RU2282025C1 - Oil field development method - Google Patents

Abstract

FIELD: oil industry, particularly to develop oil field by providing forced fluid production via producing wells.

SUBSTANCE: method involves separating local elevated productive reservoir areas having producing wells and forcedly extracting fluid through above producing wells. The forced fluid extraction is carried out at initial development stage. To extract fluid production wells providing water content in extracted product of more that 60% are used. Forced extraction rate is increased from 1.5 to several dozens of times. Product is withdrawn from each well up to reaching full or 96% water content in product. Then product production from the well is stopped and necessary time delay is exercised. After that product is extracted from well in cyclic regime including forcedly extracting product from well up to full of 96% water content reaching; stopping product extraction and exercising technological time delay to reduce water content in the product.

EFFECT: increased oil recovery.

2 cl, 1 ex

Description

The invention relates to the oil industry and can find application in the development of oil deposits by establishing a forced mode of fluid withdrawal through production wells.

A known method for the development of oil deposits, including the cyclic injection of a working agent through injection wells and the selection of oil through production wells. A development area with a low oil saturation of the formation and with an excess of the degree of water cut of the extracted product over the degree of development of the initial recoverable reserves is allocated to the deposits. At the development site, the cyclic mode of operation of injection wells is carried out with the restriction of injection volumes below the volume of fluid withdrawal in the area. Up to 30% of production extraction is redistributed from production wells with a water cut of more than 60% to production wells with a water cut of less than 60% with an intensification of production from low-water wells. Production wells with a water cut of more than 96%, located near the injection wells, start at the moment of stopping the injection wells and stop when starting the injection wells. Production wells with a water cut of more than 96%, placed on deposits, start and stop in accordance with the start and stop of injection wells to reduce reservoir pressure and redistribute the direction of flow of reservoir fluids. The development of the site in the established mode is continued until the reservoir pressure decreases at the development site with an oil saturation of more than 0.55 to the reservoir pressure of less than 0.5-1.0 MPa of the initial one, at the development site with an oil saturation of less than 0.55, until the reservoir pressure is less than the initial 2-4 MPa (RF Patent No. 2096593, CL E 21 B 43/20, publ. 1997.11.20).

The known method does not allow to develop an oil reservoir with the achievement of high oil recovery.

Closest to the proposed invention in technical essence is a method of developing an oil field at the final stage by establishing a forced selection mode. According to the method of developing an oil field at the final stage, additional oil recovery is carried out using the existing well stock. For this, a liquid selection is established on them, briefly superior to the previous selection. This forced selection of fluid is carried out at the well. It is selected from the number of wells located in the area of the dome uplift, which is closer to the estimated maximum absolute mark on the dome uplift. Set the mode of fluid selection, which allows you to create a pressure gradient that would exceed the previous pressure gradient by the calculated value (RF Patent No. 2120543, CL E 21 B 43/18, publ. 20.10.1998. - prototype).

The known method allows to intensify the development of the field, however, oil recovery remains at a low level.

The proposed method solves the problem of increasing oil recovery.

The problem is solved in that in the method of developing an oil reservoir, including the allocation of locally elevated sections of the reservoir with production wells and conducting in selected areas of forced fluid withdrawal through production wells, according to the invention, forced selection is carried out at the initial stage of development, production wells are used for forced selection with a water cut of produced products more than 60%, for each well, the maximum possible output is set as forced selection fluid flow up to the technically feasible, forcing is carried out at each well until full watering or a cost-effective level of production, the well is stopped, technological exposure is carried out until the water cut is reduced, further liquid is taken from the well in a cyclic mode: established forced take-up until full watering or cost-effective production level - well shut-off with technological exposure to reduce water cut in the liquid.

Additionally, work is carried out on selective isolation or shutdown of the flooded part of the formation with compositions containing a large volume of fillers.

The features of the invention are:

1. the allocation of locally elevated sections of the reservoir with producing wells;

2. conducting in selected areas of forced fluid withdrawal through production wells;

3. forced selection at the initial stage of development;

4. use for forced selection of producing wells with a water cut of produced products more than 60%;

5. for each well, as a forced selection, the establishment of the maximum possible fluid withdrawal up to the technically possible;

6. at each well, carrying out the established forced selection to complete watering or a profitable production level;

7. well shutdown;

8. holding technological exposure to reduce the water content of the liquid;

9. further withdrawal of fluid from the well in a cyclic mode: established forced withdrawal until full watering or a profitable production level — well shutdown with technological shutter speed to reduce water cut in the fluid;

10. additional work on selective isolation or shutdown of the flooded part of the formation with compositions containing a large volume of fillers.

