RU2285787C1 - Depleted gas pool development method - Google Patents

Abstract

FIELD: gas production industry, particularly to develop gas deposits at later stages.

SUBSTANCE: method involves extracting product from gas well through at least one producing well with constant gas-water contact position control. The gas-water contact position is carried out with respect to lower perforation orifices of producing well and if gas-water contact is spaced 0.5-3 m from above orifices or if water is present in well product heterogeneous gas-liquid mixture is also injected in well and forced into productive pool. Heterogeneous gas-liquid mixture has aeration factor equal to 4-8. Heterogeneous gas-liquid mixture volume is not less than 5.5 volumes of pore productive pool space defined in radial direction from well bore. The well is left as it is to equalize pool and bottom-hole pressure values. Then product is extracted from gas well under gas-water contact position control to provide water front displacement in well below gas-water contact level.

EFFECT: increased efficiency due to reduced risk of well flooding along with increased well management reserves.

6 cl, 1 ex

Description

The present invention relates to the field of gas production and, in particular, may find application in the development of depleted gas deposits at a late stage of its development.

A known method of developing a depleted gas reservoir, characterized by watering the production of a producing well. The known method involves increasing the flow rate of the well above the design to remove water from the well [see, for example, US Pat. USA 4090564, 05.23.1978].

The disadvantage of this method is its low efficiency, due to the danger of even more watering the well and the possibility of spontaneous killing.

A known method of developing a depleted gas reservoir, comprising supplying a gas-liquid mixture to a production well with the necessary speed and taking a well production — gas through the annulus (see, for example, AS USSR No. 1789669, January 23, 1993).

The disadvantage of this method is its low efficiency, as well as the need to comply with a certain rate of supply of a gas-liquid mixture into the well, which suppresses the rate of rise of gas bubbles in the liquid with its separation in the bottom of the well so that it can be taken into the annulus.

The technical result of the invention is to increase the efficiency of the method by significantly reducing the risk of watering the well with an increase in the reserves for controlling the operation of the well.

The necessary technical result is achieved by the fact that the method of developing a depleted gas reservoir involves extracting products from the gas reservoir through at least one production well with constant monitoring of the position of the gas-water contact relative to the lower holes of the perforation of the producing well and at a distance of the gas-water contact from said holes of 0.5 -3 m or when water is contained in the production of a well, injection into a well and squeezing into a reservoir a heterogeneous gas-liquid mixture with aeration ratio of 4-8 p At reservoir pressure and in a volume of not less than 5.5 m of the pore space of this reservoir along the radius from the wellbore, holding the well until the formation and bottomhole pressures are equal and then extracting the product from the gas well with periodic monitoring of the gas-water contact position and the possibility of displacing the water front in the well below the gas-water contact.

Besides:

holding the production well until the formation and bottomhole pressures are equalized is carried out for 10-20 hours;

the injection into the well and the injection into the reservoir of a gas-liquid mixture is carried out with an aeration rate of 5;

after selling the gas-liquid mixture into the reservoir, additional selling of the non-hardening insulating mixture is carried out;

the gas-liquid mixture contains a surfactant in an amount of 0.05-1.0%;

as a non-hardening insulating mixture, a viscoelastic composition is used.

The essence of the invention lies in the fact that the development of depleted gas deposits in accordance with known methods is carried out, as a rule, in an non-optimal mode of product selection, associated either with the selection of a significant amount of ballast associated water, or with unintentional well shutdowns due to this water. In cases where the gas-water contact in the producing well rises above the lower perforation holes, such emergency measures as urgent shut-down of the well for conservation followed by the installation of an insulating cement bridge does not bring results. Due to the depression funnel formed in the borehole during its operation, there is a bypass of the plugged zone underlying the gas reservoir with water. At the same time, there is also a difficult gas inflow into the producing well due to the cement that clogs the productive part of the gas reservoir.

In accordance with the invention, it has been experimentally established that it is possible to develop a depleted gas reservoir in the mode of minimum water cut of the product with a minimum deviation from the design mode of the well. This mode of operation of the well is ensured by the use of a gas-liquid mixture in such a volume and with such properties that the capillary effects of pinching of the gas-liquid mixture in the washed water-developing zones are manifested in a power-law dependence on the pressure displacing them. The fact is that a gas-liquid heterogeneous mixture prepared on a hydrophilic liquid - water can only enter the aquifer. The low molecular weight gases contained in this mixture obey the laws of ideal gases. Gas bubbles are compressed to sizes smaller than the pore channels of the aquifer. With the necessary gas content in the gas-liquid mixture (aeration ratio of 4-8 at reservoir pressure) and the volume of the gas-liquid mixture (not less than 5.5 m of the pore space of the aquifer of the formation along the radius from the wellbore), a sharp fact was obtained experimentally for various types of reservoirs ( spasmodic) increase in the pressure of breakdown (shear) of the gas-liquid mixture after holding the producing well until the formation and bottomhole pressures are equal in it. It is this pressure that determines the long-term (stable) mudding of the bottom-hole zone of the producing well under various operating conditions. The same effects provide the possibility of a significant decrease in the level of bottom water, for example, due to repression in the production well much lower than the lower perforation holes with an extremely slow rate of recovery, which ensures a long anhydrous design mode of operation of the production well. In an extreme case, due to short-term repression, the level of plantar water can again be reduced to the required value.

