CO2-brine injectivity tests in high co2 content carbonate field, sarawak basin, offshore east Malaysia

A Giwelli,A Saeedi,M Myers,L Esteban,R Noble,M Ghasemiziarani,S Salwani Md Shah,Mz Kashim,Mb Clennell,C White,S Vialle,B Nicot

doi:10.1051/e3sconf/20198904005

Abstract

We conducted relatively long duration core-flooding tests on three representative core samples under reservoir conditions to quantify the potential impact of flow rates on fines production/permeability change. Supercritical CO2 was injected cyclically with incremental increases in flow rate (2─14 ml/min) with live brine until a total of 7 cycles were completed. To avoid unwanted fluid-rock reaction when live brine was injected into the sample, and to mimic the in-situ geochemical conditions of the reservoir, a packed column was installed on the inflow accumulator line to pre-equilibrate the fluid before entering the core sample. The change in the gas porosity and permeability of the tested plug samples due to different mechanisms (dissolution and/or precipitation) that may occur during scCO2/live brine injection was investigated. Nuclear magnetic resonance (NMR) T2 determination, X-ray CT scans and chemical analyses of the produced brine were also conducted. Results of pre- and post-test analyses (poroperm, NMR, X-ray CT) showed no clear evidence of formation damage even after long testing cycles and only minor or no dissolution (after large injected pore volumes (PVs) ~ 200). The critical flow rates (if there is one) were higher than the maximum rates applied. Chemical analyses of the core effluent showed that the rock samples for which a pre-column was installed do not experience carbonate dissolution.

Highlights

Carbon capture and storage (CCS) has been identified as transformative technologies to achieve deep reductions in CO2 emissions specified under the Kyoto Protocol
We aimed to evaluate the effect of supercritical CO2 flow rates on fines production/permeability change and particle mobilization caused by geochemical effects, which might occur during storage operations in a carbonate gas field with approximately 70% CO2 content located in East Malaysia’s waters
We examined the effect of supercritical CO2 (scCO2) flow rates on fines production/permeability change by looking for the minimum flow rate at which small particles detach and migrate within the pores of the formation

Summary

Introduction

Carbon capture and storage (CCS) has been identified as transformative technologies to achieve deep reductions in CO2 emissions specified under the Kyoto Protocol. Geological storage has been a major attractive options for CO2 disposal owing to its reasonable capacity, secure and longer retention times and technical feasibility [1]. Among all the elements that qualify geological media as viable storage options, injectivity is one of the key parameters that determine the success of CO2 storage in field operations. Within the constraint of maximum allowable wellhead pressure limits, a high injection rate is often desired. This might prompt injectivity-related problems due to: salting-out effects at the near-bore region due to brine vaporization by injected CO2 [2,3,4,5], multiphase-flow effects [6 and 7] and scale/fines formation and mobilization caused by geochemical effects and mechanical dragging [8]. No study has been reported investigating the injectivity issues for highly heterogeneous and complex carbonate fields, though there are some studies that have been conducted on parameterizing CO2 injectivity in carbonates [9,10,11,12]

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