RU2324046C2 - Method of temporary isolation of reservoir - Google Patents

Abstract

FIELD: gas-and-oil producing industry.

SUBSTANCE: packer is constituted by inserting isolating material into bottomhole formation zone with following destruction and development of borehole cavity. Cement grout with sawdust wood filler is used as isolation material. Bridge made from the same isolating material is installed without pressure as a packer, in the gap of reservoir. Bridge is drilled out. Shield of layer of isolating material is left at internal walls of borehole cavity. Inner diameter of shield is more than external diameter of additional casing pipe which is inserted into borehole cavity with following cementation with backfill. Development of borehole cavity is performed after backfill is bound and additional casing pipe and backfill and isolating material in bottomhole formation zone and internal walls of borehole cavity are perforated.

EFFECT: increased efficacy of technique.

3 dwg

Description

The invention relates to the oil and gas industry, in particular to methods for temporary isolation of productive formations during the repair of wells in order to preserve the reservoir properties of the productive formation.

A known method of temporary isolation of the bottomhole formation zone (copyright certificate No. 1423726, IPC 7 ЕВВ 33/13, 1988), including the sequential injection of liquid glass and hydrochloric acid to deposit sediment in the form of silica on the bottom and its subsequent destruction with a 40% alkaline solution .

The disadvantage of this method is the penetration of filtrates of injected solutions into the reservoir, impairing its permeability, as well as the use of concentrated solutions of aggressive substances (40% alkaline solution).

The closest solution taken as a prototype is a method of temporarily isolating highly permeable zones of the bottomhole formation zone (PPP) (copyright certificate No. 1035194, IPC 7 Е21В 33/13, 1983), including the injection of polymers of metal salts of variable valency to create a viscoelastic packer and its destruction by an acid solution.

The disadvantages of this method are:

- the complexity of preparation as a result of a large number of ingredients (11) that are part of the insulating material, as well as the need to strictly maintain the percentage ratios of these ingredients;

- low rate of dynamic shear stress and, therefore, insufficiently accurate degree of conservation of the reservoir properties of the bottomhole formation in well repair;

- high costs of insulating material for the isolation of absorbing productive formations.

The objective of the invention is to create a method of temporary isolation of the reservoir, which allows to increase the degree of conservation of the reservoir properties of the bottom hole during the repair of the well while simplifying the composition of the insulating material and the technology for its preparation, as well as reducing the cost of insulating material when isolating absorbing reservoirs.

The problem is solved by the method of temporary isolation of the reservoir, including the creation of a packer by introducing into the bottomhole formation zone an insulating material with its subsequent destruction and development of the well.

New is that a cement mortar with filler in the form of sawdust is used as an insulating material, while a bridge without pressure is installed as a packer in the interval of a productive formation of the same insulating material, while the bridge is destroyed by drilling after waiting for the insulating material to solidify with leaving the screen in the form of a thin layer of insulating material on the inner walls of the well, and the inner diameter of the screen is larger than the outer diameter of the additional casing they are lowered into the well, followed by cementing it with grouting material using conventional technology, and development of the well is carried out after waiting for the grouting material to solidify and subsequent perforation of the additional casing and insulating material located in the bottomhole formation zone and on the inner walls of the well.

The figure 1 shows the installation process of the bridge opposite the absorbing reservoir with the injection of insulating material in the bottomhole formation zone without pressure.

The figure 2 shows the isolated interval of the bottom hole after drilling the bridge with the screen in the form of a thin layer of insulating material on the inner walls of the well opposite the absorbing reservoir.

The figure 3 shows the well after launching, cementing an additional casing and subsequent perforation, ready for subsequent operation.

The essence of the proposed method is as follows.

To preserve the collector properties of the bottom hole during the repair of the well (for example, by running an additional casing followed by cementing), the tubing string with a funnel 1 is lowered into the stopped well to the roof of the absorbing productive formation 2. Then, insulating material 3 is pumped (see figure 1), consisting of cement mortar with the addition of wood sawdust, which penetrates under its own weight in the PPP 4 at intervals of perforation 5 of the well and isolates it. Further, without stopping the injection opposite the insulated interval, without pressure install a bridge 6 of the same insulating material 3 with a height not less than the height of the absorbing reservoir 2.

After that, the tubing string 2 is removed from the well, which is left to wait for the curing of the insulating material 3. At the end of the time allotted to wait for the curing of the insulating material 3, a drill bit is drilled into the well (not shown in FIGS. 1, 2, 3) and drill up the bridge 6 with the screen 7 left (see FIG. 2), which is a thin layer of insulating material on the inner walls of the well opposite the zone of the absorbing reservoir 2, so that the inner diameter D1 of the screen 7 is larger than the outer the diameter D2 of the additional casing string 8 being lowered into the well (see FIGS. 2 and 3). Next, an additional casing string 8 is lowered into the well (see FIG. 3) and fixed to the wellhead 9, and then cemented by conventional technology using grouting material 10, which freely rises behind the additional casing string 8, since it is in the zone of the absorbing reservoir 2, the relation D1> D2 holds.

After waiting for the hardening of the grouting material 10, perforation 11 of the additional casing string 8, grouting material 10, as well as the insulating material 3 located in the BCP 4 and on the inner walls of the well are perforated.

Then they develop the well and launch it into further operation.

The proposed method of temporary isolation of the reservoir allows to increase the degree of conservation of the reservoir properties of the bottomhole formation zone during well repair by improving the technological parameters of the insulating material while simplifying its composition and preparation technology, and also reduces the cost of insulating material when isolating absorbing reservoirs.

Claims (1)

A method of temporarily isolating a productive formation, including creating a packer by introducing an insulating material into the bottom-hole zone of the formation, followed by its destruction and well development, characterized in that a cement mortar with filler in the form of sawdust is used as an insulating material, and a bridge is installed as a packer without pressure in the interval of the reservoir from the same insulating material, the destruction of the bridge is carried out by drilling after waiting for the hardening of the insulating material and leaving the screen in the form of a layer of insulating material on the inner walls of the well, the inner diameter of the screen being larger than the outer diameter of the additional casing string being lowered into the well with its subsequent cementing with grouting material, and development of the well is carried out after waiting for the cementing material to solidify and subsequent perforation of the additional casing string , grouting material and insulating material located in the bottomhole formation zone and on the inner walls of the well.

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