RU2517674C1 - Development method of non-homogeneous oil deposit - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: development method of non-homogeneous oil deposit includes drilling as per any famous pattern of vertical, horizontal or directional wells. Borders of zones with various permeability are determined. The well pattern is compacted up to the value of 4 ha per a well. A displacement fluid is injected to each zone through injectors and the product is recovered from the formation in each zone through producers. At that zones with different permeability are divided into low permeable, medium permeable and high permeable. Compaction of the well pattern is made only in low permeable zones. At that the ratio of injectors and producers is selected as at least 1:5 in the high permeable zones, from 1:3 up to 1:5 in the medium permeable zones and from 1:1 up to 1:3 in the low permeable zones. When the flow rate at one zone becomes lower than the commercial production hydrofracturing is made at this site. Then permeability is determined at this site and it is referred to the respective zone with determination of the respective number of injectors and producers.

EFFECT: intensifying recovery in the low permeable zones and increasing oil recovery factor.

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Description

The invention relates to the oil and gas industry, in particular to methods for intensifying oil production from heterogeneous deposits.

A known method of developing a massive type of oil deposits with layer-by-layer heterogeneity (patent RU No. 2439298, IPC ЕВВ 43/16, published in Bulletin No. 1 of January 10, 2012), including the development of vertical production and injection wells constructed using a grid of wells, construction of additional directional shafts, injection of an agent into production wells and selection of products from production wells. Flat-hole shafts are drilled from additional injection and production wells with a bit diameter of 144 mm from the surface with a mesh compaction of 1-4 ha / well. Moreover, semi-directional shafts are drilled across the fracture of the formation with a length of 2-3 formation thicknesses, followed by casing shafts and a secondary opening productive formation, after which before launching additional wells to work in the flooded interlayers of the formation, waterproofing works are carried out from their shallow trunks, and acid treatment is carried out in oil-bearing wells.

The closest in technical essence and the achieved result is a method of developing oil deposits with layer-by-layer heterogeneity (patent RU No. 2443855, IPC ЕВВ 43/20, 43/14, published in bulletin No. 6 dated February 27, 2012), including drilling according to any of the known grids of vertical, horizontal and deviated wells, determining the boundaries of zones with different permeabilities, installing a packer in the wells at the boundary of the zones, injecting displacement fluid into each zone through injection wells and producing reservoir products from each zone through injection wells. The thickness of the effective oil saturation for the reservoir is determined, the grid of wells is compacted with additional wells up to 1-4 ha / well. Moreover, additional wells are drilled obliquely with a length of the reservoir equal to 2-3 thicknesses of the effective oil saturation, and the units for simultaneous-separate are lowered into production wells together with the packer operation, and injection - for simultaneous-separate injection, above or below the boundary of zones with different permeability in the zone of deposits with lower permeability carry out acid treatment, injection of liquid These are injected through injection wells above and below the boundaries of zones with different permeability using installations for simultaneous-separate injection, and production through production wells is carried out using installations for simultaneous-separate operation.

The disadvantages of the analogues are the inability to control the selection of products and injection of the displacing agent depending on the permeability of the zones of the reservoir, and also due to the intensive selection of products from low-permeability sections, the relatively low coefficient of oil recovery (CIN) from the reservoir.

The technical objectives of the invention are the intensification of selection from low-permeability zones due to compaction of the grid of wells, regulation of production selection and injection of the displacing agent by selecting the most optimal number of injection and producing wells depending on the permeability of the zones of the reservoir and, as a result, increasing the oil recovery factor of the entire reservoir.

Technical problems are solved by the method of developing a heterogeneous oil reservoir, including drilling along any of the known grids of vertical, horizontal and deviated wells, determining the boundaries of zones with different permeabilities, compaction of the grid of wells no more than 4 ha / well, injection of displacing fluid into each zone through injection wells and production of formation products from each zone through injection wells.

