COMPUTER MODEL SIMPLIFIES GAS FIELD PRODUCTION FORECASTING AND DEVELOPMENT PLANNING

Abstract

Production forecasting of gas fields with complex gathering systems and facilities can be a daunting task. Each individual well and reservoir has its own characteristics which, when combined with connecting pipework and production equipment, creates a highly interrelated network. To obtain meaningful results from reservoir studies, gathering system or production facilities design, the simulation of each segment must be integrated in such a manner that gas flows and pressures are balanced at each node. With the use of a computer model, the task of matching gas well deliverability and production facilities is made easier for gas fields in the Surat/Bowen Basin and Denison Trough.

The computer model takes a rigorous approach to gas field deliverability by simultaneously considering a nodal analysis of all reservoirs, wells, piping, compressors, and gas plants. By subjecting the total system description to a calculation procedure that integrates the various components, the influence of a modification to any one component is properly taken into account throughout the entire system. Consequently, variations in line sizing and loops, compressors, infield drilling, and combinations of these can be fully evaluated and optimised.

Accurate simulation results are achieved for Surat Basin gas fields by performing comprehensive field pressure surveys of the gathering system and by history matching previous years' production. The model accepts a description of the development strategy for the field so it can selectively commission compressors and tie-in new wells in order to meet projected sales contracts. The result is a complete simulation of the gas field including a calculated schedule for future development which is essential to evaluate the economic feasibility of different field development scenarios.