The Analysis of EOR Effect by In-situ CO2 Generated During Steam Injection in Heavy Oil Carbonate Reservoir

In heavy oil carbonate reservoir with steam injection, the efficiency of steam imbibition into tight matrix can be improved by the alteration of oil-wet into water-wet condition with increasing temperature. Additionally, in-situ CO2 gas generated by geochemical reaction between carbonate rock and steam may play an important role on the improvement of oil flow.

This study developed in-situ CO2 generation model and coupled it with conventional thermal multi-component reservoir simulator. Firstly, by utilizing the developed model, when steam was injected into single block tight carbonate matrix, the improvement of oil flow occurred by facilitating in-situ CO2 generation as well as thermally induced wettability alteration. Secondly, in a heavy oil fractured carbonate reservoir system including steam injector and producer, this study proposed that the implementation of in-situ CO2 generation model into conventional thermal reservoir simulator is essential for predicting the oil production more accurately.