RU2347068C1 - Method of high-viscosity oil pool development - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention refers to oil industry and can be applied for high-viscosity oil pool development. According to the method, electrical decoupling is enabled in the well between the payout bed equipment and the equipment in the other part of the well. The payout bed equipment is made of electricity-conductive material. Payout bed space is filled with high electricity-conductive liquid. Other well space is filled with non-conducting liquid. The payout bed equipment is connected to power supply. The well within payout bad is pressurised. After yield of the closest well is, at least, 0.1 m³/day, power supply is disconnected, and heat-carrier is injected through intake wells with oil withdrawal field wells.

EFFECT: higher oil recovery of high-viscosity oil pool.

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Description

The invention relates to the oil industry and may find application in the development of deposits of high viscosity oil.

There is a method of developing a reservoir of high viscosity oil, according to which wells are drilled, a working agent is injected through injection wells, oil is taken through production wells and heated by electric current. Injection wells are drilled beyond the oil content circuit below the oil-water contact. Formation water is pumped there as a working agent. An electric current is fed through injection wells into the underlying aquifer of the reservoir for its heating and, after it, heating and the oil zone. At the same time, vertical displacement of oil from the reservoir to production wells is carried out. The electric current is supplied through diametrically placed wells with electrodes with opposite potentials “plus” and “minus” located in them (RF Patent No. 2210664, publ. 2003.08.20).

The known method is accompanied by large current leaks and a small degree of heating of the reservoir. In addition, the vertical displacement of oil requires additional costs for heating not only the oil, but also the water-saturated zones of the formation, which is accompanied by significant heat loss and low efficiency of the development system. As a result, the oil recovery of the reservoir remains at a low level.

Closest to the proposed invention in technical essence is a method of developing deposits of highly viscous oil, which consists in the following. A positive electrode-anode on tubing with the connection of a submerged power cable is lowered into one of the wells in its perforation zone. The casing of another well or the column of a group of other wells of the same horizon is the negative electrode-cathode. Wells of a group of wells have a hydrodynamic connection. The process of transmitting direct electric current with a voltage of 150-450 V and a current density of 0.1-100 A / m ^{2 is} carried out (RF Patent No. 2215872, publ. 2003.11.10).

The disadvantages of this method are the large current leakage along the casing and tubing string, low current flow into the reservoir and small heating. As a result of this, there is a large consumption of electricity without performing useful work, the formation is slightly warmed up and oil recovery remains at a low level.

The proposed invention solves the problem of increasing oil recovery deposits of highly viscous oil.

The problem is solved in that in a method for developing a highly viscous oil deposit, including pumping coolant through injection wells, taking oil through producing wells and heating the reservoir with electric current, according to the invention, before the coolant is pumped into the well, they break the electrical connection between the equipment in the interval of the reservoir and the equipment in other parts of the well, equipment made from electrically conductive is used as equipment in the interval of the reservoir material, the interval of the reservoir is filled with highly conductive fluid, the other space of the well is filled with a non-conductive fluid, electrical current is supplied to the equipment in the interval of the reservoir and the interval of the reservoir is heated by the passage of electric current, the pressure in the borehole is increased in the interval of the reservoir, as the fluid is consumed it is pumped into the interval of the reservoir, after the appearance of a flow rate in the nearest well of at least 0.1 m ³ / day, the injection is restored oil carrier through injection wells and oil extraction through production wells.

The features of the invention are:

1) coolant injection through injection wells;

2) oil extraction through production wells;

3) heating the reservoir by electric current;

4) before the injection of the coolant, the organization in the well of a break in the electrical connection between the equipment in the interval of the reservoir and the equipment in the other part of the well;

5) use as equipment in the interval of the reservoir of equipment made of electrically conductive material;

6) filling the interval of the reservoir with a liquid with high electrical conductivity;

7) filling other space of the well with a non-conductive fluid;

8) bringing to the equipment in the interval of the reservoir electric current and heating the interval of the reservoir due to the passage of electric current;

9) increase in pressure in the well in the interval of the reservoir;

10) as the fluid is spent pumping it into the interval of the reservoir;

11) after a flow rate in the nearest well of at least 0.1 m ³ / day, coolant is pumped through injection wells and oil is taken through production wells.

Signs 1-3 are common with the prototype, signs 4-11 are the salient features of the invention.

SUMMARY OF THE INVENTION

The use of electric current for heating a reservoir of high-viscosity oil contributes to a very small increase in oil recovery. The proposed invention solves the problem of increasing oil recovery deposits of highly viscous oil.

The problem is solved as follows.

When developing a reservoir of highly viscous oil, coolant is pumped through injection wells, oil is taken through production wells and the reservoir is heated by electric current.

