超临界二氧化碳射流冲蚀页岩实验研究

 超临界二氧化碳射流破碎页岩是一种极具前景的页岩气钻采方法。选取渝东南露头龙马溪组页岩，基于超临界二氧化碳射流破岩试验平台，开展不同冲击压力的超临界二氧化碳射流冲蚀页岩实验；采用CT、SEM/EDX、XRD、XRF等技术研究冲蚀前后页岩试样的变化规律。研究表明：(1) 所选页岩具有低孔、高黏土含量和层理平行发育等特性；(2) 超临界二氧化碳射流冲蚀后，页岩端面呈网格化破碎，整体呈大体积层状破碎；(3) 超临界二氧化碳对页岩矿物具有腐蚀作用，导致页岩微观结构发生改变，降低了页岩的物理力学特性，有助于射流破岩。

ON THE EROSION OF SHALE IMPACTED BY SUPERCRITICALCARBON DIOXIDE JET

Supercritical carbon dioxide(SC-CO2) jet breaking shale is a prominent shale gas drilling method. The shale sample of Longmaxi Formation was collected from southeast of Chongqing area. Based on the experiment platform of SC-CO2 jet breaking rock，the collected shale samples were impact by the SC-CO2 jets with varied jet pressures. The micro changes between original and eroded shale samples were studied utilizing CT，SEM/EDX，XRD and XRF methods. It’s indicated that the collected shale is characterized by low porosity，high clay mineral content and concordant bedding；impacted by SC-CO2 jet，the end face of shale core take on grid-like broken phenomenon，while it takes on large volumetric layered broken phenomenon on the whole；the erosion of shale mineral induced by SC-CO2 may caused the changes of micro-structure of shale，which may reduce mechanical strength of shale and is conducive to the rock breaking.