11. Reservoir Performance Prediction

Reservoir performance prediction is a key aspect of the oil and gas field development planning and reserves estimation which depicts the behaviour of the reservoir in the future; its success is dependent on accurate description of the reservoir rock properties, fluid properties, rock-fluid properties and flow performance. It therefore implies that engineers must have sound knowledge of the reservoir characteristics and production operations optimization and more importantly, to develop a mathematical model that will adequately depict the physical processes occurring in the reservoir such that the outcome of any action can be predicted within reasonable engineering tolerance of errors. Several Authors such as Muskat, Tarner’s, Tracy’s and Schilthuis developed a method of reservoir performance prediction based on material balance equation (MBE) by combining the appropriate MBE with the instantaneous GOR. These techniques are iterative and the calculations are repeated at a series of assumed reservoir pressure drops. These calculations are usually based on stock-tank barrel of oil-in-place at bubble point pressure and above the bubble point pressure, the cumulative oil produced is calculated directly from he material balance equations. In this chapter, the various mathematical models and algorithms for each technique are explicitly presented and validated with case studies. Also, at the end of the chapter, several exercises and references are given to further help strengthen readers understanding of the subject matter.