Reserve Growth in Oil Fields of West Siberian Basin, Russia

Abstract

Although reserve (or field) growth has proved to be an important contributing factor in adding new reserves in mature petroleum basins, it is a poorly understood phenomenon. Although several papers have been published on the U.S. fields, there are only a few publications on fields in other petroleum provinces. This paper explores the reserve growth in the 42 largest West Siberian oil fields that contain about 55% of the basin's total oil reserves. The West Siberian oil fields show 13-fold reserve growth 20 years after the discovery year and only about 2-fold growth after the first production year. This difference in growth is attributed to extensive exploration and field delineation activities between discovery and the first production year. Because of the uncertainty in the length of evaluation time and in reported reserves during this initial period, reserve growth based on the first production year is more reliable for model development. However, reserve growth models based both on discovery year and first production year show rapid growth in the first few years and slower growth in the following years. In contrast, the reserve growth patterns for the conterminous United States and offshore Gulf of Mexico show a steady reserve increase throughout the productive lives of the fields. The different reserve booking requirements and the lack of capital investment for improved reservoir management and production technologies in West Siberia are the probable causes for the difference in the growth patterns. The models based on the first production year predict that the reserve growth potential in the 42 largest oil fields of West Siberia for a five-year period (1998–2003) ranges from 270–330 million barrels or 0.34–0.42% per year. For a similar five-year period (1996–2001), models for the conterminous United States predict a growth of 0.54–0.75% per year.