Effect of Wells’ Connectivity Enhancement on the Performance of Vapor Extraction (VAPEX) Process

Mehdi Mohammadpoor,Farshid Torabi

doi:10.2516/ogst/2014058

Abstract

Drawbacks of the thermal recovery techniques such as excessive heat loss to the surrounding formations and carbon dioxide emissions during these processes have directed the interests of researchers towards more viable alternatives such as solvent-based recovery techniques (e.g. VAPEX). One of the key parameters to implement a successful VAPEX process is to control the profiles of vapour chamber and consequently improve the areal sweep efficiency. In this regard, an optimum well configuration and well connectivity establishment between the injection and production wells are desirable. The main focus of this research is to extensively conduct series of experiments to investigate the effect of injection/production wells connectivity on the performance of VAPEX process. For this purpose, two large-scale physical models were employed. Propane and propane/carbon dioxide mixtures were selected as the injection solvents in the visual sand-packed physical models saturated with heavy oil sample from Saskatchewan (Canada) heavy oil. Various injection/production scenarios were followed and it was found that the initial connection path between the injector and producer had a significant impact on the vapour chamber profiles and consequently on the ultimate recovery performance of the VAPEX process.

Highlights

The application of numerous heavy oil recovery techniques has led to the recovery of small portions of this oil
The ultimate recovery factor of about 80% of original oil in place was observed after injecting propane as the solvent in the small model, the recovery factor achieved in large model was significantly lower and it was about 50% of original oil in place
An extensive experimental study involving injecting different solvents in two large-scale visual physical models was carried out to investigate the effect of injection-production wells connection on the recovery performance of VAPEX process

Summary

Introduction

The application of numerous heavy oil recovery techniques has led to the recovery of small portions of this oil. Increasing the capillary number and/or lowering the mobility ratio are the basic principles of Enhanced Oil Recovery (EOR) methods. About 3% of the worldwide production comes from EOR processes. The importance of choosing the most feasible recovery technique becomes increasingly important to petroleum engineers. VAPEX is an energy-efficient method of recovering high viscosity heavy oil and bitumen from reservoirs. The process uses a solvent in the miscible displacement of bitumen or heavy crude oil. VAPEX improves energy efficiency and reduces emissions and operating costs. In conventional VAPEX process, a mixture of vapourized solvent (propane and/or butane) and a commercially available non-condensable gas (methane, natural gas) is injected into the reservoir to reduce oil viscosity. While the VAPEX process became less attractive with the increase of gas price, injecting CO2 will decrease solvent cost. This can be environmentally important because nowadays CO2 sequestration itself is an important environmental issue

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Conclusion