Development of More-Efficient Gas Flooding Applicable to Shallow Reservoirs. Semi-annual Report, January 1, 2002-June 30, 2002.

Rossen, W. R. ; Johns, R. T. ; Pope, G. A.

Technical Information Center Oak Ridge Tennessee

关键词: Enhanced recovery;    Oil recovery;    Floods;    Gas injection;    Gases;   

RP-ID  :  DE2004834333

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

The objective of this research is to widen the applicability of gas flooding to shallow oil reservoirs by reducing the pressure required for miscibility using gas enrichment and increasing sweep efficiency with foam. Task 1 examines the potential for improved oil recovery with enriched gases. Subtask 1.1 examines the effect of dispersion processes on oil recovery and the extent of enrichment needed in the presence of dispersion. Subtask 1.2 develops a fast, efficient method to predict the extent of enrichment needed for crude oils at a given pressure. Task 2 develops improved foam processes to increase sweep efficiency in gas flooding. Subtask 2.1 comprises mechanistic experimental studies of foams with N(sub 2) gas. Subtask 2.2 conducts experiments with CO(sub 2) foam. Subtask 2.3 develops and applies a simulator for foam processes in field application. Regarding Task 1, several very important results were achieved this period for subtask 1.2. In particular, we successfully developed a robust Windows-based code to calculate MMP and MME for fluid characterizations that consist of any number of pseudocomponents. We also were successful in developing a new technique to quantify the displacement mechanism of a gas flood--that is, to determine the fraction of a displacement that is vaporizing or condensing. These new technologies will be very important to develop new correlations and to determine important parameters for the design of gas injection floods. Regarding Task 2, several results were achieved: (1) A detailed study of the accuracy of foam simulation validates the model with fits to analytical fractional-flow solutions. It shows that there is no way to represent surfactant-concentration effects on foam without some numerical artifacts. (2) New results on capillary crossflow with foam show that this is much less detrimental than earlier studies had argued. (3) It was shown that the extremely useful model of Stone for gravity segregation with foam is rigorously true as long as the standard assumptions of fractional-flow theory apply. Without this proof, it was always possible that this powerful model would break down in some important application.