科研之友
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摘要
It is necessary to establish a multi-media coupling flow model for shale gas reservoirs in order to understand the shale gas flowing rules and accurately evaluate the hydraulic fracturing effects. In this paper, migration rules were comprehensively investigated on the basis of kerogen, inorganic matrix and fracture physical properties of shale gas reservoirs, including nano-scale gas viscosity slippage, Knudsen diffusion, adsorption-desorption and surface diffusion. The multi-scale medium filtration mechanisms of shale gas reservoirs were characterized comprehensively by using the apparent permeability. Then, a multi-media coupling flow model for shale gas reservoirs was established considering the reservoir fracturing characteristics and cross-scale fluid mass transfer mechanisms. Based on Laplace transformation and Stehfest numerical inversion, the semi-analytical solutions of dimensionless pseudo-pressure and production at the bottom hole with closed boundary single fracture were calculated under constant production rate and pressure. Finally, a case study was made on the model by using field parameters after it was verified. It is shown that kerogen is an important hydrocarbon source medium for shale gas reservoirs and it contributes to the cumulative shale gas production increment of 12% if kerogen content rises by 10%. Inorganic matrix slippage effect and Knudsen diffusion have more effects on gas flow rate in the middle period of the production, and also increase the depletion rate of pore pressure. The flow rules of staged-fracturing horizontal wells in shale gas reservoirs were investigated by using this flow model. It is indicated that there are seven flow stages (i.e., linear flow, bilinear flow, "bi-cross flow", inorganic matrix stable flow, pseudo boundary flow, "trilinear"flow and closed boundary flow) if wellbore storage and skin effect are not taken into consideration.
- 出版日期2016
- 单位中国石油大学（华东）
