Work

Study on the Interaction Mechanisms among CO2, the Formation Water, and Tight Sandy Conglomerate

Year: 2025

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide Tight sandy conglomerate reservoirs exhibit poor physical properties, strong heterogeneity, and significant development challenges due to low permeability. Understanding the interaction of CO 2 with such formations is critical for enhanced oil recovery (EOR). Experimental studies on the interaction mechanisms among CO 2, formation water, and tight sandy conglomerate were conducted. The results indicate that under the reservoir conditions of 89 °C and 37.0 MPa, the solubility of CO 2 in the formation water is significantly influenced by temperature, pressure, and salinity. After dissolving in formation water, CO 2 forms carbonic acid, which triggers dissolution reactions of minerals such as feldspar under acidic conditions. This leads to a reduction in feldspar mineral content and a 0.31% decrease in core mass. Concurrently, the rock’s microscopic surface becomes rougher with numerous dissolution pores and cavities emerging. The average pore-throat radius increases, and the displacement pressure decreases. These alterations improve the rock’s pore structure by enlarging pore-throat dimensions, creating additional flow channels for oil and gas migration. Consequently, the permeability increases by 7.4–11.0%, thereby enhancing the production capacity of tight sandy conglomerate reservoirs.

Source: ACS Omega

DOI: 10.1021/acsomega.5c05004

Authors: Haiming Gao, Kaigui Liao, Ge Wu, Wanfen Pu, Yong Heng

Institutions: Sinopec (China), Southwest Petroleum University, State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation

Language: English

Topic: CO2 Sequestration and Geologic Interactions

Subfield: Environmental Engineering

Field: Environmental Science

Domain: Physical Sciences

SDG: Climate action

Open Access status: gold

Estimated APC paid: $1,935