Numerical Simulation of Electrical-Heating Assisted SAGD in Heterogeneous Heavy Oil Reservoirs

Abstract In order to massively enhance the performance of heterogeneous SAGD projects, the targeted Electrical-Heating in poor steam chamber segment assisted SAGD (EH-SAGD) was proposed, the simulation method was established coupling geo-mechanics of both payzone and interbeds, and delivery of energy by electrical heating into the subsurface. The screening criteria of EH-SAGD was formed and the typical SAGD wellpair performance was predicted and compared. As the EH-SAGD is quite complex in its mechanisms, the precise simulation must reflect the impact of these mechanisms. Therefore, systematic experiments were carried out firstly to provide the key parameters of the rock and fluid to the simulation model. The geo-mechanic characteristics of barriers with different rock types was obtained by tri-axial compression tests, and the mineral composition change and reaction at elevated temperatures were obtained by means of X ray diffraction and interpretation. The numerical simulation model of EH-SAGD was established based on the experimental results. The geo-mechanic model were added into the simulation based on the experimental results illustrating the Young's modulus, Poisson's ratio, compression strength, yield stress and the corresponding changes of the porosity and permeability. From numerical simulation, the screening criteria for reservoirs that feasible for EH-SAGD was optimized by multi-parameters. The SAGD wellpairs with barriers in between the horizontal segments were the applicable targets for electrical heating. The combination heating of downhole heaters in both injector and producer was recommended for rapid breakthrough of the barriers. The heat power of the heaters with time was also optimized which required the highest power of 2500W/m for each heater. Following which a typical SAGD wellpair was selected to make the comparison. It is simulated that by targeted electrical heating, the oil drainage route can be established, the steam chamber along the whole horizontal segment can be developed, and the oil rate can be enhanced by 45% from conventional SAGD. It is forecasted that the oil recovery factor of EH-SAGD is 12.1% higher than SAGD. The results indicate that the EH-SAGD has encouraging effect to enhance the oil rate, steam chamber uniformity, and the final oil recovery factor, which is a practical and novel EOR approach for heterogeneous SAGD reservoirs.