New Integrated Analytical Approach for Multiphase Inflow Performance Relationship

Abstract

This paper introduces an analytical approach for generating the inflow performance relationships (IPR) of different reservoirs depleted by different wellbore types at different conditions. The main focus of this paper is given to multiphase flow (oil, gas, water) and two-phase flow (oil, gas) during transient and pseudo-steady state flow conditions. The proposed approach presents new integrated models for the IPR that correlates the wellbore pressure with the multiphase total flow rate or the normalized pressure and rate by the bubble point pressure and single-phase flow rate at this pressure. These models consider the changes in reservoir fluid physical properties and reservoir relative permeabilities by coupling PVT data and relative permeability curves. The motivation of this study is reducing the uncertainty in the IPR of reservoirs undergoing the multiphase flow. Predicting multiphase IPRs may go throughout three tasks. The first is developing the pressure functions of reservoir mobility and total compressibility by developing several correlations for reservoir fluid properties such as oil, gas, and water formation volume factor as well as gas solubility in oil and water. Several correlations are needed also for relative permeability behavior of the three fluids with the pressure. These correlations can be generated by the multi-regression analysis of PVT data and relative permeability curves. The second represents developing the analytical models for the flow regimes that could be developed during the entire production life of the reservoirs. The single and multiphase flow IPRs for different flow regimes are predicted in the third task. The proposed IPR in this study is plotted between the wellbore pressure and the total flow rate at reservoir condition or the normalized reservoir pressure and flow rate. The observations obtained from this study are: 1) The proposed approach for the multiphase flow IPRs is not only time-variant but also depends on the flow condition whether transient or pseudo-steady state flow. 2) The IPR of the multiphase flow gives lower performance than the single-phase flow. 3) The IPR of the early time transient production is better than the late time pseudo-steady state production. 4) It is highly recommended to develop the models of fluid properties for each reservoir instead of using the models presented in the literature. The novel points presented in this paper are: 1) Introducing a new approach for the inflow performance relationships in the reservoirs experiencing multiphase flow and depleted by horizontal wells or multiple hydraulic fractures. 2) Introducing the pressure functions of the multiphase flow reservoir mobility and multiphase flow total reservoir compressibility that consider the changes in reservoir fluid properties and relative permeabilities with production time and pressure in constructing the IPRs.