Prospects of geochemical monitoring on the basis of borehole oil samples at bypassed oil reserves localization

Abstract

© 2020 International Multidisciplinary Scientific Geoconference. All rights reserved. During the oil field development process some of productive formation areas remain undrained which brings to decrease of total recovery factor. Conventional methods of reservoir development control including well testing, tracer studies as well as reservoir simulation have significant limitations when analyzing the inter-well space. To localize oil saturated undrained areas in the inter-well space, it is necessary to develop new approaches, and one of them may be the geochemical survey based on analysis of gas components dissolved in oil. Many authors have shown that the composition of oil and gas dissolved varies during field development process. For such components as isobutane and butane (and their ratio) these variations can be explained by microbiological activity. Based on the above-mentioned regularities, it is assumed that it is possible to detect the presence of remained oil reserves in the inter-well space. The perspective approach proposed is based on continuous isobutane-butane ratios survey in the produced hydrocarbons. Such studies are promising for large mature production fields, where water flooding was extensively applied. The terrigenous deposits of the upper Devonian of the giant Romashkino oil field are selected as the object under consideration. Today, the field is at the last stage of development and the search for oil-saturated areas that are not affected by development in the Devonian deposits has become an urgent task. In this article, the zonation of the isobutane-butane ratio and the dynamics of change are analyzed. A strategy for searching for bypassed oil areas has been developed.