SU1301961A1 - Method of isolating formations in well and viscoelastic composition - Google Patents

Abstract

The invention relates to the field of well casing and is intended for the process of casing cementing and for the installation of cement bridges. The purpose of the invention is to obtain a sealed support that prevents fluid flow in the cemented annulus. The method includes sequential injection of hardening cement material with non-hardening. Non-hardening material is disposed against impermeable formations. A thermodynamically stable and elastic elastic composition is used as a non-hardening material. It is aerated with a degree of aeration of 20-60. The elastic composition was made on the basis of aqueous solutions of trivalent chromium salt (CTX) and polyacrylamide mixed in ratios 1: 5-30. The ratio of ingredients to the composition of the sulphate, wt%: polyacrylamide 0.8-10.0; STH Oh, 03-1, o; water - the rest. The use of STX as a gelling agent ensures the thermodynamic stability of the composition. When installing a cement bridge, part of the composition is located inside the bridge, and some - under it. This prevents the gravitational movement of the cement slurry from a given interval. In the case of the formation of fluid-conducting channels and a pressure differential, the composition is deformed and self-compacted, preventing fluid flow. 2 sec. and 2 z. p. ft-ly, 3 silt, 3 tab. (O SL g CO with O5

Description

The invention relates to the fastening of wells, namely to the process of casing cementing and the installation of cement bridges.

The purpose of the invention is to obtain a sealed lining, preventing flush plugs in the cemented electric tubular space, and ensuring the thermodynamic stability of the visco-elastic composition.

FIG. 1 shows an example of using a non-hardening composition to seal certain areas when a cement bridge is installed; FIG. 2 - the same, when cementing the annulus (a - non-hardening composition, b - impermeable formations; c - fluid-containing formations; d - cement stone d - washing liquid); in fig. 3 is a diagram of a working chamber of an experimental installation on which the proposed method of segregation of layers is tested.

The chamber contains a cylindrical body 1, a lid 2, an inlet 3 and an outlet 4 nozzles, 5 and 6 - taps, a sleeve 7, imitating a casing, portions of cement slurry 8 and 9, a film of mud 10, VUS 11, bottom 12.

Example. In the process of pumping cement mortar into the well (both when cementing casing strings and when installing cement bridges between individual portions of cement, a portion is pumped into the viscoelastic fluid (Table 1 p.2), and this composition is inside the cement mortar column and location is chosen so that it turns out to be 40 tav based on aqueous solutions of salt

trivalent chromium and polyacrylamide, mixed in a ratio of 1: 5-30.

In tab. Figure 1 shows thermodynamically stable viscoelastic compositions and their properties.

So, to obtain the composition 1, 1000 ml of Dzerzhinsky PAA was mixed with a conditional viscosity of 220 seconds according to SPV-5 and

against an impermeable reservoir separating the multi-pressure reservoir on a site with a centered column. When installing a cement bridge, part of the composition is located inside the bridge, and part - 45 under it (Fig. 1). The latter also prevents the gravitational movement of cement mortar from a given interval. After hardening

the cement slurry, in the case of the formation of the 50 Mixture was mixed for 5, the composition of the fluid-conducting channels and the pressure drop, the composition is deformed and self-compacted, preventing fluid flow. In the case of the formation of channels, for example, between the backfill chamber Kam-55 and was left for storage in the herm and the walls of the casing or the wall of a desiccator closed. Through the casing and the walls of the well, the pressure of fluids in which there can be no more plasticity, occurs

20 ml of 10% solution. Cr (SO)

a stirrer with an impeller, as a result of which its volume increased by 50 ml due to 1 aeration. After 5 minutes, the solution acquired in the elastic properties, 8, 12 and 16 months. Determining whether the water department. In order to obtain composition 6, this composition was carbonated C1nne, with a differential pressure that was drained from the composition into the channel. Under the action of this pressure differential, the composition expands into the channel and, due to its viscoelastic forces, clogs it, preventing fluid flow.

The laboratory tests of the method are carried out on the instrument, the circuit of the working chamber of which is depicted in FIG. Then in the chamber between two portions of the Portland cement solution is placed in the elastic elastic

composition. In some cases it is pre-gassed, in others it is not. The masses in the resilient compositions, as well as portions of the cement slurry, are the same in all cases. Hardening

cement mortar occurs within 24 hours at a pressure of 4 kg / cm without water. The pressure is then released and the tightness of the system is determined. For this, water is forced through it. In the case where the non-hardening composition is not aerated, the system is leaking due to cracks in the clay film and the inability of the composition to plug

their. Water penetrates cracks along the entire length of the chamber at a pressure of O - O, 1 kg / cm. When the non-hardening composition is aerated, water penetrates through the system at pressures exceeding

4 kg / cm, despite similar

cracking in a clay film. As a non-hardening grouting material, thermodynamically resistant in the elastic elastic covalent chromium and polyacrylamide, mixed in ratios of 1: 5-30, are used.

