RU2342516C1 - Method of execution of repair-insulating operations in well - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention refers to oil producing industry, particularly to methods of supplying backfill material into well for execution of repair-insulating operations; invention is designed for additional pressurisation of flow string. The method consists in assembly of a cement bridge, in theoretical assessment of volume and level of backfill material in the well, in lowering the flow string, in pumping backfill material into the well to a damaged interval. After completion of the cement bridge installation before pumping backfill material fluid is withdrawn from the well, the safe depth of flow string placement is calculated, then flow string is lifted and its low end is set for 30 or more meters above the calculated safe depth of flow string placement.

EFFECT: facilitating normal completion of repair-insulating operations owing to exclusion of dilution of backfill material and avoiding lower part of flow string clamping during supply of backfill material into the well.

2 ex

Description

The proposal relates to the oil industry, in particular to methods for the production of repair and insulation works in the well, and is intended for the sealing of production cores.

A known method of repair and insulation work in the well [Improving the quality of cementing materials for re-cementing and improving its technology, I. A. Serenko, A. G. Avetisov, S. V. Usov, G. A. Eremin, A.T. Koshelev, N.A. Sidorov, Review. inf. Ser. Drilling. - M.: VNIIOENG, 1984. - Issue 17 (79), p. 40]. This method includes the sequential injection of grouting material and squeezing fluid along the casing string.

The disadvantage of this method is the low success of the repair and insulation works, since in the production of repair and insulation works, the cement slurry is mixed with the squeezing liquid.

When describing a method for isolating water inflow zones in a well, a method for performing repair and insulating works is described, including the injection of grouting material into the insulated interval through tubing installed below the insulated interval. The grouting material containing the builder is displaced into the annular space between the casting pipes and the casing. Further, the filling pipes are lifted and injected when they are raised the next portion of the builder [RF patent No. 2239048, ЕВВ 33/13, BI No. 30, 2004]. The known method is not effective enough, since the filling pipes are in the cementing material with a short curing time, therefore, there is a high probability of sticking them in the well and dilution of the cementing material with the borehole fluid is not excluded.

The closest technical solution to the proposed method is a method of repair and insulation works, including the installation of a cement bridge, the descent of the pipe string, the injection of grouting material into the well to the damage interval along the pipe, lowered into the casing. The grouting material is pumped into the well through the casting column based on the conditions for its levels to correspond to the values of hydrostatic pressure in the column and annular space. Further, the filling pipes are raised 30-100 m above the theoretically determined level of cementing material in the well. After that, by creating pressure in the casting column, the material is caught in the damage zone [Improving the quality of grouting materials for re-cementing and improving its technology. / I.A.Serenko, A.G. Avetisov, S.V. Usov, G.A. Eremin, A.T. Koshelev, N.A. Sidorov: Obz. inf. Ser. Drilling. - M.: VNIIOENG, 1984. - Issue 17 (79), p. 40].

The disadvantage of this method is the low success of the repair and insulation works, because in the production of repair and insulation works, the grouting material is mixed both with the squeezing fluid and with the fluid located in the wellbore. Moreover, for the implementation of this method, certain requirements are imposed on the squeezing fluid and grouting material, and a slight difference in the specific gravities leads to the ejection of grouting material from the repaired area. In addition, the lower part of the column of casting pipes is in the grouting material, therefore, there is a high probability of sticking them in the well.

The technical task of the proposal is to increase the success of repair and insulation works by eliminating the dilution of grouting material and eliminating the seizure of the lower part of the filling pipes during the repair and insulation works in the well.

The problem is solved by the method of repair and insulation work in the well, including the installation of a cement bridge, the theoretical determination of the volume and level of grouting material in the well, the descent of the casting pipe string, the injection of grouting material into the well, to the damage interval.

New is that after installing the cement bridge, before injecting the grouting material, the liquid is removed from the well, calculation is made to determine the safe installation depth of the filling pipes N by the formula:

H = N _{TS m} - N _tm ,

where N _ts.m. - depth of installation of the cement bridge, m;

N _tm - the estimated height of the grouting material in the casing, m;

where V _tm - the volume of injected grouting material, m ³ ;

V _{1m rt} - the volume of 1 m of the inner space of the casing, m ³ ,

raise the filling pipes and set their lower end 30 and more meters above the calculated safe installation depth of the filling pipes.

The analysis of patent and scientific and technical literature allowed us to conclude that there are no technical solutions containing essential features of the claimed method that perform a similar task, therefore, we can conclude that the criteria of "novelty" and "inventive step" are met.

The essence of the proposed method is as follows. After determining the leakage interval of the production string, the pressure and throttle response in the failure interval are determined. A cement bridge is installed, then the lower end of the column of casting pipes is lowered to the installation site of the cement bridge and the compressor removes fluid from the well. Depending on the injectivity of the violation interval, the required amount of grouting material is determined.

Further, by calculating, determine the safe zone for installing the column of casting pipes, that is, 30 or more meters above the calculated safe depth:

N = N _c.m. -N _tm ,

where N _ts.m. - depth of installation of the cement bridge, m;

N _tm - the estimated height of the grouting material in the casing, m

где

Where

V _tm - the volume of injected grouting material, m ³ ;

V _{1m rt} - the volume of 1 m of the inner space of the casing pipes, m ³ ;

V _{1m rt} - is determined from the guide for the overhaul of oil and gas wells, depending on the diameter of the casing and wall thickness.

After that, the filling pipes are lifted and the lower end of the filling pipes is installed in a safe zone from the interval of repair and insulation works, that is, 30 or more meters above the calculated safe depth.

