EOR Development Screening of a Heterogeneous Heavy Oil Field - Challenges and Solutions

Abstract

This paper covers EOR development concept screening from a sub-surface perspective. The field in question is a medium sized heavy oil field with complex geology that is located in South Oman. The two front running concepts considered are steam and polymer flood, both of which present their own challenges. Common to both concepts are the difficulty in obtaining adequate conformance in a field that is characterised by high and highly variable permeabilities in a channelised environment and that includes lateral extensive shales that break the system up into vertically distinct sand units. Additional challenges are presented by a permeable regional scale aquifer, an erosive top surface that reduces the equivalent oil column (EOC) in the core of the field leaving thicker columns laterally close to the edge aquifer and the friable nature of the sand that makes sand control necessary. Challenges specific to steam are the relatively high initial pressure, inferred connection to a regional-scale strong aquifer, and relatively high CAPEX associated with the development. Polymer on the other hand represents a relatively untested option for oil with viscosities of greater than 400cP as are present in this field. Modelling work used to identify risks and the subsequent development potential of these two options is presented. Potential development and maturation solutions for the various options are discussed and concepts are compared.

Data Analysis and Updated Screening Criteria for Polymer Flooding Based on Oilfield Data

“…However, higher oil viscosities require higher polymer viscosities to improve the mobility ratio and displace more oil. The higher polymer viscosity can be achieved by three conditions-a higher-molecular-weight polymer to keep concentration low (Zaitoun et al 1998;Wang et al 2008); a higher polymer concentration to keep the same molecular weight (Asghari and Nakutnyy 2008;Hincapie et al 2011); and the use of low-salinity makeup water to prepare polymers (Strauss et al 2010). Increasing polymer viscosity reduces the injectivity; therefore, horizontal wells and hydraulically fracturing the formation near the wellbore if a reservoir has low mobility may be required to meet the injectivity requirement (Wassmuth et al 2007(Wassmuth et al , 2009Seright 2010;Strauss et al 2010;Chang 2011;Moe Soe Let et al 2012).…”

Experimental investigation of steam‐CO2‐foam flooding: combination of CO2‐foam flooding and steam injection as an effective enhanced oil recovery (EOR) method in heavy oil reservoirs

“…In addition, polymer may not to be able to flow through low permeability formation . Hence, polymer flooding is usually conducted in medium–light oil reservoirs with high permeability . In polymer flooding, injection is usually performed under high pressure conditions which may cause formation fracturing in shallow reservoirs .…”

Study on Flow Mechanism of Gas Injection in Porous Carbonate Core

“…Based on the determination of minimum miscibility pressure and swelling properties parameter variation study, gas flooding experiments for long core is carried out. Discussing whether the hydrocarbon gas injection is fit for Savark formation and exploring the optimization methods to enhanced oil recovery rate [4][5][6][7][8].…”