Reaction model of low asphaltene heavy oil from ramped temperature oxidation experimental analyses and numerical simulations

Abstract

In situ combustion (ISC) is an advanced thermal recovery technique for crude oil exploitation. The crude oil reaction models with accurate kinetic data are crucial to predict the ISC process. This study investigated the China Xinjiang crude oil reaction kinetics through Ramped Temperature Oxidation (RTO) experiments and numerical simulations. Three different ISC behaviors with low-temperature oxidation (LTO), Negative Temperature Gradient Region (NTGR) reactions and high-temperature oxidation (HTO) were observed from the RTO experiments. The effects of the air injection rate and heating rate on the temperature profile and effluent gas composition were carefully investigated. Experimental results showed that the higher air injection rate and lower heating rate enhanced the heat generation, mainly from the more intensive exothermic HTO reactions. A simplified crude oil reaction model involving LTO, NTGR, and HTO was proposed and implemented with a numerical model to simulate the RTO behaviors. This study also suggested a workflow to build the reaction scheme and calibrate the kinetic data for good predictability and generalization. Acceptable consistency was achieved between the RTO experiments and numerical simulation, which demonstrates the proposed reaction model was predictive to capture the key oxidation mechanism and reproduce the ISC behaviors of the Xinjiang crude oil.