WO2018220292A1

WO2018220292A1 - Facility for heating the production zone of the reservoir of a well for extracting hydrocarbons

Info

Publication number: WO2018220292A1
Application number: PCT/FR2018/000143
Authority: WO
Inventors: Jean-Aurélien Damour; Guillaume Coeffe; Daren JOHANNSON
Original assignee: Majus Limited
Priority date: 2017-05-29
Filing date: 2018-05-28
Publication date: 2018-12-06
Also published as: EP3631154A1; FR3066777A1; CA3063273A1; US20200182030A1; FR3066777B1; EP3631154B1

Abstract

The invention relates to a facility (1) for heating the production zone of the reservoir (12) of a well in order to extract hydrocarbons through a well (2) connecting the surface to said reservoir, comprising a substantially cylindrical casing (3) for consolidating the borehole, extraction means for extracting (4) hydrocarbons, and injection means for injecting the hot fluid from the surface towards the reservoir. Said facility comprises a first pipe (8) that passes through the well (2) and is thermally insulated from the injection of the hot fluid from the surface to the reservoir, a second pipe (11) surrounding the first pipe (8), for returning the hot fluid to the surface, and a third pipe (7) for extracting the hydrocarbons, which is independent from the first and second pipes (8, 11), said pipes extending from the surface to the reservoir.

Description

Reheating facility in the producing area Shaft deposit for hydrocarbon extraction

The technical sector of the present invention is that of reheating facilities of the well deposit for the extraction of hydrocarbons present in the geological deposits.

It is known to date to extract liquids from the soil, for example hydrocarbons, resting in underground deposits that can be several kilometers in the ground. After drilling a hole from the surface to the deposit where the liquid to be extracted, it consolidates the hole as drilling with pipes degressive diameter. All of these pipes constitute an envelope. In the producing zone, towards the buried end, this envelope is pierced with a number of orifices to provide access to the liquid. This pierced part is designated by the term strainer or drain along its length. A pipe of constant diameter and smaller than that of the casing is introduced into the previous casing in order to reach the bottom of the bore to pump the liquid to the surface. This pipe is therefore an extraction pipe. This pipe can be equipped with a downhole pump.

A problem frequently encountered is the low value of the absolute or total flow of the wellbore. This flow is related to several factors, but it is essentially the viscosity of the extracted liquid which poses a problem. This liquid is all the more viscous as its temperature is low. Depending on the composition of the liquids to be extracted, another problem may appear. In the case of a liquid containing fractions that can solidify, for example paraffins or asphaltenes, these fractions tend to solidify and this especially as the temperature drops. These fractions tend to be deposited and then come gradually to close the orifices of the producing zone, at the level of the envelope, and in the deposit itself in the vicinity of 1 envelope.

It is therefore observed that the high viscosity and the deposits solids lead to slowdowns of the flow, which increases the cost of production per unit volume, which may lead to the closure of a well.

In order to remedy this problem, several solutions have already been proposed. One can refer for example to US-2757738 and US-4344485.

One solution is to inject into the reservoir zone a solvent of the heavy fractions. A disadvantage is the need to provide logistics around this solvent: supply, storage ... Another disadvantage lies in the fact that the chemical action of the solvent relates only to certain fractions.

Another solution by providing heat is to have, at the bottom of the well in the drain, a heater. This heater is advantageously an electrical resistance. The difficult diffusion of this thermal power generates very important temperatures. There then arise problems of choice of materials, both for the resistance, for the end of the casing and / or the extraction pipe. Given its location downhole, it is difficult to achieve such a reliable and easily maintainable resistance. Finally, for reasons of safety, it is difficult to bring large amounts of electrical energy downhole, typically 100 to 500 kW.

Another solution is to inject, through the extraction pipe, water vapor under pressure. Several disadvantages are related to this method. Given the long length of a well, which can reach several kilometers, it is difficult to guarantee that the steam reaches the bottom of the well. In addition, the use of the extraction pipe for this purpose requires a complete cessation of production during this phase. This method has the disadvantages of discontinuous production (known as English Huff n 'Puff).

It is known that the injection of heat into an oil well promotes flow from the producing rock and through the strainer or drain. The heat acts in two ways: it decreases the viscosity of crude oil thus promoting its flow and it prevents the formation of deposits, paraffins and asphaltenes, or even melts if deposits prior to the heat injection existed.

The methods acting by supply of heat have a double effect. They act on the deposits and on the fluidity of the heated liquid, thus increasing the extractable flow and the efficiency of the extraction.

