Formation opener agent for low permeable reservoir of oilfield

Abstract

The present invention relates to a stratum opener agent which is applied to oilfield low permeability reservoir. The stratum opener agent comprises two parts: pre-disposal liquid and acid inhibitor system; according to the weight percentage, the pre-disposal liquid consists of solvent and surfactant as follows: 1-3% of organic solvent such as higher alcohol, 0.2-1% of non-ionized surfactant polyoxyethylene alkylolamide, 0.3-0.5% of pentadecane alkyl sulfonate, and the residual quantity of stratum water; according to the weight percentage, the acid inhibitor system comprises 5-10% of low-carbon organic acid, 1-3% of hydrofluoric acid, 0.5% of inhibitor thio-phosphate imidazoline polyoxyethylene ether, 1% of adsorption inhibitor and the residual quantity of water; the adsorption inhibitor comprises 0.5-2% of ethyl dimethylene-bi-cetyltrimethylammonium ammonium bromide, 0.2-1% of quaternary ammonium salt small kation, 2-5% of inorganic salt, 0.2% of 1,3-amine group propyl alcohol N-methyl sodium phosphate or potassium dihydrogen phosphate or sodium hexametaphosphate. The stratum opener agent can effectively improve the seepage capability of reservoir and achieve the objects of decompression and augmented injection and improving the yielding.

Description

Technical field: [0001] The invention relates to a chemical preparation injected downhole in the field of oil production in oil fields, in particular to a formation dredging agent applied to low-permeability reservoirs in oil fields. Background technique: [0002] The physical characteristics of low-permeability reservoirs in oilfields: low permeability, less than 50md, small effective thickness, and serious plane heterogeneity. Crude oil has many heavy components, strong adsorption, poor fluidity, weak water absorption capacity, medium speed sensitivity, medium strong water sensitivity, medium strong acid sensitivity, small pore radius of oil layer, significantly increased clay content and shale content, generally above 10%, Slight clogging of this type of oil layer during water injection development can cause injection pressure to rise and injection is difficult, resulting in widespread occurrence of under-injection wells, which seriously affects oilfield water injection d...

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Problems solved by technology

Crude oil has many heavy components, strong adsorption, poor fluidity, weak water absorption capacity, medium speed sensitivity, medium strong water sensitivity, medium strong acid sensitivity, small pore radius of oil layer, significantly increased clay content and shale content, generally above 10%, Slight clogging of this type of oil layer during water injection development can cause injection pressure to rise, making injection difficult, resulting in widespread occurrence of under-injection wells, seriously affecting water injection development in oilfields

The conventional method is to adopt acidification, fracturing or acid fracturing. The cost of fracturing and acid fracturing is high. The acidification measures currently used mainly include nitric acid powder acidification, compound acid acidification, soil acid acidification, improved soil acid acidification, and hot gas acid acidification. Acidification measures are aimed at different blockages such as mechanical impurities, organic blockage, inorganic salt precipitation blockage, colloidal asphaltenes, etc., and there are disadvantages such as too fast acid rock reaction, small treatment radius, secondary pollution, and short validity period.

Clay plugging with a large plugging radius cannot be effectively removed, which affects the development effect of low permeability reservoirs

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