Improving PVT Laboratory Measurements: A Guide to Best Practices

Abstract Accurate reservoir fluid characterization relies on minimizing subjective modifications of laboratory measurements using Equations-of-State (EOS). When PVT laboratories encounter unreliable data and lack sufficient oil volumes for re-testing, they often rely on adjustments using EOS. This study proposes a comprehensive review of the PVT standard operating procedures, from sample collection to data reporting, to improve the accuracy and reliability of experimental data, eliminating the need for EOS adjustments and ensuring robust reservoir fluid characterization. Several key enhancements emerged from this proposal, aimed at optimizing laboratory measurements, data collection, verification, and calculations. Notably, these improvements include the implementation of a process-side gauge for accurate pressure measurements, standardizing volume measurement practices, refining equipment setup to achieve "stock tank stage" equilibrium at atmospheric pressure, and streamlining gas sampling processes for floating piston PVT-type cells. Furthermore, supplementary quality control checks are introduced to validate separator pressure and volume measurements at each stage, material balance, and dead oil volume determination. Implementing this proposed procedure will facilitate the straightforward application of raw data to calculate reservoir fluid PVT properties without modifications or EOS corrections. The proposed workflow delivers significant benefits including efficient use of valuable pressurized crude oil samples, and a considerable decrease in PVT experimental repetition rates. Notably, the primary goal of this proposal is to significantly decrease experimental repetition rates. Additionally, by eliminating EOS-based correction, the acquired data truly represents the intrinsic attributes of the reservoir fluids without any theoretical biases. Ultimately, the implementation of these insights enhances decision making in reservoir engineering applications. This study offers effective strategies to overcome equipment limitations. The adoption of the proposed equipment modifications and enhanced procedure enable both researchers and laboratory professionals to utilize best-in-class practices, thereby facilitating the generation of accurate and more reliable PVT laboratory data.