RU2215872C2 - Method of oil formation stimulation - Google Patents

Abstract

FIELD: oil production; applicable in development of pools with high-viscosity oil, including bitumen oils for recovery of residual oil, selective waterproofing of formations, improvement of reservoir properties of oil-bearing formation, cleaning of bottomhole zones from mineral clusters and deposits of asphalt-resinous substances. SUBSTANCE: method includes running into one of wells, in zone of its perforation, of positive electrode-anode on tubing with connection of power immersed cable. Casing string of other well or string of group of other wells of same horizon serves as negative electrode-cathode. Wells of one group have hydrodynamic communication. Direct current with voltage of 150-450 V and current density of 0.1-100 A/sq. m is supplied to said electrodes. Current flow through formation multicomponent mixture results in its intensive heating. The higher is current density, the higher is temperature. Electrochemical, electrolytic, ion-plasma processes take place. Dissolved solid mineral clusters are withdrawn from formation to improve reservoir properties due to depression produced by pumps in all wells. Presence of high temperature results in change of oil viscosity to improve its fluidity and its displacement by agent. Relief temperature of formation is restored. Method provides for treatment of many wells economically efficiently without use of additional expensive chemical reagents, with observed ecological safety of oil recovery technology, considerable reduction of stimulation cost. EFFECT: higher efficiency of method. 1 ex

Description

 The method relates to the field of oil production and can be used in the development of deposits with highly viscous oil, including bitumen, for the extraction of residual oil, selective waterproofing of reservoirs, improving the reservoir properties of oil-saturated formations, cleaning the bottom-hole zones of mineral clots and deposits of asphalt-resinous substances )

 A known method of developing an oil field according to a. from. USSR 1694872, IPC E 21 V 43/24, publ. 11.30.91, in which the impact on the oil reservoir is carried out by passing an electric current through electrodes placed in the bottom waters under the oil reservoir.

 This method is inefficient and has limited technological capabilities.

Closest to the proposed one is a method of influencing an oil reservoir, including the process of transmitting a constant electric current with a voltage of 150-450 V and a current density of 0.1-10 A / cm ² through a multicomponent well mixture. As a cathode, a well casing. An electrode is installed as an anode in the zone of its perforation. Produce a continuous injection of saline water from the wellhead (RF patent 2163662, IPC E 21 B 43/25, publ. 02.27.2001).

 The disadvantages of this method are the increased load on the well string when injecting water under pressure, the ability to process a limited zone of the formation, the effect is only in the zone of one well, even if there are more than one well in the well, resulting in low efficiency of the method.

The problem is achieved by the method of exposure to the oil reservoir, including the process of transmitting a constant electric current voltage of 150-450 V and a density of 0.1-10 A through a multicomponent reservoir mixture by electrical communication between the electrodes using casing pipes as the cathode and as the anode - an electrode lowered into the well perforation zone, characterized in that casing of pipes of one or a group of wells of the same horizon having hydrodynamic are used as cathode Us. To install the anode, a well of the same horizon, not included in the indicated group of wells, is used for electrical communication between the electrodes through a section of the oil reservoir from one well to another or a group of wells of the same horizon in the zone of their hydrodynamic connection, and the process is carried out at a constant voltage electric current of 20-150 and 450-1000 V and current density of 10-100 A / m ² while continuously creating depression in all wells.

 The positive electrode can be made in the form of a squirrel wheel.

 The current flowing through the multicomponent formation mixture leads to its intense heating, the higher the temperature, the higher the current density.

 Electrochemical, electrolytic, ion-plasma processes form insoluble precipitates, which, precipitating in water-saturated pores, clog them.

 Oxygen and hydrogen form acidic and alkaline environments with high temperature, respectively. The thermo-acidic medium interacts with the rock of the formation, and the thermo-alkaline medium reduces the surface tension of oil, improving the leaching properties of the displacing agent, dissolves solid mineral clots and ASB, which are removed from the formation due to the depression created in the wells by pumps, improving reservoir properties.

 The presence of high temperature leads to a change in the viscosity of the oil, improves its fluidity and displacement by the agent.

 The relict temperature of the reservoir is restored.

 At the initial moment, the electrical contact between the electrodes occurs through a narrow channel of the water-saturated zone of the formation, the temperature of the multicomponent mixture in the channel begins to increase, the electrical conductivity decreases, the electrical resistance in the channel increases, and this leads to a gradual expansion of the conduction channel. With a prolonged transmission of electric current and maintaining the current density unchanged due to an increase in voltage, the zone of coverage of the water-saturated region of the formation occupies the entire zone of hydrodynamic communication between the wells.

 In addition, during the exposure, the polarization zone of the oil-water contact is restored, which in turn increases the oil displacement zone, reducing the percentage of water cut in the well.

 An example implementation.

The debit of well A decreased to 9 m ³ / day, the water cut of the well was 96%, the mineralization of the displacing agent was 12%.

The debit of well B is 1.5 m ³ / day, the water cut is 25%.

In the interval of perforation of well A on the tubing with the power cable connected, lower the positive electrode, the surface area of which is 960 cm ² .

 A negative conductor is connected to the casing of another well.

DC voltage 450 V, current density 0.2 A / cm ² .

 As a result of the impact, the debit of the wells increased by 40%, the water cut decreased by 15%.

Thus, enhanced oil recovery occurs in all wells affected by the impact due to:
- involvement in the development of areas with high resistance to the displacing agent,
- improving the reservoir properties of the oil reservoir,
- isolation of water by sedimentation of insoluble sediments from a displacing agent (multicomponent reservoir mixture),
- cleaning the bottom-hole zones of wells from ASV and mineral clots,
- increase the temperature of the reservoir in the zones of hydrodynamic communication wells,
- restoration of the polarization zone in the area of oil-water contact.

 The method allows cost-effective processing of many wells without the use of additional expensive chemicals, while observing the environmental safety of oil production technology, significantly reduces the cost of exposure.

Claims (1)

A method of influencing an oil reservoir, including the process of transmitting a direct electric current of 150-450 V voltage and a current density of 0.1-10 A / m ² through a multicomponent reservoir mixture by performing electrical communication between the electrodes using pipe casing as a cathode, and as anode - an electrode lowered into the well perforation zone, characterized in that the casing of one or a group of wells of the same horizon having hydrodynamic coupling is used as a cathode to install the anode they use a well of the same horizon, not included in the indicated group of wells, carry out electrical communication between the electrodes through a section of the oil reservoir from one well to another or a group of wells of the same horizon in the zone of their hydrodynamic connection, and the process is conducted at a constant electric current voltage of 20 -150 V and 450-1000 V and a current density of 10-100 A / m ² with the continuous creation of depression in all wells.