RU2034131C1 - Method for development of multilayer gas or gas-condensate fields - Google Patents

Abstract

FIELD: mining industry. SUBSTANCE: method for development of multilayer gas or gas-condensate fields includes bypass of gas or gas-condensate from lower to upper layers. Gas is bypassed to zone of gas-oil contact. Pressure and bypassing are regulated at the level of upper layer. Gas bypassing is effected in each well in the volume determined by formula given in invention description. In case of presence of excessive pressure for gas bypassing, wells are operated as producing ones. EFFECT: higher efficiency. 1 dwg

Description

 The invention relates to the downhole development of gas and gas condensate fields and can be used for the development of multilayer deposits in the case when the development of the underlying reservoirs is unprofitable when organizing their separate operation.

There is a method of developing multilayer gas (gas condensate) fields, which consists in drilling production wells that open all productive formations, and gas production from them [1]
However, this method is implemented only in the case of slight differences in reservoir pressure and gas composition of the deposits of the field.

Closest to the proposed is a method of developing multi-layer gas and gas condensate fields by drilling production wells to the upper productive horizon and bypass wells to the lower horizon [2]
This method of operating development facilities requires significant costs for the construction of a fund of production wells of lower development facilities with a well production transport system, which is not economically feasible.

 The aim of the invention is to increase the development efficiency by ensuring the development of the lower object without additional capital investments in its development of production wells and preventing premature flooding of the wells of the upper reservoir during the manifestation of the water pressure regime in it.

(1) где k, h соответственно проницаемость и толщина интервала верхнего пласта, в который осуществляется перепуск газа, м², м;
μ вязкость перепускаемого газа, МПа с;
R половина расстояния между соседними перепускными скважинами, м;
R_c радиус перепускных скважин, м;
Р_ст, Р_с, Р соответственно атмосферное давление, давление перепуска газа в перепускной скважине и давление в верхнем пласте, МПа, причем при наличии избыточного газа для перепуска перепускные скважины работают как добывающие.The goal is achieved by the fact that when implementing the method of developing a multilayer gas or gas condensate field, including drilling production wells on the upper reservoir, drilling bypass wells on the lower reservoir, transferring gas or gas condensate from the lower reservoir, transferring gas or gas condensate to the gas-water contact zone of the upper reservoir with uniform coverage of its entire plane, pressure and bypass are regulated in bypass wells at the level of the upper layer, and bypass of gas or gas condensate and carried out to the extent determined by the formula for each borehole:
Q

(1) where k, h, respectively, the permeability and thickness of the interval of the upper reservoir, in which the bypass gas, m ² , m;
μ viscosity of the bypassed gas, MPa s;
R half the distance between adjacent bypass wells, m;
R _{c the} radius of the bypass wells, m;
P _st , P _c , P, respectively, atmospheric pressure, gas bypass pressure in the bypass well and pressure in the upper reservoir, MPa, and in the presence of excess gas for bypass, the bypass wells operate as producing ones.

 The drawing shows a diagram of an implementation of the proposed method.

 In the process of exploration of a multilayer field, development objects are distinguished by combining formations with close reservoir pressures, reservoir fluid compositions and with uniform water pressure systems. Drilling production wells at the upper object, taking it for the main object of development. As the productive formations of the upper main object are developed and the reservoir pressure decreases, the manifestation of the water pressure regime may begin in them, i.e. raising gas-water contact (GVK) and watering production wells. To slow down this process, bypass wells are constructed at the lower and upper main development objects and gas is transferred from the lower productive formations with high reservoir pressure to the GWC interval of the upper main object with uniform coverage of its entire plane. As the bypass interval, the most permeable layers of the upper object in the GWC region are selected. The volume of gas bypass for each well is regulated by maintaining the necessary pressure in the bypass well at the depth of the gas bypass using a flow regulator and determine its value by the formula (1).

