EXPLORING THE POTENTIAL FOR OPERATIONAL OVERSIGHT OF REMAINING RECOVERABLE RESERVES THROUGHOUT VARIOUS PHASES OF OIL PRODUCTION FACILITY DEVELOPMENT
Authors: Gasham Zeynalov, Vafadar Gachayev Gasham Zeynalov, Vafadar Gachayev 
Published: July 2024

Assessing oil recovery rates through geological and hydrodynamic modeling incurs significant financial and time investments. Consequently, recalculations of recoverable hydrocarbon reserves occur infrequently, leading to potential discrepancies between approved factors and actual conditions. To ensure accuracy in assessing residual recoverable reserves, it's crucial to promptly monitor the validity of oil recovery factors, especially concerning their achievability within specific timeframes. This article examines the practice of annually assessing geological and economic reserves according to international standards. Operational monitoring methods include analog-statistical techniques, displacement characteristics, and production decline rate analysis, each reliant on initial data quality and production object development stages. The effectiveness of these methods is illustrated through specific examples. Analog-statistical dependencies, tailored to operational facilities' geological indicators, prove most effective for early-stage development. In advanced stages, methods based on displacement characteristics and production decline rates gain reliability, factoring in economic development profitability limits. Statistical dependencies incorporating technological indicators can enhance control measures. Integrating diverse methodological approaches ensures a more dependable assessment of production object residual recoverable reserves.
When determining residual recoverable reserves and designing the development of oil fields, the main characteristic that determines the reliability of forecast calculations is the accuracy of estimating the oil recovery factor. The value of the oil recovery factor characterizes the share of initial recoverable reserves that can be extracted from the subsoil from the initial geological reserves when developing a deposit using modern proven technology and production techniques to the limit of economic profitability while complying with the requirements of subsoil and environmental protection. The most common method for estimating the oil recovery factor is digital geological-hydrodynamic modeling, in which the processes occurring during the development of oil deposits are simulated using software. This method has been introduced in the Russian oil industry since the mid-90s. XX century, recommended for use by current regulations [1].
Based on digital geological and hydrodynamic modeling, various options for the development of oil deposits are calculated, differing in the number of production and injection wells, the rate of reserve withdrawal, etc. Examples of the effective use of digital geological and hydrodynamic modeling in designing the development of oil fields are given in works [2–4], in including for the territory of the Perm region [5–10]. The most economically feasible option for field development is approved by the authorized government bodies, and each production facility is characterized by a design oil recovery factor. There is no doubt that the construction of digital geological and hydrodynamic modeling in the presence of standard geological and technological data is the most reliable way to determine the oil recovery factor. However, this method requires very large financial and time costs, which leads to significant time intervals between calculations of the Oil Recovery Factor, which in most cases exceed 10 years. As a result, over time, the approved Oil Recovery Factor may significantly lose relevance both due to the discrepancy between the design development indicators and the actual ones, and due to changes in the economic conditions of development. Taking this into account, it is extremely important for production facilities to quickly monitor the validity of the Oil Recovery Factor, including its objective achievability in a specific time frame.
Keywords: Remaining recoverable reserves, efficiency of oil extraction, operational facility, design of oil field development, evaluation of geological and economic reserves, displacement patterns, decline in oil production rate.