SU941546A1 - Method of liquidation plugging of exhausted wells - Google Patents

Description

one

The invention relates to mining, in particular to the extraction of sulfur by the method of underground smelting, and can be used in the elimination of spent serodetane wells.

There is a method of temporarily plugging of gray wells, which includes filling the well with molten sulfur 1.

The disadvantage of this method is the high consumption of sulfur during the liquidation of wells.

There is a method of liquidating plugging of used wells, including filling them with hardening material based on cement or clay 2.

The disadvantage of this method is the possibility of absorbing cement slurries by highly permeable rocks formed as a result of sulfur smelting, which leads to a large consumption of the solution, does not ensure reliable abandonment of wells under specific conditions of underground smelting of sulfur and increases plugging time.

The purpose of the invention is to reduce the time required for the elimination of spent serum wells.

This goal is achieved by using a hardening material to fill the wells, the density of which is less than the density of formation water, for example, molten bitumen or a mixture of molten bitumen and sulfur at a ratio, weight. %:

Bitum80-85

, 0 Sulfur15-20

The method is carried out as follows.

The developed well consists of three coaxially arranged columns: casing, water and sulfur, each of which is equipped at the mouth with gate valves. The water pressure at the wellhead is 5 MPa; the water temperature in the well bore is 140 ° C.

To eliminate the well is used

bitumen, for example, BN-U, having

20 at normal temperature density

THIS is kg / m and hardening at + 60 ° С.

The bitumen is heated in a digester to 220 ° C, after which it is pumped sequentially into casing, water and sulfur columns using a plunger pump. Volume

the bitumen is calculated so that the level of the section between the bitumen and the water displaced by it is at the level of the sulfuric roof.

A bitumen temperature of 220 ° C is chosen because at a given temperature bitumen has the lowest viscosity. A further increase in temperature is not allowed in order to avoid bitumen ignition. Since the well and the surrounding rocks are heated to a temperature of more than 140 ° C, bitumen can be pumped into the reservoir under pressure, above them, the pressure of the reservoir water at the mouth, for example, 1-2 atm.

After the completion of the bitumen injection, the valves are closed, the bitumen is disconnected. The wellhead is excavated and held for aging. Bitumen in the exposed portion of the wellbore hardens. This makes it possible to cut the top of the well, cover the well with a lid and level the surface.

The sufficient strength of the cork of solidified bitumen in the upper part of the well is justified by the following calculation.

To accelerate the hardening of bitumen and to increase its strength, sulfur is added in the amount of 15-20 / 0 to the last portion of the injected bitumen. At the same time, the solidification temperature of bitumen rises to 95 ° C and it loses its plasticity.

The addition of sulfur in an amount of less than 15% does not lead to a significant increase in the strength of the cement mixture, and with the addition of more than 20% sulfur, the mixture of bitumen and sulfur is stratified (sulfur crystals precipitate, and a layer of pure bitumen remains in the form of a plug).

Due to the fact that the density of the hardening substance (bitumen) is less than the density of formation water, leakage is excluded

into the goaf, as it floats on the surface of the water filling the wells.

The proposed method for the elimination of plugging of spent serodonochnye wells allows eliminating waste wells immediately after the end of their operation, which reduces the loss of hot water due to uncontrolled emissions, as well as accelerates land reclamation and transfer to agriculture.

Claims (3)

1. Method of liquidation plugging of used wells, including their filling with hardening material, characterized in that, in order to reduce the time required for the elimination of spent serum wells, they are filled with hardening material, the density of which is less than the density of formation water. 2. A method according to claim 1, characterized in that molten bitumen is used as a hardening material. 3. A method according to claim 2, characterized in that a mixture of molten bitumen and sulfur is used as a hardening material with a ratio, weight. %: Bitum80-85 Sulfur15-20 Information sources, taken into account in the examination 1. USSR author's certificate on application no. 2904696/22-03, cl. E 21 B 43/00, 25.02.80. 2.Bashkatov D.N. and others. Handbook of drilling wells for water. M., "Nedra, 1979, p. 396 (prototype).