As a grouting material, various resins can be used, for example, acetone-formaldehyde, urea-formaldehyde, phenol-formaldehyde, etc., water glass, etc. The injection of grouting material into the zone of repair and insulation works in the well is carried out after removing the fluid from the well.

Dilution of grouting materials with a liquid located in the wellbore significantly affects the quality of the stone formed and, accordingly, the success of repair and insulation works. Removing the fluid from the well eliminates the contact of the grouting material with the fluid, thereby increasing the strength properties of the formed stone, increasing the success of repair and insulation works and the duration of the effect, and since the lower part of the filling pipes is removed from the danger zone, grabbing it is impossible.

Example No. 1 of the practical implementation of the method.

Drowned the well. Interval pressure testing of the production casing revealed the place of violation of the tightness of the production casing. At a depth of 267-268 m, a leak of 146 mm production casing was discovered (wall thickness 7 mm). Pressure drop from 12 to 4 MPa in 30 minutes. A cement bridge was installed at a depth of 271 m, then a shoe for the filling pipes was installed at a depth of 270.8 m, and the compressor removed fluid from the well. The calculation was made to determine the safe installation depth of the casting pipe string:

From the guide to the overhaul of oil and gas wells [A.S. Yashin, S.V. Avilov, O.A. Gamazov. “Handbook for the overhaul of oil and gas wells. M., "Nedra", 1973, p. 164], knowing the diameter of the casing pipes and wall thickness, the diameter of the casing pipe is 146 m, the wall thickness is 7 mm, therefore, the volume of 1 m of the inner space of the casing pipe is 0.0137 m ³ .

V _tm = 0.1 m ³ ; V _{1 m.t.} = 0.0137 m ³ ;

H = H _ts.m. -H _tm ;

N = 271-51 = 220 m - calculated safe installation depth of the filling pipes.

The shoe of the filling pipes was lifted to a safe depth of 190 m (220-30 m). 0.7 m ^{3 of} grouting material based on acetone-formaldehyde resin and an aqueous solution of caustic soda was prepared on the surface in the measuring unit of the cementing unit CA-320M.

The prepared grouting material was pumped into the “dry” well through filling pipes, after which the well was added to the wellhead with squeezing fluid and the grouting material was pumped into the disturbance interval until zero injectivity was obtained. The well was left under pressure for the curing time of the grouting material. After that, by way of filling pipes, a glass of hardened grouting material was determined, and it was drilled. When tested for tightness under a pressure of 12 MPa and reducing the level of swab production casing showed complete tightness. They completed the development and commissioning of the well.

Example No. 2 of the practical implementation of the method.

Drowned the well. Interval pressure testing of the production casing revealed the place of violation of the tightness of the production casing. At a depth of 235-238 m, a leakage of 168 mm production casing was detected (wall thickness 7 mm). Pressure drop from 10 to 1 MPa in 30 minutes. A cement bridge was installed at a depth of 241 m, then a shoe for the filling pipes was installed at a depth of 240.8 m, and the compressor removed fluid from the well. The calculation was made to determine the safe installation depth of the casting pipe string:

From the guide to the overhaul of oil and gas wells [A.S. Yashin, S.V. Avilov, O.A. Gamazov. “Handbook for the overhaul of oil and gas wells. M., "Nedra", 1973, p. 164], knowing the diameter of the casing pipes and wall thickness, the diameter of the casing pipe is 168 m, the wall thickness is 7 mm, therefore, the volume of 1 m of the inner space of the casing pipe is 0.0186 m ³ .

V _tm = 0.7 m ³ ; V _{1 m vol.t} = 0.0186 m ³ ;

H = H _m -H _tm ;

N = 241-54 = 187 m - calculated safe installation depth of the filling pipes.

The shoe of the filling pipes was lifted to a safe depth of 147 m (187-40 m). On the surface in the measuring unit of the cementing unit CA-320 M, 1 m ^{3 of} grouting material was prepared based on acetone-formaldehyde resin and an aqueous solution of caustic soda.

The prepared grouting material was pumped into the “dry” well through filling pipes, after which the well was added to the wellhead with squeezing fluid and the grouting material was pumped into the disturbance interval until zero injectivity was obtained. The well was left under pressure for the curing time of the grouting material. After that, by way of filling pipes, a glass of hardened grouting material was determined, and it was drilled. When tested for tightness under a pressure of 10 MPa and a decrease in the level of swabbing, the production casing showed complete tightness. They completed the development and commissioning of the well.

Thus, in this proposal, a result is achieved - increasing the efficiency of repair work and the duration of the effect by eliminating the dilution of grouting material, reducing the complexity of the technology, the duration of repair work and eliminating the likelihood of sticking the bottom of the filling pipes in the well during the repair and insulation work.

Claims (1)

A method of performing repair and insulation works in a well, including installing a cement bridge, theoretically determining the volume and level of grouting material in a well, lowering a column of filling pipes, injecting grouting material into the well to a damage interval, characterized in that after installing the cement bridge, before injecting grouting material, liquid is removed from the well, calculation is made to determine the safe installation depth of the filling pipes N by the formula H = N _{TS m} - N _tm , where N _ts.m. - depth of installation of the cement bridge, m; N _tm - the estimated height of the grouting material in the casing, m;

where V _tm - the volume of injected grouting material, m ³ ; V _{1m about.T.} - the volume of 1 m of the inner space of the casing, m ³ , raise the filling pipes and set their lower end 30 m or more above the calculated safe installation depth of the filling pipes.