EP2588711A2

EP2588711A2 - Flow control valve for polymer solutions

Info

Publication number: EP2588711A2
Application number: EP11743865.5A
Authority: EP
Inventors: Guy Chauveteau; Stéphane JOUENNE
Original assignee: Total SE
Current assignee: TotalEnergies SE
Priority date: 2010-07-02
Filing date: 2011-07-01
Publication date: 2013-05-08
Also published as: WO2012001671A3; WO2012001671A2; CA2804042A1; AP2013006692A0; US9260937B2; FR2962153B1; FR2962153A1; US20130098620A1

Abstract

The invention relates to a method for injecting a fluid into an underground formation, in which method: - a fluid is carried along at least one injection pipe (1); - the injection pipe (1) comprises a main part (6) comprising a single tube, and a flow control valve (8) comprising at least ten fluid carrying tubes (2) arranged in parallel; and in which the ratio of the cross section of the single tube of the main part (6) to the sum of the cross sections of the fluid carrying tubes (2) in the flow control valve (8) is less than or equal to 5, preferably less than or equal to 3, and as a particular preference less than or equal to 1.5; - the flow rate of fluid passing through the injection pipe (1) is adjusted by splitting the fluid between all or some of the fluid carrying tubes (2) of the flow control valve (8); - the fluid from the injection pipe (1) is injected into the underground formation. The invention also relates to a flow control valve (8) notably suited to implementing this method and to an installation notably for injecting a fluid for example into an underground formation to implement this method.

Description

VALVE CONTROL OF FLOW FOR SOLUTIONS OF

POLYMERS

FIELD OF THE INVENTION

The present invention relates to a flow control valve adapted to the transport of fluids such as polymer solutions, as well as to a fluid injection method, in particular in an underground formation and a transport installation, in particular for fluid injection, for example in an underground formation using said flow control valve.

TECHNICAL BACKGROUND

The use of polymer solutions, especially polyacrylamide, is known in the context of the enhanced recovery of hydrocarbons contained in an underground formation (EOR). Thus, after hydrocarbon recovery operations by means of the natural pressure of the so-called "primary" reservoir, a so-called "secondary" hydrocarbon recovery is generally carried out, during which a polymer solution is injected into the reactor. underground formation by one or more injection wells, and extracting a mixture of hydrocarbons and polymer solution by one or more production wells.

It is preferred to use a polymer solution and not water because of the often too great mobility of the water: the efficiency of the sweeping is improved by adding polymer to the water of injection, as well as the conditions of production (percentage of water produced reduced). This results in a higher recovery rate when it is decided to stop production (because of a percentage of water produced too high).

When several injection wells are used, it is generally necessary to operate at different pressures according to the wells, in order to adapt to the local configuration of the subterranean formation, and to correct the effects of the heterogeneity of said formation. underground. Now, several injection wells (or all the injection wells) are generally supplied with fluid by the same source of polymer solution. So it is necessary to have flow control valves for each injection well, particularly in offshore (offshore) operations, where it would be too complex or too expensive to provide a feed line and a pump per well injection.

Of the flow control valves available for the above application, Cameron Willis proposes a model which consists of a cage pierced with holes. The fluid inlet is on the periphery of the cage, and the outlet is in the center of the cage. The accessible surface for the fluid inlet is adjusted by a movable piston moving parallel to the axis of the cage. For a given flow rate, the pressure drop increases when the accessible surface at the inlet of the fluid decreases. However, this system leads to a strong degradation of the polymer solutions used for enhanced hydrocarbon recovery, and therefore to a decrease in the viscosity thereof, which greatly affects their effectiveness.

In addition, US 4,510,993 discloses a flow control valve for polymer solutions, in which the flow rate is regulated by a needle penetrating into an orifice. The document states that the polymers are not degraded until the flow rate exceeds 30 gallons / min, ie 7 m ³ / h. However, it is known that such a geometry (needle valve type) is degrading. Thus, the degradation of the polymer solutions in this type of system becomes high at more realistic flow rates of the order of 100 m ³ / h. In addition, such a system presents significant risks of mechanical wear.

US 3,477,467 discloses a flow control valve suitable for a polymer solution, wherein the pressure drop is achieved by passing the polymer solution through a vertical tube filled with sand or beads. The adjustment of the quantity of sand or balls makes it possible to regulate the flow rate. However, this system also has the disadvantage of degrading the polymer solutions, and it also presents significant risks of mechanical wear of the valve and damage of the porous medium with time. In addition, implementation is difficult.

