A method for determining the formation conditions of gas-water inversion distribution relationship in tight sandstone

Abstract

The invention provides a method for determining a formation conditions of a gas water inversion distribution relationship of a tight sandstone. The method comprises the following steps of 1) obtaininga first critical plugging pressure by performing first formation water saturation on a tight sandstone sample and performing a differential pressure natural gas charging experiment; 2) making the tight sandstone sample subjected to secondary formation water saturation anda pulsed natural gas charging experiment to obtain a second critical plugging pressure; 3) according to the first critical plugging pressure and the second critical plugging pressure, obtaining the actual critical plugging pressure of the tight sandstone sample; 4) determining the upper limit of the permeability and the upper limit of the porosity according to the actual critical plugging pressure, permeability and porosity; 5) according to the upper limit of the permeability or the upper limit of the porosity and the actual critical plugging pressure, determining the critical pore throat radius distribution when the gas water inversion is formed. The method can accurately determine the critical conditions for the formation of the gas water inversion under the actual formation conditions of tight sandstone gas reservoirs.

Description

technical field [0001] The invention relates to a method for determining the formation conditions of tight sandstone gas-water inversion distribution relationship, and belongs to the field of unconventional oil and gas exploration and development. Background technique [0002] The research on tight sandstone gas began in the 1950s, and has undergone the research evolution of subtle gas reservoirs, deep basin gas reservoirs, basin center gas, tight sandstone gas and continuous natural gas accumulation. In tight sandstone reservoirs with an absolute permeability lower than 1 mD), the natural gas that needs to be industrially exploited through fracturing or other special gas recovery processes is defined as tight sandstone gas. Tight sandstone gas, as an important part of unconventional oil and gas resources, has always been the focus of research by scholars at home and abroad. It is believed that tight sandstone gas reservoirs have low porosity and ultra-low permeability, lens...

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Problems solved by technology

However, these studies are limited to proving the existence of gas-water inversion in gas reservoirs, which are very different from the actual formation conditions, and cannot be directly applied to tight sandstone gas reservoirs.

[0005] With the increasing demand for tight sandstone gas exploration and development, the current research can no longer meet the needs of effectively determining favorable exploration areas of tight sandstone gas reservoirs and accurately deploying injection-production development plans. A scientific method for the formation conditions of gas-water inversion phenomenon under formation conditions

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