Dynamic seismic imaging driven by logging while drilling in ultra-deep targets

The ultra-deep oil and gas targets are usually overlaid by extremely thick and complex media. The velocities of seismic waves estimated from the observed data at the surface easily deviate from the true values in the subsurface, which will lead to inaccurate seismic imaging and thus significantly increase the risk and cost of deep well drilling. Improving migration velocity model with the interval velocity obtained from well logging while drilling can drive prestack depth migration of the next round and reduce well-seismic mis-tie. Accordingly, we can relocate deep target and timely adjust the rest drilling trajectory. To meet the above requirements, we introduce a dynamic seismic imaging method driven by the logging while drilling technology. First, contrained by the relative geological time (RGT) volume, the migration velocity model around the well is updated according to the difference between Backus average of logging velocity and migration velocity at the well location. Then, the seismic imaging volume ahead the drill-bit is updated before the next drilling stage by combining wave-equation-based redatuming and local 3D prestack depth migration, which are leveraged by the massively parallel architecture of graphic processing units (GPUs) to accelerate the computation. The simulation test with the field seismic data and well-log velocity demonstrates the validity of the proposed approach, and reveals the potential to support intelligent drilling of the ultra-deep targets.