Experimental and Numerical Investigation of Hydrocarbon Co-Injection with Steam in the Steam Assisted Gravity Drainage Process for In-Situ Heavy Oil and Bitumen Recovery
Creators: name: Hosseininejad Mohebati, Moslem
Publisher: name: Graduate Studies
Year: 2014
Subjects: subject: Engineering--Petroleum
subject: Heavy Oil
subject: Bitumen
subject: in-situ recovery
subject: SAGD
subject: Solvent
subject: Solvent Assisted-SAGD
subject: hydrocarbon additives
subject: hybrid processes
subject: SA-SAGD
subject: Steam Assisted Gravity Drainage

description: Heavy oil and bitumen are expected to become increasingly important sources of fuel in the coming decades. Steam Assisted Gravity Drainage (SAGD) is a commercially viable and widely used recovery technique for Alberta's heavy oil and bitumen. However, it remains an expensive technique and requires large energy input in the form of steam for each barrel of recovered oil. There are, in fact, opportunities to improve technical, economical and environmental aspects of SAGD performance. Co-injecting a hydrocarbon additive with steam in the form of a hybrid process offers the potential of lower energy and water consumption and reduced greenhouse gas emissions as well as higher oil rates and recoveries. The objective of this research is to evaluate hydrocarbon additives to steam in SAGD for achieving greater energy efficiency and environmental sustainability. Although several studies have investigated the effect of different hydrocarbon additives to steam in SAGD, very few of them have taken a systematic approach towards evaluating this process. Most reported studies did not include physical experiments at reservoir conditions. Some of those that addressed the issue by experimental methods did not adequately discuss the operating conditions at which hydrocarbon addition can be most beneficial. In fact, the effect of a hydrocarbon additive on the performance of SAGD and the role it plays in the steam chamber are not clear. Co-injecting a hydrocarbon additive with steam could improve or adversely affect the energy efficiency and oil rate of SAGD. This improvement or inhibition can theoretically occur via different mechanisms such as: formation of an insulator layer at the top of the steam chamber and dissolution of solvent in the heavy oil. Several parameters like operating condition, phase behavior of the hydrocarbon additive, original reservoir fluid composition, and reservoir physical properties affect the performance of the process and determine the mechanisms that occur in the reservoir. All these factors and effects should be identified and evaluated before injecting a hydrocarbon additive with steam. Moreover, hydrocarbon additive co-injection should be optimized by further investigation and assessment of the process based on the identified parameters. In this study, both numerical modeling and physical model experiments were used to evaluate the effectiveness of hydrocarbon additives in improving the SAGD process. Extensive field scale numerical modeling was conducted and important factors controlling the hybrid steam-hydrocarbon additive process were identified and evaluated. For the experimental phase of the work, a 3 dimensional partially-scaled physical model was designed and built to assess the hybrid process at operating pressures similar to the field conditions. Five different SAGD and Solvent Assisted-SAGD (SA-SAGD) experiments were conducted at different operating pressures. Hexane, which was found to be the most beneficial additive to steam in the numerical simulation phase, was co-injected with steam at different operating pressures. SAGD and SA-SAGD experiments were compared for oil rates, oil recovery, cumulative and instantaneous steam oil ratio (SOR), shape of steam chamber, energy balance of the experiments, residual oil saturation, and RF versus PV steam injected. Furthermore, experimental results were up-scaled to field scale using the scaling parameters to predict the field scale performance of SA-SAGD. As a final step of this research experimental results were modeled and matched with numerical simulation and further insights of the process were obtained and effect of some parameters that could not be examined in the lab were investigated with the tuned numerical model.