RU2459938C1 - Oil deposit development method - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: oil is extracted through production wells, working agent is pumped through injection wells, and hydraulic fracturing of formation in wells is performed. In order to perform hydraulic fracturings in wells, deposit zones with high pressure drop, large oil reserves and pattern arrangement of not less than 1.5 ha/well are chosen. In chosen zones there chosen are production wells with skin factor that has been changed from "-" to "+" during the development and with water content of not more than 40%. Injection well with which the chosen production wells respond is determined, formation hydraulic fracturing is performed in certain injection well; after that, formation hydraulic fracturing is performed in the chosen production wells.

EFFECT: increasing oil recovery of oil deposit with coverage of larger surface area.

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Description

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

A known method of developing many reservoir oil deposits, in which hydraulic fracturing is carried out not immediately across all the layers, but selectively, in the zone of low permeability reservoirs. A highly permeable formation with a permeability of three or more times higher than the average across the layers, the so-called super collector, is isolated. At the same time, at this stage, its perforation is excluded. After the project selection of oil reserves, perforation of a highly permeable formation is carried out with the subsequent operation of the latter. A barrel with vertical entry into the production facility is performed to ensure the maximum fracture pressure gradient and to create the optimal hydraulic fracture. At the same time, hydraulic fracturing is carried out in the injection well stock at low permeability intervals. To create a vertical filtration between a high-permeability interlayer - non-perforated and low-permeable, a horizontal lateral trunk is carried out in a low-permeable interval followed by interval hydraulic fracturing (RF patent No. 2374435, CL ЕВВ 43/16, Е21В 43/26, publ. 11/27/2009).

A known method of developing an oil field with hydraulic fracturing, including drilling production and injection wells, injection of a displacing agent into injection wells and the selection of fluids through production wells. Hydraulic fracturing is planned, for which an indicator fluid is injected into the hydraulic fracturing well under pressure, which does not react with formation water, oil and host rock. The azimuth of the well adjacent to the formation is recorded relative to the mentioned well, into which the maximum amount of the indicator fluid has arrived in a certain time and / or into which the indicator fluid has arrived at the highest speed. Accepted azimuth for the direction of the planned fracture crack. The direction of the front of the displacing agent and the water cut of the wells are determined, which determine the need for hydraulic fracturing. When hydraulic fracturing is carried out, the indicator fluid is re-pumped into the hydraulic fracturing well and the actual direction of the hydraulic fracture is determined to increase the level of oil displacement from the formation (RF patent No. 2349740, CL ЕВВ 43/16, Е21В 47/10, publ. March 20, 2009).

Closest to the proposed invention in technical essence is a method of developing an oil field, according to which the selection of oil through production wells, injection of a working agent through injection wells, determination of water cut of produced products and hydraulic fracturing in the well are carried out. The water cut of the reservoir is determined as the average water cut in the reference wells or in wells with isolated water inflows, compared with the water cut of the produced products in the well. A detailed vector profile design of the section of the formation is carried out and the thickness and continuity of the bridge between the aquifer or flooded reservoir and the reservoir are analyzed. If the water cut in the well exceeds the average water cut of the formation, then the water cut in the well is equal to the average water cut of the formation. Hydraulic fracturing of a productive formation is carried out in a well with an average water cut of the formation of less than 70% and in the presence of a continuous bridge at least 3 m thick between an aquifer or a waterlogged formation and a productive formation (patent of the Russian Federation No. 2382184, class ЕВВ 43/16, Е21В 43/26, publ 02.20.2010 - prototype).

All of the above technical solutions in the conditions of an oil field solve only the local problem of increasing oil recovery in a small near-wellbore space, without affecting the whole process of the impact of the reservoir.

The proposed invention solves the problem of increasing oil recovery of oil deposits with exposure to a larger area.

