Loose sandstone reservoir alkali sensitivity evaluation method

Abstract

The invention relates to the field of oil-gas reservoir sensitivity evaluation methods, and in particular to a loose sandstone reservoir alkali sensitivity evaluation method which comprises the following steps: grinding and crushing loose sandstone reservoir rock samples, screening and drying, performing reaction with alkali solutions of different pH values, filtering mixtures obtained after the reaction, drying, weighing, finally calculating rock core recycling rates, and evaluating the loose sandstone reservoir alkali sensitivity damage degrees according to the rock core recycling rates. By adopting the method, the problems that in a common oil-gas reservoir alkali sensitivity mobile experiment method, loose sandstone is very hard to drill to take a columnar rock core applicable to mobile experiment, an artificial rock core is relatively greatly different from actual situations, or a loose rock core which is unsealed or preserved for a relatively long time cannot be tested or evaluated can be solved, and by using a rock core recycling method, the alkali sensitivity of a rock core can be effectively evaluated under the condition that a complete columnar rock core cannot be obtained, testing results can be generally accordant with those of rock samples of complete columnar rock cores, and thus having potential market values.

Description

technical field [0001] The invention relates to the field of sensitivity evaluation methods for oil and gas reservoirs, in particular to an evaluation method for alkali sensitivity of unconsolidated sandstone reservoirs. Background technique [0002] Reservoir sensitivity refers to the physical and chemical reaction between the oil and gas reservoir formation and the foreign fluid when it encounters the foreign fluid whose properties are quite different from its own, or the pore structure and permeability caused by the excessive flow of fluid in the reservoir. The nature of the change. Reservoir alkali sensitivity is a kind of sensitivity, which means that after the alkaline working fluid enters the reservoir, it reacts with the reservoir rock or reservoir fluid, produces precipitation or causes particle migration, and makes the reservoir seepage decline in capacity. In conventional reservoir alkali-sensitivity flow experiments, for unconsolidated sandstone reservoirs, sea...

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Problems solved by technology

However, for those loose cores that have been unsealed and placed in the core bank for a long time, or cemented loose or even unconsolidated cores, it is impossible to drill columnar cores suitable for core flow experiments, and it is impossible to complete the routine tests according to conventional standards and experimental methods. Alkali sensitivity test content, if artificial cores are used, the experimental results may be quite different from the actual conditions of the reservoir, which is not representative

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