US 4,617,991 proposes a flow control system comprising a device actuated by the transport of a polymer solution, such as a hydraulic pump or a motor. This type of device is adapted to recover energy from the flow of the polymer solution. The system makes it possible to avoid the degradation of a low-flow polymer solution (at most about 1.3 m ³ / h). However, it does not allow avoid the phenomenon of degradation at a higher rate. Indeed, although the energy is dissipated outside rather than inside the pipe, the degradation remains a function of the geometry of the dissipation system inside the pipe.

US 4,276,904 discloses an apparatus for modifying a fluid flow rate by passing the fluid through a limited number of tubes of different lengths and diameters. The pressure drop is adjusted by passing the fluid in one of the combinations between the different tubes. This system is bulky, difficult to implement (the apparatus comprises in particular a large number of valves, which must be operated independently, at the outlet of each of the tubes) and not very flexible (that is to say that it makes it difficult to fine-tune the pressure drop and the flow). Such a system can not allow to create a sufficient pressure drop at a high rate.

There is therefore a real need to develop a flow control valve suitable for injecting polymer solutions into an underground formation that does not have the disadvantages mentioned above. In particular, there is a need to develop a flow control valve that does not induce significant degradation of the polymer solutions used in enhanced hydrocarbon recovery, even at high flow rates.

SUMMARY OF THE INVENTION

The invention firstly relates to a method for injecting a fluid into an underground formation, in which:

a fluid is conveyed in at least one injection pipe;

- The injection pipe comprises a main part comprising a single tube, and a flow control valve comprising at least ten fluid transport tubes (preferably at least one hundred) arranged in parallel; and wherein the ratio of the single tube section of the main portion to the sum of the sections of the fluid transport tubes of the flow control valve is less than or equal to 5, preferably less than or equal to 3, and particularly preferred less than or equal to 1, 5,

the flow rate of the fluid flowing in the injection pipe is adjusted by distributing the fluid in all or part of the fluid transport tubes of the flow control valve; - The fluid from the injection line is injected into the subterranean formation.

According to one embodiment:

at least a portion of the fluid transport tubes have a section at least ten times smaller than the section of the single tube of the main part, preferably at least a hundred times smaller, particularly preferably at least a thousand times less and ideally at least less ten thousand times lower; and or

each transport tube is of constant section along its length, and / or

said transport tubes are cylinders and extend along a longitudinal axis and / or the axes of said cylinders are parallel to each other, and / or

the section of said transport tubes is circular.

According to one embodiment, the adjustment of the fluid flow rate in the injection line is effected by selectively sealing all or part of the fluid transport tubes.

According to one embodiment, the fluid is distributed in a plurality of injection lines by pumping means, each injection line comprising a main part comprising a single tube and a flow control valve comprising at least ten (of preferably at least 100) fluid transport tubes arranged in parallel, the flow rate of the fluid flowing in each injection pipe being adjusted by distributing the fluid in all or part of the fluid transport tubes, and the fluid from the pipes of injection being injected into the subterranean formation.

According to one embodiment, the fluid transport tubes do not all have identical sections, and are preferably arranged in groups of fluid transport tubes substantially identical section.

According to one embodiment:

at least a portion of the fluid transport tubes have a cross section of from 0.012 to 100 mm ² , preferably from 0.05 to 50 mm ² , and more preferably from 0.8 to 30 mm ² ; and or

at least one fluid transport tube has a section of 1 to

100 cm ² , preferably from 1 to 50 cm ² ; and or all the fluid transport tubes have a length of 1 cm to 10 m, preferably 10 cm to 3 m, and more preferably 30 cm to 1.5 m.

According to one embodiment, the fluid is an aqueous solution of a polymer whose molecular mass is greater than 10 ⁶ Da.

According to one embodiment, the fluid is an aqueous solution of polymer, preferably an aqueous solution of polyacrylamide.

According to one embodiment, the fluid is an emulsion, preferably an oil / water emulsion.

According to one embodiment, the method described above comprises a step of recovering hydrocarbons from the underground formation and optionally treating recovered hydrocarbons.

