RU2526039C1 - Well water production isolation composition - Google Patents

Abstract

FIELD: oil-and-gas industry.

SUBSTANCE: proposed composition comprises 17-59 wt % of "Vitam" reagent, 20-40 wt % of sodium silicate, 1-3 wt % of wood flour and 20-40 wt % of 10%-solution of polyaluminium chloride.

EFFECT: higher isolation capacity.

2 tbl

Description

The invention relates to the oil and gas industry, in particular to compositions for isolating water inflow in a well.

A known composition for isolating water inflows into a well, including an aqueous solution of sodium silicate, sodium silicofluoride, triacetin and wood flour (patent RU No. 2244819, IPC E21B 43/32, publ. 20.01.2005, Bull. No. 2) in the following ratio of components mass%:

an aqueous solution of sodium silicate with a density of 1.36 g / cm ³ and silicate module M = 3.0 90.0-95.0 sodium silicofluoride 3.0-8.0 wood flour 1.0-4.0 triacetin 1.0-4.0

A disadvantage of the known composition is that when it is injected, insoluble part of sodium silicofluoride is precipitated in the pump of the cementing unit due to the low solubility of this reagent - 7.62 g / l (Big Encyclopedic Dictionary. Chemistry. - M .: Big Russian Encyclopedia, 2000 . - P.362), therefore, compliance with the technology and accurate dosing of the components of the composition is required. Stopping the pumping process to clean a clogged pump can lead to an emergency — curing the composition in the tubing.

The closest analogue is a composition for isolating water in a well (patent RU No. 2354678, IPC C09K 8/487, publ. 05/10/2009, Bull. No. 13), including a copolymer of sodium methacrylate and methacrylic acid (reagent "Vitam") and glycidyl derivatives of 5,5-dimethylhydantoin in the following ratios of components,% wt .:

copolymer of sodium methacrylate and methacrylic acid 6-13 glycidyl derivatives of 5,5-dimethylhydantoin 1.6-7.0 water rest

moreover, the ratio of carboxyl groups of the copolymer to epoxy groups of these derivatives is from 1: 1 to 1: 0.5. In the interaction of the copolymer of sodium methacrylate and glycidyl derivatives of 5,5-dimethylhydantoin with formation water containing polyvalent metal ions, a bulk gel is formed.

A disadvantage of the known composition is that the resulting gel in fresh water is destroyed over time, so the water cut of the oil increases, and the overhaul period of the well decreases.

The technical task of the proposal is to increase the insulating ability of the composition by increasing the stability of the resulting gel.

The problem is solved by the composition for isolating water inflow in the well, including reagent "Vitam", sodium silicate, wood flour and structure-forming agent.

New is that as a builder it contains a 10% solution of polyaluminium chloride in the following ratios of components,% mass:

reagent "Vitam" 17-59 sodium silicate 20-40 wood flour 1-3 10% solution of polyaluminium chloride 20-40

The reagents used in the inventive composition are presented in table 1.

Table 1 Reagents used in the claimed composition Reagent Name Name GOST or TU Appearance Liquid sodium glass (sodium silicate) GOST 13078-81 Thick yellow or gray liquid without mechanical impurities and inclusions visible to the naked eye Reagent Vitam TU 2458-028-25690359-2007 as amended. No. 1 Viscous, colorless or yellowish liquid Wood flour GOST 16361-87 Fibrous, water-swellable, natural material obtained by mechanically chopping wood Polyaluminium chloride (POLYPACS-30 LF brand) The protocol of certification tests of GIV PV CJSC No. 166/11 of February 26, 2011 Light yellow powder

The optimal concentration of a solution of polyaluminium chloride is 10%, when using a solution of this concentration, a dense gel is formed, when using a concentration of a solution of polyaluminium chloride of less than 10%, a loose gel is formed, using a concentration of more than 10% is impractical, since it slightly affects the density of the resulting gel. The presence of the Vitam reagent in the carboxyl groups gives it a polymer character. The wood flour contained in the composition swells upon contact with water and reinforces the gel throughout. A positive result from the use of the composition during repair and insulation works remains for a long time due to the plugging effect created by the technical wood flour swollen in water.