Finally, mention may also be made of FR-2881788, which describes a device in which a hot fluid is circulated in order to bring the rock locally to a higher temperature potential by conduction in order to fluidify the hydrocarbons, via a pipe insulated. The hot fluid is recovered in mixture with the hydrocarbons. The disadvantage of this device is that the hot fluid is mixed with the extracted hydrocarbons at the producing zone and thus the flow rate that will be accepted by the downhole pump must be increased by a factor of 5 to 30 depending on the flow rate of circulation and increase in well production.

In the case where the coolant is water, it is then necessary on the surface to separate the mixture thus formed.

Another disadvantage of this device in the case where the surface-heated fluid is the fluid extracted from the well, is that the boiler required to heat the fluid will have to be sized to heat a hydrocarbon mixture containing heavy elements and a portion of water too. The design of the boiler will be more complex and the boiler more expensive. For example, the elements

Boiler heaters should have a lower pfd than to heat a thermal oil. Maintenance of a boiler heating a mixture

Heavy hydrocarbon need to control the deposits that may appear on the heating elements.

The object of the present invention is to provide a system for improving the productivity of a well and increasing the recoverable reserves by a contribution of heat in the reservoir at the production zone of the well deposit by separating the coolant and the hydrocarbons extracted.

The subject of the invention is therefore a heating plant of the production zone of the well deposit for the extraction of hydrocarbons through the well connecting the surface to a deposit, comprising a substantially cylindrical envelope consolidating said well and a means hydrocarbon extraction tube housed inside said casing and means for circulating a heat-transfer fluid from the surface towards the deposit, characterized in that it comprises through the well a first thermally insulated pipe of injection from the surface of the hot fluid to the deposit, a second pipe surrounding the first pipe to return the hot fluid to the surface and a third hydrocarbon extraction pipe independent of the first and second pipes, said pipes extending from the surface to the deposit.

Surface equipment consists of a tank or expansion tank, a pump and a heater. The hot fluid exiting the heater flows in the thermally insulated pipe to the end thereof and then rises to the surface between the thermally insulated pipe and the second heating pipe.

According to one characteristic of the invention, the first and second pipes are connected to a hot fluid production station provided with a storage tank or expansion tank, a pump and a heater to ensure a circulation of continuous hot fluid in said pipes.

According to another characteristic of the invention, the first duct is open at its distal end and the second duct is closed at its distal end.

According to another characteristic of the invention, the first pipe is thermally insulated using a compression-resistant insulator, either by its compressive strength properties or by the addition of spacers regularly between the first and the second pipe. ■ Advantageously, the third pipe is connected to an extraction unit to surface up the hydrocarbons produced in the strainer or drain.

According to yet another characteristic of the invention, the third pipe is open at its distal end and provided with a downhole pump.

According to yet another characteristic of the invention, the first pipe consists of a first inner tube surrounded by a second concentric outer tube and a thermal insulator housed in the space between the two tubes.

Advantageously, the thermal insulation is a microporous material and a reduced pressure is established in the space between the two tubes.

According to yet another characteristic of the invention, the reduced pressure between the two tubes of the first pipe is between 1 and 100 mbar.

According to yet another characteristic of the invention, the first pipe is provided with a heating electric wire disposed against the inner wall of the inner tube.

According to yet another characteristic of the invention, the heat transfer fluid for heating the deposit is an industrial thermal oil.

The invention also relates to the application of the closed-loop circulation system to the closed-circuit preheating of a deposit upstream chronologically of the hydrocarbon extraction phase.

An advantage of the invention lies in the realization of a closed circuit for the supply of heat to the bottom of the well. Thus, heat is provided both on paraffins, asphaltenes or agglomerates of bitumen that it melts, than on the liquid it heats up at the bottom of the well.

Another advantage of the invention lies in the fact that there is no mixing of the hot fluid and recovered hydrocarbons thus allowing the elimination of a hydrocarbon separation station. Another advantage of the invention lies in the absence of pollution of the deposit since the hot fluid does not contaminate this deposit.

Another advantage of the invention lies in the use of even polluting fluid.

The hot fluid may be chosen from fluids used in heating installations, for example an industrial thermal oil or water.

The hot fluid exiting the heater flows in the first thermally insulated pipe to the end thereof and then rises to the surface between the first thermally insulated pipe and the second heating pipe. During this rise, the heat energy contained in the hot fluid is dissipated by conducto-convection in the oil produced in the drain and in the deposit itself.

The temperature of the hot fluid is maximum at the surface at the outlet of the heater. Thermal losses and therefore the decrease of the fluid temperature are low during the descent into the thermally insulated pipe. During the rise of the hot fluid to the surface, the heat exchange with the oil produced in the drain is important to allow the exchange of heat and the fluid temperature decreases sharply.

