RU2351631C1 - Back filling composition - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention refers to oil extraction, particularly to back filling compositions designed for isolation of zones of loss and for repair-isolation works in well. The composition contains a clay powder, sodium metha-xylitol, poly-acryl-amide, water and plasticizer - a product on base of saponated stillage bottoms from production of synthetic fat acids containing not less, than 30% of solid residue, not less, than 1.7 mg-equiv/l of sodium soaps of synthetic fat acids and not more, than 0.1% of free alkali per solid residue or a product on base on saponated with potassium hydroxide or mixture of potassium hydroxide and sodium hydroxide stillage bottoms form production of fat acids of vegetable or animal oil with titre from 5 to 65 and with contents of residual alkali not less, than 0.05% per solid residue at the following ratio of ingredients, wt parts: clay powder 60-90; sodium metha-xylitol 5-30; poly-acryl-amide 0.01-0.5; the above said plasticiser 1-10, water 80-150.

EFFECT: upgraded isolating efficiency due to increased value of plastic hardness of forming back-filling stone and due to maintaining this value during considerable period of time with simultaneous maintaining good mobility and pumping ability at initial period of time.

2 tbl

Description

The invention relates to the field of oil production, in particular to grouting compositions designed to isolate absorption zones and conduct repair and insulation works in the well.

A known composition for isolating produced water in a well (RF Patent No. 2137905, class ЕВВ 33/138, publ. 1999), containing in wt.%: Sodium metasilicate 4.0-10.0; a product based on saponified bottoms from the production of synthetic fatty acids, containing not less than 30% solids, not less than 1.7 mEq / l of sodium soaps of synthetic fatty acids and not more than 1.0% free alkali, based on dry solids ( in terms of the active basis) 0.5-3.0; hydroxyethyl cellulose 0.1-0.45 and water - the rest. The specified composition is intended for use to isolate the absorption zones or to limit water inflow during the drilling and repair of wells, to create a waterproof screen when uncoupling water-saturated and oil-and-gas-saturated formations, to eliminate annular flows and to align injection profiles of injection wells, as well as to reduce the permeability of the filter cake and the mud zone before cementing the wellbore.

However, this known composition does not provide a screen with high plastic strength. In addition, due to the high initial viscosity, this composition is characterized by low selectivity, it easily penetrates both water-washed zones and low-permeable oil-saturated areas of the bottomhole zone and clogs them, which can lead to a decrease in oil production.

Also known is a composition for isolating absorbing layers in a well (RF Patent No. 2211913, class ЕВВ 33/138, publ. 2003), containing an aqueous solution of hydrochloric acid of 10-15% concentration and an organic additive - a product based on saponified bottoms residues from the production of synthetic fatty acids containing not less than 30% solids, not less than 1.7 mEq / l of sodium soaps of synthetic fatty acids and not more than 0.1% free alkali, based on dry solids. The specified known composition is pumped into the well simultaneously-separately in the form of two streams.

The disadvantage of this known composition is the technological difficulties associated with the need for simultaneous dosage of two streams. In addition, one of the streams is a corrosion-active component - acid, which requires the use of additional measures for corrosion protection. At the same time, the grouting mass resulting from the reaction of the components creates a screen with low plastic strength, especially at elevated temperatures, which does not provide reliable insulation.

The closest to the proposed technical solution for the totality of signs and purpose is a non-hardening grouting composition (RF Patent No. 2120539, CL ЕВВ 33/138, publ. 1998), containing in parts by weight: clay powder 70-80, sodium metasilicate 8 -25, polyacrylamide 0.001-0.005 and water - 100. It is designed to eliminate the zones of absorption of the drilling fluid, as well as for repair and insulation works and for leveling the injectivity profile in injection wells.

The main disadvantages of this known grouting composition are as follows:

- insufficient insulation efficiency due to insufficient plastic strength of the hardening grouting mass;

- the need to prepare a composition with limited mobility at the initial moment to obtain high strength during curing.

The technical result achieved by the proposed grouting composition is to increase its insulation efficiency by increasing the plastic strength of the resulting grouting stone and maintaining this value for a long time while maintaining good mobility and pumpability of the composition in the initial period of time.

The specified technical result is achieved by the proposed grouting composition containing clay powder, sodium metasilicate, polyacrylamide and water, while according to the invention it additionally contains a plasticizer - a product based on saponified bottoms from the production of synthetic fatty acids containing at least 30% solids, at least 1 , 7 mEq / l sodium soaps of synthetic fatty acids and not more than 0.1% free alkali, based on the dry residue, or a product based on saponified potassium hydroxide or a mixture of hydroxide Potassium hydroxide and sodium resid from vegetable and / or animal origin production of fatty acids having a titre of 5 to 65 and a residual alkali content of not less than 0.05% on a dry residue in the following ratio of ingredients in parts by weight .:

Clay powder 60-90 Sodium metasilicate 5-30 Polyacrylamide 0.01-0.5 The specified plasticizer 1-10 Water 80-150.

The specified technical result is achieved due to the following. The increased, compared with the prototype, the content of polyacrylamide provides the formation of a more branched and strong coagulation structure with increased plastic strength, increasing over time. And the presence as the plasticizer of these substances in the declared amounts contributes to the preparation of the proposed grouting composition, characterized by low viscosity and easy pumpability in the initial period. Thus, the use of a combination of high PAA and a plasticizer of the claimed type led to an unobvious effect - the composition has easy pumpability and low viscosity in the initial period of time and high (higher than in the prototype) plastic strength after curing.

