Numerical Evaluation of Hydrocarbon Additives to Steam in the SAGD Process

Abstract

Summary 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 heavy oil and bitumen. However, it remains an expensive technique and requires large energy input in the form of steam. Energy intensity of SAGD, as well as environmental concerns such as fresh water usage and CO2 emission, make it imperative to find new oil extraction technologies. Coinjecting a hydrocarbon additive with steam offers the potential of higher oil rates and recoveries with lower energy and water consumption. A reservoir simulation study using a 20X12X15 3D Cartesian model and Athabasca fluid and reservoir properties was conducted to evaluate this process. The role of hydrocarbon additive in the steam chamber and its effect on the performance of SAGD was investigated. Simulation results revealed the parameters that will have the greatest impact on the process performance and indicated the effectiveness of each hydrocarbon additive in improving the performance of SAGD. The results also showed that selecting the most suitable hydrocarbon additive depends on the operating conditions as well as the original reservoir fluid composition.

Analysis of steam–solvent–bitumen phase behavior and solvent mass transfer for improving the performance of the ES-SAGD process

“…The production well is operated at a maximum steam rate of 5 m 3 /day in order to prevent extensive steam loss. To initialize SAGD, a start-up procedure is simulated for heating up both the injection and production wellbores to ensure a high steam quality at the sand surface (Nasr et al, 2000).For the ES-SAGD case, C6 is injected into the reservoir as a surrogate of solvent with steam (Li and Mamora, 2011;Mohebati et al, 2010), with other parameters the same as the SAGD case. The k-values of C6 at different pressures and temperatures, provided by STARS User's Manual (2011), are used in the simulation.…”

A semi-analytical solution to optimize single-component solvent coinjection with steam during SAGD

“…It is common practice to use a single component to represent bitumen in research on SAGD and coinjection processes [14,22,24,32,33]. Reliable characterization of bitumen/solvent/ water interactions for coinjection processes has not been established in the literature.…”

“…Distributions of the L-phase viscosity and density are generated using the mixing rules given in Eqs. (14) and (15). The distribution of x sL can be obtained by using Eq.…”

“…Besides promising results of coinjection tests, there are also reports showing that coinjection resulted in little improvement or even worse performance compared to SAGD [12][13][14][15]. Proper design is important for the practicality of coinjection processes [16].…”

Observations on the Mechanisms of Solvent-Additive SAGD Processes

“…Solvent-additive SAGD processes (SAP) are the subject of a growing number of numerical studies [3,8,10,11,17,20,23,25], physical models [1,3,7,9,14,18,[20][21][22]24], and field tests[6,12,13]; and has been or is planned to be commercially implemented[15], based on pilot success. Serious interest in SAP followed from successful trials with butane addition, at Senlac[13] and later Christina Lake[12].…”