Abstract

Supercritical carbon dioxide (SC-CO2) jet can break rocks with higher rates and lower threshold pressures than water jet due to the unique fluid properties. The abrasive SC-CO2 jet technique, which is formed by adding abrasive particles to the SC-CO2 jet, was proposed and studied. It is expected to achieve better cutting performance than water jet and SC-CO2 jet. Considering the low fluid viscosity, whether the SC-CO2 jet has satisfactory particle carrying capacity has to be determined. In effort to investigate the motion of the abrasive particle and the feasibility of abrasive SC-CO2 jet, numerical simulations on the flow field of the jet under different ambient conditions were carried out, as well as the comparisons with another three particle-laden jets. The results show that SC-CO2 jet has better particle carrying capacity than the other three fluids. Moreover, temperature rise slightly impairs the capacity meanwhile both the fluid and particle velocities increase, exerting better impinging effect of the abrasive jet. Besides, SC-CO2 jet can fully carry particles with the diameter in the range of 0.1~2.4mm to form the abrasive SC-CO2 jet. Particles with larger diameter will obtain higher impinging velocity on the impinged target.

1. INTRODUCTION

Inman [1] pointed out that the large-scale, multi-stage hydraulic fracturing, coupled with horizontal drilling, has led to a boom of the development of the shale gas in the US and may help achieve "a thriving US economy" in the future. However, Hughes [2] assumed that it will also bring difficulties like sustainability, high cost, water contamination and other environmental concerns and so forth. Likewise, according to EIA [3], shale gas industries in China in early stages of development are facing both technical and water resource challenges, in addition to the difficult terrain and high overall costs. Considering the huge consumption and exploration of natural gas worldwide, Wang et al [4] thought that it is in urgent need to make progresses in operating fluids. According to Rogala et al [5], emphasis has been placed on the alternatives to hydraulic fracturing or the non-aqueous fracturing technologies due to its technical and environmental advantages. Among the fluids, supercritical carbon dioxide (SC-CO2) is hopeful to replace water as a drilling fluid or the abrasive-laden fluid in hydraulic fracturing in shale gas development.

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