UPGRADE OF CONVENTIONAL RESERVOIR ENGINEERING METHODS FOR MANAGING DIFFICULT FIELDS; APPLICATION TO ZEIT BAY RESERVOIR

Abstract

This work presents an integrated approach, which upgrades the conventional reservoir engineering methods for managing difficult fields. The approach was successfully applied to set the management policy and future development plans for Zeit Bay field in absence of a working reservoir simulation model, in addition to the prevailing uncertainties and non-definition of several reservoir parameters causing severe limitations on the direct application of conventional methods.

Zeit Bay field is a complex combination drive reservoir, comprised of a tilted fractured granite (Basement) block on-lapped by a progressive sequence of Sandstones and Carbonates, with an overlaying sheet ofHammam Faraun (HF) and Sidri members of Belayim formation. The primary recovery mechanisms are mainly solution gas drive, gas cap

expansion, aquifer support and gravity drainage. This is in addition to a secondary recovery scheme of gas re-injection into the original gas cap . This complicated nature of the field, together with the data limitation and prevailing uncertainties restricting a reliable description of the Basement reservoir, was behind the non-availability of a representative reservoir simulation model.

With the gas and water breakthrough and its accompanying decrease in production, it became necessary to depend on the conventional reservoir engineering methods as the only alternative for reservoir management in the absence of a working reservoir simulation model.