Evaluation of the economic efficiency of the WAG process based on experimental data for one of the domestic oil fields

Abstract

The challenge related to the need for an increase of the recovery factor concerns numerous mature, also domestic oilfields, including the most important ones – located in Main Dolomite formation. Satisfactory recovery factor can be ensured only through applying an effective enhanced oil recovery method (EOR). Water Alternating Gas (WAG), as one of the most effective EOR methods, has been tested in conditions characteristic for domestic deposits in carbonate formations. The results of experimental and simulation works carried out at the Oil and Gas Institute (INiG – PIB) indicate significant potential for the application of the WAG method in domestic conditions. An unquestionable advantage of the WAG method is the opportunity to utilize various types of gases, including flue/waste gas or low-energy natural gas. This issue deserves special attention because, as we know, the reduction in the emissions of gases involved in global warming is critical for the future of our planet. Their utilization in EOR methods, coupled with their safe storage in geological structures, constitute measures that reduce the environmental footprint of produced oil. In the article, based on the of experimental results, a simplified economic analysis of the utilization of four gas types in the form of acidic gases (carbon dioxide and its mixture with hydrogen sulfide) and natural gases (high and very high nitrogen content) in the WAG method was carried out. That allowed to identify the most economically optimal variants of the WAG method. The results showed that despite significantly lower effectiveness of nitrogen-rich natural gases in enhancing oil recovery (in the context of recovery factor), their application might be justified in economic terms. The selection of the optimal variant for enhancing recovery is strongly influenced by the assumed (current) cost of acquiring the injected media, and of course by the current (and forecasted) crude oil price.