RU2105132C1 - Method for production of expanding plugging material - Google Patents

Abstract

FIELD: oil and gas production industry. SUBSTANCE: this relates to strengthening of oil and gas wells by means of expanding plugging material. According to method, required material is produced by mixing portland cement and clay. Mixture of these two components is additionally subjected to disintegration treatment with collision velocity of particles equal to 150-250 m/s. Used in this process in function of clay is such variety of clay as mountain leather or hydromicaceous slate. EFFECT: higher efficiency. 1 tbl

Description

 The invention relates to the field of fastening of oil and gas wells, and in particular to the production of expanding grouting materials.

 Known methods for producing expanding grouting materials by introducing into Portland cement expanding components (additives), for example magnesium oxide or calcium oxide [1].

 The disadvantage of these methods is the high density of the resulting cement mixture.

 The closest is the method of producing grouting materials by dry mixing cement and clay in predetermined proportions [2]. The best results are obtained using bentonite clay.

 The disadvantage of this method is the low strength of the obtained stone and the absence of the expansion effect during hardening.

 The aim of the invention is to obtain an expanding grouting material.

 This goal is achieved by the fact that in the known method for producing grouting material, including mixing Portland cement and clay, the resulting mixture is additionally subjected to disintegration processing at a collision speed of 150 - 250 m / s, and palygorskite or hydromica clay is used.

 The scientific and technical literature [1, 2] describes various methods for producing expanding grouting material, in particular, a method for dry mixing cement and clay in predetermined proportions is known. However, simply adding clay to the cement reduces the amount of hydrosilicate binder (hardening products) per unit volume. In addition, the addition of clay increases the water content of the cement slurry due to the increased water demand of the clay. All this leads to a decrease in the strength of the obtained stone, and since clay has a high hydration activity, the process of its swelling takes place during the preparation and injection of cement mortar. As a result of this, when the cement slurry hardens in the annulus, it shrinks or, at best, there is no expansion.

 When using grouting material prepared by the proposed method, the following effects are observed.

In the process of collision of clay particles with the fingers of the disintegrator and between themselves, a large amount of heat is generated, and local temperature flashes at the moment of collision can reach 600-800 ^o C.

 Such a temperature leads to partial dehydration of the clay and its superficial “burning out”. This, in turn, leads to a slowed down process of hydration and swelling of clay.

 According to the existing cementing technology, grouting material after preparation on the surface is transported to the annulus of the well, where it hardens. In this case, the clay begins to swell due to interaction with the mixing fluid and create proppant pressure inside the hardening cement slurry at its early stages of hardening, while the strength of the cement stone is low. This leads to the expansion of grouting material and increase the tightness of its contact with the rock and casing.

 In this case, the pressure created by the hardening cement stone is significantly higher than the pressure created by traditional expanding cements.

 An increase in the specific surface of cement and its activation during disintegration processing increases the strength of the entrusted stone and thereby compensates for its decrease due to the introduction of clay.

 Comparative analysis with the prototype showed that the inventive method for producing expandable grouting material differs from the known one in that the resulting mixture is subjected to disintegrant processing, so the claimed technical solution meets the criterion of "novelty."

 In the patent and scientific literature there is no information about the use of clay as an expanding additive to cementing materials. The new purpose of clay and the new properties of the resulting cement material indicate the conformity of the claimed technical solution to the criterion of "inventive step".

To implement the method, it is necessary to use clays with a rigid structural lattice such as palygorskite or hydromica. According to the data given in [3], in these clays in the temperature range of 600 - 800 ^o C, the effect of removal of adsorption-bound water is observed. The use of bentonite (montmorillonite) clays does not give the necessary effect, because adsorption bound water is removed from them at higher temperatures.

 When performing this method, the cement and clay are mixed, after which the mixture is loaded into the disintegrator, where it is processed under various conditions - particle collision speeds.

 An increase in the impact velocity above 250 m / s leads to the fact that a large fraction of the clay is subjected to heat treatment and “burn out”, therefore, its hydration and swelling are sharply slowed down and will occur after the stone has hardened. This leads to cracking and a decrease in strength. If the particle collision velocity is less than 150 m / s, there is not enough energy to remove adsorption-bound water from the clay, so the expansion effect in the cement mixture will decrease. The results of experiments on the study of grouting materials obtained by the proposed method are shown in the table.

 An example of a specific implementation of the proposed method will show on experience N 3.

 700 g of cement PTsT-DO-20 of the Novo-Troitsk cement plant and 300 g of clay of the Chimsaysky quarry in the Aktobe region were taken. Republic of Kazakhstan.

 These components were manually mixed for 5 minutes. Then they were passed through a laboratory D-32 disintegrator at a collision speed of 200 m / s, which corresponded to a disintegrator rotor speed of 12,000 rpm. After processing, the grouting material was closed with 700 ml of drinking water. The spreadability of the resulting solution was determined using an AzNII cone, density was determined using a hydrometer, and setting time was determined using a Vic needle. From the prepared solution, samples were prepared — beams of 4x4x16 cm in size, with the help of which bending and compression strengths were determined. These tests are standard and were performed according to GOST (4). The expansion of the cement slurry was determined on a special installation, the scheme and principle of operation of which are described in (5).

 The grouting material obtained by this method is delivered to the wells in any package according to the requirement of the customer. The technology of cementing wells in this case is no different from the traditionally adopted in the drilling company. This indicates the compliance of the proposed solution with the criterion of "industrial applicability".

 Analysis of the table shows that compositions with the addition of 10-30% hydromica or palygorskite clay treated under conditions providing a collision speed of 150-250 m / s are most suitable for fixing wells (experiments N 2, 3, 4, 5, 6, 9, 10, 11).

 Sources of information.

 1. Danyushevsky V.S., Aliev V.M., Tolstykh I.F. Reference guide for cementing materials. M., Nedra, 1987, p. 156.

 2. Danyushevsky V. S., Aliev V. M., Tolstykh I. F. Reference book on cementing materials. M., Nedra, 1987, p.113.

 3. Agabalianets EG Flushing fluids for difficult drilling conditions. M., Nedra, 1982.

 4. Danyushevsky V.S., Aliev V.M., Tolstykh I.F. Reference guide for cementing materials. M., Nedra, 1987, p. 240 - 272.

 5. Danyushevsky V.S., Aliev V.M., Tolstykh I.F. Reference guide for cementing materials. M., Nedra, p. 340 - 341.

Claims (1)

 A method of obtaining an expanding grouting material by displacing Portland cement and clay, characterized in that the resulting mixture is further subjected to disintegration processing at a collision speed of 150 to 250 m / s, and the clay is palygorskite or hydromica.

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