RU2519144C1 - Preparation method of compound for acid-soluble plugging stone production - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method can be applied in preparation of compounds mainly used for fixation of waterproof compounds in a horizontal well bore, for temporary formation blocking and setting of a supporting plug for offshoot kick-off. The method of compound preparation for production of acid-soluble plugging stone involves mixing microcalcite with 160-315 mcm particle size with plain oil-well portland cement, adding air-entraining agent "Aeroplast" to fresh water and mixing of plain oil-well portland cement with microcalcite using fresh water, with adding air-entraining agent "Aeroplast", with the following mixture ratio: plain oil-well portland cement - 59.9-64.95 weight fraction; microcalcite - 35-40 weight fraction; air-entraining agent "Aeroplast" - 0.05-0,1 weight fraction; fresh water - 50 weight fraction.

EFFECT: increased strength of acid-soluble plugging stone.

1 ex, 2 tbl

Description

The proposal relates to the oil industry, in particular to methods for preparing compositions for obtaining acid-soluble cement stone. These methods can be used to prepare compositions used primarily for fixing water-proofing compositions in a horizontal wellbore, temporarily blocking formations, and installing a support bridge in order to kill the lateral wellbore.

A known method of operating a well, comprising preparing a composition to obtain acid-soluble cement stone (patent RU No. 2320854, IPC E21B 43/00, publ. March 27, 2008). The preparation of the composition for obtaining acid-soluble cement stone includes mixing cement and chalk with a volume ratio of 1: (0.1-0.4), respectively, and subsequent mixing of the resulting dry mixture with water.

The disadvantage of this method is that the cement stone obtained from the used cement-chalk solution, during acid treatment is destroyed for a long time.

The closest in technical essence and the achieved result is a method of producing a cement grout foam composition for a grouting packer or bridge (patent RU No. 2089717, IPC E21 VZZ / 138, publ. 09/10/1997). The method includes preparing an acid-soluble grouting foam-cement composition by mixing 37-60 wt.h. cement and 7-30 parts by weight chalk (calcium carbonate), the subsequent dissolution of 0.5 wt.h. surfactant syntanol in 38 wt.h. water and the subsequent mixing of a mixture of cement and chalk with a solution of Sintanol in water.

The disadvantage of this method is the low strength obtained by curing the composition of the cement stone, which does not allow it to be used when implementing activities that require the installation of a bridge in the well with high strength characteristics, for example, for installing a support bridge for the purpose of cutting the lateral wellbore.

The technical task of the proposal is to increase the strength of acid-soluble cement stone, achieved by increasing the resistance to mechanical stress of acid-soluble cement stone.

The technical problem is solved by the proposed method of preparing a composition for producing an acid-soluble cement stone, including mixing cement with calcium carbonate, mixing water with a blowing agent and then mixing the mixture of cement with calcium carbonate and water with a blowing agent.

New is that, as calcium carbonate, microcalcite with a particle size of 160-315 μm is used, which is mixed with an additive-free grouting Portland cement, an Aeroplast air-entraining additive is added as a foaming agent, which is added to fresh water and mixed, then a mixture of an additive-free grouting portland cement with microcalcite shut with fresh water with the addition of the air-attracting additive "Aeroplast", in the following ratio of components, parts by weight:

cementless Portland cement 59.9-64.95 microcalcite 35-40 Aeroplast air-entraining additive 0.05-0.1 fresh water fifty.

To prepare the specified composition using the following components:

- Portland cement without additive grouting that meets the requirements of GOST 1581-96 is used as cement;

- microcalcite is a product of grinding and fine grinding of natural marble, meets the requirements of TU 5743-002-63925093-2009;

- “Aeroplast” is an air-entraining additive based on modified naphthalenesulfonates, meets the requirements of TU 5745-030-58042865-2008;

- the water is fresh.

In the proposed method of preparing a composition for producing an acid-soluble cement stone, a baseless cement cement is used as the basis for providing the cement stone. To ensure the acid solubility of the cement stone, microcalcite, which is a product of grinding and fine grinding of natural marble, is introduced into the prepared composition. The use of microcalcite instead of chalk, which is used as a component that provides acid solubility in the closest in technical essence and the achieved result grouting foam cement composition, allows to increase the strength of cement stone. The increase in strength when using microcalcite is provided due to the best strength characteristics of microcalcite (marble) in comparison with chalk. For marble, the compressive strength is 4-8 times and the hardness on the Mohs scale is 3-4 times greater than that of chalk. This is due to the difference in the nature of the bond between individual crystals in the structure of calcium carbonate (Kireyev V.A. Course in Physical Chemistry / V.A. Kireyev. - 3rd ed., Revised and enlarged. - M.: Chemistry, 1975. - p. .136). Introduction to the composition of the additive “Aeroplast” due to the involvement of air provides foamed cement stone, which dissolves with acid faster than non-foamed.

To establish the optimal ratio of components in the proposed method for preparing the composition and assessing the possibility of using the composition, laboratory studies were carried out. In laboratory studies, the density, spreadability and setting time of the composition were determined, as well as the compressive and bending strength of the acid-soluble cement stone, the dissolution time of the acid-soluble cement stone in a 15% aqueous hydrochloric acid solution.