The number of bypass wells is determined from the following considerations. Bypassed gas, creating a gas barrier to the water along the GWC plane, is filtered into the productive strata of the main object and is produced together with its stratum fluid. Therefore, in order to ensure that the reservoir pressure in the upper main object does not decrease in the bypass interval in the GWC area, it is necessary to maintain the equality of the volumes of gas produced and the bypassed, then the maximum number of bypass wells n is determined by dividing the gas production volume Q _d.g. to the bypass flow rate for one bypass well n = Q _d.y. / Q. However, even when bypassing smaller volumes of gas compared to the amount of gas produced, in addition to gas production from lower objects, the effect of slowing down the flooding of the upper main development object is achieved. When organizing gas bypass from the lower objects to the upper development object, in comparison with the separate exploitation of the lower objects by their production wells, productive formations drain for a longer time and even when the bypass products are flooded, since there is no need to raise the well products to the wellhead and transport it to the gas treatment point .

 Exploratory wells can be used as bypass wells; if necessary, some wells are additionally drilled.

4,25 м³/c 368

Отбор газа из верхнего основного объекта составляет 50 млн м³/сут. Для полной компенсации отбираемого газа необходимо 136 перепускных скважин с такой производительностью, которые за 5 лет смогут перепустить почти все запасы нижних объектов в верхний, если же задаются сроком перепуска газа, например 30 годами, что соответствует срокам разработки основного объекта, то понадобится около 20 перепускных скважин.PRI me R. During field exploration, 4 objects were discovered and identified. The main gas reserves (210 billion m ³ ) are concentrated in the upper main fourth facility. The reserves of the lower objects I-III are concentrated in productive formations of insignificant capacity (about 100 billion m ³ ), therefore, the development of their separate grid of production wells is considered unprofitable, and their connection to the development together with the upper main object is impossible due to the significant difference in reservoir pressures and dangers of watering wells. Therefore, it was decided to develop the lower objects by transferring gas from objects I-III to the GWC interval of the main upper object IV for specially constructed bypass wells 1, 2. The bypass volumes are regulated by the flow regulator 3 installed in the tubing string 4. The bypass wells are equipped with circulation valves 5 and packers 6 mounted below the valve. The main object is developed by production wells, the current reservoir pressure in it at the level of GVK is 6.5 MPa. The average reservoir pressure at facilities I-III is 16.0 MPa. For the values of other quantities in formula (1): k = 1 10 ^-12 m ^2, h = 2 m, R = 500 m, R _c = 0.1 m, μ0.1 m˙ P˙a s and while maintaining P _c = 10 MPa bypass production rate for one well will be:
Q

4.25 m ³ / s 368

Gas extraction from the upper main facility is 50 million m ³ / day. To completely compensate for the gas being taken, 136 bypass wells with such productivity are needed that in 5 years will be able to transfer almost all the reserves of the lower objects to the upper, but if they are set by the gas bypass period, for example 30 years, which corresponds to the development time of the main object, then about 20 bypass wells will be required wells.

 The feasibility of this method is that due to the bypass of high pressure gas of the lower objects to the GWC interval of the upper main development object, a later deadline for commissioning booster compressor stations at group gas treatment plants is ensured, the gas recovery coefficient of the main object increases, since the life of the main object is extended during the gas regime, the period of constant gas production is extended, significant capital investments are saved due to the exclusion of the arrangement of of existing facilities with production wells and gas collection networks.

Claims (1)

METHOD FOR THE DEVELOPMENT OF A MULTIPLAST GAS OR GAS-CONDENSATE FIELD, including drilling production wells on the upper productive layer, drilling bypass wells on the lower layer, bypassing gas or gas condensate from the lower layer, characterized in that, in order to increase development efficiency without additional development of the lower object investments in its arrangement with production wells and the prevention of premature flooding of the upper formation wells in the process showed water in the upper reservoir, gas or gas condensate is transferred to the gas-water contact zone of the upper reservoir with uniform coverage of its entire plane, pressure and bypass are regulated in the bypass wells at the level of the upper reservoir, and gas or gas condensate by each well is carried out in the volume carried out according to the formula

where K is the permeability of the upper layer, m ² ;
h is the thickness of the upper layer, m;
μ viscosity of the bypassed gas, MPa.s;
R half the distance between adjacent bypass wells, m;
R _{with the} radius of the bypass well, m;
P _{c t} atmospheric pressure, MPa;
P _with gas bypass pressure in the bypass well, MPa;
P pressure in the upper reservoir, MPa,
moreover, in the presence of excess gas for bypass, the bypass wells operate as producing.

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