Schlumberger

Technical Paper: Pore-Pressure Estimation Ahead of the Bit While Drilling by Seismic and Well Data Integration

Society: SEG
Paper Number: 2012-1138
Presentation Date: 2012
 

Pore pressure is one of the formation properties that have a direct impact on drilling and completion of wells. In particular, overpressure is one of the most common drilling hazards that present a safety risk and cost the industry large amounts of money every year.

Pre-drill estimates of formation pressures in a drilling location are made to help guide drilling plans. These estimates typically have large uncertainties. We present a method that reduces the uncertainty in formation pressures ahead of the bit by making optimum use of seismic data and new information obtained in real time from the well being drilled. During drilling adjustments are made to the rock-physics transform based on Logging While Drilling (LWD) data calibrating it to local geology. In addition, we show that the velocity estimates ahead of the bit are improved by integrating while-drilling checkshot information with surface seismic data.

Field study results from a Gulf of Mexico well show that this new method provides a significantly better formation pressure estimate ahead of the bit compared with pre-drill predictions.

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