New insights into the non-isothermal oxidation of tight oil: Experimental study and theoretical prediction

A better understanding of the influence factor investigation and oxidation behavior prediction for the crude oil could supply valuable insights into the reactivity of crude oil and feasibility of air injection process. In this study, non-isothermal oxidation experiments have been conducted via thermal analyses (thermogravimetry/differential scanning calorimetry/pressurized differential scanning calorimetry, TG/DSC/PDSC) with different heating rates (5, 10, and 15 C/min) and experimental pressures (1, 3, and 5 MPa) in order to investigate the influences on oxidation behaviors, exothermic characteristics, and kinetic parameters of typical tight oil. In addition, the distributed activation energy method (DAEM) was employed to determine accurate kinetic parameters for whole oxidation process and to further predict the oxidation behavior with the reconstruction of TG and conversion curves. The results showed that, heating-rate increment would lead to inadequate oxidation process with more reaction occurrence in a shorter time. Inversely, more rapid heat release, higher exothermic peaks with lower temperature ranges were detected in PDSC curves, indicating high pressure in actual oil reservoir would strengthen the oxidation progress with more heat generation to enhance oil recovery. Then, based on specific activation energy distribution and DAEM, the calculated TG and conversion curves presented a satisfactory fitting relation with experimental data, demonstrating a reasonable prediction of oxidation behavior and kinetic characteristic for the crude oil under specific heating-rate. The understandings in this study not only provided new insights on the verification of obtained kinetic parameters, but also the accurate prediction of crude oil oxidation behavior.