Investigation of Trapped Oil Mechanisms and Opportunities for Improved Oil Recovery in Deepwater Gulf of Mexico

Abstract

Abstract Deepwater Gulf of Mexico oil fields (DW GoM) typically get modest ultimate recovery factors in the 10% - 35% range, because reservoirs tend to be small, deep, and complex. The remaining oil target for Improved Oil Recovery (IOR) is tempting large, with about 30 Billion Bbl estimated to be left in discovered fields at abandonment. Procedures on by-passed oil mechanisms analysis are based on analysis of field data compiled by Minerals Management Service, on data extracted from focused literature reviews, and on original work to analyze by-passed oil mechanisms and describe the remaining oil distribution in turbidite reservoirs of DW GoM. This paper describes a study on oil trapping mechanism, by-passed oil categories and their distributions. It is key part of study directed at recommending a select group of IOR processes for multi-million dollar research and development funding by Research Partnership to Secure Energy for America (RPSEA). The performance of 450 oil reservoirs in 83 deepwater Gulf of Mexico fields has been evaluated and characterized by geological setting, reservoir properties, and development constraints. The results have been used to estimate statistically the average oil recovery, prominent reservoir drive mechanisms, oil trapping due to structural and depositional complexity, and reservoir volume not connected to wells. The term "Trapped Oil Mechanisms" is used in this work to define the reasons for projected remaining oil in-place under current operating practices. In this paper we review the detailed assessment of several signicant reservoirs in two fields and then present the overall summary of trapped oil mechanisms for Neogene reservoirs in the deepwater Gulf of Mexico. The results of this work are being used to define IOR processes targeted at reducing the projected ROIP.