The invention also relates to a flow control valve intended to be connected to a single tube of a pipe, said valve comprising:

at least ten (preferably at least one hundred) fluid transport tubes arranged in parallel;

means for connecting to a main part of the single tube of the pipe, situated at one end of the fluid transport tubes, and where the ratio of the section of the single tube of the main part to the sum of the sections of the transport tubes fluid flow of the flow control valve is less than or equal to 5, preferably less than or equal to 3, and particularly preferably less than or equal to 1, 5.

According to one embodiment, the flow control valve comprises means for closing off at least part of the fluid transport tubes.

According to one embodiment, the closure means comprise a diaphragm, fins, a plug valve or a piston.

According to one embodiment:

at least one fluid transport tube has a cross section of 1 to 100 cm ² , preferably 1 to 50 cm ^2; and or all the fluid transport tubes have a length of 1 cm to 10 m, preferably 10 cm to 3 m, and more preferably 30 cm to 1.5 m.

The invention also relates to a transport installation, in particular for injecting a fluid, for example into a subterranean formation, comprising at least one pipe, in particular an injection pipe, said pipe including an injection pipe comprising:

a main part which comprises a single tube, and

- A flow control valve as described above, connected to the single tube of the main part by the connecting means.

According to one embodiment of this installation:

each transport tube is of constant section along its length; and or

the section of said transport tubes is circular.

According to one embodiment, the installation comprises a plurality of injection pipes, in particular connected to pumping means, each pipe including injection comprising a main part comprising a single tube and a flow control valve as described. above.

For the purposes of the present invention, the term "single fluid supply tube" is intended to mean the main part of a single tube of a pipe. The pipe may be a pipe for conveying a fluid, a pipe for pumping a fluid. Preferably, the pipe is a pipe for injecting a fluid.

The present invention overcomes the disadvantages of the state of the art. In particular, it provides a flow control valve which does not induce significant degradation of the polymer solutions used in the context of enhanced hydrocarbon recovery, even at high flow rates. This is accomplished through the use of a beam having a large number of fluid transport tubes (also called capillaries in the following) arranged in parallel. In the system according to the invention, the pressure losses are created essentially by friction of the fluid transported on the walls of the capillaries, and not the passage of geometric contractions. In particular, the effective contraction ratio in the system (i.e., the ratio between the useful section for the fluid upstream of the inlet of the capillaries and the useful section for the fluid in the capillaries) is small. Thus, the elongational velocity gradient remains moderate throughout the system (unlike most devices of the state of the art), which makes it possible to degrade only few or almost no polymers, even at a rate Student.

According to some particular embodiments, the invention also has one or preferably more of the advantageous features listed below.

Because the polymer solutions are poorly degraded by virtue of the invention, substantial savings can be realized in terms of the total amount of polymer to be used to mobilize hydrocarbons from a subterranean formation.

- When the flow control valve according to the invention comprises means for closing the capillaries, it is possible to regulate at will and substantially continuously the pressure drop and the flow in the valve by sealing a greater or lesser number capillaries and / or by selectively closing the capillaries having a given size. This system is simpler to implement than that of US 4,276,904, wherein the adjustment of the flow rate and the pressure drop is effected by actuating, via valves, a large number of separate closure devices.

- The use of capillaries of different diameters in the same flow control valve makes it possible to regulate the pressure drop and the flow in the valve in a larger range of values than when all the capillaries are identical.

- The flow control valve according to the invention is robust and may have relatively small dimensions, well suited for incorporation into conventional fluid distribution networks to the underground formations.

BRIEF DESCRIPTION OF THE FIGURES Figure 1 schematically shows an embodiment of a flow control valve according to the invention, integrated into an injection pipe.

FIG. 2 corresponds to the section along the direction AA of the flow control valve of FIG. 1.

FIG. 3 corresponds to the section along the direction AA of the flow control valve of FIG. 1, according to another embodiment.

Figure 4 schematically shows another embodiment of a flow control valve according to the invention, integrated into an injection line.

FIG. 5 corresponds to the section along the direction BB of the flow control valve of FIG. 4.

Figures 6 and 7 show schematically another embodiment of a flow control valve according to the invention, integrated into an injection line.

Figure 8 gives the percentage degradation of a polymer solution (ordinate) as a function of the pressure drop (in bar, 1 bar = 0.1 MPa) for different internal capillary diameters (see Example 1). .

