RU2259473C2 - Water-flooded reservoir development method (variants) - Google Patents

Abstract

FIELD: oil reservoir development, particularly for developing water-flooded ones.

SUBSTANCE: method involves withdrawing oil through production wells and ejecting working substance through ejection wells. To prevent water ingress from well bore into oil-saturated formation area formation is perforated in water-oil interface zone so that lower part of oil-saturation formation interval and upper part of water-flooded formation interval are penetrated. This provides oil relative permeability retention in oil-saturated formation area. To prevent formation mudding during initial perforation thereof drilling is performed in depression, balance and repression modes with pressure of not more than 3 MPa. As far as oil is depleted perforation interval is extended towards oil-saturated formation area.

EFFECT: possibility to retain oil relative permeability of oil-saturated formation area.

2 cl, 2 dwg

Description

The invention relates to the oil and gas industry, and in particular to methods for developing flooded oil fields.

Known methods for developing flooded oil deposits [1,2,3,4], including the selection of oil through production wells and the injection of a working agent through injection.

At the same time, in order to reduce water withdrawal through production wells, hydrophobizing or sediment-forming solutions are pumped into injection wells to clog the most permeable or fractured porous sections of the formation, or such operations are carried out simultaneously through both injection and production wells.

There is also known a method of developing an oil reservoir [5], which includes pumping water into injection wells, extracting oil through production wells and hydrophobizing water inflows of a reservoir, injecting liquids into production wells to restore phase permeability to oil of a reservoir, for example, selectively water-insulating hydrocarbon-based solutions, followed by a change in the direction of movement of the formation products during its selection.

There is a method of developing an oil reservoir [6], which includes pumping water into injection wells, extracting oil through the producing wells, hydrophobizing the reservoir, and the oil is selected by deep pumps. Moreover, to change the direction of movement of the product during its selection, the shank is lowered below the perforation zone [prototype].

The disadvantage of the prototype is the need to install a shank by hanging below the pump or below the packer.

The objective of the present invention is to preserve the phase permeability of the formation in oil without using shanks.

The task in one embodiment is achieved by the fact that by the method of developing an irrigated oil reservoir, including pumping water into injection wells, taking oil through production wells while maintaining phase permeability for oil, according to the invention, the primary drilling of the formation is carried out in a depression or equilibrium mode, and the selection oil is carried out from the perforation interval with a width of 1 to 1.5 m, produced in the oil-water section, with the width of the perforation interval per oil-saturated part one hundred and not more than 75% and the rate of opening the upper part of the oil saturated reservoir interval, and the lower part - watered formation interval, wherein at least production of reserves carried expansion slot perforation toward the oil-saturated portion of the formation.

The task in another embodiment is achieved by the fact that by the method of developing an irrigated oil reservoir, including pumping water into injection wells, taking oil through production wells while maintaining the phase permeability of the oil, according to the invention, the primary drilling of the formation is carried out in a repression mode of not more than 3 MPa, and the selection of oil is carried out from the perforation interval with a width of 1 to 1.5 m, produced in the oil-water section, with the perforation width per oil-saturated part of the reservoir is not large e 75% and the rate of opening the upper part of the oil saturated reservoir interval, and the lower part - watered formation interval, wherein at least production of reserves carried expansion slot perforation toward the oil-saturated portion of the formation.

The interval for perforation is selected from a width of 1 to 1.5 m and the width of the perforation interval per oil-saturated part of the formation is not more than 75%.

When taking products from the reservoir at perforated intervals, water flows from the flooded (washed) part of the reservoir, and oil from the oil-saturated part of the reservoir.

Due to the lower density, oil entering the wellbore pops up and fills the entire annular space between the production string and the deflated equipment above the production suction point.

Water in the wellbore accumulates below the product suction point due to gravity separation processes.

The suction point of the product coming from the formation into the wellbore is located at the bottom of the pump casing. And when the liner is deflated, the inlet of the lower part of the liner serves as the suction point of the product (the shank is the tubing attached to the pump below the pump).

The water located in the wellbore during the shutdown of the well, penetrating the perforation interval, reduces the phase permeability of oil in the oil-saturated part of the reservoir. This increases the phase permeability of water, leads to the formation of a water cone during operation and a decrease in the content of oil in selected products.

