|Texas Tech University
|Air Injection; Shale Oil; Kinetic Study; Thermal-Oxidative Behavior; Thermalgravimetry (TG); Differential Scanning Calorimetry (DSC)
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Due to the poor injectivity of water and chemicals, AIP (air injection process) could be an alternative option among other EOR techniques for developing shale reservoirs. As the success of this process mainly relies on the oil and rock properties, usually, the first feasibility study is to investigate the thermal-oxidative behavior of samples from the target reservoir. However, information on implementing AIP with shale oil reservoirs have been limited, up to now, as no literature presents the work on investigating thermal-oxidative behavior of shale oil. This study is a new trial on implementing the AIP technology in a shale oil reservoir by investigating the thermal-oxidative behavior of shale oil and mixture of oil and shale cuttings. The target shale oil (40°API, 3 cp at 25℃) and shale cuttings were collected from the Wolfcamp formation in Texas, US, and two thermal analysis apparatuses known as TG (thermogravimetry) and DSC (Differential scanning calorimetry) were performed on both shale oil and the mixture of oil and shale cuttings. Different reaction stages were defined by both TG/DTG (the derivative of thermogravimetry) and DSC result curves. The shale cuttings were performed by the X-Ray experiment and it is observed that the shale sample contains a great amount of illite (20% wt) which has been claimed has strong catalytic ability on the crude oil combustion behavior. And this study has reconfirmed that the illite has strong catalytic ability for crude oil combustion process from aspects of both thermograms analyzing and kinetic studies. Moreover, in order to more intuitively demonstrate the catalytic effect of the shale cuttings, a series of comparable tests are conducted by the mixture of sand with oil. Stronger exothermic behavior as well as lower activation energy values were observed after addition of shale cuttings with oil during the combustion process, which indicates that Wolfcamp shale oil has great oxidation potential and is a positive sign of application of AIP technology. The effect of heating rates are also discussed in the paper, whereas the thermal hysteresis was observed in this study. In order to diminish this inconvenience, it is recommended that such similar thermal experiments with a light crude oil might have better performance under low heating rate value (e.p. 1~10 °C/min). The ASTM method and Arrhenius method are applied to estimate the kinetic parameters which gives inconsistent results thus bring us new insights on how to interpret the kinetic data from different methods. This screening study will help us better understand and have a more quantitative idea on the AIP recovery performance when applied to shale oil reservoirs. Advisors/Committee Members: Jia, Hu (committee member), Soliman, Mohamed Y. (committee member), Bateman, Richard (committee member), Sheng, James J. (Committee Chair).