In tab. 1 shows thermodynamically stable viscoelastic compositions and their properties.

So, to obtain the composition 1, 1000 ml of Dzerzhinsky PAA was mixed with a conditional viscosity of 220 seconds according to SPV-5 and

The mixture was mixed on an anic and mixed and was stored in a methically closed desiccator. Cheree

20 ml of 10% solution. Cr (SO)

The mixture was mixed on an anic and mixed and was stored in a hermetically sealed desiccator. Through

a stirrer with an impeller, as a result of which its volume increased by 50 ml due to 1 aeration. After 5 min, the solution acquired the elastic elastic properties; the mixture was mixed on a me5; it was animated and left for storage in a hermetically closed desiccator. Through

4, 8, 12 and 16 months. Determining whether the water department. In order to obtain composition 6, this composition was carbonated with C1nne, increasing the intensity of mixing. To obtain the composition 7, 1000m of 0.82% Japanese polyacrylamide SPD-20 are taken and mixed with 15 ml of a 20% aqueous solution of chromium sulfate,

The results are shown in Table. 1 and indicate that the proposed WCS formulation has very little water separation for a long time and the absence of syneresis and, therefore, is thermodynamically stable. The temperature range of application of the composition is 0-100 ° C. The lower limit is caused by the freezing temperature of the composition, the upper one - by the temperature at which the elastic properties of the composition decrease by approximately two times compared with their values at 20 ° C. The elastic properties can be judged by the magnitude of the normal stresses presented in the table (the composition numbers and the contents of the ingredients correspond to table 1).

Experiments were carried out to study the tightness of the system, including compressing the aerated MAS placed in a closed cavity. Last connected to channels.

The results of studies of the insulating ability of various thermodynamically stable viscoelastic compositions (according to Table 1) are listed in Table. 3

According to the examples given (Table 3), the positive effect increases with increasing gas content in the composition from 5 to 30 vol.%. Considering that the proposed method is most appropriately used in wells up to 2000 m in depth, in order to ensure the specified gas containment on the surface of the well, the composition must be aerated with a carbonation degree from 10 to 60.

From the data table. 1-3, it is clear that the known composition in the proposed method cannot be used, since it is thermodynamically unstable and, several hours after cementing, self-destructs (Table 1) and. cannot interfere with fluid flow (Table 31, and its structural and mechanical characteristics are insufficient even to prevent from 5 to 30 parts by weight of polyacrylamide).

ascending .. b-, ci-jo, not to mention the containment of pressure drops, since the minimum tensile strength of the HVUS, at which the bubbling of gas with a diameter up to 10 mm does not occur, is about 0.8 kPa.

An example of the preparation of the MAS. PAA in the amount of 300 kg is dissolved in 1 m of technical water to obtain a solution with a conditional viscosity according to SPV-5 for 180–200 s. Chromium nitrate is introduced into the solution in the form of a 20% solution in a volume of 5 liters and mixed. The composition is injected into the well after the first portion of cement slurry with simultaneous aeration.

Claims (4)

1. A method of separating formations in a well, including sequential injection of hardening plugging material with a non-hardening material, characterized in that, in order to obtain a sealed support, preventing fluid flow in the cemented annulus, non-hardening plugging material is positioned against impermeable formations, and as a non-hardening reservoir, the non-hardening plugging material is positioned against impermeable formations, and as a non-hardening reservoir, the non-hardening plugging material is positioned against impermeable formations, and as a non-hardening reservoir, the non-hardening plugging material is positioned against impermeable formations, as a non-hardening formation, in the quality of non-hardening reservoir, and as a non-hardening cementing material. Thermodynamically stable composition is used. 2. A method according to claim 1, wherein the thermodynamically stable visco-elastic composition is aerated with a degree of aeration of 20-60. 3. In zoelastic composition, including polyacrylamide, gelling agent and water, characterized in that, in order to ensure its thermodynamic stability, the salt of trivalent chromium is used as a gelling agent in the following ratio of ingredients, wt.%: Polyacrylamide 0,8-10,0 Salt of trivalent chromium Water 4. The composition of clause 3, 0.03-1.0 The rest is different in that it is 1 ma.ch. salts of trivalent chromium it contains 20 100 3.2 2.11.8 1.6 2.43.2 1.2 3.2 3.5 t, 6 1.1 0.9 0.8 -0.61.6 0.6 1.3 1.7 Table 1 Table 3 known composition containing, wt.% g PAA 2,6J (NH) iCrj ,, 4; Na, 4; barite 5.2; 0.1; and water 91.3. known composition containing, in wt.%: PAA 5,0 .; 0, -8; Na ,, S 1,2; barite 12.9; HCI 0, i; water 80. FIG. one FIG. 2 fig.Z