Figure 9 provides the percent degradation of a polymer solution (ordinate) versus head loss (in bar) for different capillary lengths (see Example 2).

Figure 10 provides the percent degradation of a polymer solution (ordinate) versus flow rate (in mL / min) for different capillary lengths (see Example 2).

In FIGS. 8 to 10, "ID" means capillary internal diameter, and

"L" means capillary length.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The invention is now described in more detail and without limitation in the description which follows.

With reference to FIG. 1, a transport pipe, in particular an injection pipe 1 intended to inject a fluid, for example into a subterranean formation, comprises at least one main part 6 comprising a single tube, and a flow control valve. 8 connected to the main part 6 by connection means 3, for example a connecting flange.

The main part 6 of the pipe is connected at its other end to fluid supply means (not shown). Generally, these supply means comprise a fluid reservoir and pumping means. In principle, a plurality of injection lines is connected to a single fluid reservoir and to single pumping means. The pumping means are adapted to circulate the fluid under pressure in the injection pipes, successively in the single tube of the main part 6 of each pipe, then through the flow control valve 8.

The fluid used is preferably a polymer solution, in particular a solution of hydrophilic polymer of high molecular weight, for example, whose molecular mass is greater than 10 ⁶ Da (daltons, 1 Da = 1 g / mol). Preferably the molecular weight of the polymer is between 1.5 ^* 10 ⁶ Da and 50 ^* 10 ⁶ Da, more preferably between 8 ^* 10 ⁶ Da and 35 ^* 10 ⁶ Da. More preferably, the polymer solution is a polyacrylamide solution. Polyacrylamide, which is not very sensitive to biodegradation and is less expensive than biopolymers, is very widely used, but it is particularly sensitive to mechanical degradation because it is a relatively flexible polymer that adopts a pelota configuration that is stretched when it is stretched. located in a strong elongational flow (for example, a contraction), which leads to the breaking of the carbon-carbon bond.

The invention can also be implemented with other types of fluids, in particular fluids capable of mechanical degradation, and for example emulsions, in particular oil / water emulsions.

According to one embodiment (not shown), the end of the injection pipe 1, located opposite the fluid supply means (that is to say the end of the injection pipe 1 through which the fluid exits and is released into the underground formation) is directly constituted by the flow control valve 8. According to this embodiment, the fluid is injected into the underground formation directly out of the flow control valve. 8.

However, according to another (preferred) embodiment, the end of the flow control valve 8, situated opposite the main part 6 of the injection pipe 1, is connected to a second main part 7 comprising a single tube, via connecting means 4, for example a connecting flange. The fluid therefore circulates in the tube of the main part 6, then through the flow control valve 8, then in the tube of the second main part 7, before being injected into the subterranean formation. This configuration allows on the one hand to provide specific means at the end of the injection pipe 1 adapted to a optimum distribution of the fluid in the underground formation, and secondly to simplify the operation and eventual maintenance of the flow control valve 8, in relation to the case in which it is located at the end of the pipe injection 1, that is to say necessarily in depth before entering the underground formation.

The flow control valve 8 comprises a plurality of fluid transport tubes 2 arranged in parallel in the direction of flow. In the context of the present application, this term "in parallel" means that the fluid transport tubes 2 are arranged in such a way that the fluid coming from the single tube of the main part 6 can (in the absence of closure) distributed in all the fluid transport tubes 2. In other words, the total flow of fluid in the injection line 1 is the sum of the individual fluid flow rates in the different fluid transport tubes 2, each of these flow rates individual being non-zero (except sealing part of the fluid transport tubes 2). The term "in parallel" does not necessarily imply that the axes of the fluid transport tubes 2 are geometrically parallel to each other, although such a situation is possible, and even preferable for simplicity of design. . The tubes may for example be wound in parallel.

The fluid transport tubes 2 may be parallel slots formed in one or more blocks of material.

According to the invention, the number of fluid transport tubes 2 is greater than or equal to 10, preferably greater than or equal to 100, or greater than or equal to 200, or greater than or equal to 500, or greater than or equal to 1000, or greater than or equal to 1500, or greater than or equal to 2000, or greater than or equal to 5000. Indeed, the presence of a large number of fluid transport tubes 2 can generate a significant pressure drop with a minimum of degradation of the fluid for a given flow rate.

