RU2447271C1 - Method to develop small deposits and separate lenses of oil deposit - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: according to the method, vertical and horizontal injection and producing wells are drilled, horizontal injection wells are drilled in parallel to the oil pool outline and/or lines of collector substitution and at least 70 metres inside the deposit from the lines specified in plan. The bottomhole of the previous well and the point of entry into the bed of the subsequent well are arranged at the distance from each other of at least 50 m. The horizontal bore is drilled with length of at least 2 distances of the confirmed grid of wells. Products are taken via producing wells. The working fluid is pumped via injection wells. Whenever the bed pressure drops below the values of 80% from the initial one and/or during watering of horizontal wells started for production, more than 90% of them are placed under injection, displacing oil to the centre of the deposit and from zones of substitution to a non-collector into a zone of collectors development.

EFFECT: improved oil recovery of the deposit.

1 ex, 1 dwg

Description

The invention relates to the oil industry and may find application in the development of small reservoirs of oil of reservoir or massive type, dead ends and lenses.

A known method of developing an oil field, according to which the design number of injection and production wells are drilled. Waterflood and extract oil to the surface, followed by drilling additional wells, taking into account volumetric heterogeneity of the reservoir. Additional development of the field is carried out with the simultaneous search and extraction of residual reserves by drilling horizontal and sidetracks from wells that have been put into circulation due to technical and technological reasons. Sidetracks are drilled in the direction of that of the neighboring surrounding wells, which also has technological performance indicators, in which its oil-water factor at the time of equal flooding of the surrounding wells would be maximum (RF Patent No. 2172395, publ. 08/20/2001).

The known method does not allow to develop a field with high oil recovery.

Closest to the proposed invention in technical essence is a method of developing a heterogeneous oil field, which involves drilling the design number of injection and production wells, flooding and oil recovery to the surface, followed by drilling additional wells that take into account volumetric heterogeneity of the reservoir, which is determined by the results of field operation and modeling . Additional wells are drilled with a horizontal wellbore or horizontal wells are drilled from old wells, and horizontal wells are drawn along the line connecting stagnant oil pillars, and if there are replacement zones, lenses, dead ends or zones with low reservoir properties, along the line connecting these zones ( RF patent No. 2101475, publ. 01/10/1998 - prototype).

The method does not allow to cover the entire oil reservoir by exposure, as a result of which the oil recovery of the reservoir remains at a low level.

The proposed invention solves the problem of increasing oil recovery deposits.

The problem is solved in that in a method for developing small deposits and individual lenses of an oil field, including drilling vertical and horizontal injection and production wells, selecting products through production wells, pumping a working agent through injection wells, according to the invention, the drilling of horizontal injection wells is performed in parallel with the oil contour and / or reservoir replacement lines and at least 70 m into the reservoir from the indicated lines in the plan, the bottom of the previous well and the point of entry into the reservoir the next well is placed at a distance of at least 50 m from each other, a horizontal well is drilled with a length of at least 2 distances of the approved grid of wells, with a decrease in reservoir pressure below 80% of the initial and / or when watering horizontal wells launched for production, more than 90% they are transferred under injection, displacing oil to the center of the reservoir and from substitution zones to the non-reservoir to the reservoir development zone.

SUMMARY OF THE INVENTION

Known methods for developing small deposits and individual lenses of an oil field do not allow exposure of the entire oil pool, do not allow oil to be displaced to the production fund of wells without losses, prevent outflow of oil and displacing agent over the oil circuit, and thus achieve high oil recovery. The proposed invention solves the problem of increasing oil recovery deposits. The problem is solved as follows.

During the development of small deposits and individual lenses of an oil field, vertical and horizontal injection and production wells are drilled, production is taken through production wells, and a working agent is injected through injection wells. Drilling of injection horizontal wells is performed parallel to the oil content circuit and / or reservoir replacement lines and at least 70 meters into the reservoir from the indicated lines in the plan. The bottom of the previous well and the entry point into the formation of the next well are placed at a distance of at least 50 m from each other. This ensures that there are no breakthroughs of the injected agent beyond the oil content in the aquifer. A horizontal well is drilled with a length of at least 2 distances of the approved grid of wells. Studies are being carried out to determine the current reservoir pressure in the selection zone. If the reservoir pressure decreases below 80% of the initial and / or when watering horizontal wells launched for production, more than 90% transfer them to injection, displacing oil to the center of the reservoir and from the replacement zones to the non-reservoir in the reservoir development zone.

Figure 1 presents the layout of production and injection wells in the deposits.

