RU2485294C1 - Development method of low-amplitude oil-gas deposits with limited dimensions as to surface area and with small layer of oil and gas content - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: according to the proposed method, a test well is drilled; seismic exploration is performed; a central part of the deposit is determined as per seismic exploration results. Then, in the central part of the deposit there drilled is a vertical production confirmation well of increased diameter; gas extraction is performed in accelerated modes; at that, advanced set of geological field and gas dynamic researches is performed and the most productive part of the deposit and initial reserves are determined. Then, gas extraction is stopped; lower part of the shaft of the operation confirmation well is removed, and out of it there drilled is one or two side shafts in upper part of the deposit, not closer than 2-5 m from gas-water contact, in the direction of its most productive part. Then, development works are performed and gas extraction is performed from side shafts by means of small extractions of 0.5-0.9% of initial reserves in a partial load mode with depressions per formation of not more than 0.2-0.3 MPa and production rate of not more than 100-150 thousand m³/day.

EFFECT: improving the method's efficiency owing to reducing the costs for development of deposits.

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Description

The invention relates to the oil and gas industry, in particular to the development of low-amplitude oil and gas deposits with a limited area and a small oil and gas floor, designed for gas supply to local consumers for their own needs.

In Western Siberia, along with large oil and gas fields, there are many smaller deposits with small from 5 to 20 m thick low-permeable productive formations, the so-called low-amplitude fields with a small oil and gas potential. Almost all of them are underdeveloped and are in the reserve fund. Low-amplitude oil-and-gas bearing deposits are understood as deposits with a reservoir thickness of up to 60 m [Maltsev A.I. et al. Conceptual approaches to the development of small gas fields in the north of Western Siberia // Oilfield business. 2011, No. 10. - S.20-22], and a reservoir with a small oil and gas potential is understood as a low-amplitude oil and gas bearing reservoir with a thickness of 5 to 20 m.

The main reasons hampering the development of these deposits are the complex geological structure, low productivity and remoteness of deposits from the routes of oil and gas pipelines. However, such deposits can be a raw material base for local consumers [Remizov V.V. and others. Gasification of the regions of Russia, taking into account the development of small deposits of gas and oil. New high technologies for the oil and gas industry and energy of the future // First International Congress. - M .: 1997. - S.74-92].

There is a method of developing low-amplitude oil and gas fields, including the drilling of vertical exploratory wells for additional exploration of deposits and half-directed production wells for production and subsequent transportation to the consumer of hydrocarbons [Maltsev A.I. et al. Conceptual approaches to the development of small gas fields in the north of Western Siberia // Oilfield business. 2011. No. 10. - S.20-22].

The disadvantage of this method is the high cost of developing low-amplitude oil and gas deposits with limited size and with a small oil and gas potential.

Achievable technical result, which is obtained as a result of the invention, is to reduce the cost of developing low-amplitude oil and gas deposits with limited space and a small oil and gas potential.

The technical result is achieved by the fact that the method of developing small-amplitude oil and gas deposits with a limited size and with a small oil and gas potential floor consists in drilling reference wells, conducting seismic surveys, determining the central part of the reservoir by seismic results, and then drilling the vertical operational section in the central part of the reservoir exploratory well of increased diameter, carry out the selection of gas in forced modes, while conducting an expanded complex of production and geological x and gas-dynamic studies, determine the most productive part of the reservoir and initial reserves, stop gas production, liquidate the lower part of the well of the exploration well, then one or two sidetracks are drilled from it in the upper part of the reservoir, not closer than 2-5 m from the gas-water contact , in the direction of the most productive part of it, carry out development work and produce gas from the sidetracks in small selections of 0.5-0.9% of the initial reserves in a gentle mode with depressions on the formation of not more than 0.2-0.3 MPa and working d ebit not higher than 100-150 thousand m ³ / day.

The figure shows a diagram of the implementation of the proposed method.

The development of a small-amplitude oil and gas deposit with a limited size and a small oil and gas floor is carried out by drilling in the central part of the deposit, determined by the results of drilling of reference wells and seismic exploration, of one vertical exploration well 1 of an increased diameter, in which an expanded complex of field-geological and gas-dynamic research. This well 1 allows combining gas production and transportation to the local consumer with additional exploration of the reservoir, and the increased diameter of the well allows lateral shafts to be drilled from it 2. The additional exploration of the reservoir is carried out by complex geophysical surveys both in the production and exploration well and by conducting volumetric seismic exploration of the reservoir, for example 3D seismic. After obtaining reliable geological and geophysical and field information from the exploratory well 1 in the direction of the most productive thickness of the reservoir, one or more sidetracks 2 are drilled with the old main trunk 3. The sidetracks 2 are drilled in the upper part of the reservoir 4 at an angle of more than 80 degrees to reduce drilling costs and the possibility of obtaining the greatest working flow rate at a distance of at least 2-5 m from the gas-water contact 5 to prevent watering the well. A tubing string (not shown) for transporting hydrocarbon feed goes down to the upper side barrel 2. If necessary, they are filled with proppant to prevent sanding of the side shafts 2 and the formation of sand and clay plugs in them.

