STUDY OF THE INFLUENCE OF STABILIZING REAGENTS ON FILTRATION OF TAMPONATION SOLUTIONS

Abstract

Laboratory studies were carried out to determine the coagulability of carboxymethyl cellulose, oxyl, spent sulphite alcohol liquor, hypan, metas, polyacrylamide and starch under the action of electrolytes that accelerate ageing. Based on the results of laboratory tests, sodium and potassium chloride did not cause coagulation in any of the stabiliser solutions tested. Ferric chloride causes coagulation of all stabilisers except oxyl, and when ammonium sulphate is added, all stabilisers except spent sulphite alcohol and oxyl coagulate. Baking soda causes coagulation of polyacrylamide. When calcium chloride and calcium nitrate are added, carboxymethylcellulose, starch, hypanes and metases coagulate. The studies carried out have shown that the listed reagents, filter reducers are compatible with each other and do not cause mutual coagulation. The coagulation threshold of stabiliser solutions has been determined. Laboratory studies on the influence of reagents-stabilisers and accelerators of setting conditions on the properties of cement slurry and stone (filtration, spreading, setting conditions and strength) were carried out. It was found that the optimum addition of carboxymethyl cellulose to reduce filtration is 0.75%. It is recommended to add 8% soda to accelerate the setting time of the cement slurry with the addition of carboxymethyl cellulose. The use of sodium silicate instead of soda causes an increase in filtration and a significant decrease in flow. The addition of polyacrylamide instead of carboxymethylcellulose to the cement slurry results in a decrease in filtration with a very significant thickening of the solution and an increase in setting time. Based on laboratory studies, the optimum addition of bentonite was selected to reduce filtration of the cement slurry. Laboratory studies were carried out on the effect of two stabilising reagents (carboxymethylcellulose + oxyl, carboxymethylcellulose + spent sulphite-alcohol liquor) on the main properties of the tested cement slurry formulation. The addition of oxyl to the proposed formulation reduced the filtration of the cement slurry, while the addition of spent sulphite alcohol slightly increased it. It was found that the cement slurry with the addition of oxyl caused a slight expansion (up to 0.1%) of the cement stone when hardened in water. The recommended formulation of the backfilling solution with reduced filtration for cementing the casings of low-temperature wells is as follows: oil-well Portland cement PCT І-50 + 5% bentonite + 0.75% carboxymethylcellulose + 0.3% oxyl + 8% soda with a water-cement ratio of 0.65.