Experimental Studies of Thermal Solvent Oil Recovery Process for Live Heavy Oil

Abstract

VAPEX and related processes for the recovery of heavy oil and bitumen have potential application to oils containing some methane in solution. A set of experiments has been completed to evaluate the potential for thermal VAPEX operations in heavy oils containing significant dissolved methane content. Three experiments were run to evaluate a VAPEX process operating in a reservoir in which the oil had significant initial methane saturation. The first experiment tested a 3-component mixture (C1-C2-C3) that was used in an earlier non-thermal dead oil VAPEX test. The second experiment used horizontally offset wells and 100% ethane as the working solvent. The production well was heated to reflux the solvent in situ. The third experiment also used horizontally offset wells and 100% ethane, plus steam. The steam was injected into the production well to reflux the solvent. Results indicated that the live oil inhibited solvent absorption, and hence production rates, but that a properly designed solvent system could produce oil at reasonable rates. Oil production from the steam-heated well/ethane experiment was similar to that from the electrically heated well/ethane reflux experiment. The experiments provided a database which can be used for economic comparison of process options, and for developing numerical simulations for field predictions. Introduction Some heavy oil reservoirs cannot be produced by cold production. They may be immobile at reservoir temperature, or they may have some initial oil mobility and some reservoir drive energy, but the sand strength precludes the production of sand or wormholes. These reservoirs may be dead oil, as in the case of Athabasca bitumen, or they may have some dissolved gas, as in the case of Cold Lake reservoirs. The VAPEX process(1) has been considered as a means of mobilizing heavy oil or bitumen. Figure 1 illustrates the concept of the VAPEX process. Heating a horizontal wellbore is a possible means of mobilizing these oils. Heat will reduce viscosity sufficiently to produce a large increase in oil rate. Heat also serves to initiate communication between an injection well and the producer, enabling solvent injection. Heat may also serve to speed the diffusion of the solvent into the oil. Heat may be injected by injecting steam, or by injecting heated Solvent(2). The wellbore may be heated by means of an electrical heater or a steam or glycol loop. Heat vapourizes the injected solvent. Solvent vapour moves to the oil interface at the edge of the vapour chamber and dissolves in the oil. The diluted oil is reduced in viscosity and flows down the edge of the vapour chamber to the production well. The vapourized solvent is driven out of the oil by the heat as it enters the near wellbore region or the production well. The vapourized solvent will return to the vapour chamber, where it will mobilize additional oil. The result is a Thermal Solvent Reflux process(3). The process concept is illustrated in Figure 2. FIGURE 1: VAPEX process (Available In Full Paper) FIGURE 2: The thermal solvent process (Available In Full Paper)

A Critical Review of Hybrid Steam-Solvent Processes to Recover Heavy Oil

“…Condensed solvent around the interface of the steam chamber dilutes the oil and in conjunction with heat, reduces its viscosity (Nasr and Ayodele, 2006;Nasr et al, 2002;Nasr et al, 2003) The details of most of the experiments are not in public domain yet. Addition of variable amount of heat in different forms was proposed by many researchers (Frauenfeld et al, 2005;Frauenfeld et al, 2006;Ivory et al, 2010) to accelerate and enhance the economics of VAPEX. In these publications the details of Propane, n-Hexane and a multi-component diluent co-injection with steam were explained.…”

“…SAGD is the preferred in-situ technology to recover heavy oil and bitumen from Canadian reservoirs. Several experiments were conducted by Frauenfeld et al (2005Frauenfeld et al ( , 2006 at ARC examining different solvents. The main drive mechanism is gravity drainage.…”

Effect of Temperature on VAPEX Performance

“…Refluxing was successful in reducing the volume of the solvent that must be pumped to the surface, separated from the oil, purified, stored, and reinjected from the surface (Frauenfeld et al 2005). Another attempt in developing hybrid processes was SAS, which involved alternating injection of steam and solvent in continuous cycles, using a well configuration similar to that of SAGD.…”

Application of Solvent Alternating SAGD Process to Improve SAGD Performance in Athabasca Bitumen Reservoir

“…Therefore, several researchers tried to investigate the performance of solvent co-injection with steam processes to enhance the recovery of bitumen and heavy oil using conventional vertical wells (Farouq Ali and Abad, 1976;Redford, 1982;Shu and Hartman, 1988;Sarma et al, 1996). Thanks to developments in horizontal well drilling technologies during the last two decades, other hybrid methods were introduced mainly based on SAGD and VAPEX concepts such as solvent-aided process (SAP) (Gupta et al, 2005), expanding solvent SAGD (ES-SAGD) (Nasr et al, 2002 and2003), steam-alternating solvent (SAS) (Zhao et al, 2005 and, N-SOLV (Nenniger, 2000), thermal solvent recovery (Frauenfeld et al, 2007) and naphtha-assisted gravity drainage (NAGD) (Palmgren and Edmunds, 1995). Nasr et al (2002) presented a new hybrid method, namely expanding solvent SAGD (ES-SAGD) after several comprehensive experiments to enhance the efficiency of SAGD process and compensate its drawbacks.…”