RU2681716C1 - Cement slurry for the oil and gas wells cementing - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to the used in the oil and gas wells cementing cement slurries. Oil and gas wells cementing cement slurry, containing Portland cement, adhesive additive, water loss reducer, defoamer and water, as an adhesive additive contains the Silor-Ultra T glue, as the water loss reducer is the water-soluble cellulose ether, the carboxymethylcellulose, as the plasticizer is the lignosulfonate, as the defoamer, the tributyl phosphate is used in the following ratio of components, wt. %: Portland cement – 100, the said adhesive additive is 1.0–2.0 in excess of 100, the specified loss of water loss is 0.01–0.1 in excess of 100, said plasticizer is 0.05–0.15 in excess of 100, tributyl phosphate is 0.05–0.1 in excess of 100, water to water-cement ratio is 0.36–0.38.

EFFECT: technical result is increase in the cement stone impact resistance and adhesive properties.

1 cl, 1 tbl

Description

The invention relates to cement slurries used in cementing oil and gas wells.

A well-known grouting mortar containing grouting cement, silica fume and water (see Pat. RU 2057250, IPC 7 ЕВВ 33/138, 03/27/1996) [1], this grouting mortar is designed for cementing gas-oil wells with temperatures above 110 ° C, it the disadvantage is the low resistance of the resulting cement stone to shock loads.

The closest analogue to the invention in its technological essence is cement slurry for cementing oil and gas wells, containing, by weight. %: Portland cement - 100, and over 100 penetrating additive 3, water-soluble cellulose ether 0.03 - 0.1, plasticizer - lignosulfonate 0.3-0.7, tributyl phosphate - 0.01-1.0, water to a water-cement ratio of 0 , 38-0.42 (see Pat. RU 2542013, C1, 02.20.2015.6 p.) [2].

The disadvantage of this solution is the insufficiently high adhesion of the resulting cement stone to the bounding surface.

The objective of the invention is the development of technological, grouting mortar, cement stone which has increased resistance to shock loads and high adhesion to bounding surfaces.

The task is achieved by introducing additives into the cement cement.

The essence of the invention lies in the fact that the cement slurry includes Portland cement, an adhesive additive, a fluid loss reducer, an antifoam and water, characterized in that it contains an adhesive adhesive Silor-Ultra T (manufactured according to TU 5772-001-90679544 - 2013) , in the following ratio of components, mass. %:

- Portland cement - 100

- the specified adhesive additive -1,0-2,0 in excess of 100

- the specified fluid loss reducer - 0.01-0.1 in excess of 100

- the specified plasticizer is 0.05-0.15 in excess of 100

tributyl phosphate - 0.05-0.1 in excess of 100

water to a water-cement ratio - 0.36-0.38.

From the patent and scientific and technical literature, we are not aware of grouting materials containing a combination of the above components in the proposed quality ratio, which allows us to conclude that the claimed technical solution is new.

The technical result achieved during the implementation of the invention consists in the fact that the components in the composition of the grouting mortar in the indicated amounts together increase the strength of the cement stone, improve its adhesion characteristics, and increase resistance to shock loads.

The specified adhesive additive fills the voids of the crystalline structure of hydratable cement, blocks small channels and capillaries of cement. This improves the structure of the grouting material between the pores, as a result of which the impact resistance of the cement stone and its adhesive properties are increased.

Cellulose ethers, when dissolved, break up in water into large molecules that cover the particles of cement mortar (adsorb on them) and create protective layers around the latter. This increases the hydrophilicity of cement particles and the aggregative stability of the system. The macromolecules of such reagents, as well as the layers formed by them on the elementary crystals of the cement mortar, increase the density of the filter cake, resulting in a decrease in the water separation of cement mortars.

The plasticizer lignosulfonate allows you to get the necessary flowability and mobility of the solution, and tributyl phosphate - extinguishes the foam.

From the existing level of technology, we do not know that this composition in a cement slurry provides the combination of the above properties, which allows us to conclude that the proposed technical solution meets the criterion of "inventive step".

Cement slurry is prepared as follows. Prepare a dry mixture in a predetermined quantitative ratio of cement, lignosulfonate and cellulose ether. The adhesive adhesive Silor-Ultra T (TU 5772-001-90679544 - 2013, publication date 10/25/2013) is a two-component composition on a polyurethane basis [3]: 1st component - dark brown liquid, 2nd component - the liquid is light beige in color, these components are mixed respectively in a 2: 1 ratio, after which the adhesive adhesive Silor-Ultra T and tributyl phosphate are added during the mixing of the mixture into the mixing liquid.

Grouting and technological properties of the resulting grouting mortar are presented in the table.

As you can see from the table, grouting mortar allows you to achieve your goal: cement stone has higher resistance to shock loads and adhesion to bounding surfaces compared to analogues

This cement slurry was tested with the fastening of two production oil wells at the Pokachevsky field in Western Siberia.

An example of the use of cement slurry.

For cementing one production string at the Pokachevskoye field (cementing interval 300 m), a dry cement mixture was previously prepared on the basis of the well fixing workshop, consisting of:

- Portland cement - 12000 kg (100%);

- the specified fluid loss reducer - 12.0 kg (0.1% in excess of 100%);

- the specified plasticizer is 12 kg (0.1% in excess of 100%).

At a water-cement ratio of 0.38, the mixture was mixed, the adhesive adhesive Silor-Ultra T - 120 kg (1.0% in excess of 100%) was added to the prepared cement slurry in an averaging tank, tributyl phosphate - 12 kg (0.1% in excess of 100%) ) was added to the solution during the mixing of cement.

After waiting for the cement to harden, standard geophysical studies were carried out to determine the quality of fastening in the contact zones of the cement stone - rock and cement stone - the walls of the column, the height of the grout and its uniformity in density.

The research results are positive.

The use of the proposed cement slurry will increase the strength of the cement contact with the column and rock, the quality of the separation of the layers.

Information sources:

1. P. RU 2057250, IPC 7 Е21В 33/138, 03/27/1996

2. P. RU 2542013, C1, 02.20.2015, 6 p.

3. [Electronic resource]. - Access mode: http://silor-sprut.ru/index/silor_ultra_t/0-17

Note:

* - the resistance of cement stone to shock loads is characterized by the specific work spent on its destruction. Impact resistance was determined using a copra designed in accordance with the requirements of GOST 30353-95 “Floors. Impact test method. "

Claims (7)

 Cement slurry for cementing oil and gas wells containing Portland cement, an adhesive additive, a fluid loss reducer, antifoam and water, characterized in that it contains Silor-Ultra T glue as an adhesive additive, and a water-soluble cellulose ether carboxymethyl cellulose as a water loss reducer plasticizer lignosulfonate, as antifoam tributyl phosphate in the following ratio of components, mass. %: - portland cement-100 - the specified adhesive additive -1,0-2,0 in excess of 100 - the specified fluid loss reducer - 0.01-0.1 in excess of 100 - the specified plasticizer is 0.05-0.15 in excess of 100 tributyl phosphate - 0.05-0.1 in excess of 100 water to a water-cement ratio - 0.36-0.38.