The deposit is drilled along the design grid with producing vertical and horizontal wells, oil is produced through production wells;

drill vertical injection wells. Horizontal injection wells are drilled parallel to the oil contour and / or reservoir replacement lines (external oil-water contact (VNK) or internal VNK circuit) and at least L = 70 m into the reservoir from the indicated lines in the plan. Drilling horizontal injection wells is carried out so that when drilling the previous horizontal well, for example, well 1, there remains a distance in the plan that allows you to change the azimuth of the drilling of the next horizontal injection well, for example, 2 so that the bottom of the previous one overlaps the entry point to the next one by a distance R not less than 50 meters. This ensures that there are no breakthroughs of the injected agent beyond the oil content path into the aquifer, oil is displaced to the center of the reservoir and from the replacement zones to the reservoir development zone. The length of the horizontal wellbore is performed by at least 2 distances of the approved grid of wells, not excluding the possibility of using injection horizontal wells at the initial stage as production wells. Clarify the geological structure of the reservoir, reservoir properties. The results are compared with the data of geological and hydrodynamic modeling, taking into account the current development conditions, studies are being carried out to determine the current reservoir pressure in the selection zone.

Using the information obtained, with a decrease in reservoir pressure below 80% of the initial or when watering horizontal injection wells launched for production, up to 90% according to the proposed method, they are transferred under injection, displacing oil to the center of the reservoir and from the replacement zones to the reservoir development zone, preventing the outflow of oil beyond the oil-bearing circuit into the aquifer and maximally covering the reservoir with drainage.

Displacing fluid is injected into injection wells and products are extracted from production wells. During operation, measurements are made of oil, water and injection.

Concrete example

The implementation of this method is illustrated by the example of a small deposit of 2.25 × 1.750 km in terrigenous carbonaceous sediments at a depth of 1070 m. The deposit is drilled by vertical, directional and horizontal wells according to the design grid with a distance between the wells of 300 meters. Horizontal injection wells are drilled parallel to the contour and 75 meters from it in plan with overlapping bottom faces of the previous entry points into the formation, ensuring during development there are no breakthroughs of the injected agent beyond the oil-bearing contour into the aquifer. The length of the horizontal wellbore is 750 meters, that is, 2.5 distances of the approved grid of wells. According to the method, horizontal injection wells are mastered as production wells. Carry out the arrangement. According to the results of drilling, the geological structure of the reservoir and the reservoir properties of oil-bearing rocks are specified. The collector has an area distribution. The results are compared with the data of geological and hydrodynamic modeling, taking into account the current development conditions. During operation, measurements are made of oil, water and injection. The average production rate of producing vertical and directional wells (A) is on average 15 tons / day, horizontal horizontal No. 4, launched for production - 27.6 tons / day, the average water cut of 3.5%.

After three years of development, the water cut of a horizontal injection well launched for production No. 4 increased to 92%. The well was launched for injection. The injectivity of injection well No. 4 is 100 m ³ / day, that is, two times higher than the average injection rate in the aircraft. The pressure in the selection zone for well 16 increased to 9.6 MPa. The production rate of mining aircraft No. 16 of the first row increased from 15 to 23 tons / day, water cut to 10%.

The cumulative oil production at the injection unit No. 4 for three years of operation as an oil producer amounted to 9.8 thousand tons. Moreover, the cost of constructing a horizontal well (GS) amounted to 143% of the cost of building a conventional directional well (BC), that is, 24.3 million rubles. Savings on the construction of six injection hydraulic power plants instead of nine aircraft amounted to 7.2 million rubles. The initial additional daily production rate by the method averaged 8.0 tons / day, the additional annual production of aircraft No. 16 is on average 2.72 thousand tons, for three years of development without maintaining reservoir pressure - 7.8 thousand tons, for seven years after the development of injection, taking into account the fall - 14.5 thousand tons The savings according to the method consist of evaluating the technological effect of production per aircraft No. 16 for 7 years, which amounted to 14.5 thousand tons, cumulative production over three years of the hydroelectric power station launched for production, is 14.2 thousand tons and saving on construction one GS No. 4 - 8.5 thousand rubles.

Evaluation of the technological effect:

E = (C-C) ∙ ΔQn + ΔCs = (9.0-5.8) ∙ 28.7 + 26.7 = 118.54 million rubles.,

where ΔQн - additional oil production, thousand tons,

C - oil price 9.0 thousand rubles / t,

With - the cost of production of one ton of oil, thousand rubles / ton 5.8 thousand rubles / ton;

Tss - the price difference for the construction of one gas station, replacing three aircraft.

The calculation of the oil recovery of the deposit showed that when applying the proposed method, oil recovery of the deposit is 66% (according to the prototype - 48%).

The application of the proposed method will improve oil recovery deposits.

Claims (1)

A method for developing small deposits and individual lenses of an oil field, including drilling vertical and horizontal injection and production wells, selecting products through production wells, injecting a working agent through injection wells, characterized in that the drilling of horizontal injection wells is performed parallel to the oil contour and / or replacement lines the reservoir and at least 70 m into the reservoir from the indicated lines in the plan, the bottom of the previous well and the entry point into the reservoir of the subsequent well they are drilled at a distance of at least 50 m from each other, a horizontal well is drilled with a length of at least 2 distances of the approved grid of wells, with a decrease in reservoir pressure below 80% of the initial and / or when watering horizontal wells launched for production, more than 90% translate them under injection, displacing oil to the center of the reservoir and from substitution zones to the non-reservoir to the reservoir development zone.

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