RU2505668C1 - Method of developing oil pool using horizontal multibranch wells - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method consists in drilling vertical pressure wells and horizontal producers, in pumping heat carrier through pressure wells, and in withdrawal of production via horizontal producers. Producers are made as multibranch horizontal wells which are drilled upwards oil-water contact, and vertical wells are made at distance not less than 50 m from bottoms of multibranch horizontal wells. Opening of vertical well deposits is made again upwards and downwards of respective bottom of horizontal well, casing string is landed to each injection well and packer is set between openings, displacement agent is pumped through the upper opening into tubular annulus and through the lower opening into casing string.

EFFECT: increasing reservoir recovery, field oil production rate, increasing reservoir coverage by operations, maximum involvement of remaining reserves into development.

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Description

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

There is a method of developing a highly viscous oil deposit (patent RU No. 2434127, IPC ЕВВ 43/24, publ. Bull. No. 32 of 11/20/2011), including drilling vertical injection and producing horizontal wells, pumping coolant through injection wells, selecting products through producing horizontal wells. A two-mouth horizontal production well is drilled using one diverter near the bottom of the productive formation, and a vertical injection well is installed with a bottom located above the middle part of the horizontal section of the production well at a distance that excludes coolant breakthrough, while the productive formation is conventionally divided into several zones with different temperature conditions, when the coolant is injected as the reservoir warms up and when the maximum water cut of the well production is reached, the selection begins with a lower, more f heated zone, after reaching a production temperature of 80-90% of the breakthrough temperature, selection is transferred to lower temperature zones, isolating zones with a high temperature close to the breakthrough temperature by deaf packers, when the temperature rises in new selection zones, the selection zones are moved to colder zones with high-temperature zones being cut off by deaf packers, and when the temperature drops to a decrease in yield below the required value, the selection zones are transferred to zones with higher temperatures, which are below 70% of the breakthrough temperature and the packers are retrieving.

The disadvantages of the method are the difficulty in building a double-well horizontal well, an increase in the cost of building wells for organizing heat exposure.

The closest in technical essence and the achieved result is a method of developing a highly viscous oil deposit (patent RU No. 2334095, IPC ЕВВ 43/24, publ. Bull. No. 26 dated 09/20/2008), including drilling vertical injection wells and horizontal production wells, the injection of the working agent through injection wells and the selection of oil through production wells. The horizontal wellbore of the production well is carried out 1.5-2.5 m above the bottom of the productive formation, the horizontal well is perforated, the bottom of the vertical injection well, perforated in the interval 0.5- above, is placed 3.5-4.5 m above the horizontal well of the well, 1.5 m from the bottom, the vertical injection well is placed from the vertical wellbore of the producing well at a distance greater than 2/3 of the length of the horizontal section of the producing well, up to the end of the horizontal wellbore. ar in alternation with air.

The main disadvantage of this method is the low efficiency of the oil displacement process due to uneven heating of the formation throughout the horizontal bore interval by the exposure agent.

The technical objectives of the present invention are to increase oil recovery, increase the efficiency of the oil displacement process by injecting the working agent above and below the hypsometric position of the trajectory of the bottom of the horizontal branch of the producing well, increasing the coverage of the formation due to drilling of branched horizontal wells, involving residual oil reserves in the development.

The technical problem is solved by a method of developing an oil reservoir using branched horizontal wells, including drilling vertical injection and producing horizontal wells, pumping a displacing agent through injection wells, and selecting products through producing horizontal wells.

New is that producing wells are built in the form of branched horizontal wells that are drilled above the level of water-oil contact (VOC), and vertical ones - at a distance of not less than 50 m from the bottom of branched horizontal wells, produce a secondary opening of a vertical well deposit above and below the corresponding bottom horizontal well, a pipe string is lowered into each injection well with the installation of a packer between the openings, the displacing agent is pumped through the upper opening through the annulus, and cut bottom opening - along the pipe string.

SUMMARY OF THE INVENTION

The proposed method solves the problem of increasing the efficiency of oil displacement, increasing oil recovery, increasing the rate of selection, increasing coverage by the effect of area and vertical.

The drawing shows a diagram of the implementation of the proposed method for the development of oil deposits,

where 1 is the site of oil deposits; 2 - horizontal production well; 3, 4, 5 - vertical injection wells; 6 - water-oil contact (WOC); 7, 7 ¹ - perforation intervals; 8 - tubing string (tubing); 9 - packer.

