A close look at the H-C phase Diagram and Hydrocarbon Reservoir Classification and Behavior

Abstract

H-C phase diagram of reservoir fluids is an important tool used in explaining reservoir fluids behavior during the life period of any reservoir. In this paper, detailed analysis of certain terms of the Pressure–Temperature Diagram (P-T diagram) are presented and discussed. Some of these terms are redefined since the already existing definitions does not fit all cases and conditions of reservoir pressure and temperature, and hence, new definitions are given to such terms so as to make them fit all possible conditions that might exist in the reservoir. Special attention was given to explain and analyze the phase behavior inside the phase envelope (two phase region) of the P-T diagram. Among such terms for example, new definitions and analysis are given to the quality lines to give them much more interest and importance in the P-T diagram as they should be given than just representing the percentages of both liquid and gas phases. The new given definition will open new interpretations and add more interesting and valuable importance to the quality lines. Another new definition is given herein to the Cricondenbar Pressure to make it fit all possible conditions on the P-T diagram since the existing definition does not fit all pressure and temperature conditions. This paper also include some explanations regarding the retrograde gas condensation process and region on the P-T diagram. Finally, the herein mentioned factors and definitions will add more important and wider interpretations and applications for the P-T Diagram for a better understanding of H-C reservoirs. Such interpretations might be applied, also to the fluid flow control inside the reservoir and in the choosing of the best EOR method to apply whenever and wherever it is necessary.