--> An Integrated Model for EOR Using Downhole Steam Generation

AAPG ACE 2018

Datapages, Inc.Print this page

An Integrated Model for EOR Using Downhole Steam Generation

Abstract

Traditional thermally enhanced oil recovery (TEOR) methods such as steam-assisted gravity drainage (SAGD) need to show improved recovery factors and reduced environmental pollution before bitumen can be economically produced. The Solvent Thermal Resource Innovation Process (STRIP), a downhole steam-generation technology, has the capacity to overcome the shortcomings of traditional methods by delivering all of the combustion heat to the payzone. Moreover, by dissolving into the oil to swell it and reduce its viscosity, the CO2 combustion product enhances oil mobility and can be partially sequestered in the bitumen reservoir. In this study, a geologic model and a multiphase, multicomponent reservoir simulation framework are used to evaluate the STRIP technology. Currently, commercial simulators such as CMG-STARS (thermal and advanced-processes reservoir simulator) use the K-value approach to simulate TEOR. However, the method cannot simulate STRIP’s CO2 and steam co-injection because the K-value method does not consider miscible gas injection. On the other hand, CMG’s GEM (compositional simulator) includes the effects of miscible gases, but is isothermal. The novel simulation framework developed here leverages and combines the individual strengths of STARS (thermal features) and GEM (compositional features). In this framework, STARS simulates steam injection (but cannot directly simulate the effects of CO2) and is the governing model that synchronizes temperature, pressure, and phase saturations for two parallel iterations of the GEM model (GEM-1 and GEM-2) at each time step. GEM-1 simulates hot-water injection, but at an increased rate to yield a pressure field equivalent to STARS. This injection rate is specified in GEM-2 to ensure maintenance of the pressure field, but the GEM-2 model also simulates CO2-hotwater co-injection and matches both water and oil production from the GEM-1 model by altering relative permeabilities. Finally, the updated relative permeabilities are fed back to STARS and iteration proceeds. Simulation results from this framework are benchmarked against a steam-injection simulation from STARS using the traditional K-value method. The results indicate superior performances of STRIP compared with traditional TEOR methods due to the CO2 co-injection through a lower SOR (steam oil ratio).