In one or more wells, an electrical connection is broken between the equipment in the interval of the reservoir and the equipment in the other part of the well. To do this, cut the casing above the reservoir, the place of the cut is filled with a fastening material with high electrical resistance such as cement, liquid glass solution, etc. The tubing string is made up of pipes with dividing dielectric inserts between the pipes. As equipment in the interval of the reservoir, equipment is used made of an electrically conductive material, for example steel, aluminum alloys, copper, etc. The interval of the reservoir is filled with a liquid with high electrical conductivity, which can be used mineralized water, produced water of the developed reservoir, etc. Other well space is filled with a non-conductive fluid, for example, any hydrocarbon fluid such as oil, a wide fraction of light hydrocarbons, diesel fuel, etc. The interval of the reservoir may be separated from the top of the well by a packer or some other separating device. Hydrocarbon fluid, having a lower density, occupies an upper position in the well. An electric current is supplied to the equipment in the interval of the reservoir, for example, by cable and the interval of the reservoir is heated by the passage of electric current from the well into the rock. This eliminates the leakage of current along the casing string, tubing string and fluid in the well. All electrical energy enters the reservoir and heats the rock and oil. Oil liquefies, becomes mobile. Increase the pressure in the well in the interval of the reservoir. Gradually, fluid flow into the reservoir. As the fluid is consumed, it is pumped into the interval of the reservoir. After a flow rate in the nearest well of at least 0.1 m ³ / day, the electric current is switched off and the coolant is pumped through injection wells and oil is taken through production wells.

Steam or similar exposure to a large extent leads to local heating of the near-wellbore zone and steam breakthrough through the heated channel to the producing well. The heating of the reservoir passes through the formed channels (languages) of the passage of steam. Coverage of the formation by the impact becomes incomplete, and oil recovery remains low.

Preliminary heating of the formation with electric current according to the proposed technology makes it possible to uniformly heat the near-wellbore zone, create a zone of liquefied oil sufficient for the flow in the formation, and when pressure increases in the interval of the productive formation, it allows you to quickly create a hydrodynamic connection between the wells and start developing the reservoir. At the same time, due to uniform heating, the coverage of the formation increases by exposure. Due to this, the oil recovery of the deposit increases, and the rate of development of the deposit increases.

An example of a specific implementation of the method

A highly viscous oil reservoir is developed at a depth of 90 m, represented by heterogeneous formations with a thickness of 20-30 m with a temperature of 8 ° C, a pressure of 0.5 MPa, an oil saturation of 0.70 units, a porosity of 30%, and a permeability of 0.265 μm ² , s oil having a density of 956 kg / m ³ and a viscosity of 7000 MPa · s. The deposit is developed according to a seven-point development system with an injection well in the center of the development element. The distance between the wells is 100 m.

In the injection well, an electrical connection is broken between the equipment in the interval of the reservoir and the equipment in the other part of the well. To do this, cut the casing above the reservoir, fill the cut with cement mortar and carry out technological exposure to wait for the cement to harden. The tubing string is made up of pipes with dividing dielectric inserts between the fiberglass pipes. As equipment in the interval of the reservoir use a steel string of tubing. The interval of the reservoir is filled with mineralized water with a density of 1.08 g / cm ³ . Other well space above the reservoir is filled with oil. An alternating electric current of 150-450 V and a current density of 0.1-100 A / m ² through the cable is supplied to the tubing string in the interval of the productive formation and the interval of the formation is heated by passing electric current from the well to the rock. Oil in the space near the well liquefies, becomes mobile. At the wellhead, pressure is created within 10 MPa, which extends to the interval of the reservoir. Gradually, fluid flow into the reservoir. As the fluid is consumed, it is pumped into the interval of the reservoir by circulation. After injectivity of the well of the order of 10 m ³ / day, a flow rate of about 0.1-0.2 m ³ / day in the nearest wells is noted. Turn off the electric current. Steam is pumped through the central injection well, and oil is taken through 6 surrounding production wells.

As a result, it is possible to uniformly warm up the near-wellbore zone and increase oil recovery by 3%.

Claims (1)

A method for developing a highly viscous oil deposit, including pumping coolant through injection wells and extracting oil through producing wells, characterized in that prior to pumping coolant in the well, an electrical connection is broken between equipment in the interval of the reservoir and equipment in the other part of the well, as equipment in the interval of the reservoir use equipment made of electrically conductive material, the interval of the reservoir is filled with high electric fluid conductivity, other space of the well is filled with a non-conductive fluid, an electric current is supplied to the equipment in the interval of the reservoir and the interval of the reservoir is heated by the passage of electric current, pressure is increased in the well in the interval of the reservoir, as it is spent, it is pumped into the interval of the reservoir, after flow rate in the near wellbore at least 0.1 m ³ / day reduced download coolant through the injection wells and oil through selection extractive ck Azhinov.