variety of well conditions.
When completing a well, the tubular metal part 7 is mounted as part of the well tubular structure and lowered into the borehole as part of the well tubular structure, e.g. by connecting the well tubular structure to a tubing, such as a drill pipe. Before inserting the annular barriers 1, the annular space may be pre-pressurised to a pressure above 5 bar, preferably above 50 bar and more preferably above 100 bar. By pre-pressurising the annular space 15, the expansion ratio provided by the decomposition of the compound 16 can be decreased, and the expansion can thus be controlled to a higher degree than when the space is not pre-pressurised.
The annular barrier 1 may also comprise a chamber filled with a second compound, and the annular space is filled with the first compound. When the well tubular structure 3 is pressurised, the pressurised fluid moves a piston 41 shearing a shear pin, and the first and the second compounds are mixed into the space through the fluid channel, and the reaction there between expands the sleeve.
The first and second compounds may be calcium carbonate and hydrochloric acid which, when mixed, react (and do not decompose) and generate calcium chloride, water and carbon dioxide and thereby create an increased pressure resulting in an expansion of the annular barrier 1.
In another embodiment, the annular space comprises several chemicals which are already mixed into the compound and which react when heated to a certain temperature and thermally decompose.
Furthermore, the first and second compounds could be chemicals mixed into the annular space and could be diesel and oxygen, e.g. in the form of air, reacting and not decomposing at a temperature of 210° C., and thereby creating an expansion of the expandable sleeve. The chemicals, i.e. the first and second compounds, could also be diethyl ether and oxygen, e.g. in the form of air, reacting at a temperature of 160° C.
Also, the annular space may comprise more than one chemical, and a spark or electrical ignition could start a chemical reaction (not decomposition) between the chemicals, creating an increased volume resulting in an expansion of the annular barrier 1. The chemicals could be sodium chlorate, barium peroxide and potassium perchlorate.
In addition, the annular space may be filled with water, and by using electricity through wires on the outside of the well tubular structure 3, hydrogen and oxygen are generated via electrolysis.
As shown in
In order to heat the compound 16 in the space of the annular barrier 1 locally, the tubular metal part 7 further comprises a heating wire 19, such as an electric wire, arranged in an abutment to the tubular metal part 7 as shown in the cross-sectional view of
The downhole system 100 shown in
By fluid or well fluid is meant any kind of fluid that may be present in oil or gas wells downhole, such as natural gas, oil, oil mud, crude oil, water, etc. By gas is meant any kind of gas composition present in a well, completion, or open hole, and by oil is meant any kind of oil composition, such as crude oil, an oil-containing fluid, etc. Gas, oil, and water fluids may thus all comprise other elements or substances than gas, oil, and/or water, respectively.
By a casing is meant any kind of pipe, tubing, tubular, liner, string etc. used downhole in relation to oil or natural gas production.
In the event that the tool is not submergible all the way into the casing, a downhole tractor can be used to push the tool all the way into position in the well. The downhole tractor may have projectable arms having wheels, wherein the wheels contact the inner surface of the casing for propelling the tractor and the tool forward in the casing. A downhole tractor is any kind of driving tool capable of pushing or pulling tools in a well downhole, such as a Well Tractor®.
Although the invention has been described in the above in connection with preferred embodiments of the invention, it will be evident for a person skilled in the art that several modifications are conceivable without departing from the invention as defined by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 13193848.2 | Nov 2013 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2014/075129 | 11/20/2014 | WO | 00 |