The method is carried out in the following sequence.

At least one branched horizontal production well 2 is drilled in oil reservoir 1 in the reservoir above the level of WOC 6, through which production is subsequently selected. At a distance of not less than 50 m from the corresponding faces (I, II, III) of the horizontal well 2, vertical injection wells 3, 4, 5 are constructed, the annular space is cemented in the injection wells 3, 4, 5, and a secondary opening of the deposit is made with the formation of perforations 7, 7 ¹ above and below hypsometric position trajectory corresponding horizontal section of the production well 2. descends into each injection well 3, 4, 5 column tubing 8 with the installation of the packer 9 between opened s 7, ^{1 July} avoid overflows of displacing agent.

Next, to equalize the injectivity profile, a water-insulating composition is injected into an injection well 3, for example, a polymer, a gel-forming composition, squeezed into the reservoir in the volume necessary to partially isolate the water inflow from the water-saturated part of the reservoir 1. The volume is equal to the volume of the wellbore at a pressure in the annulus of not more than 2-3 MPa.

Further, a displacing agent is fed into injection wells 3, 4, 5 through the upper opening 7 along the annulus, and through the lower opening 7 ¹ through the pipe string 8, which allows you to adjust the waterflooding front above and below the corresponding faces (I, II, III) horizontal producing well 2, which contributes to a uniform distribution of the displacement front. The volume of the displacing agent is determined by calculation and is 2.5 m per 1 ton of oil produced. As a displacing agent, water or a heated reagent is used depending on the type of collector and the viscosity intervals of the reservoir. Then carry out the selection of products.

Concrete example

An oil reservoir 1 with a terrigenous reservoir is being developed. The deposit has a highly productive zone 50-60 m thick with a temperature of 25 ° C, a pressure of 13 MPa, an oil saturation of 0.93 units, a porosity of 26%, a permeability of 0.82 μm ² , an oil density of 911 kg / m ³ and a viscosity of 56 MPa · s.

On oil reservoir 1 in the reservoir above the level of VNK 6, one branched horizontal production well 2 with three faces (I, II, III) is drilled 25 m. At a distance of 75 m from the corresponding faces (I, II, III) of the horizontal well 2, three vertical injection wells 3, 4, 5 are constructed. An annular space is cemented in the injection wells 3, 4, 5, and a second opening of the deposit is made with the formation of perforations 7 , 7 ¹ above and below the hypsometric position of the trajectory of the corresponding horizontal wellbore of the producing well 2. The tubing string 8 is lowered into each injection well 3, 4, 5 with the packer 9 installed between the openings 7, 7 ¹ .

Next, a water-insulating composition is injected into the injection well 3, squeezing into the reservoir in an amount necessary to partially isolate the water inflow from the water-saturated part of the reservoir 1 and comprising 2 m ³ .

Then, heated water is supplied through injection wells 3, 4, 5 through the upper opening 7 through the annulus, and through the lower opening 7 ¹ through the pipe string 8. The volume of the displacing agent is determined by calculation and is 2.5 m ³ per 1 ton of oil produced . Then carry out the selection of products through producing branched horizontal well 2.

Thanks to the application of the proposed method for developing an oil reservoir using branched horizontal wells, the rate of oil extraction increases to 11% of recoverable reserves.

The operation of the site is designed to achieve a design oil recovery of 0.5. During the development of the entire interval, the coverage of the formation with the impact increases, oil recovery increased by 16%, additional oil production for the entire life of the site amounted to 246 thousand tons of oil.

The application of the proposed method will increase oil recovery, the rate of oil recovery, increase the coverage of the reservoir by exposure, and maximize the involvement of residual oil reserves in the development.

Claims (1)

A method of developing an oil reservoir using branched horizontal wells, including drilling vertical injection and producing horizontal wells, injecting a displacing agent through injection wells, selecting products through producing horizontal wells, characterized in that the producing wells are constructed in the form of branched horizontal wells that are drilled above a level water-oil contact - VNK, and vertical - at a distance of not less than 50 m from the bottom of branched horizontal wells, secondary opening of the vertical well deposit is performed above and below the corresponding bottom of the horizontal well, a pipe string is inserted into each injection well with a packer between the openings, the displacing agent is pumped through the upper opening through the annulus, and through the lower opening through the pipe string.