RU2209953C1 - Method of oil pool development - Google Patents

Abstract

FIELD: oil producing industry; applicable in development of oil pools with bottom water. SUBSTANCE: method includes building-up of pressure differential on formation and withdrawal of product through producing wells. In development of oil pool with carbonate reservoirs having vertical fractures, producing formation is subject to intensifying treatment through producing wells. In oil withdrawal, bottomhole pressures in these wells are set with value of pressure differential at absolute elevation of water-oil contact of 0.5-1.5 Mpa for creation of conditions of uniform rise of water level in oil pool. EFFECT: reduced rate of well water encroachment and increased water-free oil production period. 1 ex

Description

 The invention relates to the oil industry and may find application in the development of deposits with bottom water.

 There is a method of developing an oil reservoir, including drilling a reservoir, selecting products from production wells, maintaining pressure in the formation at a level that provides a static level in the mouth zone of the producing well, and periodic oil selection (Patent RF 2138625, class E 21 B 43 / 20, published. 1999).

 The known method leads to a slowdown in the selection of oil from the reservoir due to the frequency of oil selection.

 Closest to the invention in technical essence is a method of developing an oil reservoir in the late stage in the presence of an oil-water contact, including the development of an oil reservoir by in-line well systems, perforation in production wells above the oil-water contact, taking products through them, injecting water through injection wells, conducting geophysical surveys to control the movement of the oil-water contact, the transfer of the water injection front from one row of wells to another, in which casing string below the oil-water contact, forced pumping of water is carried out with maximum depression on the formation to create a water-saturated zone, then the perforated interval is insulated in the casing opposite the water-saturated part of the formation, the oil-saturated part of the formation is perforated above the oil-water contact, and production selection is carried out with minimal depression on the formation (RF patent 2178517, CL E 21 B 43/16, published. 2002.01.20 - prototype).

 The disadvantage of this method is the rapid water cut of wells in the reservoir, which occurs due to the uneven selection of oil in the zones of the reservoir and the uneven rise of the oil-water contact.

 The invention solves the problem of reducing the rate of water cut in wells and increasing the waterless period of oil production.

 The problem is solved in that in the method of developing an oil reservoir, including establishing a depression on the formation and taking products through production wells, according to the invention, when developing an oil reservoir with carbonate reservoirs having a vertical fracture, in the producing wells, stimulation treatments of the producing formation are carried out, and during the selection of oil establish bottomhole pressures in these wells with a depression value at the absolute mark of the oil-water contact of 0.5 - 1.5 MPa to create conditions for uniform yatiya water level in the oil reservoir.

The features of the invention are:
1) the establishment of depression on the reservoir;
2) the selection of oil through production wells;
3) conducting stimulation treatments of the reservoir in producing wells;
4) establishment of bottomhole pressures in wells with a depression value at the absolute mark of the oil-water contact of 0.5 - 1.5 MPa to create conditions for a uniform increase in the water level in the oil reservoir.

Signs 1, 2 are common with the prototype, signs 3-4 are essential distinguishing features of the invention - the invention
When developing an oil deposit, a gradual flooding of oil occurs. A significant part of the reserves remains buried in the deposits. The invention solves the problem of reducing the rate of water cut in wells and increasing the waterless period of oil production. The problem is solved by the following set of features.

 An oil reservoir with a carbonate fractured-pore-cavernous reservoir having a pronounced vertical fracturing is being developed. In the deposits, products are selected through production wells and, possibly, the injection of a working agent through injection wells. In producing wells, work is underway to improve the opening, that is, they carry out stimulation treatments: expanding wells in the interval of the productive formation, acidizing, claying, water repellentization, etc. Depression on the formation in production wells is brought to a minimum, based on the pumping condition equipment. At the same time, production fluid selections are also established in production wells, leading to the same depression at the absolute mark of the oil-water contact. This is the so-called bottomhole pressure on the water mirror. Due to this, conditions are created for a uniform increase in the water level in the reservoir. This is also facilitated by the maintenance of optimal specific fluid withdrawals from wells.

Concrete example
An oil reservoir is developed with the following characteristics: the average depth is 892 m, the type of deposit is massive, the reservoir is carbonate, the average total thickness is 17.2 m, the average effective oil saturated thickness is 8.8 m, the porosity is 0.141, and the average oil saturation is 0.79, permeability - 0.145 μm ² , reservoir temperature - 23 ^o C, reservoir pressure - 7.4 MPa, oil viscosity in reservoir conditions - 52.9 MPa • s, oil density in reservoir conditions - 0.884 t / m ³ , the saturation pressure of oil with gas is 1.3 MPa, the gas content of oil is 4.7 m ³ / t, the viscosity of the water in the reservoir Slovenia - 1.1 MPa • s, water density - 1.036 kg / m ³ .

 The deposits are selected through 20 production wells. In production wells, stimulation treatments are carried out: expansion of wells in the interval of the reservoir and acid treatments. Depression on the reservoir in production wells is brought closer to the minimum, based on the working condition of the pumping equipment, and set within 0.5 - 1.5 MPa. The absolute mark of the oil-water contact is 543 m. The bottomhole pressure in the well is set equal to 0.8 MPa. As a result of these measures, the anhydrous period at the development site was 1 year, while at the adjacent site with the classical development system, the anhydrous period ended after 4 months.

 Application of the proposed method will reduce the rate of water cut in wells and increase the waterless period of oil production.

Claims (1)

 A method of developing an oil reservoir, including establishing a depression on the formation and selecting products through production wells, characterized in that during the development of the oil reservoir with carbonate reservoirs having vertical fracture, the production wells are subjected to intensification treatments, and during oil extraction, bottomhole pressures are set in these wells with a depression value at the absolute mark of the oil-water contact of 0.5 - 1.5 MPa to create conditions for a uniform rise in the water level in the oil deposits.