An efficient semi-analytic multi-phase simulator for complex reservoirs

Recent advances in microcomputer technology, combined with modern reservoir pressure transient analysis techniques have provided the means for the development of accurate and computationally efficient reservoir transient analysis simulation models. These models may be used to analyze or predict the pressure or rate transient performance of a well which is completed in a reservoir which may contain a number of reservoir complexities.; This dissertation presents the results of research conducted during the development and testing of a multi-phase, semi-analytic reservoir simulator. This research has resulted in the development of new computational techniques for analyzing the performance of wells completed in complex reservoirs. The new developments include techniques for computing the fluid saturation and pressure profiles in reservoirs in which multiple mobile fluid phases are present. The simulator has been developed for predicting the performance of vertical and vertically fractured wells.; The reservoir simulator developed during this research is computationally efficient and has been used on mainframe and personal computers. Ideal applications for this simulator are cases in which the quality and/or quantity of the reservoir simulation input data does not warrant the use of a more sophisticated simulator. The semi-analytic simulator can be used to perform preliminary or sensitivity analyses of the reservoir simulation data. Performing the preliminary analyses with the semi-analytic simulator generally reduces the time required to history match production data from complex reservoirs. Some reservoir complexities which hinder efforts to history match production data are layered reservoir effects and multi-phase flow. Simulation of the performance of reservoirs with these complexities may require weeks or months to adequately perform using a finite difference simulation model.; The Gas Research Institute (GRI) has funded a significant amount of reservoir research using finite difference simulation models. The average engineer may often not apply this technology due to limited access to a finite difference simulation model or may lack the training necessary to use the model. This research was therefore funded by the Gas Research Institute to develop a personal computer model which engineers could readily use to analyze the performance of complex reservoirs.