Quick Screening of Pareto-Optimal Operating Conditions for Expanding Solvent–Steam Assisted Gravity Drainage Using Hybrid Multi-Objective Optimization Approach

Baehyun Min,Krupa Kannan,Sanjay Srinivasan

doi:10.3390/en10070966

Abstract

Solvent–steam mixture is a key factor in controlling the economic efficiency of the solvent-aided thermal injection process for producing bitumen in a highly viscous oil sands reservoir. This paper depicts a strategy to quickly provide trade-off operating conditions of the Expanding Solvent–Steam Assisted Gravity Drainage (ES-SAGD) process based on Pareto-optimality. Response surface models are employed to evaluate multiple ES-SAGD scenarios at low computational costs. The surrogate models play a role of objective-estimators in the multi-objective optimization that provides qualified ES-SAGD scenarios regarding bitumen recovery, steam–energy efficiency, and solvent-energy efficiency. The developed hybrid approach detects positive or negative correlations among the performance indicators of the ES-SAGD process. The derived Pareto-optimal operating conditions give flexibility in field development planning and thereby help decision makers determine the operating parameters of the ES-SAGD process based on their preferences.

Highlights

Steam Assisted Gravity Drainage (SAGD) is a thermal injection technique useful for producing bitumen by lowering its viscosity sufficiently in oil sands reservoirs [1]
This paper demonstrated the framework of the hybrid multi-objective optimization approach integrated with the polynomial response surface models and implemented the method for screening the Pareto-optimal operating conditions of the Expanding Solvent–Steam Assisted Gravity Drainage (ES-SAGD) process quickly
The response surface models substituting to the expensive thermal reservoir simulator allowed fast calculation of bitumen recovery and solvent–steam injection efficiency

Summary

Introduction

Steam Assisted Gravity Drainage (SAGD) is a thermal injection technique useful for producing bitumen by lowering its viscosity (typically greater than 10,000 cP under reservoir conditions) sufficiently in oil sands reservoirs [1]. One salient issue in the SAGD process is how to save the volume of steam injected into the formation while achieving high bitumen recovery [2,3,4,5]. The ES-SAGD process co-injects light hydrocarbon solvent with steam for enhancing the thermal injection efficiency [6,7,8,9,10,11]. Nasr et al [6] showed that the steam–solvent co-injection could increase bitumen production rate while decreasing steam injection rate compared to SAGD Injected solvent condenses at the vapor/liquid boundary of the steam chamber and creates a diluted interface for further reducing the viscosity of heated bitumen [12].

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