Published December 2009

Prediction of sections characteristics based on technology data in case of Caspian cavity

S.K. Buktibayeva

Perspectives of oil and gas researches in Caspian cavity related to deeply submerged under-salt sediments of underpermsk, coal and devonian ages. However, as analysts states, drilling operations in Caspian cavity region coupled with significant problems. Taking into account geological structure complexity of Caspian region and the fact that section consist of rocks with different lithology, it’s necessary to conduct monitoring and forecast abnormal formation pressures while drilling using technological drilling parameters and drilling fluids characteristics. In the article are shown results of the analysis of intervals with abnormal high pore pressure and required drilling fluids densities based on data from wells projected and drilled in Tengiz, West Prorva, Aktum and Kokmay fields. Well designs have been adjusted based on results of the researches. There was an attempt made to forecast lithological and pressure characteristics of considered section for the purpose of adjustment design data. Using projected technological data pore pressure gradients, fracture gradients, appropriate mud weight were calculated. Calculations confirmed presence of abnormal high pore pressures at the depth below 2000 meters. Comparison the results of pore pressure calculations and seismic exploration data showed pretty close coincidence.