Predicting borehole stability before drilling by seismic inversion

The new model of predicting borehole stability before drilling was presented using seismic interval velocity inversion to control borehole instability effectively.The prediction model was based on logging constrained inversion method using convolution model.Based on the seismic information and constrained logging and geological data in prospecting area,horizon calibration by compiling synthetic seismic record and construction of initial wave impedance model were important factors in this technique.An ultimate wave impedance model and velocity data with high resolution could be obtained using broadband constrained inversion.The borehole stability prediction before drilling could be achieved based on inversion result and prediction models such as statistics model,trend surface model,neural network model and rock mechanics model.The interval velocity curve and safe drilling fluid density range of a exploration well in Tarim Oilfield have been predicted using the new method.Comparison of prediction result and field data indicate that the proposed method has the high accuracy and can meet the engineering requirement.