RU2848500C1 - Method for developing a massive type oil field - Google Patents

Abstract

FIELD: method of developing a massive oil deposit.

SUBSTANCE: geophysical surveys are conducted on the deposit under consideration, and structural maps are constructed. At the highest point of the massive deposit and/or dome in a carbonate reservoir with a thickness of 9-14 m, a three-bore branched horizontal well is drilled with horizontal shafts 220-250 m long, with deep perforation along the horizontal sections, each perforation hole being no more than 20 m away from the previous one, in which case there are 11-13 holes evenly spaced along the horizontal wellbores in a spiral with a depth of 1.5 m, with a lateral angle between horizontal shafts of 120°, with access to the horizontal at the entrance to the productive formation after 60-65 m and at the same time at least 3 m above the base of the deposit and/or at least 5 m from the VNK. Oil production is carried out, and when the oil flow rate reaches 0.5 t/day, in order to extract the reserves as fully as possible or to extract the remaining reserves, vertical injection wells are drilled according to the design well grid of at least 300×300 m, at the midpoint between neighbouring horizontal production branches. Injection of the displacement agent is started and oil production from the three-bore horizontal branch well is continued.

EFFECT: production of maximum drainage coverage of a massive deposit in carbonate reservoirs with relatively small thicknesses and the achievement of the most complete extraction of oil reserves in terms of area and section, a reduction in the number of wells drilled and the achievement of a high oil recovery rate in the area due to deep perforation.

1 cl, 1 dwg

Description

The invention relates to the oil producing industry, in particular to methods for developing a section of a massive deposit in a carbonate reservoir.

A method for developing an oil deposit is known (RU patent no. 2823943, IPC E21B 43/16, published 30.07.2024, bulletin no. 22), including drilling one or more horizontal production wells in a formation with a thickness of at least 10 m above the base of the deposit of at least 3 m, and a vertical injection well - at a distance of 1/3 of the approved interwell space of the producing vertical well stock on the deposit from the bottom of the horizontal production well, secondary opening of the deposit in a vertical injection well above the hypsometric mark of the base of the deposit, but not above the position of the horizontal shaft of the production well, opening the lower aquifer, pumping by downhole pumping in a vertical injection well from the lower aquifer with a pressure 10% higher initial reservoir pressure and an injection cycle of 7 days of injection and 5 days of downtime.

The disadvantages of this method are uneven development of oil reserves, insufficient development of residual oil reserves and low oil recovery at the oil deposit site.

The closest technical solution to the proposed invention is a method for developing an oil reservoir using horizontal wells (RU patent no. 2474677, IPC E21B 43/16, published 10.02.2013, bulletin no. 4), which provides for the placement of horizontal production wells in parallel, with branches ascending to the roof of the formation being drilled sequentially from the horizontal sections in different directions in more permeable sections, with rows of vertical wells being placed between the horizontal sections with the distance between the wells in the rows being 1.2-1.4 times greater than the distance to the horizontal section of the nearest horizontal production well, wherein one vertical well in each row is an injection well, and the rest are production wells, and as the vertical production wells become flooded to 90%, they are converted into injection wells.

The known method does not allow for the full development of the reserves of a deposit area and requires drilling a large number of wells and branches, which leads to an increase in material costs for the construction of wells and the development of the oil deposit.

The technical objectives are to achieve maximum drainage coverage of a massive deposit in carbonate reservoirs with relatively small thicknesses and to achieve the most complete development of oil reserves by area and section, to reduce the number of wells drilled and to achieve a high oil recovery factor in the area due to deep perforation.

Technical problems are solved by developing a section of a massive oil deposit, which includes drilling horizontal and vertical wells, pumping a displacing agent through injection wells, and extracting deposit products through production wells.

What is new is that geophysical surveys are carried out at the deposit under consideration, structural maps are constructed, a production three-hole branched horizontal well is drilled at the highest elevation of the massive deposit area and/or dome in a carbonate reservoir with thicknesses of 9-14 m, with horizontal trunks of 220-250 m long, with perforation along its horizontal sections, with each perforation hole being no more than 20 m away from the previous one, having in this case 11-13 holes, evenly spaced along the wellbores in a spiral with a depth of 1.5 m, a lateral angle between the horizontal trunks of 120°, with an exit to the horizontal at the entrance to the productive formation after 60-65 m and at the same time above the base of the deposit at least 3 m and/or from the water-oil contact at least 5 m, oil production is carried out, upon reaching the oil flow rate 0.5 t/day, vertical injection wells are drilled along a designed well grid of at least 300×300 m near the boundaries of the site, at the midpoint of the distance relative to the adjacent bottomholes of the producing horizontal branches, they begin pumping the displacing agent and continue oil production from a three-well branched horizontal well.

