RU2053357C1 - Method for repair and isolation work in wells - Google Patents

Abstract

FIELD: well repairs. SUBSTANCE: made in flow string are filling holes. Main and additional packer members are installed in filling string before its lowering. Number of additional packer members should correspond to the number of producing formations. They are installed between producing formations. Then, filling string is run into well and filling string-to-casing annulus is separated. Separation is effected in zone of producing formations and in zone of special holes. Isolation material is injected under pressure. Injection is accomplished concurrently with separation of filling string-to-casing annulus. Duration of separation, at least, equals the duration of injection of isolation material. EFFECT: higher efficiency of repair and isolation work in zone of producing formations distributed over the well bore. 2 dwg

Description

 The invention relates to the oil and gas industry, and in particular to methods for eliminating annular fluid flows, fluids into productive production formations in oil and gas wells, mainly with multilayer deposits.

There is a method of eliminating annular crossflows, which consists in the fact that in the production casing in the flow interval special openings are made for pumping insulating material into the near-barrel zone, a cement bridge is installed below these openings (plug-plug, explosive packer), lowered into the well at the pump-compressor pipes (tubing) packer, seal annular space directly above the holes and pump insulation material through them under pressure into the near-barrel zone [1]
The disadvantage of this method is that if there are two or more perforation zones in the production casing opposite the productive formations in the multilayer reservoir located above the special holes, the insulating material pumped into the near-barrel zone enters the annular space and into the overlying productive formations through the perforation zones located over the packer. In some cases, this circumstance leads to such complications as tubing sticking with a packer, and generally reduces the reliability of insulation work under pressure due to the overflow of injected insulation material through the annular space into the productive formations located above. In addition, the known method does not allow performing insulation work on elimination of annular flows into two or more productive formations that have a message in the near-barrel zone with sources of annular flows (aquifers or gas-bearing formations) at the same time through one interval of special openings. To implement the known method, additional costs are required for the installation and subsequent drilling of a cement bridge (packer plug, explosive packer).

The closest in technical essence is the method of selective injection of insulating material into the near-wellbore zone of the well through special openings in the production casing, including lowering the packer pipes with sealing units and a bypass valve between them into the interval of special (filling) openings into the well on the casing string, and supplying insulating material to pipe string, sealing of annulus, injection of insulating material through the bypass valve of the packer into the near-well zone of the well [2]
This method has the main disadvantages, as the method described above, except for the need for installation and subsequent drilling of a cement bridge (packer plug, explosive packer). In addition, in the known method, the insulating material injected into the near-barrel zone will enter, along with the overlying ones, in the underlying productive formations through perforation zones located under the packer.

 The purpose of the invention is to increase the efficiency of repair and insulation works in the zone of productive formations dispersed along the wellbore.

 In FIG. 1 shows a well with several reservoirs in the presence of casing flows from an aquifer. The well is cased with a production string perforated in the zone of productive formations and with special holes for injecting insulation material through them into the near-well zone of the well. A casting string is lowered into the production casing, equipped with a packer containing packer elements and a bypass valve between them, as well as additional packer elements placed between productive formations.

 Figure 2 shows a well with a divided annulus between the reservoirs and in the area of special openings during the injection of insulating material into the near-wellbore zone of the well.

 The proposed method is implemented as follows in a well with a zone of productive formations dispersed along the wellbore.

 In the production casing, fill holes are made for injecting insulating material into the annulus of the well. A casting column with a packer element is lowered into the production casing, onto which additional packing elements are installed in an amount equal to the number of productive formations and these additional elements are placed between the productive formations. Separation of the annular space is carried out by means of packing elements in the zone of the filling holes and in the zone of the productive formations and at the same time injection of the insulating material is carried out under pressure, while the separation of the annular space is maintained at least equal to the duration of the injection of the insulating material.

Distinctive (from the prototype) are the following additional features:
additional packing elements are installed on the casting column in an amount equal to the number of productive formations and with the condition of their placement between the productive formations;
separation of annular space is carried out in the zone of productive formations and in the zone of filling holes;
injection of the insulating material under pressure is carried out simultaneously with the separation of the annular space;
the separation time of the annular space is taken to be at least equal to the duration of the injection of insulating material.

 An example of the practical use of the proposed method for repair and insulation works on the elimination of annular flows from an aquifer 1, located in the interval 2900-2920 m, in a well with four productive formations 2,3,4 and 5, located respectively in the intervals of 2860-2865 m, 2880-2885 m, 2935-2940 m and 2955-2960 m. The well was cased by production string 6 with a diameter of 168 mm, in which there are four perforated sections 7.8.9 and 10, made respectively in the intervals of productive formations 2,3,4 and 5.

 In the production casing, special holes 11 are made in the range of 2892-2893 m for injection of insulating material into the near-stem zone, after which a hydraulic packer of the PRS type, consisting of packing elements 13.14 and a bypass valve 15, is lowered into the well on the casing 12 in the interval 2890 -2895 m and four additional packing elements 16,17,18,19 at intervals of 2850-2851 m, 2872-2873 m, 2947-2948 m and 2968-2969 m. Insulating material is fed into the casting column 12, the annular space is sealed with packing elements 13 and 14 packers and 16,17,18 and 19, ozdavaya in the drilling string 12 internal pressure of 5.0-6.0 MPa is injected through the valve 15 in the insulating material near-wellbore region of the well under pressure sufficient to pick-up of the material in the well. It is held for 20-25 minutes and the overpressure in the casting column 12 is smoothly relieved, after this, the well is flushed through the check valve through the check valve 20 in the lower part of the casting string 12 and the well is left alone for the period of insulation material solidification.

 As special cases discussed above, the general case of repair and insulation of the well, there may be cases of repair work in wells with one productive formation 3 and casing flows into this formation from the aquifer 1. In this case, except for the packer, they are lowered into the well on the casting string 12 only one packer element 17.

Claims (1)

 METHOD FOR REPAIR AND INSULATION WORKS IN WELLS, including filling holes in the production casing, lowering the filling casing with a packing element, uncoupling the annular space and injecting insulating material under pressure, characterized in that, in order to increase the efficiency of repair and insulation works in the zone of productive formations dispersed along the wellbore, additional packing elements are installed on the filling column in an amount equal to the number of productive formations, and with viem their placement between the productive formation and dissociation of annular space is carried out in the zone of the productive strata in the area of the fill ports, the injection pressure of the insulating material is carried out simultaneously with the disconnection of annular space, the length of which receiving at least equal to the duration of the injection of the insulating material.

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