An advantage of the invention lies in the possibility of using an industrial thermal oil as heat transfer fluid. The volume of oil required in the closed loop formed by the first and the second pipe is between 500 liters to 3000 liters. Such a thermal oil, standard in the industry, will have a composition optimized to be heated to the desired temperature, typically 200 ° C or up to 300 ° C and will allow the use of surface equipment, pump and heater, standard in industry and less complex.

Indeed, heating a hydrocarbon mixture at temperatures of the order of 200 ° C has the risk of creating solid deposits on the heating elements of the boiler can cause a decrease in the heating power see the rise in temperature of the heating element concerned and its degradation. The method of heating a thermal oil will be simpler since the composition thereof is uniform and will be selected so as not to create deposits at the desired temperature.

Another advantage of the invention is that the amount of water contained in the hydrocarbon produced no longer influences the design of the heater. If water is present in the hydrocarbon to be heated, from 0 to more than 90%, the heater will have to bring more energy to raise the temperature of the mixture of the same value and if steam appears, the efficiency of the exchanger drops.

Another advantage of the invention is that after a modification of the wellhead, this installation is independent of the other standard well production equipment and can therefore be installed and removed according to the needs of the well leaving the equipment in place. standards of production of well bottoms and also of surface.

Another advantage of the invention lies in the fact that the pipes for the closed-loop circulation of the hot fluid can be made from rolled pipes known as "coiled tubing". The double wall thermally insulated pipe can be produced from two coiled tubings and inserted into the second larger diameter pipe, which can be a coiled tubing as well. This triple pipe can be wrapped around a "coiled tubing" wheel for transportation and installed in a single operation by a "coiled tubing" unit in the well. Special parts are installed at each end of the coiled tubing to isolate or communicate the annular rings as required by closed loop circulation.

Another configuration of this invention is the use of this circulation in a closed circuit to preheat a deposit upstream chronologically of the hydrocarbon extraction phase. Such preheating is necessary for some methods of recovering heavy hydrocarbons such as SAGD (Steam-Assisted Gravity Drainage). In this configuration, there is no third pipe to raise the hydrocarbons; it is a preheating phase of the deposit only. An advantage of this configuration is that this preheating can be achieved with moving surface equipment using a high temperature thermal oil, 200 ° C or higher. This preheating configuration can advantageously replace preheating by steam injection for reasons of cost and planning of operations on a petroleum field.

Other characteristics, details and advantages of the invention will emerge more clearly from the detailed description given below as an indication in relation to drawings in which:

FIG. 1 illustrates the upper part of an installation according to the invention,

FIG. 2 is a section taken at the hydrocarbon deposit,

FIG. 3 is a section along AA of FIG. 1, and

FIG. 4 is a section BB of FIG. 2.

An oil well is generally composed of two essential parts, an outer pipe (designated by the English word casing) responsible for consolidating the outer wall of the well in the ground and an inner pipe (designated by the English word tubing) allowing the oil recovery on the surface. A strainer or drain serves two purposes: it filters the extracted crude oil back to the surface and prevents the collapse of the drilled hole in the producing area. Various manual and automatic valves ensure the seals and the safety of the well with respect to the outside. For more precision, reference may be made to patent FR-2881788, which illustrates the conditions of production of a well by heat input.

The invention will now be described in more detail by noting that FIG. 1 illustrates the upper and outer portion of the wellbore and FIG. where are the hydrocarbons to be extracted. As previously stated, it is a question of warming the producing zone of the well deposit in order to extract the hydrocarbons still present in the deposit.

According to Figure 1, there is partially shown the upper part of the heating system 1 of extraction ducts according to the invention wherein the vertical drilled well 2 is consolidated by a cylindrical metal shell 3. This well is related to a deposit as will be explained below. In the metal casing 3, a hydrocarbon extraction means 4 is introduced at the surface and inside said casing 3 and means 5 make it possible to circulate a hot fluid from the surface towards the deposit to be heated and then to new on the surface.

The extraction means 4 consist of an extraction unit 6 and a pipe 7 connecting this unit to the hydrocarbon deposit.

The means 5 comprise a first channel. 8 thermally insulated to circulate in a closed circuit from the surface of the hot fluid to the deposit and back to the surface. This pipe 8 is connected to a unit 9 for heating and injecting the hot fluid continuously with a continuous control of the temperature and the flow rate. This heating unit comprises a tank 23 or an expansion tank, a pump 10 and a heater 24. It goes without saying that this pipe 8 connects the unit 9 to the hydrocarbon deposit that is heat. The expansion vessel 23 makes it possible to accommodate the increase in volume of the hot oil in the closed circuit and thus avoid any overpressure in the circuit.