With reference to FIGS. 2 and 3, the fluid transport tubes 2 are grouped into a bundle, which may be contained in a sheath 9. For the sake of simplicity, it is possible for the sheath 9 to have the same shape as the main part 6 and the second main part 7 of the pipe. The sheath 9 is advantageously cylindrical in shape with a circular base but may also have another shape (for example a cylindrical shape with a square base). The fluid transport tubes 2 may themselves have a section of circular shape or other (for example square).

In the context of the present application, by "section" of a tube is meant the surface of the internal space of the tube which is perpendicular to the axis main tube, that is to say perpendicular to the mean direction of the flow of the fluid. Generally, each tube has a constant section along its axis. If however this section varies along the axis, we retain the minimum value of the section for the definition of the term.

At least a portion of the fluid transport tubes 2 have a section at least 10 times smaller than the section of the single tube of the main part 6 (and at the section of the single tube of the second main part 7), preferably at least 100 times lower, particularly preferably at least 1000 times lower and ideally at least 10,000 times lower. The use of a large number of fluid transport tubes 2 whose section is small relative to the section of the tube of the main part 6 allows to create a significant pressure drop with a minimum of degradation of the fluid, for a given flow rate.

For example, at least a portion of the fluid transport tubes 2 may have a cross section of from 0.012 to 100 mm ² , preferably from 0.05 to 50 mm ² , and more preferably from 0.8 to 30 mm ² . Still by way of example, for circular cylindrical fluid transport tubes 2, the internal diameter is from 0.125 to 1 1 mm, preferably from 0.25 to 8 mm, and more particularly preferably from 1 to 6 mm; for a main part 6 of circular cylindrical shape, the internal diameter is preferably from 1 to 30 cm.

The flow control valve 8 may be devoid of closure means. In this case, the fluid always flows in all the fluid transport tubes 2, and the pressure drop generated can not be adjusted by the operator independently of the flow rate.

However, it is preferred to provide closure means 5 for fluid transport tubes 2, operable remotely (for example by hydraulic control or electrical control). Preferably these closure means 5 are arranged at the inlet of the fluid transport tubes 2 (that is to say are located at the interface between the main part 6 of the pipe and the fluid transport tubes 2) or possibly at the outlet thereof (that is to say at the interface between the second main part 7 of the pipe and the fluid transport tubes 2).

It is preferred, for reasons of simplicity, that the closure means 5 comprise a single mobile part or a set of moving parts cooperating together (for example a plate, a set of integral vanes, a piston, a diaphragm or other), and not no more moving parts to be operated independently of each other.

All fluid transport tubes 2 may be identical in shape and section. However, it is preferred that the fluid transport tubes 2 do not all have an identical section. In particular, it is useful to provide relatively large fluid transport tubes 2, in addition to the small fluid transport tubes 2 described above.

By passing the fluid through the larger fluid transport tubes 2, the pressure drop is reduced for a given flow rate.

For example, it is possible for all of the fluid transport tubes 2 to be divided into two different sizes (or two sections) or three different sizes (or three sections) or more. Three sizes are provided in the embodiment of Figures 2 and 3, that is to say that the fluid transport tubes 2 are divided into large tubes 2a, medium tubes 2b and small tubes 2c.

For example, the larger tubes (especially the large tubes 2a in the embodiment of Figures 2 and 3) advantageously have a section of 1 to 100 cm ² , preferably 1 to 50 cm ² .

Thus, selective sealing of the large fluid transport tubes 2 makes it possible to create a significant loss of pressure by forcing the fluid to pass through the small fluid transport tubes 2. And the opening of the fluid transport tubes 2 of large size (associated or not with the closure of the small fluid transport tubes 2) can greatly reduce the pressure drop by allowing the fluid to pass through the tubes small fluid transport 2.

The configuration of the closure means 5 is therefore advantageously adapted to the arrangement of the fluid transport tubes 2. The fluid transport tubes 2 are advantageously grouped according to their size (or section), in order to facilitate the selective sealing of the tubes fluid transport 2 depending on their size.

Thus, in the case illustrated in FIG. 2, the small tubes 2c are arranged in the center, the average tubes 2b around the small tubes 2c and the large tubes 2a around the average tubes 2b, that is to say on the periphery. This configuration allows selective closure of the tubes easily by using shutter means constituted by a diaphragm.

