CO2 Well Injectivity: Effect of Viscous Forces on Precipitated Minerals

Abstract

TX 75083-3836, U.S.A., fax ϩ1-972-952-9435Abstract Carbon Capture and Storage (CCS) is particularly attractive for the oil and gas industry due to the potential of Enhanced Oil Recovery (EOR). The presence of adequate well injectivity is identified as a prerequisite for CCS and CO 2 EOR projects. Mineral precipitation in the vicinity of the well is suggested as a possible injectivity impairment mechanism. After mineral precipitation and formation dryout, continuous injection of CO 2 into the formation could redistribute precipitates and alter injectivity. In this work, we investigated the effect of viscous force on precipitated minerals and the resulting consequences on permability and injectivity. The influence of supercritical CO 2 injection rate, initial core permeability and saturating brine salinity were investigated. We observed that, injectivity impairment has a maximum immediately after mineral precipitation. Continuous injection of supercritical CO 2 into the core after mineral precipitation is seen to reduce injectivity impairment induced by precipitated minerals. In most numerical and geochemical models, static injectivity impairment as a result of mineral precipitation is often assumed. Our findings suggest that injectivity remains dynamic throughout the injection process. Therefore, changes in CO 2 injectivity after mineral precipitation could be complex to model and understanding of the processes is a good point to start.

Carbon Capture and Storage in Depleted Oil and Gas Reservoirs: The Viewpoint of Wellbore Injectivity

“…The porosity and permeability of the reservoir are increased when rock minerals dissolve, whereas they are decreased when carbonate or sulfate compounds precipitate [49]. Sokama-Neuyam and Ursin's [99] study presents evidence that mineral dissolution negatively impacts CO 2 injectivity, reducing the efficiency of CO 2 injection. Injectivity impairment experienced a reduction of 9% when brine salinity was halved.…”

“…Injectivity impairment experienced a reduction of 9% when brine salinity was halved. The experimented sample belonged to Kocurek Industries, Caldwell, TX, USA, and the impairment of injectivity was measured via the pressure drop measurements [99].…”

Well Injectivity during CO2 Geosequestration: A Review of Hydro-Physical, Chemical, and Geomechanical Effects

“…Among the proposed storage sites, the potential of deep saline aquifers is believed to be higher, due to their wider geographical spread and larger capacities. − In a recent study, it is estimated that, theoretically, aquifers benefit from much larger CO 2 storage capacity balanced against other geological candidates (9500 gigatons in aquifers compared to 820 and 120 gigatons in depleted hydrocarbon reservoirs and coal seams, respectively) . However, CO 2 storage into aquifers is of a greater complexity, as it causes various hydro-physical, chemical, and geomechanical interactions that affect the injectivity of wellbores. − …”