Pressure Regime Evaluation, Role and Contribution in Well Planning, Zeit Bay Field, Gulf of Suez, Egypt
By
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.