岩石含水率对微波穿透深度的影响

Influences of the rock water cut on the penetrated depth of the microwave

微波辅助破岩技术是近年来正在研究的一项钻井提速新技术,有着巨大的技术优势。实际微波钻井过程中,岩石含水率的变化会造成微波对岩石穿透深度的差异,从而影响微波破岩效率。以216mm空气钻井为载体,建立井眼微波照射岩石模型,选取大庆砂岩为研究对象,通过理论分析和数值仿真方法研究了砂岩含水率对微波穿透深度和能量利用率的影响。结果表明,随着砂岩含水率从4%增加到32%,频率为2.45GHz的微波穿透深度从18.5mm减小到8.4mm,微波能量利用率从54.78%降低到28.72%。由于数值仿真考虑了岩石加热后内部的热传递作用,获得的结果更接近于真实情况。该仿真方法可提前预测微波对不同含水率岩石的穿透深度,为微波辅助破岩钻井提速优化设计提供了理论依据。

Microwave-assisted rock breaking technique is currently studying new drilling-speed enhancing technique, which is with a huge technical advantage.In the process of the actual microwave drilling, the change of the rock water cut will cause the difference of the microwave penetrated depth and affect the efficiency of the microwave breaking rock. Taking216 mm air drilling as the carrier, the model of the borehole microwave irradiation rock was established, and moreover choosing Daqing sandstone as the studying object, with the help of the theoretical analysis and numerical simulating method, the influences of the sandstone watercut on the microwave penetrated depth and energy utilization were researched. The results show that with the rise of the watercut from 4% to 32%, the penetrated depth of2.45 GHz microwave decreases from18.5 mm to 8.4 mm, and the microwave energy utilization decreases from 54.78% to28.72%. Because the inner heat transferring action was considered in the numerical simulation after the rock was heated, the obtained results were closer to the real situation. Therefore, the simulating method can be used to predict the microwave penetrated depth in advance for the rocks with different watercuts,and furthermore can provide the theoretical evidence for the velocity-enhancing and optimizing designs of the microwave-added drilling.