Reservoir Fluid Sampling and Characterization—Key to Efficient Reservoir Management

Abstract

Abstract Reservoir fluid properties play a key role in the design and optimization of production processes and facilities for efficient reservoir management. Inaccurate and unreliable fluid characterization leads to high uncertainties in in-place hydrocarbon volume estimates, negatively impacting ultimate recovery predictions and hence the asset value. Obtaining reliable PVT properties of reservoir fluids starts with the acquisition of adequate volumes of representative fluid samples followed by PVT data measurement and phase behavior modeling. Subsequent laboratory analysis should be monitored through established quality control procedures to provide high quality data. The fluid characterization methodology should employ best-practice techniques to model fluid behavior as functions of pressure, temperature, and fluid composition. In this paper, we discuss key steps in sampling and fluid characterization for a wide spectrum of fluid types ranging from extra-heavy oils to lighter gas-condensates including complex near-critical fluids. Using several field examples, sampling tool design and procedures for obtaining representative samples are discussed. Laboratory fluid analysis strategies for various fluid types are highlighted with an emphasis on employing quality control and quality assurance procedures. The importance of special PVT tests to capture fluid behavior under different production strategies ranging from simple depletion to complex tertiary recovery is emphasized. Application of recommended fluid modeling techniques such as C7+ characterization and Gibb's energy minimization are demonstrated through field examples.