The method of preparation of the composition to obtain acid-soluble cement stone in laboratory conditions is as follows. Additive grouting Portland cement and microcalcite with a particle size of 160-315 μm are mixed together. Aeroplast air-entraining additive is added to fresh water (hereinafter - to water) and mixed. A mixture of cementless Portland cement with microcalcite is placed in a glass and closed with fresh water with the addition of the Aeroplast air-entraining additive. The resulting mixture was stirred with a paddle mixer.

In the preparation of the resulting mixture, microcalcite is well dispersed in fresh water. When the composition is mixed with a paddle mixer, a stable finely dispersed system is formed, containing particles of additive cement plug Portland cement, microcalcite and entrained air. Subsequently, the composition is cured and acid-soluble cement stone is formed.

The density of the composition is determined using a pycnometer according to GOST 26798.1-96. The spreadability of the composition is determined using a cone form and a measuring table according to GOST 26798.1-96. The setting time is determined using the device "Vika" according to GOST 310.3-76. The compressive and bending strength of acid-soluble cement stone is determined according to GOST 26798.1-96 using a press that meets the requirements of GOST 310.4-81. During the dissolution, the time interval was taken from the moment the sample of acid-soluble cement stone was placed in a 15% aqueous hydrochloric acid solution until the moment when the sample loses its solidity, it passes from a solid state to a suspension of solid particles in a liquid.

When conducting laboratory tests, it was found that the use of 50 parts by weight is optimal. fresh water. When using more than 50 parts by weight fresh water increases the yield of the composition to obtain acid-soluble cement stone. At the same time, when using less than 50 parts by weight fresh water decreases the strength of the resulting acid-soluble cement stone, most likely due to the lack of water for cement hydration. In the future, 50 wt.h. fresh water. The research results are shown in table 1.

In the process of research, the following was established.

With a content of more than 40 parts by weight microcalcite, when using microcalcite with a particle size of more than 315 microns, and also when the content in the composition is more than 0.1 wt.h. air-entraining additives "Aeroplast" the strength of acid-soluble cement stone is significantly reduced. In this case, a decrease in the strength of acid-soluble cement stone is most likely caused by a decrease in the content of mineral binder — an unadulterated cement in Portland cement, an increase in the size of “centers of decrease in strength” such as microcalcite particles, and an increase in the number of voids filled with air.

When the content is less than 35 parts by weight microcalcite, the use of microcalcite with a particle size of less than 160 microns, and also when the content in the composition is less than 0.05 wt.h. Aeroplast air-entraining additives significantly increase the dissolution time of acid-soluble cement stone. In this case, an increase in the dissolution time of an acid-soluble cement stone is most likely caused by, respectively, a decrease in the content of the acid-soluble material, a more dense laying of microcalcite with a smaller particle size, which causes a decrease in the permeability of the acid-soluble cement stone, and also less air entrainment, which reduces the degree of foaming and permeability of cement stone for a 15% aqueous hydrochloric acid solution. Therefore, in order to prepare a composition for obtaining acid-soluble cement stone, the following ratio of components, parts by weight, was selected:

cementless Portland cement 59.9-64.95 microcalcite 35-40 Aeroplast air-entraining additive 0.05-0.1 fresh water fifty

Table 2 shows the results of comparing the strength characteristics of acid-soluble cement stone obtained by the proposed method and its closest analogue. From these results it follows that the strength characteristics of the cement stone obtained by the proposed method significantly exceed the strength characteristics of the cement stone obtained by the closest analogue of this method.

This confirms a significant increase in the strength obtained by the proposed method of acid-soluble cement stone, achieved by increasing the resistance to mechanical stress of obviously weak sections in the structure of acid-soluble cement stone by summing up the effects obtained by mixing the components of the composition in a certain sequence, using microcalcite as calcium carbonate with optimal particle size and optimal ratio of components in the composition e.

Increasing the strength of acid-soluble cement stone will reduce the volume of the composition used when fixing the waterproofing compositions in the horizontal wellbore, temporarily blocking the formations, and installing a support bridge in order to kill the lateral wellbore. Due to this, time savings of 15 - 20% of the time spent and a reduction in the preparation and use of the composition are achieved.

An example of practical application.