In the case illustrated in FIG. 3, the small tubes 2c, the average tubes 2b and the large tubes 2a are distributed in disc sectors. This configuration allows selective closure of the tubes easily using closure means having fins.

According to another configuration not shown, still with a sheath 9 of circular cylindrical shape, the tubes are distributed in crescents, which allows selective closure of the tubes easily using a ball valve.

According to the variant illustrated in FIGS. 4 and 5 (in which the reference numbers have the same meaning as above, unless otherwise stated), the main axis of the flow control valve 8 is perpendicular to the main axis of the the main part 6 of the pipe, that is to say that the pipe is L-shaped in the vicinity of the flow control valve 8. The sheath 9 has a cylindrical shape with a square section. The tubes are divided into bands according to their size. This configuration allows selective closure of the easy tubes by using closure means comprising a piston 10.

According to the variant illustrated in FIGS. 6 and 7 (in which the reference numbers have the same meaning as above, unless otherwise stated), the main axis of the flow control valve 8 is parallel to the main axis of the main part 6 of the pipe. The sheath 9 has a cylindrical shape with a square section (see again FIG. 5 corresponding to the section B-B). The tubes are divided into bands according to their size. This configuration allows selective closure of the tubes easily using a closure means 1 1 of pyramidal shape with a square base. This configuration makes it possible to minimize the contraction ratio at the inlet of the tubes.

In general, the fluid transport tubes 2 are preferably substantially all the same length (dimension along their main axis, that is to say in the mean direction of flow) for reasons of simplicity of design. A length of 1 cm to 10 m is preferred, preferably 10 cm to 3 m, and more preferably 30 cm to 1.5 m. It has been found by the inventors that the degradation of a polymer solution occurs essentially only at the inlet of the tubes and not over their entire length. Consequently, using a relatively large length of tubes makes it possible to obtain a significant pressure drop (at a given flow rate) without generating significant degradation. However, it is also desirable to avoid using excessively long tubes to avoid complicating the implementation of the invention and the manufacture of the valve. The bundle of fluid transport tubes 2 according to the invention can be manufactured by assembling (gluing, welding or otherwise) individual tubes or by drilling holes in plates followed by assembly (gluing, welding or otherwise) of plates aligning the holes.

It is advantageous to provide that the respective internal spaces of the fluid transport tubes 2 form an assembly as compact as possible, that is to say to provide that the section of the sheath 9 which is not available for the passage fluid is as small as possible. This makes it possible to limit the local contraction ratios and thus to limit the degradation of the fluid.

In this respect, in particular, it is useful that the overall contraction ratio of the valve (defined as the ratio of the single tube section of the main portion 6 to the sum of the sections of the fluid transport tubes 2) is greater than 1 and less than or equal to 5, preferably less than or equal to 3, and particularly preferably less than or equal to 1, 5.

The set of geometric characteristics of the flow control valve 8, namely mainly the number, the section and the length of the fluid transport tubes 2, are chosen as a function of the flow range and the range of loss of flow. desired load for driving.

The invention can be implemented in the context of a farm located offshore (offshore) or not.

The hydrocarbons are recovered by one or more production wells in a manner known per se, and may undergo a subsequent treatment known per se, comprising, for example, solids removal, gas / liquid separation, water / oil separation, dehydration, upgrading, refining or other.

The use of the valve according to the invention is not limited to the field of enhanced oil recovery. It can be used in all technical fields that require the movement of a fluid under pressure, said fluid being sensitive to mechanical damage.

EXAMPLES

The following examples illustrate the invention without limiting it.

Example 1 - Influence of the internal diameter of the capillaries

Degradation measurements of a polyacrylamide solution are carried out as it passes through capillary tubes. The Polyacrylamide is commercial hydrolyzed polyacrylamide 3630S supplied by SNF. The injected solutions are prepared at a concentration of 800 ppm in a synthetic brine at 35 g / l.

The polyacrylamide solution is fed by a tube of internal diameter 2 mm, and passes into a capillary tube of smaller internal diameter, namely 0.75 mm, 0.5 mm, 0.25 mm or 0.18 mm. The length of each capillary is 30 cm.

