High pressure air injection kinetic model for Bazhenov Shale Formation based on a set of oxidation studies

Abstract

Modeling of high pressure air injection (HPAI) is a complicated process, where many parameters must be taken into account. One of the key aspects is to build a chemical reactions model for HPAI process, especially in oil shales, which is still under development. For successful HPAI implementation in the field, numerous laboratory and numerical studies must be done.The purpose of this study was to develop a HPAI kinetic model for Bazhenov Shale Formation by applying a complex approach including a set of oxidation experiments and complementary numerical simulation.Oxidation behavior of Bazhenov shales was studied by accelerating rate calorimetry (ARC), ramped-temperature oxidation (RTO) and pressurized differential scanning calorimetry (PDSC). Based on obtained data and experimental observations, the basic set of chemical reactions was proposed. It can represent an oxidation behavior and chemical changes of both oil and kerogen, occurring in HPAI process in Bazhenov Formation. Moreover, reactions kinetic model was developed. During validation of the numerical model with the experimental results, it was revealed that kerogen or its derivatives undergo oxidation in several temperature regions. Therefore, it should be represented by individual pseudo-components, which reflect their different physical-chemical properties. As a result, a minimum set of kerogen pseudo-components in solid phase that are necessary for describing oxidation reactions in low temperature region (LTR) and high temperature region (HTR) and pyrolysis reaction was determined.The application of experimental results has made it possible to substantially reduce the uncertainties revealed in air injection modeling in oil shales. Proposed chemical reactions and their kinetics were validated by experimental data and thus can be used as a start model for high-pressure air injection modeling in oil shales.