Signs 1 and 2 are common with the prototype, signs 3-9 are the salient features of the invention, sign 10 is a particular feature of the invention.

SUMMARY OF THE INVENTION

When developing productive formations of an oil field with porous-cavernous reservoirs and pronounced vertical fracturing and cavernousness after 2-3 months of production, production wells are flooded along the cracks with bottom water. At the same time, significant oil reserves remain buried. The use of the forced selection mode through production wells in the domed part of the reservoir helps to intensify development, but they have very little effect on oil recovery. The proposed method solves the problem of increasing oil recovery deposits.

The problem is solved as follows.

Build a map of the structural surface of the reservoir and the profile of the reservoir. To account for the cleavage phenomenon, locally elevated areas are distinguished on the structural map. The fund of wells with high water cut is revealed - more than 60%, located in locally elevated areas. Productivity coefficients are determined by highly watered wells by field hydrodynamic studies. The maximum possible fluid withdrawal is determined up to the technically possible periodic pumping. The appropriate pumps are selected and the wells are transferred to the highest possible fluid withdrawal.

Moreover, due to cleavage in elevated areas, the openness of cracks in the oil-bearing part is higher than in the aquifer. The percentage of water cut in the initial period of the forced regime is sharply reduced, and then restored to the same level (before the event). Liquid withdrawal from wells increases from 1.5 to tens of times for each well individually. After increasing the selection, the productivity coefficient may increase or decrease if it is possible to pump out the level before receiving the pump at the development stage. The selection is conducted to complete watering or a profitable production level.

If oil reserves are not withdrawn (only water is withdrawn), work is carried out to selectively isolate or shut off part of the flooded reservoir with insulating compounds such as SNPKh9633, NBP, KSS with the addition of a larger volume of fillers such as oil-cement mixtures, clay powder, highly viscous oil refining wastes.

Concrete example

An oil field is being developed with the following characteristics: depth - 892 m, temperature 23 ° C, pressure 7.4 MPa, reservoir thickness 17.2 m, reservoir type - massive, reservoir type - pore-fissured-cavernous carbonates, porosity 0.141, permeability 0.145 μm ² , oil saturation 0.79, oil viscosity 52.9 MPa · s, oil density 0.917 t / m ³ . The deposit has been developed for 7 years. The current water cut of the produced oil is 71.7%. The deposit is at the initial stage of development.

The deposit is being developed in natural mode. Liquid is taken through 365 producing wells. Locally elevated sections of the reservoir with the peaks of 506, 515, 520 m are identified. It is determined that there are three producing wells in the allocated domes with a water cut of produced products of more than 60%. For the first of these wells, a productivity coefficient is determined, which is 27, respectively. Based on a certain productivity coefficient, the maximum possible fluid withdrawal is calculated up to the technically possible one. The technically possible maximum forced fluid withdrawal from the well is set equal to 400 m ³ / day. The established forced selection is carried out until the water of the produced fluid is 96% wet (margin of profitability). Stop the well. Spend technological exposure for 15 days. At the same time, in the initial period, the water cut of the liquid decreases (to 60% or less), followed by an increase in water cut as it is taken. Further fluid withdrawal from the well is carried out in a cyclic mode: established forced selection until complete watering or a profitable production level — well shutdown with technological shutter speed until the water cut is reduced.

Similarly, oil is produced through other wells at the peak 515 m.

Through the well at the peak mark of 520 m, only produced water is drawn. In this well, work is carried out on the selective isolation of a part of the flooded formation with insulating compositions of the type SNPX9633 with the addition of a large amount of clay powder (up to 50-70%). After that, operations are performed as in the first well.

Development is carried out until the full development of oil reserves.

As a result, it is possible to increase oil recovery by 3%.

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

Claims (2)

1. A method of developing an oil deposit, including the allocation of locally elevated sections of the reservoir with production wells and conducting in selected areas of forced fluid withdrawal through production wells, characterized in that forced selection is carried out at the initial stage of development, for forced selection use production wells with flooding produced production of more than 60%, for each well as forced selection, selection is established with its increase from 1.5 to tens of times, for which each well is subjected to the established forced selection until 96% is completely flooded or to water the produced products, the well is shut off, technological exposure is carried out to reduce the watering of the produced products, further product sampling from the well is carried out in a cyclic mode: installed forced sampling to full watering or to 96% watering - well shutdown with technological exposure to reduce water cut in the produced products. 2. The method according to claim 1, characterized in that it additionally conducts work on selective isolation or shutdown of the flooded part of the formation with compositions containing fillers.