RU2315858C1 - Method for bottomhole productive reservoir zone treatment - Google Patents

Abstract

FIELD: oil industry, particularly enhanced recovery methods for obtaining hydrocarbons by repressuring or vacuum methods.

SUBSTANCE: method involves lowering pipe string in well; installing pipe string shoe provided with cavitational generator within productive reservoir range; injecting working agent; flushing bottom zone; injecting and forcing hydrocarbon solvent in reservoir. Pipe string shoe has integrated cavitational generator with working diffusers. Number of working diffusers is equal to 2 - 4 pairs. The working diffusers are transversal to well bore axis and are grouped in pairs tangentially directed to well bore wall so that 30-60° angle is defined in-between. Working agent is injected under depression in stalling cavitation regime along with cavitational generator reciprocation inside perforated reservoir thickness range.

EFFECT: increased well producing ability due to increased cavitational field power, cavitational field energy direction on productive reservoir along with production string protection against breaking cavitational field action on productive reservoir in depression state.

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Description

The invention relates to the oil industry and can be used in the treatment of the bottom-hole zone of the reservoir of producing and injection wells.

Known are cavitation oscillators of fluid pressure oscillations operating in the periodically discontinuous cavitation mode, which are Venturi tubes with an inlet nozzle and a diffuser (Pilipenko V.V. Cavitation oscillations. Kiev: Naukova Dumka, 1989).

A known method of processing productive formations by supplying a processing agent with a pump through a pipe string and a cavitation generator represented by a venturi directed along the axis of the wellbore (Melamed Yu.A. Hydropulse technology - great opportunities and a wide range of applications. Exploration and protection of mineral resources . - M .: Nedra, 1993., 6, p. 19. RF patent No. 2070286, MKI E21B 43/26, 97). However, this method has a serious drawback when the productive formations are located at a depth of a thousand or more meters and it is not possible to realize an effective cavitation process due to the high static pressure.

Closest to the proposed technical solution, a method is known where the operation of a cavitation generator is combined with the operation of a deep jet pump (patent No. 2224883), which reduces the pressure on the bottom and thereby creates conditions for the operation of a cavitation generator. The disadvantage of this method is that the only diffuser of the cavitation generator is directed along the axis of the wellbore. Therefore, the energy of the cavitation field created by the generator is only partially directed to the reservoir. The bulk of the energy is distributed along the wellbore and is absorbed by a liquid column. In addition, the generator in the processing process is in one place, therefore, sections of the productive formation that are remote from the generator receive significantly less impact, and with large thicknesses of the formation they remain completely unaffected.

The technical problem. Increasing well productivity by increasing the power of the cavitation field, directing the energy of the cavitation field directly to the reservoir while protecting the production string from destruction and exposure of the cavitation field to the reservoir in a state of depression.

The proposed technical solution is aimed at increasing the efficiency of processing the productive formation throughout its thickness due to the fact that the face is washed, the hydrocarbon solvent is pumped and pumped into the formation, while the shoe of the pipe string is equipped with an integral cavitation generator, the number of working diffusers of which is from two to four pairs perpendicular to the axis of the wellbore and directed tangentially in pairs, at an angle of 30-60 ° to the wall of the wellbore, and the injection of the working agent uschestvlyayut depression, disruptive cavitation mode and simultaneous reciprocation in a cavitation generator perforated reservoir interval thickness.

The method is as follows: washing the bottom of the well from dirt is carried out with an aqueous solution of ML-81, or ML-81B, or FLEK-DG-002. After that, the calculated amount of hydrocarbon solvent (miaprom, distillate, toluene, hexane fraction, etc.) is pumped into the well and forced into the formation. The shoe of the pipe string is raised to the middle of the wellbore and with the help of a swab, the liquid level in the wellbore is reduced to a value corresponding to the bottomhole pressure. They raise the pipe string, equip the shoe of the column with an integrated cavitation generator, lower it into the well and set it in the interval of the sole of the reservoir. At the mouth, the pipe string is tied to the pump unit using a high-pressure hose or in any other way that moves the pipe string up and down in the process of pumping the working agent, and is suspended on the hook of the lifting unit. A pumping unit pumps a working agent (water, an aqueous surfactant solution) into a pipe string in a mode that provides a shear cavitation process in the generator. At this time, the lift slowly moves the pipe string with the generator from the bottom of the formation to the roof, and then also slowly lowers from the roof to the bottom, etc. If the thickness of the reservoir is greater than the height of the installation, the processing is carried out in parts. The exposure time should be at least one hour for each meter of the thickness of the reservoir.

An example of a specific implementation.

Tests of the method were performed at well No. 7403 of the Sarmanovskaya area of NGDU Jalilneft, OAO Tatneft.

Geological and technical characteristics of the well:

1. Productive horizon D1 2. Artificial slaughter 1791 m 3. Perforation interval 1751-1756 m 4. Reservoir pressure 13.5 MPa 5. Flow rate 7.7 m ³ / day 6. Water cut 52.3% 7. Static level 516 m 8. Dynamic level 1206 m

Technology execution

1. We lowered the tubing string into the well before artificial slaughter (1791 m).

2. An aqueous solution of ML-81 0.2% concentration washed the bottom and the wellbore.

3. 4 m ³ hydrocarbon solvent were pumped into the tubing string and pushed into the formation.

4. The shoe of the tubing string was lifted to an interval of 1100 m and swabbed (reduced liquid level in the well) to 1000 m.

5. The tubing string was raised and the shoe of the column was equipped with an integrated cavitation generator with three pairs of diffusers tangential to the walls of the wellbore at an angle of 45 °.

6. The tubing string was lowered into the well and the generator was installed in the interval of 1756 m.

7. At the mouth, the tubing string was tied to the AN-700 pump unit using a high-pressure hose with a margin of 7 m.

8. The suction hose of the pump unit was equipped with a filter and lowered into a container with a working agent (ML-81 aqueous solution. ML-81 concentration in water 0.01%).

9. We turned on the pump unit and started pumping the working agent at a pressure of 22 MPa (design mode of the generator for a given well depth). At the same time, using a lifting installation, they began to slowly move the generator to the formation roof. Having reached the roof, an interval of 1751 m, they stopped the rise and began a slow descent of the generator to the bottom of the formation. In this mode, the work lasted for six hours. After completion of the stimulation operation, the pipe string was lifted, the generator was dismantled, the well was washed with oil, the pumping equipment was lowered and the well was put into operation. Ten days later, the wells performed hydrodynamic studies and established:

1. The fluid flow rate amounted to 12 m ³ / day 2. Water cut decreased to 40% 3. The static level rose to 383 m 4. The dynamic level has risen to 1112 m

Thus, as a result of cavitation effects on the productive formation of well No. 7403, the oil production rate doubled and amounted to 6 tons / day.

Claims (1)

A method for treating the bottom-hole zone of a productive formation, including the descent of a pipe string into a well, installing a shoe of a pipe string equipped with a cavitation generator in the interval of a productive formation and pumping a working agent, characterized in that the face is washed, the hydrocarbon solvent is pumped and pumped into the reservoir, the shoe of the pipe string is equipped with an integral cavitation generator, the number of working diffusers of which is from two to four pairs located perpendicular to the axis of the barrel with wells and directed in pairs along the tangent to the wall of the wellbore at an angle of 30-60 °, and the injection of the working agent is carried out during depression, in the mode of stall cavitation and simultaneous reciprocating movement of the cavitation generator in the interval of the perforated thickness of the reservoir.