Experimental Investigation and Numerical Simulation of Dynamic Characteristics for Multithermal Fluid-Assisted SAGD in Extraheavy Oil Reservoir

Zhenhua Xu,Xiaokun Zhang,Pengcheng Liu,Lanxiang Shi,Zhe Yuan,Botao Kang,Zhenyi Cao,Zhongwei Wu

doi:10.2113/2021/8369713

Abstract

AbstractLoss of the vast majority of heat and steam is an unavoidable problem encountered during conventional steam-assisted gravity drainage (SAGD) in extraheavy oil reservoirs. The noncondensate gas coinjection technique of reducing energy consumption and enhancing oil recovery can effectively solve this problem. Aiming at extraheavy oil with a high initial viscosity, the influence of noncondensate gases in multithermal fluids on the physical parameters of extraheavy oil was experimentally studied; the production characteristics and mechanism of multithermal fluid-assisted SAGD were studied through numerical simulation. A comparative investigation of the conventional SAGD and multithermal fluid-assisted SAGD injection schemes was conducted. The characteristics and mechanism of the steam chamber during the production processes were analyzed. The results show that a steam-gas-oil system forms in the steam chamber in the case of multithermal fluids. The steam chamber can be partitioned into four zones, and the flow of the oil mainly occurs in the steam condensation zone and the oil drainage zone. The injected multithermal fluids increase the horizontal expansion of the steam chamber, while the dissolved carbon dioxide reduces the residual oil saturation. Moreover, the nitrogen injection significantly reduces the heat loss and increases the heat utilization for multithermal fluid-assisted SAGD in developing extraheavy oil reservoirs.

Highlights

Extraheavy oil reservoirs with a high initial viscosity under reservoir conditions are usually effectively exploited using thermal methods [1]
The low utilization rate and high-energy loss of the Steam-assisted gravity drainage (SAGD) process are major problems, which result in its limited application [4]
Heavy oil has different components and physical properties, and the selection of suitable solvents is crucial to the successful development of the expansive solvent-SAGD (ES-SAGD) technique [14,15,16,17,18,19]

Summary

Introduction

Extraheavy oil reservoirs with a high initial viscosity under reservoir conditions are usually effectively exploited using thermal methods [1]. The steam-assisted and gas push (SAGP) process was presented as a new heavy oil reservoir development technique [25, 26]. The role of multithermal fluids in the development of extraheavy oil reservoirs was studied using models of different dimensions of SAGD physical experiments [41, 42]. The influence of the injection of noncondensate gases into extraheavy oil was studied experimentally, and the production characteristics and mechanism of multithermal fluid-assisted SAGD were studied through the numerical simulation of two different injection schemes. The simulation performances and results were analyzed and revealed that thermal coinjection fluids are an effective process for enhancing oil recovery in extraheavy oil reservoirs

Experiments

Experimental Materials

Experimental Procedures

Numerical Simulation

Results and Discussion

Conclusions