RU2122630C1 - Method of developing oil pool at late stage of its operation - Google Patents

Abstract

FIELD: oil-producing industry, more specifically, development of oil pools. SUBSTANCE: method includes drilling of intercrossing rows of injection wells to form closed contours of injection. Located within these contours are producing wells with establishment of withdrawal zones. Producing wells located between injection contour and withdrawal zone are operated periodically. At each period engaged in operation are those wells which are located in zone affected by shun-in for this period injection wells. Displacement agent is injected through injection wells and oil is withdrawal through producing wells. Injected to these wells, located between injection contour and withdrawal zone and featuring the limit rate of water encroachment, and to injection wells in zone affected by producing wells are chemical reagents increasing filtering resistance of highly permeable formation zones. EFFECT: redistributed filtering flows withdrawal of oil from zones weakly affected by stimulation and prevented premature water cutting of recovered products.

Description

 The invention relates to the oil industry and can be used in the development of oil deposits in the late stages of field exploitation.

 A known method of developing an oil reservoir, including exposure cycles by changing the volume of injection of the displacing agent through the injection wells and changing the selection of fluid through the production wells, the injection of the displacing agent through the injection wells is carried out simultaneously with the cessation of fluid withdrawal through the high-water producing wells, and during the half-cycle of the termination of injection the displacing agent produce forced fluid withdrawal through production wells [1].

 There is a method of developing an oil reservoir, which involves drilling it in intersecting rows of injection wells that form an injection circuit and operate alternately, placing production wells inside the injection circuit to form a tightening zone, and producing wells located between the pressure loop and the tightening zone include periodic operation, that in each period, those wells that are in the zone of influence of the injection wells stopped for this period are included in the operation [2].

 The disadvantage of this method is its low efficiency due to the fact that the effect of cycling wells with periodic shutdown of production wells does not appear after the formation of washed zones, the bulk of the displacing agent is filtered through high-permeability layers into production wells arbitrarily located in the reservoir.

 The present invention is based on the task of creating a highly efficient integrated method for developing an oil reservoir, which allows, due to the redistribution of filtration flows, to more fully extract oil from areas poorly affected by exposure and to prevent premature flooding of produced products.

 The problem is solved by creating a method of developing an oil reservoir at a late stage of operation, including drilling it with intersecting rows of injection wells that form closed injection circuits and working alternately, placing production wells inside the contour with the establishment of a zone of contraction, production wells located between the injection circuit and the zone of contraction , include in the work periodically so that in each period those wells that are in the zone of influence injected during this period, injection of a displacing agent through injection wells and oil extraction through production wells, moreover, when developing an oil reservoir with low permeability inclusions in production wells located between the injection circuit and the tightening zone and reaching the maximum water cut, and in injection wells located in the zone of influence of these producing wells is injected with chemicals that increase the filtration resistance of the flooded highly permeable zones of the formation.

 When developing an oil deposit, zones with undeveloped oil reserves are distinguished, intersecting rows of injection wells are placed in them in such a way that they form closed injection circuits. Production wells are placed inside the injection circuit to form a contraction zone. Cycle injection of the displacing agent through injection wells is carried out, which are periodically and alternately turned on and off. Oil is extracted through production wells, they operate cyclically - at each time period, those production wells that are in the zone of influence of injection wells stopped for this period work. By creating a high pressure circuit, oil flows move toward the center, increasing its production.

 When developing an oil reservoir, the presence of low-permeability inclusions located arbitrarily relative to production and injection wells does not allow uniformly leading the displacement front to production wells located in the contraction zone. Also, the injected displacing agent through a narrow space can break into the contraction zone and prematurely flood the formation. To prevent these phenomena, a hydrodynamic connection is established between heavily watered production wells and injection wells located in the zone of influence of these production wells, to production wells located between the injection circuit and the tightening zone and reaching the maximum water cut, and to injection wells located in the zone of influence of these production wells wells, inject chemicals that increase filtration resistance. As chemical reagents, for example, polymer dispersed systems (PDS), PDS with aluminum chloride, hypo-hydrochloric acid mixtures, and others, which, after injection into inhomogeneous strongly flooded formations due to increased filtration resistance in highly flooded areas, can change the direction of motion of the injected displacing agent, can be used .

 PDS injection is carried out according to RD 39-5765678-259-88R, PDS with aluminum chloride according to the “Instructions for the application of technology for impacting water-oil reservoirs with polymer-dispersed systems with gel-forming compositions”, water-isolating composition consisting of multivalent metals and alkaline runoff of caprolactam production, according to RD 39 -202-2-94.

 In field conditions, the method is as follows.

 Five parallel rows of injection wells with a distance between the rows of 550 m are placed on a specific deposit with an area of 260 ha. Additional rows of injection wells located perpendicular to the main rows of injection wells, which with the main rows form an injection circuit, are placed between the rows of injection wells every 6 to 8 wells. Inside the injection circuit, a different number (20-30) of producing wells are located, on which bottomhole pressure is set close to the pressure of oil saturation with gas. The outer boundary of these extractive constitutes the contraction zone. Between the injection circuit and the contraction zone, 15 to 25 producing wells are placed. The cyclic operating mode of the injection wells is established, and the operating mode of part of the producing wells depends on the operating mode of the injection wells, i.e. in cyclic mode with stops and re-starts of injection and production wells.

 With progressive watering of any producing well, indicating a displacement of the displacing agent in the direction of the contraction zone, a local impact on this highly permeable or fractured area is performed by pumping in reagents that create a residual resistance factor to limit the movement of the displacing agent in the form of rims from 0.05 to 0, 15 of the pore volume. Reagents are injected into production wells as well as into injection wells located in the zone of influence of these production wells. The amount of injected reagents is determined according to the current RD for the injection of these reagents. The main criteria of the chemical injection technology is the injectivity of the wells, the thickness of the flooded layer and the injection pressure, which exceeds the initial pressure by no more than 25%, but not higher than the pressure of the pressure of the columns.

 Then, after the necessary amount of chemicals has been pumped, injection and production wells operate in the same mode.

 The measures taken lead to the alignment of the entire displacement front to the contraction zone.

 After several years of development, with oil water cut in production wells of more than 80%, a contraction zone is reduced to 5 to 10% of production wells.

 The claimed invention in comparison with the known one has the following technical and economic advantages: it allows to selectively act on individual sections of the reservoir with washed zones and to prevent premature breakthrough of water into the zone of oil contraction; the injection of expensive polyacrylamide is reduced; due to the complex effect on the reservoir, the oil recovery coefficient increases from 0.47% to 10.2 - 23.1%.

Sources of information
1. A.s. N 1553658, cl. E 21 B 43/20, 1990.

 2. A.s. N 1825395, cl. E 21 B 43/30, 1993.

Claims (1)

 A method of developing an oil reservoir at a late stage of operation, including drilling it with intersecting rows of injection wells forming closed injection circuits located inside the production well contour with establishing a tightening zone, producing wells located between the pressure loop and tightening zone, include periodic operation so that in each period, those wells that are in the zone of influence of the injection wells stopped for that period, include agent through injection wells and oil extraction through production wells, characterized in that when developing an oil reservoir with low permeability inclusions in production wells located between the injection circuit and the tightening zone and having reached the maximum water cut, and in injection wells located in the zone of influence of these production wells, chemicals are added that increase the filtration resistance of the flooded highly permeable zones of the formation.