Assessing the application of miscible CO2 flooding in oil reservoirs: a case study from Pakistan

Amanat Ali Bhatti,Syed Mohammad Mahmood,Arshad Raza,Raoof Gholami

doi:10.1007/s13202-018-0504-x

Abstract

Miscible carbon dioxide (CO2) flooding has been recognized as a promising approach to enhance the recovery of oil reservoirs. However, depending on the injection strategy and rock/fluid characteristics, efficiency of the miscible CO2 flooding varies from reservoir to reservoir. Although, many studies have been carried out to evaluate the performance of the miscible CO2 flooding, a specific strategy which can be strictly followed for a hydrocarbon reservoir has not been established yet. The aim of this study is to assess one of Pakistan’s oil reservoirs for miscible CO2 flooding by applying a modified screening criterion and numerical modeling. As such, the most recent miscible CO2 screening criteria were modified, and a numerical modeling was applied on the prospective reservoir. Based on the results obtained, South oil reservoir (S3) is chosen for a detailed assessment of miscible CO2 flooding. It was also found that implementation of CO2 water-alternating gas (CO2-WAG) injection at early stages of production can increase the production life of the reservoir.

Highlights

Major oil reservoirs around the globe have an average recovery factor of 20–40% (International 2006; Sandrea 2007)
The aim of this paper is to show how oil fields can be screened for miscible C O2 flooding and why an optimum injection strategy must be chosen for production enhancement
Preliminary screening for CO2-EOR is an essential step to determine a suitable oil reservoir for a detailed assessment

Summary

Introduction

Major oil reservoirs around the globe have an average recovery factor of 20–40% (International 2006; Sandrea 2007) As such, their complete development often requires secondary recovery (injection of gas or water), and tertiary/enhanced oil recovery (EOR) methods (injection of miscible/immiscible fluids, chemical or thermal) (Orr et al 1982). The most common EOR methods were established in the early 1970s (Muggeridge et al 2014) and are further classified into gas, chemical and thermal. To optimize recovery of miscible CO2 flooding, continuous CO2 injection (CCO2) and CO2 water-alternating gas (CO2-WAG) injection are often used as well-known injection strategies (Caudle and Dyes 1958). The results of statistical analysis showed that the CO2-WAG is very suitable and cost effective compared to the C CO2

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Conclusion