In a conventionally vertical well, decommissioned due to high water cut, a new sidetrack with a horizontal end was cut. A liner was lowered and cemented into a lateral trunk with a horizontal end, drilled to a depth of 1399 m, to a depth of 1358 m. The Bobrikovsky horizon, composed of terrigenous rocks, began to be exploited by the well through an open trunk in the interval 1358–1399 m. After two years of operation, the well’s production was flooded to 99%. In order to reduce the water cut of the products in the well, water insulation works were carried out. The work was carried out as follows. A string of tubing (tubing) was lowered into the well to a depth of 1358 m. The space between the tubing string and the liner was filled with a high-viscosity oil-emulsion emulsion of known composition (patent RU No. 2283422, IPC E21 VZZ / 138, published on September 10, 2006, Bulletin No. 25) prepared by mixing commercial oil, Silor silicone fluid and water in a volume ratio of 76: 4: 20, respectively. 35 parts by weight were loaded into the Sespel 964809 cement truck, which meets the requirements of TU 4526-001-38990270-2002. microcalcite with a particle size of 315 microns and 64.95 wt.h. cementless Portland cement. Then, microcalcite and additive-free grouting Portland cement were retreated into the second Sespel 964809 cement truck. To mix microcalcite and additive-free grouting Portland cement, repetition was repeated three times. Then a mixture of microcalcite and cementless Portland cement grinded in the mixing and averaging unit USO-16, which meets the requirements of TU 26.16.258-88. In the meter of the cementing unit CA-320, corresponding to the requirements of TU 4523 010-05753336-2000, 0.1 wt.h. Aeroplast air-entraining additives and 50 parts by weight fresh water. Next, the mixture of cementless Portland cement with microcalcite in the USO-16 installation was closed with fresh water with the addition of the Aeroplast air-entraining additive supplied from the cement aggregate CA-320. Thus, a composition was prepared to obtain acid-soluble cement stone. Then 20 m ³ oil-emulsion emulsion was sequentially pumped into the well through the tubing string into the open hole interval, the prepared composition for obtaining acid-soluble cement stone and oil-emulsion emulsion again in a volume equal to the volume of the tubing string. Next, the tubing string was lifted from the well and oil-emulsion emulsion was added to the well. The well was left for 24 hours during the curing of the composition to obtain acid-soluble cement stone. Then, in order to dissolve the bridge from the cement stone that remained in the horizontal section of the borehole, a bath of 15% aqueous hydrochloric acid was installed; after four hours, the well was washed to the bottom. Then the pump was lowered into it and put into operation.

Similarly to the given example, work was carried out with the preparation of other compositions to obtain acid-soluble cement stone, the content of the components in which and the test results are shown in table 1.

Table 1 The results of the study of the properties of the composition prepared by the proposed method No. The content of the components in the composition, The size Composition Properties Strength Time p.p. parts by weight particles Density, Rasteka The timing through 48 dissolution Cement Aeroplast Fresh water Microcalcite micro calcite, microns kg / m ³ capacity mm setting, h-min h., MPa 15% HC1, min The beginning
lo the end Bend Compression one 49.97 0,03 fifty fifty 80 1590 225 9-30 12-10 0.6 1,5 98 2 54.96 0.04 fifty 45 one hundred 1580 227 9-35 11-20 0.7 1.9 79 3 59.95 0.05 fifty 40 160 1560 235 8-05 10-50 1,5 4.4 60 four 59.9 od fifty 40 315 1500 243 7-50 10-20 1,6 4,5 29th 5 62,43 0,075 fifty 37.5 235 1530 238 7-45 10-15 1,6 4.6 77 6 64.9 0.1 fifty 35 315 1490 241 7-40 10-10 1.8 4.7 86 7 64.95 0.05 fifty 35 160 1550 234 7-20 9-50 1.9 4.9 124 8 69.89 0.11 fifty thirty 500 1480 242 6-05 8-20 1.3 2,8 25 9 74.87 0.13 fifty 25 500 1460 247 6-20 7-45 1,1 2,4 32

table 2 Comparison of the strength of cement stone obtained after the curing of the compositions prepared by the proposed method and the closest analogue No. The content of the components in the composition prepared by the proposed method, parts by weight The strength of cement stone after 48 hours, MPa Cement Aeroplast Microcalcite / particle size of microcalcite, microns Water Bend Compression one 59.95 0.05 40/160 fifty 1,5 4.4 2 59.9 0.1 40/315 fifty 1,6 4,5 3 64.9 0.1 35/315 fifty 1.8 4.7 four 64.95 0.05 35/160 fifty 1.9 4.9 - The content of components in the composition prepared according to the closest analogue of the proposed method, parts by weight - - Cement a piece of chalk Syntanol Water 5 60 7 0.5 33 1,1 2.6 6 fifty 17 0.5 33 0.9 1.7 7 43 24 0.5 33 0.6 1,2 8 37 thirty 0.5 33 0.6 1,1

Claims (1)

A method of preparing a composition for producing an acid-soluble cement stone, comprising mixing cement with calcium carbonate, mixing water with a blowing agent and then mixing a mixture of cement with calcium carbonate and water with a blowing additive, characterized in that microcalcite with a particle size of 160- is used as calcium carbonate 315 μm, which is mixed with additive-free grouting Portland cement, as the foaming additive, the Aeroplast air-entraining additive is used, which I add in fresh water and stirred, then the mixture with Portland cement grouting bezdobavochnogo microcalcite shuts fresh water with the addition of air-entraining "AEROPLAST" additives in the following ratio, mass parts .:
cementless Portland cement 59.9-64.95 microcalcite 35-40 Aeroplast air-entraining additive 0.05-0.1 fresh water fifty