Abstract
Carbonate reservoirs account for 60% share in global oil reserves, and CO2-EOR process is employed in these carbonate fields for effective oil recovery and retention as well. Recent research reports that fines migration may lead to reservoir formation damage in oil bearing limestone and dolomite rocks. Although carbonate reservoirs are poor in clay minerals, some mass of clay fines existence in certain carbonate formations will cause severe damage to permeability and well productivity. This paper reports the single-phase flow of subcritical CO2 in porous limestone rock core containing kaolinite clay fines. Fines are natural reservoir minerals (example, quartz) and clay particles such as kaolinite, illite, feldspar, smectite, and montmorillonite. But, this paper explores this CO2-clay fines behavior in limestone rock as a function of kaolinite. So, two sets of core flood experiments were performed in the rock temperatures 120 °C and 160 °C. Initially, kaolinite clay has been injected into the limestone core in the form of suspension and then dried for hours in order to retain the solid fines in the internal pore chambers of the core. After that, the CO2 under subcritical condition has been injected into the porous limestone core for fines mobilization and injected gas recovery. The major observations that are reported from the experimental tests are there is an increase in gas saturation for increasing injection time. Steady rise of heat transfer coefficient and enthalpy was noted for increasing gas saturation and time. Concentration of fines linearly soars with respect to elevating PVI and permeability declines for rising time. Pressure in the limestone core shows abnormal and nonlinear variation. Finally, gas discharge rate declines for increasing injection time. Experimental data are tested against the statistical model (regression), and the outcome indicated good agreement. Overall, this paper has successfully established the CO2 effects on kaolinite clay fines behavior and its impact on oil recovery in carbonate fields.
Highlights
CO2 injection in carbonate reservoir either for carbon capture and storage (CCS) or enhanced oil recovery (EOR) will lead to many complicated geochemical and surface reactions (Singh et al 2018; Agada et al 2016)
Higher saturation was recorded at 160 °C, and implied that higher rock core temperature can enhance the saturation of the fluid, especially gas in limestone reservoirs. 120 °C indicated close gas saturation value, and this linear increase in the gas saturation is attributed to surface energy, pore volume, pore chamber radius, and C O2 diffusion (Li et al 2018; Kanimozhi et al 2018; Dullien 1992)
This is absolutely required for the mass transfer that is fluid and particle displacements. CO2 flow in porous media generates a high degree of supercritical heat transfer (Zhalan et al 2014), but extreme temperatures in limestone rock leads to calcination and thermal decomposition (Valverde 2015)
Summary
CO2 injection in carbonate reservoir either for carbon capture and storage (CCS) or enhanced oil recovery (EOR) will lead to many complicated geochemical and surface reactions (Singh et al 2018; Agada et al 2016). Fines migration in carbonate fields is posing great risk to reservoir formation damage and well productivity deterioration. An introduction about fines is already described in abstract section and, usually, kaolinite clay fines are common in a sandstone reservoir since these reservoir rocks contain. Journal of Petroleum Exploration and Production Technology (2020) 10:883–891 quartz and feldspar, and the pore walls of sandstone rocks are coated with kaolinite clay (Wu et al 2012). Clay minerals, especially kaolinite, are discovered in certain carbonate oil reservoirs, for instance, Bombay High Oil Field in India during 1981 (Rao 1981). The fine mass balance equation is mentioned as follows (Yang et al 2016; You et al 2016): c+ s+ t a
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