At the same time, through the perforation interval 6, the well is studied in forced modes to ensure maximum field and geological information, and gas production from the sidetracks 2 is carried out with small withdrawals in the amount of 0.5-0.9% of the initial reserves in a gentle mode with slight depressions per formation not more than 0.2-0.3 MPa and a constant working flow rate of not higher than 100-150 thousand m ³ / day, which allows for a 30-50 year operation period.

Maintaining constant working flow rate and depression on the formation ensures the preservation of the bottom-hole zone of the formation, prevents its destruction, sand removal and the formation of sand-clay plugs, pulling bottom water and watering the well. The preservation of small gas withdrawals contributes to the slow rate of formation pressure drop, the preservation of a sufficiently high pressure at the wellhead, and the implementation of uncompressed well operation.

Example 1

In the process of developing a small-amplitude oil and gas reservoir, production is carried out through an exploratory well, the shoe of which is located at a distance of 2 m from the gas-water contact. At the same time, gas extraction is carried out in the amount of 0.9% of the initial reserves with a depression of 0.2 MPa per reservoir and a constant working flow rate of 100 thousand m ³ / day.

At a distance of less than 2 m, the GWC rises in 1-2 years, which is confirmed by the experience of developing gas fields where the rate of GWC rise is fixed at 1.5-2.0 m / year [Theory and practice of overhaul of wells at low reservoir pressures / M.G. Geikhman, G.P. Zozulya, A.V. Kustyshev, V.V.Dmitruk, L.U. Chabaev. - M .: IRC Gazprom, 2008. - P.12.].

With gas withdrawal of more than 0.9% of the initial reserves, a rather high rate of decrease in reserves and, correspondingly, reservoir pressure occurs, leading to premature introduction of formation water into the reservoir and to watering the well.

In case of depression on the formation of less than 0.2 MPa, insufficient extraction of gas from the formation is observed, which leads to well hydration due to low gas flow rates or other complications, such as insufficient cleaning of the bottom-hole zone from mechanical impurities.

Well operation with a working flow rate below 100 thousand m ³ / day. leads to the formation of hydrates and to insufficient speed to remove liquid and sand from the bottom, to self-capping the well.

Example 2

In the process of developing a low-amplitude oil and gas reservoir, production is carried out through an exploratory well, the shoe of which is located at a distance of 3 m from the gas-water contact. At the same time, gas extraction is carried out in the amount of 0.7% of the initial reserves with a depression of 0.3 MPa per formation and a constant working flow rate of 120 thousand m ³ / day. Experience shows that these are the most optimal conditions for the development of low-amplitude deposits with a low oil and gas potential and the exploitation of exploratory wells drilled on these deposits.

Example 3

In the process, the development of a low-amplitude oil and gas reservoir is carried out through an exploratory well, the shoe of which is located at a distance of 5 m from the gas-water contact. At the same time, gas extraction is carried out at a rate of 0.5% of the initial reserves with a depression of 0.3 MPa per formation and a constant working flow rate of 150 thousand m ³ / day.

At a distance of more than 5 m, due to the small thickness of the reservoir, there is a large reduction in its drained zone, for example, at a thickness of 10 m, the reduction in the thickness of the drained zone will be 50%, which will negatively affect the working flow rate.

When gas extraction is less than 0.5% of the initial reserves, an insufficient rate of gas extraction and production is observed, which leads to unprofitable development of this deposit.

With a depression on the formation of more than 0.3 MPa, destruction of the bottom-hole zone of the formation is observed, leading to the removal of sand and the formation of sand-clay plugs.

During the operation of the well with a working flow rate of more than 150 thousand m ³ / day, the destruction of the bottom-hole zone of the formation and the removal of sand with the formation of sand-clay plugs are observed.

The advantage of the method is to reduce the cost of additional exploration of the reservoir, eliminating the need to drill new exploration and production wells, combining gas production and transportation to the local consumer with the additional exploration of the reservoir.

Claims (1)

A method for developing low-amplitude oil and gas deposits with a limited size area and a small oil and gas potential floor, namely, that support wells are drilled, seismic surveys are carried out, the central part of the reservoir is determined by seismic results, and then an enlarged vertical exploration well is drilled in the central part of the reservoir, carry out gas sampling in forced modes, while conducting an expanded set of field-geological and gas-dynamic studies, determining they share the most productive part of the deposit and initial reserves, stop gas production, liquidate the lower part of the well of the exploration well, then one or two sidetracks are drilled from it in the upper part of the deposit, not closer than 2-5 m from the gas-water contact, in the direction of the most productive parts of it, carry out development work and carry out gas production from sidetracks in small selections of 0.5-0.9% of the initial reserves in a gentle mode with depressions on the formation of not more than 0.2-0.3 MPa and a working flow rate of not higher than 100 -150 thousand m ³ / day.

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