Shale fracturing fluid forced imbibition and flowback experiment method under condition of containing adsorbed gas

Abstract

The invention discloses a shale fracturing fluid forced imbibition and flowback experiment method under the condition of containing adsorbed gas. The method comprises the steps of: connecting crack development, crack underdevelopment and base block shale in series to form a shale multi-scale reservoir seepage space; putting the sample into a long rock core holder; and injecting methane gas into aclamper; after pore pressure and methane adsorption balance are controlled through a rock core outlet end back-pressure valve, achieving forced imbibition of the fracturing fluid under the action of positive pressure difference of a rock core inlet end, enabling the outlet end to monitor methane gas replaced in the imbibition process of the fracturing fluid, and in the flowback stage, simulating the flowback process of the fracturing fluid by setting the pressure difference through the rock core inlet end back-pressure valve. In the process, the core resistance is monitored in real time, and the imbibition and retention amount of the fracturing fluid in the shale multi-scale reservoir seepage space are reflected through the resistance. According to the method, the imbibition and flowback processes of the fracturing fluid in the shale multi-scale reservoir seepage space under the condition of containing the adsorbed gas can be truly simulated, and references are provided for optimizingthe soaking time and formulating a reasonable flowback system after the shale gas well is fractured.

Description

technical field [0001] The invention relates to the technical field of petroleum and natural gas engineering, in particular to the technical field of shale gas development, in particular to an experimental method for forced imbibition and flowback of shale fracturing fluid under the condition of adsorbed gas. Background technique [0002] Shale gas is an important unconventional energy source, and horizontal well staged hydraulic fracturing technology is one of the important means to realize the commercial exploitation of shale gas. Compared with conventional sandstone and carbonate reservoirs, shale gas reservoirs are characterized by high content of clay minerals, rich in organic matter, well-developed lamellation and multi-scale pore structure. The shale gas production process includes the diffusion of free gas, seepage and desorption, diffusion and seepage of adsorbed gas. The retention of fracturing fluid has a significant impact on gas production. Therefore, simulati...

AI Technical Summary

Problems solved by technology

The current indoor experimental methods for fracturing fluid imbibition and flowback in shale reservoirs mainly have the following two deficiencies: ① Failure to fully consider the influence of shale multi-scale seepage storage space on fracturing fluid imbibition behavior

② Failure to fully consider the influence of adsorbed gas on the imbibition behavior of fracturing fluid

Adsorbed gas accounts for 20% to 85% of shale gas, ignoring the adsorbed gas in organic matter and clay minerals will not be able to accurately describe the imbibition and flowback behavior of fracturing fluids

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