This first pipe 8 is surrounded by a second pipe 11 to return the hot fluid to the unit 9. The pipes 8 and 11 constitute with the hot fluid production unit 9 a closed circuit for continuous circulation of this hot fluid.

FIG. 2 shows the installation according to the invention at the hydrocarbon deposit 12 which has a substantially vertical portion 13 and a substantially horizontal portion 14 of length 1. In this figure is found the casing 3 whose end is provided with radial perforations 15 at its end in the bearing 12. These perforations allow the entrance of the liquid 16 in the envelope 3. This portion 14 of the envelope is commonly called strainer and there are the pipes 7, 8 and 11. The pipe 7 extends from the surface to the beginning of the strainer 14 like this is visible on this figure.

In this strainer 14 of the casing 3, the first duct 8 is open at its distal end 17 and the second duct 11 is closed at its distal end 18 by a transverse wall.

The insulator 21 may be a powdery material commonly used in this field. To reinforce the thermal insulation, the free or annular space delimited between the two tubes 19 and 20 is subjected to a reduced pressure. This reduced pressure can be between 1 and 100 mbar.

It is also possible to provide a heating electric wire applied at the level of the inner tube 19 so as to reinforce the thermal input of the pipe 8 as will be explained in connection with FIGS. 3 and 4.

The hot fluid circulating in a closed circuit in the reservoir 12 can act thermally. By reheating the deposit, its activity can be dissolving in order to limit, reduce or eliminate deposits, such as paraffins, asphaltenes or agglomerates of bitumen, which during their solidification would be deposited around the perforations 15 of the envelope 3, until they come to close them. Since it is a closed circulation circuit, the deposit 12 does not undergo any contamination by the fluid used.

The fact of using a hot fluid confers a double action. The heat melts the already solidified or deposited fractions. The heat, dissipated by conducto-convection in the envelope 3 filled with fluid then by conduction in the deposit, acts moreover, decreasing the viscosity of the hydrocarbon 16. The latter becomes more fluid by being heated. By conduction in the rock of the deposit 12, the heat sent will fluidize the hydrocarbons to be extracted and thereby reduce the pressure drop. Thus, with the same pumping power, a larger amount of liquid will be extracted (improved productivity) and we can pump liquid trapped further in the tank (improving recoverable reserves).

The depth of the well can reach several hundred meters (100 to 2000 m), it is essential to bring heat to the deposit 12, to have a pipe 8 highly thermally insulated.

There is provided a pipe 8 thermally insulated. Line 8 is made according to the technique known as the English word "pipe in pipe". Between the two tubes 19 and 20 is disposed an insulator 21.

The inner tube 19 transports the hot fluid. This tube is mechanically protected by the second tube 20 of larger diameter concentric with the first tube 19 and thermally by the insulator 21.

Several possibilities are offered for producing an insulation between the two tubes 19 and 20. It is advantageous to provide a crash-resistant insulator 21 acting as a spacer, either by its compressive strength properties or by the regular addition. spacers between the first and second pipes to prevent the two tubes 19 and 20 from coming into contact with each other. A microporous material can be used as insulation between the tubes 19 and 20.

This microporous material, of the type described in patent FR-2746891, is advantageously obtained by compressing a powder, for example fumed silica. Such a compressed microporous material advantageously has a density of between 180 and 400 kg / m ³ . The insulating thermal capacities of such a material are markedly improved when it is placed in the ring under low pressure between the two tubes 19 and 20. It is also possible to produce an insulator 21 by producing a multilayer super-insulation consisting of reflector screens interposing layers of powder as described in patent FR-03.13197. The screens are constituted by a reflective sheet, for example aluminum, on which the powder is deposited, wound spirally on itself. The powder has a particle size substantially equal to 40 μτη, pores whose size is of the order of magnitude of the average free path of the gas molecules in which this powder is placed and a density of between 50 and 150 kg / m ³ . The insulating thermal capacities of such a material are significantly improved when it is placed in the ring under low pressure, between 10 ^{~ 2} and 1 mbar between the two tubes 19 and 20. This insulation, having no properties of sufficient compressive strength, requires the addition of spacers regularly between the tubes 19 and 20. The material used to make these spacers must have a good insulating behavior. Such a material may advantageously be a microporous material as described above.

A pipe as described above allows sufficient heat input to make the hydrocarbons sufficiently fluid with a boiler of 20 to 500 KW.

The installation 1 according to the invention makes it possible to increase the production of crude oil by 20 to 500%, to exploit neglected reserves and to avoid any pollution of the deposits.