Composition for isolating water inflow in the well is prepared as follows. The Vitam reagent and sodium silicate are pre-mixed, as a result of which a homogeneous, non-stratifying solution is formed. To prepare a 10% solution of polyaluminium chloride in 900 l of water with a density of 1000 kg / m ³ add 100 kg of powdered polyaluminium chloride and mix. Wood flour and a 10% solution of polyaluminium chloride are added to a solution of Vitam reagent and sodium silicate, mixed well, resulting in a dense gel that blocks the flow of water in the isolated interval.

In laboratory conditions, the composition is prepared as follows. 54 g (27% by weight) of Vitam reagent and 80 g (40% by weight) of sodium silicate are poured into a 200 ml glass beaker, mixed well. 6 g (3% by weight) of wood flour and 60 g (30% by weight) of a 10% solution of polyaluminium chloride are added to the resulting solution; a bulk gel is formed with stirring (composition No. 4, in table 2). The remaining compositions are prepared similarly (table 2).

Testing the water-insulating ability of the proposed composition and composition according to the closest analogue was carried out on reservoir models 30 cm long and 2.7 cm in internal diameter, filled with quartz sand of a fraction of 0.2-0.3 mm. The formation model was saturated with formation water, after which the compositions were pumped according to the proposal for the formulations from Table 2 and left to react. The amount of injected composition was equal to the pore volume of the reservoir model. After 36 hours, water was pumped in, the permeability was determined by the Darcy formula, and the insulation coefficient was calculated after 36 hours and 6 months. The insulation coefficient characterizes the degree of clogging of pores, a decrease in the permeability of the model, and is a measure of the effectiveness of insulation work. The average results of model tests are presented in table 2. Compounds No. 2-6 showed the best insulating ability, so they entered the claimed range.

table 2 The results of model tests of the proposed composition and composition according to the closest analogue No. The content of reagents in the proposed composition Insulation coefficient,% Sodium silicate,% wt. Reagent
"Vitam",% of the mass. Wood flour,% of the mass. 10% solution of polyaluminium chloride,% mass. After 36 hours After 6 months The composition of the claimed method one 10 69.5 0.5 twenty 90 78 2 twenty 59 one twenty 96 90 3 thirty 43 2 25 98 91 four 40 27 3 thirty one hundred 94 5 twenty 37 3 40 one hundred 93 6 40 17 3 40 97 92 7 40 10 four 46 92 84 8 45 40 5 10 94 85 The composition of the closest analogue Reagent "Vitam",% of the mass. Nitrogen-containing epoxy resin,% of the mass. Water,% of the mass. The ratio of carboxyl and epoxy groups, mol The ratio of carboxyl and amino groups, mol Insulation coefficient,% After 36 hours After 6 months 10 2.7 87.3 1: 0.5 1: 0,0025 95 80 13 7.0 80.0 1: 1 1: 0.005 one hundred 83

From the presented results it is clear that the isolation coefficient of the proposed composition after 36 hours was 96-100%, after 6 months - 90-94%, and the closest analogue, respectively, 95-100%, after 6 months - 80-83%, which indicates about the best insulating ability of the proposed composition and the stability of the obtained gel.

Thus, when using the proposed composition for isolating water inflow in the well, a volume gel is formed with high insulating ability and stability.

Claims (1)

Composition for isolating water inflow in the well, including Vitam reagent, sodium silicate, wood flour and structure-forming agent, characterized in that it contains a 10% solution of polyaluminium chloride as a structure-forming agent in the following ratios of components, wt%:
reagent "Vitam" 17-59 sodium silicate 20-40 wood flour 1-3 10% solution of polyaluminium chloride 20-40