AAPG Foundation 2019 Grants-in-Aid Projects

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Influence Factors and Mechanism Analysis of CO2-Fluid-Rock Interaction on Reservoir Pore Network in a Saline Basin: A Case Study of Shahejie Formation in the Dongpu Depression, Bohai Bay Basin, China


Consensus has been reached that CO2-fluid-rock (CRF) interaction has an effect on reservoir pore network. However, previous research focused more on minerals, porosity, permeability, and formation water composition changes before and after CRF interaction, which failed to investigate pore evolution characteristics in time-dependent interaction processes and also ignored controlling factors in salty formation water condition. The third member of Shahejie Formation (Es3) in the Dongpu Depression is characterized by three sets of interbedded salt rocks, high paleosalinity (20.2‰–42.2‰), wide range porosity (1.1%–26.5%) and permeability (0.01 md–935 md). In this project, X-ray diffraction (XRD), X-ray fluorescence (XRF) and Inductively coupled plasma mass spectrometry (ICP-MS) analyses will be conducted on Es3 sandstones and/or salty formation water firstly. CO2 will then be flooded into sandstones with different time span, temperature, CO2 concentration and pressure. Simultaneously, the 4D (3D+time) in-situ tomographical imaging will monitor the pore evolution during CFR interaction process. After the interaction, the first step will be conducted again to determine mineral and trace elemental compositions. Finally, a visual and quantitative model will be established through Avizo and MATLAB to analyse and further predict pore network during CFR interaction under different conditions. This project can not only enrich theoretical studies of controlling factors of pore network, but also provide guidance in visualizing and predicting pore network changes in CFR interaction by combining geochemistry and imaging, which will benefit oil and geothermal development as well as safe carbon storage, thus alleviate greenhouse effect.