The proposed grouting composition was prepared and tested in laboratory conditions. The following substances were used for its preparation:

- Almetyevsk clay powder, OST 39-202-86;

- sodium metasilicate (sodium salt of metasilicic acid), which is a fine crystalline powder, highly soluble in water, TU 6-18-161-82;

- polyacrylamide (PAA) brand Praestol 2540N;

- plasticizer:

- a product based on saponified bottoms from the production of synthetic fatty acids, containing not less than 30% solids, not less than 1.7 mEq / l sodium soaps of synthetic fatty acids and not more than 0.1% free alkali based on dry solids (hereinafter Reagent-1), brown paste is produced according to TU 2432-002-12064382-97;

- a product based on saponified potassium hydroxide or a mixture of potassium hydroxide and sodium hydroxide from the production of vegetable and / or animal fatty acids with a titer of 5 to 65 and with a residual alkali content of at least 0.05% by dry weight (hereinafter referred to as Reagent 2), according to TU 2432-057-53501222-2006, is a paste of dark brown color;

- Technical fresh water.

The proposed grouting composition was prepared as follows.

100 g of water, 80 g of clay powder, 5 g of plasticizer Reagent-1, 10 g of sodium metasilicate and 0.05 g of polyacrylamide (PAA) were successively loaded into a tank equipped with a frame mixer with constant stirring. The resulting mass was stirred for 0.5 hours. At this time, the preparation of the grouting composition ended. As a result, a grouting composition was obtained with the following content of ingredients, parts by weight: clay powder 80; sodium metasilicate 10; polyacrylamide 0.05; plasticizer Reagent-1 5; water 100.

Grouting compositions with different contents of the ingredients were obtained in a similar way.

In laboratory tests, at different time intervals from the moment of preparation of the grouting composition, the following properties were measured:

- relative viscosity (used a funnel with a nozzle with a diameter of 5.4 mm, a volume of 140 ml);

- plastic strength (used Rebinder plastometer).

The determination was carried out according to standard methods.

The data obtained during the tests are shown in the table.

Data on the content of ingredients in the investigated grouting compositions are shown in table 1.

Table 1 №№
composition Ingredients, parts by weight Clay powder Sodium metasilicate PAA Plasticizer Water 1 (prototype) 80 10 0.001 - one hundred 2 (prototype) 80 35 0.002 - one hundred 3 80 10 0.05 5 Reagent-1 one hundred four 60 thirty 0.01 1 Reagent-1 105 5 90 5 0.5 10 Reagent-1 105 6 90 thirty 0,07 2.5 Reagent-2 150 7 60 5 0.01 1 Reagent-2 80

In formulations 3-5 Reagent-1 contains 30% solids, 1.9 mEq / l sodium soaps of synthetic fatty acids and 0.1% free alkali based on dry solids. In compositions 6, 7, Reagent-2 is a product based on bottoms saponified with potassium hydroxide from the production of vegetable and animal fatty acids with a titer of 15 and with a residual alkali content of 0.05% by dry solids.

Data on the properties of the proposed and well-known grouting compositions are shown in table 2.

table 2 No. of composition from table 1 Conditional viscosity, s Plastic strength kPa, over time Initial moment 3 hours 24 hours 3 days 1 (prototype) 43 0.44 7.6 107.5 351 2 (prototype) 52 0.49 7.8 107.5 351 3 52 0.51 - 452 - four 57 0.5 - 390 - 5 59 0.62 - 967 - 6 49 0.5 - 488 - 7 44 0.4 9.8 375 -

The data shown in table 2 show the following:

- the simultaneous introduction of a high content of PAA and the specified type of plasticizer provides an increase in the plastic strength of the composition already in a day by 3.4-9 times, while the conditional viscosity of the proposed composition varies slightly compared with the prototype, increasing on average by ~ 10%, which guarantees good pumpability of the inventive cementing composition at the initial time;

- going beyond the boundaries of the claimed formulation leads to a deterioration in the characteristics of the composition. In this case, either the conditional viscosity rises sharply, or the plastic strength decreases.

Thus, the use of special ingredients for the preparation of the claimed composition in the indicated quantitative ratio leads to an unobvious effect - the proposed grouting composition has easy pumpability (low conditional viscosity) in the initial period of time and high (3.4-9 times higher than in the prototype ) plastic strength after the first day of curing, which ensures its manufacturability and increased insulating properties.

Claims (1)

A grouting composition containing clay powder, sodium metasilicate, polyacrylamide and water, characterized in that it additionally contains a plasticizer - a product based on saponified bottoms from the production of synthetic fatty acids, containing at least 30% solids, at least 1.7 mEq / l sodium soaps of synthetic fatty acids and not more than 0.1% free alkali based on the dry residue, or a product based on saponified potassium hydroxide or a mixture of potassium hydroxide and sodium hydroxide bottoms from the production of fatty acids a slot of vegetable and / or animal origin with a titer of 5 to 65 and with a residual alkali content of at least 0.05% by dry weight in the following ratio of ingredients, parts by weight:
Clay powder 60-90 Sodium metasilicate 5-30 Polyacrylamide 0.01-0.5 The specified plasticizer 1-10 Water 80-150