But due to the fact that the width of the perforation interval in the oil-saturated part of the reservoir is insignificant, the magnitude of the rise of the water cone is insignificant and has a reversible character. The main effect is achieved by the fact that due to the insignificant width of the perforation interval opposite the oil-saturated part, the possibility of water entering the wellbore into the perforated part of the formation is excluded. This ensures the preservation of the phase permeability of the formation in oil.

The above graphic materials (Fig. 1 and Fig. 2) explain the essence of the invention, where Fig. 1 (prototype) shows a well - 1 with a downhole pump - 2 and a liner - 3, lowered below the perforation interval - 10. Oil filtration occurs from oil-saturated part of the formation - 5, and the filtration of water from the flooded part of the formation - 6, located below the oil-water section - 4. Above the bottom of the liner - 3, the wellbore is filled with floated oil, while the perforation interval also contacts the oil, which allows to preserve the phase permeability of the formation through oil . Below the bottom of the liner, the wellbore is filled with water - 8. Arrow - 9 indicates the direction of movement of oil and water from the perforation interval during operation of the downhole pump - 2.

Figure 2 shows the well - 1, the downhole pump - 2, oil flows from the oil-saturated part of the formation - 5, and water from the water cut of the formation - 6. In the well below the pump - 2 there is oil and water. But this water does not come into contact with the oil-saturated part of the formation in the absence of perforation and therefore does not reduce the phase permeability in the oil-saturated part of the formation. Arrow - 9 indicates the direction of movement of oil and water from the perforation interval.

For the successful application of the invention, two conditions must be met:

1. With the selection of oil due to the rise of the oil-water section, it is necessary to expand the perforation interval towards the oil-saturated part of the reservoir.

2. The initial opening of the formation during drilling is carried out in the mode of depression or equilibrium. If it is impossible to fulfill this condition, repression should not exceed 3 MPa. In case of repression of more than 3 MPa, formation seams do not allow effective selection without cleaning the bottom-hole formation zone, and this is impossible without extending the perforation interval.

Sources of information

1. Description of the invention to the application No. 95103121, 6 E 21 B 43/22, 43/27, publ. in BI No. 35, 1996. “Method for the development of multi-layer oil fields”.

2. Description of the invention to the application No. 95108722, 6 E 21 V 43/20, publ. in BI No. 15, 1997. "Method for the development of oil deposits".

3. RF patent No. 2103489, 6 E 21 B 43/22, BI No. 3, 1998 "Method for the development of a water-flooded oil reservoir."

4. RF patent No. 2113590, 6 E 21 V 43/22, publ. in BI No. 17, 1998, "Method for the development of multilayer oil fields".

5. RF patent No. 2085714, 6 E 21 V 43/22, publ. in BI No. 21, 1997 dated July 27, 1997

6. RF patent No. 2173770, 7 E 21 V 43/20, publ. BI No. 26, 2001 dated September 20, 2001

Claims (2)

1. A method of developing an irrigated oil reservoir, including pumping water into injection wells, extracting oil through production wells while maintaining phase permeability for oil, characterized in that the initial drilling of the formation is carried out in a depression or equilibrium mode, and the oil is taken from the perforation width from 1 to 1.5 m, produced in the oil-water section, with a perforation interval width per oil saturated part of the formation of not more than 75% and based on the penetration of the upper part of the oil saturation formation interval, and the lower part of the flooded interval of the formation, with the development of reserves expand the perforation interval in the direction of the oil-saturated part of the formation. 2. A method of developing an irrigated oil reservoir, including pumping water into injection wells, extracting oil through production wells while maintaining phase permeability for oil, characterized in that the initial drilling of the formation is carried out in a repression mode of not more than 3 MPa, and oil is sampled from the interval perforations with a width of 1 to 1.5 m, produced in the oil-water section, with a perforation width per oil-saturated part of the formation of not more than 75% and based on the opening of the upper part of the oil-saturated Shaft reservoir and the lower part - watered formation interval, wherein at least production of reserves carried expansion slot perforation toward the oil-saturated portion of the formation.

Images