Experimental method for measuring unconventional tight gas reservoir spontaneous infiltration absorption relative permeability

Abstract

The invention discloses an experimental method for measuring unconventional tight gas reservoir spontaneous infiltration absorption relative permeability. The method comprises the following steps of (1) washing and drying a core taken from a tight gas reservoir, and then measuring a diameter D, a length L, and an original porosity phi0; (2) obtaining absolute permeability K0 of the core and an effective pore volume VP; (3) putting the core after saturated formation water into a core holder, adding confining pressure, and raising a temperature to a formation temperature; (4) injecting a nitrogen gas into the core, carrying out replacement and stopping when a water amount of a water metering pipe at a core outlet end is no longer increased; and (5) under a water flooding pressure differencedeltaP, slowly injecting the water into the core holder, carrying out a spontaneous infiltration absorption water gas displacement experiment, calculating water phase relative permeability Krw, gas phase relative permeability Krg and water saturation Sw of the core, and acquiring a gas-water two-phase relative permeability curve of a tight gas reservoir core spontaneous infiltration absorption water gas displacement process. In the invention, a theoretical basis is provided for determination of residual gas saturation of the tight gas reservoir and calculation of reserves.

Description

technical field [0001] The invention relates to an experimental method for measuring the relative permeability of spontaneous imbibition in the water flooding development process of unconventional gas reservoirs. Background technique [0002] In recent years, with the increasingly higher requirements for sustainable development and energy demand, unconventional natural gas resources have received more and more attention internationally. my country has abundant unconventional natural gas resources, which are huge in scale and far larger than conventional natural gas resources, accounting for more than 80% of the world's total oil and gas resources. However, its development and utilization are still in its infancy compared with many developed countries. The development of tight gas reservoirs will undoubtedly help alleviate the tense situation of global oil and gas supply, not only has economic benefits, but also helps to improve the environment and meet the strategic require...

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Problems solved by technology

[0004] The spontaneous imbibition process is a very important part of the water flooding development process, and many domestic and foreign experts and scholars have conducted in-depth research on the above problems (Xue Honggang. LFS low-permeability tight condensate gas reservoir seepage and reservoir damage research (D). Southwest Petroleum University. 2017; Zhou Fengjun. Experimental study on imbibition of low-permeability cores. Complex Oil and Gas Reservoirs. 2009, 2(1): 54-56). Due to the characteristics of complex rock physical properties and abnormal seepage laws in tight gas reservoirs, there are often water phases Severe trap damage, high start-up pressure gradient, difficult injection, etc.

[0005] Spontaneous imbibition gas-water relative permeability measurement is an important parameter for monitoring and evaluating water flooding development efficiency. The relative permeability curve is usually obtained by laboratory test methods, but due to the complex pore-throat structure and strong heterogeneity of tight gas reservoirs , the gas-water relative permeability curve obtained by the existing experimental testing device and method has a large error

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