The figure shows a diagram of the method.

The claimed method is carried out in the following sequence.

Geophysical studies are being carried out at the deposit in question, and structural maps are being constructed. At the highest elevation of a massive deposit area and/or a dome in a carbonate reservoir with thicknesses of 9-14 m, a three-hole branched horizontal well is drilled with a length of horizontal trunks of 220-250 m, with deep perforation along horizontal sections, and each perforation hole is no more than 20 m from the previous one, having in this case 11-13 holes located evenly along the wellbores in a spiral with a depth of 1.5 m, a lateral angle between horizontal trunks of 120°, with an exit to the horizontal at the entrance to the productive formation after 60-65 m and at the same time above the base of the deposit by at least 3 m and/or from the water-oil contact by at least 5 m. Oil production is carried out, when the oil flow rate reaches 0.5 tons/day for the most complete development of reserves or for additional development of reserves, drilled Vertical injection wells are drilled on a planned well pattern of at least 300 x 300 m, midway between the adjacent production horizontal branches. Displacement agent injection begins, and oil production from the three-well horizontal branched well continues.

An example of specific implementation.

The section of the massive deposit in the carbonate reservoir (1) has the following characteristics: depth of occurrence 905 m, absolute mark of the water-oil contact - 729 m, total thickness of the formation 14 m, permeability 0.077-0.137 μm ² , oil saturation within 75-81%.

Geophysical surveys are being conducted at the deposit in question, and structural maps are being constructed. A multilateral production horizontal well (2) is drilled at the highest point of the deposit area and/or dome, with three horizontal branches, each 250 m long, with the branch bottoms positioned at an absolute elevation of -724 m – 5 m above the water-oil contact (WOC). Deep perforation (3) is performed along the horizontal sections, each perforation hole spaced 20 m from the previous one, with 12 holes evenly spaced along the wellbore in a spiral pattern 1.5 m deep and at a 120° lateral angle between the branches, with an exit to the horizontal at the entrance to the productive formation at 60 m.

Oil is being extracted from a three-well horizontal production well. The oil flow rate has reached 0.5 tons per day. Three vertical injection wells (4) are being drilled along the planned 350x350 m well pattern, midway between the adjacent production horizontal wells.

Injection wells are being developed for injection and oil production continues from a three-well branched horizontal production well.

In this case, the development of oil reserves occurs across the entire area without the formation of residual oil pillars at the border of the allocated area.

The use of this method will allow for maximum drainage coverage of a massive deposit area in carbonate reservoirs with relatively small thicknesses and the achievement of the most complete development of oil reserves by area and section, a reduction in the number of wells drilled and the achievement of a high oil recovery factor in the area due to deep perforation.

Claims (1)

A method for developing a section of a massive deposit in a carbonate reservoir, including drilling vertical and horizontal wells, pumping displacement fluid through injection wells and extracting deposit products through production wells, characterized in that geophysical studies are carried out on the deposit in question, structural maps are constructed, at the highest elevation of the section of the massive deposit and/or dome in a carbonate reservoir with thicknesses of 9-14 m, a three-hole branched horizontal well is drilled with a length of horizontal trunks of 220-250 m, with deep perforation along horizontal sections, and each perforation hole is spaced from the previous one by no more than 20 m, having in this case 11-13 holes, located evenly along the wellbores in a spiral with a depth of 1.5 m, with a lateral angle between the horizontal trunks of 120°, with an exit to the horizontal at the entrance to the productive formation through 60-65 m and at the same time above the bottom of the reservoir by at least 3 m and/or from the water-oil contact by at least 5 m, oil is produced; when the oil flow rate reaches 0.5 t/day, vertical injection wells are drilled according to the designed well grid of at least 300×300 m, at the middle of the distance relative to the adjacent bottomholes of the producing horizontal branches, they begin pumping the displacing agent and continue producing oil from the three-bottomhole branched horizontal well.