Various flow rates are applied to the polyacrylamide solution in order to measure a pressure drop in the degrading tube of between 0 and 20 bar. For a given pressure drop, the flow is even greater than the diameter of the degrading capillary is small. Thus, the flow rate is varied between 0 and 22 cc / min in the capillary diameter 0.18 mm, between 0 and 40 cc / min in the capillary diameter 0.25 mm, between 0 and 230 cc / min in the capillary of diameter 0.5mm and between 0 and 400cc / min in the capillary diameter 0.7mm.

For each experiment, the pressure drop (pressure difference between the inlet and the outlet of the capillary) and the viscosity of the solution at the inlet (η _β ) and at the outlet (η ₈ ) of the capillary are measured. We deduce the percentage degradation of the solution according to the following formula: D = (n, er | s) / (do-RefLevel) ^x 100, where Href represents the viscosity of water. By way of comparison, the degradation obtained in a cage-shaped valve marketed by Cameron Willis is also measured on a real-life test bench under the flow conditions of an oil well (flow rate varying between 30 and 200 m ³ / h).

The results are shown in Figure 8. It is noted that for a given pressure drop, degradation decreases when the diameter of the capillary decreases. It is also noted that it is possible to obtain a degradation less than that obtained with the commercially available valve.

Example 2 - Influence of capillary length

Polyacrylamide solution degradation measurements are carried out in the same manner as in Example 1, but using capillary tubes of the same internal diameter (0.5 mm) and of different lengths.

The results are shown in Figure 9. It is noted that for a given pressure drop, the degradation decreases as the length of the capillary increases. Correlatively, for a given flow rate, the degradation is identical regardless of the length of the capillary, as can be This means that the degradation of the polymer occurs only at the inlet of the capillary tube, under the effect of the elongational speed gradient. Consequently, the use of a geometry that limits the local contraction ratios at the inlet of the capillary tubes as well as the use of long capillaries makes it possible to reduce the degradation of the polymer.

Example 3 - Possible Valve Flow Control Valves According to the Invention

In a first case, it is desired to generate a pressure drop of 15 bar for a flow rate of 100 m ³ / h with a polymer degradation of less than 36%, and with a valve of 30 cm in length. According to example 1 and FIG. 8, the polymer degradation is about 36% at 15 bar pressure drop for a capillary 30 cm long and 0.25 mm internal diameter. The corresponding flow rate is 17 mL / min. Therefore, the number of capillaries to provide to accommodate the total flow is 98000.

The corresponding total diameter of the capillary bundle obtained is approximately 13.2 cm (for an external capillary diameter of 0.4 mm and a compactness of 0.9). The overall contraction ratio for this configuration is 2.8 (versus 64 in the configuration used in Example 1). As a result, the polymer degradation achieved in this configuration is significantly less than 36%.

In a second case, it is desired to use capillaries of internal diameter 0.5 mm, to generate a pressure drop of 15 bar for a flow rate of 100 m ³ / h, with a polymer degradation of less than 20%. According to Example 2 and Figure 8, the polymer degradation is about 20%, in a 0.5 mm internal diameter capillary, for a flow rate of 55 mL / min. Consequently, the number of capillaries to be provided to accommodate the total flow rate is equal to 30303. Still according to example 2 and FIG. 10, it is determined that the length of capillary necessary to obtain a pressure drop of 15 bars is 150 cm.

The corresponding total diameter of the capillary bundle obtained is approximately 1.19 cm (for an outer capillary diameter of 0.65 mm and a compactness of 0.9). The overall contraction ratio for this configuration is 1, 9 (against 16 in the configuration used in Example 1). As a result, the polymer degradation achieved in this configuration is significantly less than 20%.

Claims

1. A method of injecting a fluid into an underground formation, wherein:

a fluid is conveyed in at least one injection pipe (1);

- the injection line (1) comprises a main part (6) comprising a single tube, and a flow control valve (8) comprising at least ten fluid transport tubes (2) arranged in parallel; and wherein the ratio of the single tube section of the main portion (6) to the sum of the sections of the fluid transport tubes (2) of the flow control valve (8) is less than or equal to 5, preferably less than or equal to 3, and particularly preferably less than or equal to 1, 5,

- The flow rate of the fluid flowing in the injection pipe (1) is adjusted by distributing the fluid in all or part of the fluid transport tubes (2) of the flow control valve (8);

- The fluid from the injection pipe (1) is injected into the subterranean formation.