New is that zones with different permeability are divided into low permeability, medium permeability and high permeability, well grids are compacted only in low permeability zones, while in high permeability zones the ratio of injection and production wells is chosen at least 1: 5, medium permeability - from 1: 3 to 1: 5, low permeability - from 1: 1 to 1: 3, after reducing the flow rate in one of the sections of the zones below the cost-effective in this section, hydraulic fracturing is performed, then the permeability in this section is determined, referring it to the corresponding uyuschey zone and from this determine the number of injection and production wells on the site.

The drawing shows a diagram of the implementation of the method.

The deposit is drilled with a rare grid of design producing 1 and injection 2 wells, the geological structure is specified, zones with high 3, medium 4 and low 5 permeability are determined, and then the boundary of 6 zones of the reservoir is determined. Moreover, wells 1 and 2 can be vertical, horizontal and inclined (conventionally shown in the drawing). In highly permeable zones 3, a multi-row water flooding system is created with a ratio of injection and production wells of at least 1: 5. In medium-permeable zones 4, the ratio of production and injection wells is maintained within the range of 1: 3-5, creating single-row or three-row flooding systems. In zones with low permeability 5, the grid of wells 1 and 2 is compacted to 1-4 ha / well, the ratio of producing 1 and injection 2 wells is set within 1: 1-3.

After reducing the flow rate in one of the sections (not shown in the drawing) of zones 3, 4 or 5 below the cost-effective in this section, hydraulic fracturing is performed, then the permeability in this section is determined and, after examination, it is assigned to the corresponding zone 3, 4 or 5. Then determine the ratio of injection 2 and production 1 wells in this area.

An example of a specific implementation.

The deposit was drilled with a rare grid of design production and injection wells, the wells can be vertical, horizontal and inclined with a distance of 800 m between them, the geological structure was clarified, zones with high (996 ppm), medium (487 ppm) and low (98 ppm) permeability were identified then, using three-dimensional models, we determined the boundaries of the zones of the deposit. In highly permeable zones, a multi-row water flooding system was created with a ratio of injection and production wells of 1: 4. In medium-permeable zones, the ratio of production and injection wells was maintained within 1: 3, creating single-row or three-row flooding systems. In zones with low permeability, a well network of 0.9 ha / well was compacted, the ratio of production and injection wells was set within 1: 2.

After reducing the flow rate in zone 4 of the section below the profitable to 2 t / day and increasing the water cut of the product to 98%, hydraulic fracturing was performed, then the permeability (1008 ppm) was determined in this section, and it was assigned to zone 5 with high permeability. Then they brought the ratio of injection 2 and production 1 wells in this zone to 1: 4. As a result, total production increased by 8% - from 80 to 96 tons / day, and instrumentation increased from 0.35 to 0.37.

The proposed method for the development of a heterogeneous oil reservoir allows to intensify the selection from low-permeability zones due to compaction of the well network, regulation of production selection and injection of the displacing agent as a result of determining the most optimal number of injection and producing wells depending on the permeability of the zones of the reservoir and, as a result, to increase the measurement factor of the entire reservoir up to 7% and additionally extract up to 10% of production.

Claims (1)

A method for developing a heterogeneous oil reservoir, including drilling along any of the known grids of vertical, horizontal and deviated wells, determining the boundaries of zones with different permeabilities, densifying a well grid of not more than 4 ha / well, injecting displacing fluid into each zone through injection wells and producing products formation from each zone through production wells, characterized in that zones with different permeability are divided into low permeability, medium permeability and high permeability, compaction of the grid of wells is carried out by only in low-permeability zones, while in high-permeability zones the ratio of injection and production wells is selected at least 1: 5, medium-permeability - from 1: 3 to 1: 5, low-permeability - from 1: 1 to 1: 3, after reducing the flow rate at one of sections of zones below the cost-effective in this section produce hydraulic fracturing, then determine the permeability in this section, relate it to the corresponding zone and from this determine the number of injection and production wells in this section.