An Experimental Study on Carbonated Water Injection of Core Samples from Tight Oil Reservoirs from Ordos Basin

Abstract

Carbonated water injection (CWI) is considered to be a win-win association for enhancing oil recovery and reducing environmental footprint. Therefore, the study of CWI potential has gained tremendous attention recently. Unfortunately, the dedicated research so far focus heavily on conventional reservoirs. In order to expand the application scope of CWI, the objective of this study is to carry out a coreflooding investigation of core samples from tight oil reservoirs. The experiments were carefully designed to assess the performance of CWI and to quantify the potential of additional oil recovery and CO2 storage capacity under various experimental conditions. We presented the results of a series of CWI coreflood experiments using the reservoir cores of tight sandstone with live crude oil. It is found that the ultimate oil recovery by CWI is higher than the conventional water injection in both secondary and tertiary recovery mode. The complex mechanisms are also investigated including CO2 content of injected carbonated water (CW), oil swelling and viscosity reduction. It was observed that both secondary and tertiary CWI could recover a significant amount of additional oil compared to conventional water injection. The results revealed that the oil recovery would be lower if CO2 concentration is reduced, but the extent of oil recovery reduction would be much less than the level of reduction in CO2 concentration. Oil swelling as a result of CO2 diffusion into the oil raised the pressure, and the reduction of subsequent oil viscosity were amongst the main mechanisms of oil recovery by CWI, which were obtained by the high pressure coreflood models and PVT studies. Higher oil recovery was obtained with the higher permeability and higher carbonation level. At the end of the injection period, an encouraging amount of dissolved CO2 was stored in the brine and the residual oil of the tight sandstone. The experimental results clearly indicate the potential of CWI for improving oil recovery and CO2 storage capacity in tight oil reservoirs. It is particularly attractive for the implementation of CWI for reservoirs that have limited access to large amounts of CO2. To the best of our knowledge, this is the first time to experimentally investigate CWI potential in tight oil reservoirs.

Carbonated Water Injection for Enhanced Oil Recovery and CO2 Geosequestration in Different CO2 Repositories: A Review of Physicochemical Processes and Recent Advances

“…CO 2 storage potential of CWI in oil reservoirs; x -axis references: 1: ref , 2: ref , 3: ref , 4: ref , 5: ref , 6: ref , 7 and 10: ref , 8: ref , 9: ref , 11: ref , 12: ref , 13: ref , 14: ref , 15: ref ).…”

“…Analogous to brine-saturated samples, numerous studies have attempted to evaluate the geochemical interactions that occur during CWI in oil-saturated samples (oil reservoirs). ,,, Carbonate reservoirs account for a greater portion of these studies compared to sandstones. EOR-CGS processes in the former are more challenging due to their extreme heterogeneity, complex fluid-rock interactions, and pore network systems …”

Enhanced Oil Recovery and CO2 Storage by Enhanced Carbonated Water Injection: A Mini-Review

“…The effectiveness of CW injection development is affected by a variety of factors such as fluid properties, reservoir conditions, and operational parameters. − As CO 2 concentration and pressure increase, and salinity decreases, CO 2 solubility in water increases. This leads to a higher oil recovery from CW injection.…”

Microcalorimetric Study of Carbonating Produced Water as a Promising CO2 Storage and Enhanced Oil Recovery Method

“…Consequently, the performance of a carbonated fluid is not impacted by heterogeneities in the rock. Zou et al [23] obtained significant additional production in tight oil reservoirs compared to conventional waterflooding in both secondary and tertiary injection modes by 20.3% and 11.3%, respectively. The proposed mechanisms in the literature for the better performance of carbonated water injection are (1) oil swelling and subsequent viscosity reduction due to CO 2 dissolution in the oil phase, (2) improvement in sweep efficiency due to reconnection of isolated droplets and fluid flow diversion, and (3) wettability alteration [9].…”