Seismic provides critical information for drilling, such as 3D structural images showing geological targets or hazards and formation properties relevant to drilling such as pore pressure. However, pre-drill estimates of formation pressures and structural depth images typically have large uncertainties. These uncertainties present drilling risks and could increase the cost of wells in the deepwater and other drilling environments. We present a new method that reduces the uncertainty up to large distances ahead of the bit by optimally integrating existing seismic data with new information acquired in real-time from the well being drilled.

Often the pre-drill seismic earth model remains mostly unchanged during drilling even though real-time LWD data contain significant new information about the formations being drilled. Real-time checkshot measurements provide constraints for the velocity model, real-time logs reveal formation tops, and other while-drilling information such as pressure measurements, mud weights, tests, and drilling events can be used to calibrate the earth model.

Recent advances in acquisition, processing, and integrated earth model building technologies have made this type of utilization of seismic and while-drilling well data to provide results in time for drilling decision making a reality. Results of two field tests are presented. First field work shows the ability of the technique to image a fault accurately in 3D space. The second field work demonstrates the ability to predict pore pressures up to 3000 ft ahead of the bit. Predicted pore pressures were within 0.25 ppg of the actual measured formation pressures.

You can access this article if you purchase or spend a download.