The problem is solved in that in the method of developing an oil reservoir, including the selection of oil through production wells, injection of a working agent through injection wells and hydraulic fracturing in wells, according to the invention, reservoir zones with high reservoir pressure and large oil reserves are selected for hydraulic fracturing in wells and a mesh density of at least 1.5 ha / well, in selected areas, producing wells are selected with a skin factor that has changed during the development process from “-” to “+”, with a water cut of not more than 40%, fissioning injection well which react with the selected production wells, hydraulic fracturing is carried out in a particular injection well, followed by hydraulic fracturing to selected production wells.

SUMMARY OF THE INVENTION

Hydraulic fracturing in a well, as a rule, leads to an increase in well productivity. So far, hydraulic fracturing has been used in individual wells, paying little attention to the effect of hydraulic fracturing in wells on oil recovery in general. The proposed invention solves the problem of increasing the oil recovery of an oil deposit with a greater exposure to hydraulic fracturing than occurs with hydraulic fracturing in one well. The problem is solved as follows.

When developing an oil reservoir, oil is taken through production wells, the working agent is injected through injection wells, and hydraulic fracturing is carried out in the wells. For hydraulic fracturing in wells, reservoir zones with a significant pressure drop, with large oil reserves and a mesh density of at least 1.5 ha / well are selected. A large reservoir pressure, usually equal to or greater than the initial reservoir pressure, indicates a large reserve of reservoir energy and high potential of the reservoir. Large undeveloped oil reserves, as a rule, at least 50% of the recoverable in this area, indicate the possibility of producing large quantities of oil. A mesh density of at least 1.5 ha / well indicates a large distance between the wells, guaranteed to be greater than the length of the fracture in the formation.

In the selected zones, production wells with deteriorating productivity and water cut of not more than 40% are selected. Deteriorated permeability is characterized by a skin factor that has changed during the development process from “-” to “+”. The changed skin factor indicates a potentially high productivity of the well, but which has changed in the direction of deterioration during development, and therefore, the possibility of improving the permeability of the near-wellbore zone. The water cut of not more than 40% guarantees during hydraulic fracturing the absence of communication with the aquifer and the watering of well products.

The injection well with which the selected production wells react is determined, hydraulic fracturing is performed in a specific injection well, and then hydraulic fracturing is carried out in the selected production wells.

As a result of these actions, the permeability of the reservoir of the reservoir in the selected area of the reservoir becomes increased, the coverage is increased by the impact of zones not previously involved in the development, the oil recovery of the reservoir is increased.

Concrete example

An oil reservoir is developed with the following characteristics: depth 1600-2100 m, reservoir pressure 13 MPa and higher, reservoir temperature 38-42 ° C, reservoir thickness 2.5 m or more, porosity from 10%, permeability from 250 mDa, oil density 0, 8 g / cm ³ reservoir reservoir terrigenous Devon. The site of the deposit is developed by flooding. Injected working agent — commercial (formation) water through injection wells; formation products are taken through production wells.

For hydraulic fracturing in wells, a zone of deposits with a large pressure drop, with significant oil reserves and a mesh density of at least 1.5 hectares / well is selected. The selected reservoir has undeveloped oil reserves in the amount of at least 2000 tons. In the selected zones, 6 producing wells are selected with the skin factor changed from “-” to “+” during development, i.e. from -1 ÷ -4 to + 2 ÷ + 4 and with water cut of extracted products no more than 40%. The injection well with which the selected production wells react is determined, hydraulic fracturing is performed in a specific injection well, and then hydraulic fracturing is carried out in the selected production wells.

As a result, the oil recovery of the reservoir increases by 4.5% and reaches 30%, while the known methods do not allow to achieve oil recovery of more than 26%.

The application of the proposed method will improve oil recovery deposits.

Claims (1)

A method of developing an oil reservoir, including the selection of oil through production wells, pumping a working agent through injection wells, and hydraulic fracturing in wells, characterized in that for fracturing in the wells, reservoir zones with high reservoir pressure, with large oil reserves and mesh density are not selected less than 1.5 ha / well, in selected areas, producing wells with a skin factor that has changed during the development process from “-” to “+”, with a water cut of not more than 40%, are selected for injection wells zhinu, which react with the selected production wells, hydraulic fracturing is carried out in a particular injection well, followed by hydraulic fracturing to selected production wells.