As a guide, a pipe 8 according to the invention may consist of an outer tube 20 of 33 mm in outer diameter with a thickness of 2 mm and an inner tube 19 of 13 mm in outer diameter with a thickness of 2 mm and is capable of transporting 20 kW at 200 ° C over an overall distance of 1000 meters. In this example, the pipe 11 may be a 60 mm outside diameter tube with a thickness of 5 mm and the cylindrical envelope of 178 mm in diameter in the vertical part and 114 mm in the drain or strainer section.

As an indication again, a pipe 8 constituted an outer tube 20 with a diameter of 60 mm and a thickness of 6 mm and an inner tube 19 with a diameter of 33 mm and a thickness of 4 mm will easily transport 200 kW at 200 ° C over a global distance of 2000. meters. In this case, the pipe 11 may be a tube of 89 mm with a thickness of 6 mm and the cylindrical envelope of 244 mm in diameter in the vertical part and 178 mm or 140 mm in the section drain or strainer.

FIG. 3 shows a section AA of FIG. 1 on which the envelope 3 has been taken up. In this envelope, there are the pipes 7, 8 and 11. The first channel 8 consists of a first tube internal 19 surrounded by a second concentric outer tube 20 and an insulator 21 housed in the space between the two tubes.

This figure also shows the heating wire 22 disposed along the outer wall of the inner tube 19 from the surface.

It goes without saying that the various elements illustrated in this FIG. 3 do not have scale and are only represented for illustrative purposes.

In Figure 4, which is a section BB of Figure 2, there is the envelope 3 equipped with pipes 8 and 11.

As previously, the first pipe 8 consists of a first inner tube 19 surrounded by a second outer tube

20 concentric and an insulator 21 housed in the space between the two tubes. The third channel 7 goes from the surface to the beginning of the strainer 14 or drain and is therefore absent in this figure.

This figure also shows the heating wire 22 disposed against the outer wall of the inner tube 19.

It goes without saying that the various elements illustrated in this figure 4 do not include scale and are represented for illustrative purposes only.

Claims

1. Heating plant (1) of the producing zone of the well (12) of a well for the extraction of hydrocarbons through the well (2) connecting the surface to this deposit (12), comprising an envelope (3) ) substantially cylindrical consolidating said drilling and hydrocarbon extraction means (4) housed inside said casing and means for circulating a hot heat transfer fluid from the surface to the deposit (12), characterized in that it comprises through the well (2) a first pipe (8) insulated thermally injection from the surface of the hot fluid to the deposit (12), a second pipe (11) surrounding the first pipe (8) to bring back the hot fluid to the surface and a third hydrocarbon extraction pipe (7) independent of the first and second pipes (8, 11), said pipes extending from the surface to the reservoir.

2. Heating plant (1) according to claim 1, characterized in that the first (8) and second (11) pipes are connected to a station (9) for producing the hot fluid comprising a reservoir (23) or an expansion tank, a pump (10) and a heater (24) to ensure a continuous flow of hot fluid in said pipes.

3. Heating plant (1) according to claim 1 or 2, characterized in that the first pipe (8) is open at its distal end (17) and in that the second pipe (11) is closed at its distal end (18).

4. Heating plant (1) according to any one of claims 1 to 3, characterized in that the first pipe (8) is thermally insulated with a compression-resistant insulator.

5. Heating plant (1) according to one of claims 1 to 4, characterized in that the third pipe (7) is connected to an extraction unit (6) to surface up the hydrocarbons produced in the strainer or drain.

6. Heating plant (1) according to claim 5, characterized in that the third pipe (7) is open at its distal end and provided with a well bottom pump.

7. Heating plant (1) according to any one of claims 1 to 6, characterized in that the first pipe (8) consists of a first inner tube (19) surrounded by a second outer tube (20) concentric and an insulator (21) housed in the space between the two tubes.

Heating installation (1) according to the claim

7, characterized in that the thermal insulation (21) is a microporous material and in that a reduced pressure is established in the space between the two tubes (19, 20).

Heating installation (1) according to the claim

8, characterized in that the reduced pressure between the two tubes (19, 20) of the first pipe (8) is between 1 and 100 mbar.

Heating installation (1) according to any one of claims 7 to 9, characterized in that the first pipe (8) is provided with a heating electric wire (22) disposed against the outer wall of the inner tube (19). ).

11. Heating plant (1) according to any one of the preceding claims, characterized in that the heat transfer fluid for heating the deposit (12) is an industrial thermal oil or water.

12. Application of the heating system (1) according to any one of the preceding claims to the preheating in a closed circuit of a deposit upstream of the hydrocarbon extraction phase.