Experimental studies of CO2-brine-rock interaction effects on permeability alteration during CO2-EOR

Mohammad Reza Okhovat,Behzad Rostami,Maryam Khosravi,Kamran Hassani

doi:10.1007/s13202-020-00883-8

Abstract

Carbon dioxide (CO2) sequestration through CO2 enhanced oil recovery (EOR) in oil reservoirs is one way to reduce this gas in the atmosphere. Undesirable chemical reactions that occur during these operations can affect the reservoir structure and characteristics. In this study, the effect of CO2-water-rock interaction on the rock permeability alteration and final oil recovery has been evaluated experimentally during CO2 injection into a carbonate rock. The effect of flow rate, displacement type and pressure were investigated during CO2 EOR injection. Different scenarios of miscible/immiscible displacement, secondary/tertiary recovery has been evaluated for different levels of connate water salinity and injection rate. The results show that the severity of damage is directly related to the injection rate, however change in displacement type from miscible to immiscible reduce the intensity of chemical reactions in porous medium. Moreover, in the tertiary CO2 injection, the chemical reactions become more severe due to the higher water saturations. Interestingly, this growth in the level of chemical reactions has a negligible impact on permeability reduction, since the major volume of possible reactions occurs in coarse and high permeable pores. Results reveal that damage is more intense in the case of more saline water.

Highlights

Greenhouse gas emissions have raised concerns about rising global temperatures
After water flooding of oil reservoirs, CO2 injection can be considered as a proper candidate for tertiary enhanced oil recovery (EOR) as it helps to decrease CO2 atmosphere (Aycaguer et al 2001; Beckwith 2011; Han et al 2016; Eliebid et al 2017; Hamid et al 2017). CO2 injection method has been studied in various light and heavy oil reservoirs (Mangalsingh and Jagai 1996; Nobakht et al 2007; Ghedan 2009; Zekri et al 2013; Ma et al 2016; Seyyedsar et al 2016)
We performed various experiments to investigate the effect of CO2 injection on permeability alteration of carbonate rocks

Summary

Introduction

Greenhouse gas emissions have raised concerns about rising global temperatures. To reduce greenhouse gas emissions such as C O2, researchers have proposed solutions such as storage of this gas in underground formations. In the process of C O2 injection into aquifer formations in order to sequester this gas, the reaction between the CO2 and the aquifer formation plus the salts present in the environment yields acids and soluble as well as insoluble compounds in the formation depending on the type of salt. This can affect the formation and change its petrophysical characteristics by activating the dissolution and sedimentation processes. During the secondary or tertiary recovery of oil by CO2, such reactions can be repeated by the interaction between CO2 and formation water

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Results

Conclusion