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

Key words:  steerable drilling  optimization  geomechanical characterisation  borehole stability  model correction while drilling

Abstract:

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.