Full Scale VAPEX Process-Climate Change Advantage and Economic Consequences A

Abstract

Abstract With the VAPEX process, combinations of vaporized solvents are injected into heavy oil and bitumen reservoirs for in situ recovery of the oil. The oil is diluted with the solvent, which reduces the viscosity so the oil drains by gravity to a horizontal production well. The VAPEX process has the potential to greatly reduce the greenhouse gas emissions for oil sands and heavy oil recovery since it is a non-thermal process that does not require the reservoir to be heated with, for example, steam. The Petroleum Recovery Institute (PRI) was the operator of a joint industry project of 16 participants with nine research performing organizations. During 1998, the project investigated the full project engineering and commercial scale economics for the VAPEX process. The supply cost economics for VAPEX oil production from the Athabasca oil sands, Cold Lake oil sands and Southeast Alberta heavy oil were determined. The work indicated that VAPEX has attractive economics and helped to define the critical field operations design issues that need to be addressed prior to proceeding with a substantial field pilot. The climate change advantages of the VAPEX process are described in the paper along with an overview of the integrated physical model, numerical simulation, facilities design, well specifications, production, transportation, and marketing work which led to calculation of the supply cost economics. Introduction The VAPEX (vapor extraction) process(1) is a non-thermal process that uses vaporized solvents that are injected into heavy oil or bitumen reservoirs. The solvent dissolves in the oil at the natural reservoir temperature, reducing the viscosity of the oil, which will then readily flow by gravity to a horizontal production well(2). The concept is described in several Canadian and USA patents(3, 4). As shown in Figure 1, twin horizontal wells are used for the recovery process. VAPEX gas is injected into the upper well where it dissolves in the oil, which then drains to the lower producer. The development of the VAPEX technology is shown pictorially in Figure 2. Since the initial patent in 1978, there has been basic and applied research and invention(2). In 1998, the PRI operated a project called "Development of Full Project Engineering and Economics for the VAPEX Process," with 16 participants and nine research performing organizations. The project continued in 1999 with Phase 2 for VAPEX operations design on "How to Operate VAPEX in the Field," which included conceptual design of two VAPEX pilot plants for an oil sands application and a heavy oil reservoir application with underlying water. The VAPEX process has several potential advantages and disadvantages for commercial scale economic oil production. The potential advantages are: no steam generation; no water processing/ recycle; lower fuel costs; greater energy efficiency; lower carbon dioxide emissions; may be advantageous in thin reservoirs or with bottom water, and potential in situ upgrading. The potential disadvantages are: solvent compression, solvent losses and potential sensitivity to reservoir heterogeneity. The advantages and disadvantages are reiterated in Tables 1 and 2.