RU2848495C1 - Method for developing a massive type oil field - Google Patents

Abstract

FIELD: method for developing a massive oil deposit.

SUBSTANCE: method includes drilling a horizontal production well and vertical injection wells, injecting a displacement agent and extracting the product through the horizontal production well. Geophysical surveys are conducted on a massive deposit in a carbonate reservoir in formations with different reservoir characteristics. Structural maps are constructed, hydrodynamic studies are carried out to determine formation pressure, and the development process is simulated. At the highest point of the deposit and/or dome, a multi-bore branched horizontal production well is drilled. The upper horizontal well is placed in the upper productive interval of the deposit with a thickness of 6-9 m, 3 m from the roof of the deposit, with a horizontal section length of 200-250 m. For the most complete recovery of oil reserves in the section, the lower horizontal well is placed in the lower productive interval of the deposit with a thickness of 9-14 m, with a horizontal section length of 250-300 m and at least 3 m above the base of the deposit and/or from the water-oil contact - WOC by at least 5-6 m, with a lateral angle between horizontal wells of 120°, with access to the horizontal at the entrance to the productive layer after 60-65 m. Oil production is underway. When the oil flow rate reaches 0.5 t/day, vertical injection wells are drilled according to the approved well grid within the site boundaries at the midpoint between neighbouring horizontal production branches, the displacement agent is injected and oil production continues from a multi-wellbore branched horizontal well.

EFFECT: achievement of maximum drainage coverage of the massive deposit in carbonate reservoirs, the most complete extraction of oil reserves by area and section, a reduction in the number of wells drilled and material costs for well construction.

1 cl, 2 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 is known for developing an oil deposit using horizontal wells (RU patent no. 2474677, IPC E21B 43/16, published 10.02.2013, bulletin no. 4), which involves placing 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; rows of vertical wells are 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; 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 closest technical solution to the proposed invention is a method for developing an oil deposit in layered carbonate reservoirs (RU patent no. 2387815, E21B 43/20, published on 27.04.2010, bulletin no. 12), which includes identifying at least two thin carbonate reservoir beds that coincide in plan, are located in close proximity to each other, separated by clay interlayers-bridges, specifying the distribution of oil-saturated thicknesses of reservoir beds over the area of the deposit, selecting areas with maximum permissible effective oil-saturated thicknesses of reservoir beds of at least two meters each, then drilling a branched horizontal well for the simultaneous development of two or more reservoir beds, placing horizontal wellbores in the most permeable intervals of the beds, and the wellbores are carried out in the direction of increasing effective oil-saturated thicknesses, and the length of the trunks is taken to be inversely proportional to their permeability.

The disadvantage of the known method is the insufficient coverage of the deposit area by drainage, which requires an increase in the number of wells drilled and an increase in material costs for the construction of wells and the development of a section of a massive heterogeneous deposit.

The technical objectives of the invention are to achieve maximum drainage coverage of a massive deposit in carbonate reservoirs, the most complete development of oil reserves by area and section, a reduction in the number of wells drilled, and a reduction in material costs for well construction.

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

What is new is that in the area of a massive deposit in a carbonate reservoir in layers with different reservoir characteristics, geophysical studies are carried out, structural maps are constructed, hydrodynamic studies are carried out with the determination of reservoir pressure and the development process is modeled, then at the highest elevation of the deposit area and/or dome, a multi-hole branched production horizontal stage well is drilled, with the upper horizontal wellbore placed in the upper productive interval of the deposit with thicknesses of 6-9 m at 3 m from the roof of the deposit with a horizontal section length of 200-250 m, for the most complete development of the oil reserves of the deposit along the section, the lower horizontal wellbore is placed in the lower productive interval of the deposit with thicknesses of 9-14 m with a horizontal section length of 250-300 m and above the base of the deposit by at least 3 m and/or from the water-oil contact - OWC by at least 5-6 m, with an angle along Laterals between horizontal wellbores 1200, with an exit to the horizontal at the entrance to the productive formation after 60-65 m, carry out oil production, when the oil flow rate reaches 0.5 tons/day, vertical injection wells are drilled according to the approved design well grid within the boundary of the site at the middle of the distance of the adjacent bottomholes of the producing horizontal branches, they begin pumping the displacing agent and continue oil production from the multi-lateral branched horizontal well.

Fig. 1 shows a diagram of the method.

Fig. 2 shows a production multi-hole branched horizontal stage well.

The method is carried out in the following sequence.

