RU1810506C - Method for completion of water-saturated gas wells - Google Patents

Abstract

The invention relates to mining, in particular to the oil and gas industry, in particular to the development of gas wells, and can be used in developing well-saturated wells with low reservoir pressure. The aim of the invention is to increase the efficiency of development of water-saturated wells with low reservoir pressure by removing capillary blocking of the near-sap ring annular zone of the reservoir with water. To do this, after removing the fluid from the wellbore by supplying a surfactant and air into the well, air is pumped into the bottomhole formation zone until the injected air is connected to the gas-bearing part of the formation and the injection pressure is stabilized. The air injection pressure is chosen to be greater than the reservoir pressure by the amount of losses to overcome the hydraulic resistance of water in the near-wellbore zone.

Description

The invention relates to mining, in particular to the oil and gas industry, to the development of gas wells, and can be used in the development of water-saturated wells with low reservoir pressure.

The purpose of the invention is to increase the efficiency of development of water-saturated wells with low reservoir pressure by removing capillary blocking of the near-wellbore zone with water.

A method for developing water-saturated gas wells is carried out as follows.

In the process of exploitation, gas wells can self-pressurize with water, for example, coming together with gas and condensing in the near-bottom zone, or due to jamming of wells during overhaul during repair and restoration works. When developing such water-saturated wells, first of all, it is necessary to remove the liquid from the wellbore, which can be accomplished by known methods and means, for example, supplying a surfactant to the well and blowing it with air.

Then, after liquid is removed from the wellbore, air is injected into the bottom-hole zone of the formation until the injected air is connected to the gas-bearing part of the formation and the injection pressure is stabilized, and the injection pressure is chosen to be greater than the formation pressure by the amount of losses to overcome the hydraulic resistance of the water in the hairline zone.

Formation in the bottom-hole zone of a productive reservoir-reservoir of a zone of moisture impregnation in the process of self-develpment of a gas well or after artificially 00

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It is theoretically sufficiently developed to suppress it for carrying out repair and restoration work in it. However, it is not possible to determine theoretically the geometric parameters of this moisture impregnation zone, since they are characterized and determined by many factors, namely:

- capacitive-phytration properties of the gas-containing reservoir;

- the power of the gas reservoir;

- the value of the current reservoir energy;

- gas velocity in the bottomhole zone;

- gas velocity along the wellbore ;.

- well operation technology;

- the quality of repair and restoration work, etc.

Therefore, the geometric parameters — volume and radius of the impregnation zone — as well as other required parameters for implementing the method of developing wells are determined empirically in each case.

. This in a particular case can be performed as follows.

1. According to experimental studies, the radius of the moisture impregnation zone around the wellbore is set from 1 to 3 m.

2. Determine the volume of gas that encloses the annular zone of moisture impregnation around the wellbore in a predetermined radius of 1 to 3 m for the opened thickness of the gas reservoir in the range of 10 to 100 m at the current reservoir pressure.

3. Determine the time of injection of the required amount of air, allowing to push moisture from the impregnation zone deep into the formation until the injected air is connected to the gas-bearing part of the formation and stabilization of the injection pressure.

4. The moment of connection of the injected air with the gas portion of the formation can be recorded, for example, by a sharp decrease in the injection pressure by the magnitude of the pressure gradient at the gas-water contact.

5. The magnitude of the pressure gradient at the gas-water contact in the pore space of the gas-containing formations is determined by measuring and comparing the values of the formation pressure in the well being watered and in the nearest adjacent working gas wells at different points in the gas formation.

So, to develop gas wells in one of the fields of Central Asia with low reservoir pressure after

carrying out repair and restoration work in them, i.e. To ensure the flow of gas from the formation into the well, air was injected with an UPK-80 compressor with a capacity of 9 m3 / min and for 1 h to 1 h 30 min into gas-bearing formations with a capacity of 20 to 40 m and within 3-4 hours into gas-bearing formations thickness from 60 to 100 m. The pressure gradient at the gas-water contact averaged 0.75 MPa. The time required to connect the injected air with the gas-bearing part of the formation was determined for formations with a thickness of 20 m for 1 hour, and for formations with a capacity of 100 m for up to 4-5 hours.

An example implementation of a method for developing water-saturated gas wells in a field with a low reservoir pressure. -: .--: -. . .: Prior to the overhaul of the wells, their flow rate was 30 thousand m3 / day at a pressure of 0.7 MPa. After a major overhaul in the well to replace tubing (tubing), the following operations were carried out.

1. Uploaded to the bottom of the well liquid surfactant (surfactant) in the amount of 16 kg at the rate of 1% by volume

a column of fluid that has formed after killing a well.

2. We connected the UPK-80 mobile compressor to the pipe space and squeezed out a column of liquid through its aeration onto the surface and purged the well to clean air. At the same time, the attempt to master the well was not successful - the well did not work.

3. Then closed the annular space and began to pump air into the reservoir for

ousting moisture from the near-well annular impregnation zone to the gas-bearing part

layer .. .- -. : U. :. :;

The initial pressure Rkn of the air injection pressure generated by the compressor was determined by the ratio: Rkn Rpl + A rgr + D Rp + A Rte + D Rsps, where Rkn is the initial value of the air pressure created by the compressor; . .

Rpl - current reservoir pressure equal to 0.7 MPa for the gas-bearing horizon;

Д Ргр - pressure gradient at the gas-water contact, determined empirically, for gas-bearing terrigenous rocks equal to an average of 0.75 MPa: DDR-value of repression on the formation; . Д Ргс - hydrodynamic drag value;

A rs.ps. - pressure of the liquid column in the wellbore.

Drr, DRGs, LR.s.ps.- depend on the discovered power of the gas-bearing formation and in total vary within 0.4 + 0.65 MPa and are constant for a particular well.

Thus, the initial ILV pressure created by the compressor was:

RCL - 0.7 MPa + 0.75 MPa + 0.65 MPa - 2.1 (± 0.1-0.2) MPa.

4. Continuous injection of air into the formation was carried out until the pressure on the compressor was sharply reduced by the pressure gradient at the gas-water contact — 0.7 + 0.8 MPa and continued to pump air into the formation until the pressure on the compressor was stabilized for a period. 20-30 min, to a value of 2.1 MPa - 0.8 MPa - 1.3 MPa.

5. After turning off the compressor, the well was first purged to clean gas, and then connected to the loop for further operation.

The proposed method for developing water-saturated gas wells can be used in gas condensate fields at a late stage of development when an abnormally low pressure is reached. .

Using the method of developing water-saturated gas wells provides the following technical and economic advantages.

1. Improving gas recovery.

2. Improving the permeability of the bottom-hole zone of gas-bearing strata.

3. Reducing energy and material costs for developing saturated wells with abnormally low reservoir pressure.

4. The ability to develop gas wells at abnormally low reservoir pressure.

5. Simultaneously drain the formation with injected air.

6. Breaking the blockade of the water-saturated part of the reservoir from water.

 r m u l a z b a t e n. A method for developing water-saturated gas wells, comprising supplying a surfactant and air to the well, removing liquid from the wellbore, from the bottom of which. in order to increase the efficiency of developing water-saturated wells with low reservoir pressure by removing capillary blocking of the near-wellbore zone with water, air is injected after the liquid is removed from the wellbore into the near-wellbore zone of the formation until the injected air is connected to the gas-bearing part of the formation and the injection pressure is stabilized, and the pressure air injection selects more reservoir pressure by the amount of loss per ripe overcoming the hydraulic resistance of water in the near-wellbore zone.