Prediction And Analysis Of Borehole Stability Based On Seismic Data

Wellbore stability is usually analyzed mechanically and chemically, and carried out after drilling. The prediction of borehole stability while drilling is mainly achieved through instruments, such as LWD. In view of LWD is too expensive, this paper presents a method to predict borehole stability while drilling based on geological statistical analysis.The paper firstly analyzes the seismic and logging data of drilled wells, obtains layered rock mechanics parameters from logging interpretation, and then through combination of geostatistical collocated co-Kriging simulation and sequential Gaussian simulation predicts the 3D data body of rock mechanics parameters for the whole block.According to the trajectory to be drilled, extract out the rock mechanics parameters of the wellbore trajectory and by use of collapse, fracture and pore pressure model, build corresponding stratified rock mechanics prediction model.During drilling, determine the layer that has been drilled to by cuttings logging, select the appropriate model for the layer to predict the three-pressure profiles for the formations to be drilled, and then adjust the properties of the mud to reduce the possibility of borehole instability. Meanwhile, the accuracy of prediction can be evaluated in comparison with logging data so as to timely adjust the parameters of the model, update and refine the model to improve prediction accuracy.