In the area of a massive deposit in a carbonate reservoir, geophysical studies are carried out in layers with different reservoir characteristics, structural maps are constructed, hydrodynamic studies are carried out to determine reservoir pressure, and the development process is modeled. Then, at the highest elevation of the deposit area and/or dome, a multi-hole branched production horizontal stage well is drilled, with the upper horizontal wellbore placed in the upper productive interval of the deposit with thicknesses of 6-9 m, 3 m from the roof of the deposit with a horizontal section length of 200-250 m. For the most complete development of the deposit's oil reserves along the section, the lower horizontal wellbore is placed in the lower productive interval of the deposit with thicknesses of 9-14 m, with a horizontal section length of 250-300 m and at least 3 m higher than the deposit base and/or at least 5-6 m from the water-oil contact - OWC, with a lateral angle between the horizontal wellbore of 120⁰, with an exit to the horizontal at the entrance to the productive formation after 60-65 m. Oil is produced. When the oil flow rate reaches 0.5 tons per day, vertical injection wells are drilled along the approved well pattern within the boundary of the well site, midway between the adjacent production horizontal branches. Displacement agent injection begins, and oil production from the multilateral horizontal well continues.

An example of specific implementation.

The section of deposit 1 (Fig. 1) of the massive type in the carbonate reservoir has the following characteristics: the depth of the upper productive layer is 905 m, the absolute mark of the oil-water contact is minus 729 m, the total thickness of the layer is 22 m, the layer is 7 m thick with a permeability of 0.084 ^μm2 , the layer is 12 m thick with a permeability of 0.122 ^μm2 , oil saturation is within 75-81%.

Geophysical studies are carried out at the deposit in question, structural maps are constructed, hydrodynamic studies are carried out, and a geological-hydrodynamic model is being developed. At the highest elevation of the deposit area and/or dome, a multi-lateral production horizontal well 2 (Figs. 1 and 2) is drilled with three horizontal branches and a 120 ⁰ angle laterally between the branches, with an exit to the horizontal at the entrance to the productive formation after 65 m. In this case, the upper horizontal borehole 3 (Fig. 2) is placed in a formation with a thickness of 7 m at a depth of 908 m with a horizontal section length of 200 m. For the most complete development of the oil reserves of the deposit along the section, the lower horizontal borehole 4 (Fig. 2) is placed in a formation with a thickness of 12 m with a horizontal section length of 250 at an absolute elevation of minus 724 m. Oil is produced from the multi-lateral production horizontal multi-lateral well. The oil flow rate reached 0.5 tons/day. According to the designed well grid of 350×350 m, three vertical injection wells 5 (Fig. 1) are drilled at the middle of the distance relative to the adjacent bottomholes of the production horizontal branches of well 2.

Injection wells 5 are being developed for injection and oil production continues from the production multi-hole branched horizontal stage well 2.

The use of this method will allow for maximum drainage coverage of a massive deposit in carbonate reservoirs, the most complete development of oil reserves by area and cross-section, a reduction in the number of wells drilled, and a reduction in material costs for well construction.

Claims (1)

A method for developing a section of a massive deposit, including drilling a production horizontal well and injection vertical wells, pumping a displacing agent and collecting product through a production horizontal well, characterized in that in the section of a massive deposit in a carbonate reservoir in formations with different reservoir characteristics, geophysical studies are carried out, structural maps are constructed, hydrodynamic studies are carried out with the determination of reservoir pressure and the development process is modeled, then at the highest elevation of the deposit section and/or dome, a multi-hole branched production horizontal stage well is drilled, wherein the upper horizontal wellbore is placed in the upper productive interval of the deposit with thicknesses of 6-9 m at 3 m from the roof of the deposit, with a horizontal section length of 200-250 m, for the most complete development of the oil reserves of the deposit along the section, the lower horizontal wellbore is placed in the lower productive interval of the deposit with thicknesses of 9-14 m, with a horizontal section length 250-300 m and above the base of the deposit by at least 3 m and/or from the water-oil contact - OWC by at least 5-6 m, with a lateral angle between horizontal wellbores of 120°, with an exit to the horizontal at the entrance to the productive formation after 60-65 m, oil is produced, when the oil flow rate reaches 0.5 tons/day, injection vertical wells are drilled according to the approved design well grid within the boundary of the site at the middle of the distance of the adjacent faces of the producing horizontal branches, the injection of the displacing agent begins and oil production from the multi-well branched horizontal well continues.