The method is as follows.

During the development of a depleted gas reservoir, products are extracted from the gas reservoir through at least one production well. In this case, constant monitoring of the position of the gas-water contact relative to the lower perforation holes of the producing well is carried out. Control is carried out by geophysical methods. When the distance of the gas-water contact from the lower perforation holes is 0.5-3 m or when water is contained in the production of the well, the gas-liquid mixture with certain characteristics and in a certain volume is pumped into the well and injected into the reservoir. The multiplicity of aeration of a gas-liquid mixture is taken 4-8 at reservoir pressure. The volume of this mixture is taken at least 5.5 m of the pore space of this formation along the radius from the wellbore. Then the well is maintained until the formation and bottomhole pressures are equalized. If necessary, the pressure at the wellhead is released. After this, products are extracted from the gas well only occasionally - with periodic monitoring of the position of the gas-water contact. In this case, anhydrous mode is provided even with gas-water contact in the well above the perforation holes. If necessary, displace the water front in the well below the gas-water contact. This is ensured by the creation of downhole repression in the well.

A specific example of the implementation of the method.

Well depth - 1980 m;

perforation intervals - 1960-1965, 1969-1974.

The lower perforation interval is flooded with formation water. The permeability of this interval is 2.591 μm ² , the porosity is 23.2%. The permeability of the upper gas saturated interval is 1.71 μm ² , and its porosity is 21%.

The reservoir pressure is 19.5 MPa.

When the distance of the gas-water contact from the lower perforation holes is 1 m or when water is contained in the production of a well, a heterogeneous gas-liquid mixture is pumped into the well based on a 1% solution of DS-RAS in water. The multiplicity of the gas-liquid mixture is taken equal to 5. The gas-liquid mixture is pumped in a volume of 6 m of the pore space of the formation along the radius from the wellbore. The injection is carried out through tubing. The selling pressure of the gas-liquid mixture is chosen such that the average diameter of the mixture bubbles does not exceed the average pore diameter of the aquifer. For this, when the gas-liquid mixture begins to leave the shoe of the tubing string, its flow rate is increased until the pressure at the bottom of the producing well is at least 32 MPa. This is necessary in order for the gas-liquid mixture to be filtered at high permeability and low permeability intervals. Then the well is maintained until the formation and bottomhole pressures are equalized for 18 hours. After that, products are extracted from the gas well only with periodic monitoring of the position of the gas-water contact after 2-3 months. In this case, anhydrous mode is provided even with gas-water contact in the well above the perforation holes. If necessary, displace the water front in the well below the gas-water contact. This is ensured by the creation of downhole repression in the well.

Claims (6)

1. The method of developing a depleted gas reservoir, comprising extracting products from the gas reservoir through at least one producing well with constant monitoring of the position of the gas-water contact relative to the lower holes of the perforation of the producing well and, at a distance of the gas-water contact from said holes of 0.5-3 m or when water is contained in a well’s products, injection into the well and selling into the reservoir a heterogeneous gas-liquid mixture with aeration ratio of 4-8 and in a volume of at least 5.5 m of the pore space of this fin radially from the wellbore to the wellbore exposure alignment formation and the bottomhole pressure and then removing the product from a gas well with a periodic control the gas-contact position and the possibility of pushing water in front of the well below the gas-water contact. 2. The method according to claim 1, characterized in that the shutter speed of the producing well to equalize the reservoir and bottomhole pressures is carried out for 10-20 hours 3. The method according to claim 1, characterized in that the injection into the well and the injection into the reservoir of a gas-liquid mixture is carried out with an aeration rate of 5. 4. The method according to claim 1, characterized in that after the gas-liquid mixture is injected into the reservoir, an additional non-hardening insulating mixture is sold. 5. The method according to claim 1, characterized in that the gas-liquid mixture contains a surfactant in an amount of 0.05-1.0%. 6. The method according to claim 4, characterized in that a viscoelastic composition is used as a non-hardening insulating mixture.