地质力学特征评价新方法在导向钻井优化中的应用

针对常规导向钻井技术在适用范围、预测能力与运行成本等方面的局限性,在考察岩石物理及力学参数和地球物理信息之间定量关系的基础上,将地震反演、地质统计、地震属性分析、岩石力学方法与钻井工程实际需求密切结合,提出地质力学特征评价新方法,基于其对导向钻井系统进行优化。新技术以常规地震和测井资料为基础,充分结合钻井、录井等实钻信息,钻前建立地质力学初始模型用于钻井设计,钻进过程中参考实钻资料随钻修正并更新钻前模型用于钻井工艺实时优化,其关键环节是准确预测钻头前方待钻地层的强度、地应力、孔隙压力、坍塌压力、破裂压力等力学参数。以井壁稳定预测及其工程运用为重点,论述导向钻井优化中岩石力学理论和地球物理算法结合运用的思路与技术流程,将该方法在西南、西北复杂探区进行应用。现场应用表明,优化的导向钻井系统可以达到理想的参数预测精度与工艺优化效果,指导安全、优质、快速、低成本钻井的能力得到了提高。

Application of a new evaluation method for geomechanical characterisation in optimizing steerable drilling technology

In consideration of the limitations of the conventional steerable drilling technology in terms of its application scope, forecasting ability and operation cost, a new evaluation method for geomechanical characterisation was proposed to optimize the steerable drilling system. The evaluation method is based on the quantitative relationships between the physical and mechanical parameters of rocks and the geophysical information, combining with seismic inversion, geological statistics, seismic attribute analysis, rock mechanics and the actual requirement of drilling engineering. The key of the optimized steerable drilling technology is to accurately predict the rock strength, in-situ stress, pore pressure, collapse pressure and fracture pressure of the formation based on conventional seismic and well logging data and by making full use of drilling and well log data obtained in real-time drilling process. Before drilling, an initial geomechanical model can be developed for drilling design, and during the drilling process, the initial model will be corrected and updated for real-time optimization of drilling technology measures. Emphasizing on the borehole stability prediction and its engineering application, this paper describes the ideas and operation process of the combination of rock mechanics theory and geophysical algorithm in the optimization of steerable drilling technology. It also presents the application of the optimized steerable drilling technology in complex exploration regions of southwestern and northwestern areas of China. The field application results show that the proposed technology can provide precise predictions of various drilling parameters and achieve effective optimization of the drilling process, and its capability for guiding safe, high quality, fast and low cost drilling has been improved.