The method of claim 1, wherein:

at least a portion of the fluid transport tubes (2) have a section at least ten times smaller than the section of the single tube of the main part (6), preferably at least a hundred times less, particularly preferably at least one thousand inferior and ideally at least ten thousand times lower; and / or each transport tube is of constant section along its length; and or

said transport tubes are cylinders and extend along a longitudinal axis and / or the axes of said cylinders are parallel to each other; and or

the section of said transport tubes is circular.

Method according to claim 1 or 2, wherein the adjustment of the fluid flow rate in the injection line (1) is effected by selectively sealing all or part of the fluid transport tubes (2).

4. Method according to one of claims 1 to 3, wherein the fluid is distributed in a plurality of injection lines by means of pumping, each injection pipe (1) comprising a main part (6) comprising a single tube and a flow control valve (8) comprising at least ten fluid transport tubes (2) arranged in parallel, the flow rate of the fluid flowing in each injection line (1) being adjusted by distributing the fluid in all or part of the fluid transport tubes (2), and the fluid from the injection lines (1) being injected into the subterranean formation.

5. Method according to one of claims 1 to 4, wherein the fluid transport tubes (2) do not all have identical sections, and are preferably arranged in groups of fluid transport tubes substantially identical section.

6. Method according to one of claims 1 to 5, wherein:

at least a portion of the fluid transport tubes (2c) have a cross section of from 0.012 to 100 mm ² , preferably from 0.05 to 50 mm ² , and more preferably from 0.8 to 30 mm ² ; and or

- At least one fluid transport tube (2a) has a section of 1 to 100 cm ² , preferably 1 to 50 cm ² ; and or

all the fluid transport tubes (2) have a length of 1 cm to 10 m, preferably 10 cm to 3 m, and more preferably 30 cm to 1.5 m.

7. Method according to one of claims 1 to 6, wherein the fluid is an aqueous solution of a polymer whose molecular mass is greater than 10 ⁶ Da.

8. Method according to one of claims 1 to 6, wherein the fluid is an aqueous solution of polymer, preferably an aqueous solution of polyacrylamide.

9. Method according to one of claims 1 to 6, wherein the fluid is an emulsion, preferably an oil / water emulsion.

10. Method according to one of claims 1 to 9, comprising a hydrocarbon recovery step from the underground formation and optionally treatment of recovered hydrocarbons.

1 1. A flow control valve (8) for connection to a single pipe of a pipe, said valve comprising:

at least ten fluid transport tubes (2) arranged in parallel; connecting means (3) to a main part of the single tube of the pipe, situated at one end of the fluid transport tubes (2) and where the ratio of the section of the single tube of the main part (6) to the sum of the sections of said fluid transport tubes (2) of the flow control valve (8) is less than or equal to 5, preferably less than or equal to 3, and particularly preferably less than or equal to 1, 5 .

12. Flow control valve (8) according to claim 1 1, comprising means for closing (5) at least a portion of the fluid transport tubes (2).

13. Flow control valve (8) according to claim 1 1 or 12, wherein the closure means (5) comprise a diaphragm, vanes, a ball valve or a piston.

Flow control valve (8) according to one of claims 1 1 to 13, wherein the fluid transport tubes (2) do not all have identical sections, and are preferably arranged in groups of tubes of fluid transport (2) substantially identical section.

15. Flow control valve (8) according to one of claims 1 1 to 14, wherein:

at least a portion of the fluid transport tubes (2c) have a cross section of from 0.012 to 100 mm ² , preferably from 0.05 to 50 mm ² , and more preferably from 0.8 to

30 mm ^2; and or

- At least one fluid transport tube (2a) has a section of 1 to 100 cm ² , preferably 1 to 50 cm ^2; and or

16. A transport installation, in particular for injecting a fluid, for example into an underground formation comprising at least one pipe, in particular an injection pipe (1), said pipe including injection pipe (1) comprising:

a main part (6) which comprises a single tube, and

- A flow control valve (8) according to one of claims 1 1 to 15, connected to the single tube of the main part (6) by the connecting means (3).

An installation according to claim 16, wherein:

the section of said transport tubes is circular.

18. Apparatus according to claim 16 or 17, comprising a plurality of injection lines in particular connected to pumping means, each pipe including injection (1) comprising a main portion (6) comprising a single tube and a valve of flow control device (8) according to one of claims 1 1 to 15.