Experimental Determination on Shale Gas Loss During the Coring Process in Eastern Sichuan Basin

Junbo He,Dongxu Jin,Jing Zhang,Jiren Tang,Yuanfei Ling

doi:10.3389/fenrg.2020.00177

Abstract

Abstract: Shale gas loss by leakage directly affects the accurate measurement of shale gas content during drilling and coring. To accurately calculate shale gas loss, in combination with the actual situation of the shale coring, considering the influence factors of the main occurrence state of shale gas (free state and adsorption state), by means of treating the three stages of the shale well core removal, ground exposure, and water bath heating and desorption as a process of desorption that changes with confining pressure, an indoor shale gas loss simulation experiment method was independently designed to determine shale gas loss. Two groups of samples with large differences in physical properties in eastern Sichuan were selected for shale gas loss simulation experiment. We propose to use the error reduction rate of shale gas loss (the percentage of the difference between the shale gas loss obtained by simulation experiment method and that obtained by the improved USBM method and curve fitting method and the amount of gas loss of core injected) to verify the accuracy of simulation experiment method. The results show that compared with the improved USBM method, the average error reduction rate of cores were: 8.64%. Compared with the curve fitting method, the average error reduction rate of cores were 25.11%, which proved that shale gas loss simulation experiment method had higher accuracy.

Highlights

In recent years, shale gas has become a hot spot in energy research around the world because of its huge reserves and as it creates less pollution in the environment (Li et al, 2014)
Before the shale gas loss simulation experiment, most of the specimens were crushed to about 1 cm particles, while part of these samples about 10 g of particles about 2 mm size were used for methane isothermal adsorption testing and ASAP2020 testing
Isothermal Adsorption Tests The difference of bulk sample with a particle size of about 1 cm, powder with a particle size of 2 mm, and a standard cylindrical specimen ofφ50 mm × 100 mm at the same quality is that the degree of damage to the microstructure is different

Summary

Introduction

Shale gas has become a hot spot in energy research around the world because of its huge reserves and as it creates less pollution in the environment (Li et al, 2014). The resource quantity of gas in shales is a prerequisite for the efficient exploration and development of shale gas. True determination of the gas content in shale at a representative location is a necessary condition for exactly determining the resource amount of gas in shales. The quantity of shale gas loss directly affects the determination of shale gas content, and has a very important role in the exact evaluation of the resource quantity of gas in shales (Dong et al, 2012).

Methods

Results

Discussion

Conclusion