Session: 11-11-01 Advances in Carbon Capture Utilization and Storage

Paper Number: 81225

81225 - Integrated Optimization of Hybrid Steam-Solvent Processes in a Post-CHOPS Reservoir With Consideration of Wormhole Networks 

As for the enormous heavy oil resources deposited in Western Canada (i.e., Alberta and Saskatchewan), cold heavy oil production with sand (CHOPS) has been the most common primary production technique to produce heavy oil, water, gas, and sand altogether by using progressive cavity pumps (PCPs). In general, typical recovery factors are low about 5-15% of original-oil-in-place (OOIP) due mainly to the in-situ generation of open channels (i.e., wormholes) in the unconsolidated formations, and thus efficient enhanced oil recovery (EOR) techniques are required for the post-CHOPS reservoirs. It is found from displacement experiments that injecting CO₂ and steam into a heavy oil reservoir may artificially restore the solution-gas drive and reduce heavy oil viscosity for increasing oil production, while addition of alkane solvents will accelerate the dissolution of CO₂ into heavy oil. Therefore, it is of practical and fundamental importance to not only properly delineate the wormhole network, but also optimize the operational parameters of steam-solvents processes to maximize oil recovery for post-CHOPS reservoirs. In this paper, an integrated technique has been developed to evaluate and optimize performance of hybrid steam-solvent processes in a post-CHOPS reservoir with consideration of wormhole networks. A reservoir geological model is developed and calibrated by history matching reservoir pressure with the oil, gas, and water production rates as the input constraints, while its wormhole network is characterized with the newly developed pressure-gradient-based (PGB) sand failure criterion. Once calibrated, the reservoir geological model incorporated with the wormhole network is then employed to evaluate and optimize performance of hybrid steam-solvent processes under various conditions, during which both net present value (NPV) and oil recovery are maximized with an integrated optimization algorithm by taking injection time, soaking time, and production time as controlling variables. It is found that a huff-n-puff process imposes a positive impact on enhancing oil recovery when wormhole network is fully generated and propagated. Among all solvent-based methods, a pure CO₂ huff-n-puff process shows a better performance than a flue gas one, while the addition of alkane solvents leads to a higher oil recovery compared with that of the CO₂ only method. Since the addition of C₃H₈ and n-C₄H₁₀ will significantly decrease the heavy oil viscosity and enhance the oil swelling, all hybrid steam-solvent injection achieves high oil recovery by taking the advantage of both hot steam and solvents injection.

Presenting Author: Daoyong (Tony) Yang Petroleum Systems Engineering

Authors:

Daoyong (Tony) Yang Petroleum Systems Engineering
Min Zhao University of Regina