Abstract
The current research of nonlinear seepage theory of shale-gas reservoir is still in its infancy. According to the characteristics of shale gas in adsorption-desorption, diffusion, slippage and seepage during accumulation, migration and production, a mathematical model of unstable seepage in dual-porosity sealed shale-gas reservoir was developed while considering Knudsen diffusion, slip-flow effect and Langmuir desorption effect. By solving the model utilizing the Stehfest numerical inversion and computer programming in Laplace space, several typical curves of bottomhole pressure were obtained. In this paper, we discussed the effects of several parameters on the pressure dynamics, i.e. storativity ratio, Langmuir volume, Langmuir pressure, adsorption-desorption, tangential momentum accommodation coefficient, flow coefficient, boundary. The results show that the desorbed gas extends the time for fluid to flow from matrix system to fracture system; the changes of Langmuir volume and Langmuir pressure associated with desorption and adsorption effect are the internal causes of the storativity ratio change; when the tangential momentum accommodation coefficient decreases, the time for pressure wave to spread to the border reduces; interporosity flow coefficient determines the occurrence time of the transition stage; boundary range restricts the time for pressure wave to spread to the border.
Highlights
With the successful development of shale gas in North America and the sharp increase in demand of natural gas in China, Chinese government and petroleum companies are attaching more and more attention on shale gas development
The results show that the desorbed gas extends the time for fluid to flow from matrix system to fracture system; the changes of Langmuir volume and Langmuir pressure associated with desorption and adsorption effect are the internal causes of the storativity ratio change; when the tangential momentum accommodation coefficient decreases, the time for pressure wave to spread to the border reduces; interporosity flow coefficient determines the occurrence time of the transition stage; boundary range restricts the time for pressure wave to spread to the border
With the tangential momentum accommodation coefficient decreasing, the concavity in the typical curve deviates to right and becomes shallower, and the time for pressure wave to spread to the border reduces
Summary
With the successful development of shale gas in North America and the sharp increase in demand of natural gas in China, Chinese government and petroleum companies are attaching more and more attention on shale gas development. In their study shale gas adsorption and desorption were considered [2]. Some scholars established a new gas well productivity formula. In their study, they considered the effect of artifici al fracturing effect and gas slippage effect. To fully understand the mechanism of seepage in shale-gas reservoir, observation of nano-pores is dispensable. Javadpour (2009) used nanoscope to observe nano-pores in the shale-gas reservoir. He calculated the apparent Darcy permeability, while considering Knudsen diffusion. Shabr et al (2011) introduced a new surface mass balance law to model transient desorption In his research, he studied nanoscale seepage mechanism in pores, while considering Knudsen diffusion and Langmuir desorption. WANG i.e. storativity ratio, Langmuir volume, Langmuir pressure, adsorption-desorption, tangential momentum accommodation coefficient, flow coefficient, boundary
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
