Impact of clay stabilizer on the methane desorption kinetics and isotherms of Longmaxi Shale, China

Abstract

Knowing methane desorption characteristics is essential to define the contribution of adsorbed gas to gas well production. To evaluate the synthetic effect of a clay stabilizer solution on methane desorption kinetics and isotherms pertaining to Longmaxi shale, an experimental setup was designed based on the volumetric method. The objective was to conduct experiments on methane adsorption and desorption kinetics and isotherms before and after clay stabilizer treatments. The experimental data were a good fit for both the intraparticle diffusion model and the Freundlich isotherm model. We analyzed the effect of the clay stabilizer on desorption kinetics and isotherms. Results show that clay stabilizer can obviously improve the diffusion rate constant and reduce the methane adsorption amount. Moreover, we analyzed the desorption efficiency before and after treatment as well as the adsorbed methane content. The results show that a higher desorption efficiency after treatment can be observed when the pressure is higher than 6.84 MPa. Meanwhile, the adsorbed methane content before and after treatment all increase when the pressure decreases, and clay stabilizer can obviously promote the adsorbed methane to free gas when the pressure is lower than 19 MPa. This can also be applied to the optimization formulation of slickwater and the design of gas well production.