Evolution of the Oil Shale Permeability under Real-Time High-Temperature Triaxial Stress in the Jimusar Area, Xinjiang

Lusheng Yang,Peng Li,Afshin Davarpanah

doi:10.1155/2021/7068973

Abstract

This paper adopts a real-time high-temperature triaxial seepage test system to study the permeability evolution of oil shale in the Jimusar area, Xinjiang, with the temperature, pore pressure, and volumetric stress. The results indicate that (1) the variation process of the oil shale permeability with the temperature can be divided into three stages: slow growth stage from 20 to 350°C, rapid growth stage from 350 to 500°C with a threshold temperature of 400°C, and growth deceleration stage from 500 to 600°C. (2) With increasing pore pressure, the permeability gradually decreases. Under a volumetric stress of 17 MPa, the permeability decreases the most rapidly from 1 to 2 MPa, and under a volumetric stress of 34 MPa, the permeability decreases the fastest from 1 to 3 MPa. (3) The oil shale permeability decreases with increasing volumetric stress. At room temperature, the decrease magnitude of the permeability is small and increases with increasing temperature. The results can provide a theoretical reference for the analysis of the seepage process of thermal fluids and pyrolysis oil and gas in oil shale.

Highlights

IntroductionOil shale is a kind of sedimentary rock containing organic matter (kerogen) with a low permeability
Oil shale is a kind of sedimentary rock containing organic matter with a low permeability
A real-time high-temperature triaxial permeability testing system independently developed by the Taiyuan Institute of Technology is employed to simulate the in situ high-temperature oil shale environment, and the variation in the oil shale permeability with the temperature in the Jimusar area of Xinjiang under real-time high-temperature triaxial stress conditions is obtained

Summary

Introduction

Oil shale is a kind of sedimentary rock containing organic matter (kerogen) with a low permeability. The utilization of oil shale can be divided into two types: ground dry distillation furnace pyrolysis and in situ thermal injection pyrolysis Among these methods, ground dry distillation faces the environmental problems involving the three waste materials, including wastewater, waste gas and waste residue, and the economic problem of a low mining efficiency [5]. In situ thermal injection oil shale mining can effectively solve the above environmental problems [6], which have attracted the attention of a large number of scholars in China and abroad. Among these scholars, Zhao et al of the Taiyuan University of Technology proposed the method of in situ steam injection for oil shale production [7]; the core of which entails the efficient injection of hightemperature superheated steam via thermal injection wells into oil shale layers. Studying the evolution law of the oil shale permeability under realtime high-temperature conditions is helpful to determine how to efficiently inject high-temperature steam into oil shale layers

Methods

Results

Discussion

Conclusion