Pressure Regime Evaluation, Role and Contribution in Well Planning, Zeit Bay Field, Gulf of Suez, Egypt
Saber Moustafa Selim1, Bassem El-Sayed Badawy1
(1) Suez Oil Company (SUCO), Cairo, Egypt
The pressure regime evaluation is an integral part of the well planning and formation evaluation process. In order to drill a well safely and economically, it is necessary to know the pore pressure and fracture pressure so that the suitable mud density can be used. The pressure regime plays an important role in minimizing the drilling cost and assists in deciding where the well is placed, especially in Zeit Bay field which is considered as a multi reservoir and hydraulically communicated. Oil and gas can be driven upwards by buoyancy or horizontal and downwards by pressure differentials, so by avoiding those reservoirs at higher pressures the risk of drilling into overpressure can be reduced. It can, however, result in a dry hole by drilling into a reservoir where the hydrocarbons have been expelled. Offset data sets can be used to provide detailed profiles of expected pressures for well proposals. Also, seismic data, log information and direct pressure measurements can be used. This information, while extremely valuable, can be subjected to regional variations and should be considered as a guide. It is vital that during the course of a well methods be adopted to evaluate changes in the formation pressures. This “real-time” information can then be used to update the initial well prognosis. By using modern methods and industry accepted concepts, relationships between Petroleum Geology and Drilling Engineering can be interpreted to give accurate estimations of formation pressures at any point during the course of a well. In addition, mathematical models and algorithms can be used to predict formation fracture pressure following the first pressure integrity (Leak-Off) test in a competent formation.