The economics of a SAGD project is related to several production performance parameters. The most significant of those are steam-oil ratio (SOR), calendar day oil rate (CDOR), ultimate recovery (recovery factor, RF), and project life. In consequence, these performance parameters are related to reservoir parameters such as reservoir thickness, permeability, oil saturation, porosity, oil viscosity, and other reservoir heterogeneities such as bottom water, top gas, and interbedded shale barriers. It would be useful to find and quantify the correlations between the SAGD performance and reservoir parameters.
In this study, a reservoir screening parameter called SPIDER (SAGD Performance Indicator) is developed to evaluate a SAGD project. This new indicator is calculated from four key reservoir parameters such as reservoir thickness (H), permeability (Kv), oil saturation (So), and porosity (Ø) to predict the SAGD performance as well as to evaluate the economics of a SAGD project. A bitumen price and an SOR economic limit are considered to incorporate into a dynamic model.
The results show there exists a relationship between SAGD performance parameters (CSOR, CDOR, and RF) and four reservoir parameters with a high correlation coefficient. Especially, there is a linear relationship between SPIDER and NPV with a correlation coefficient of higher than 0.97. This new indicator may be used as a reservoir screening parameter for a SAGD project.
An economic indicator called STEP (Equation 1) was introduced to evaluate the economics of a SAGD project using the production performance parameters such as CSOR, CDOR, and RF in the series of studies (1, 2, 3). Especially, a dynamic model for STEP called STEP-D (Equation 2) was developed to be used as an economic indicator under the changing conditions of the economic limit of SOR and heavy oil price (3).
Equation (1) (Available in full paper)
Equation (2) (Available in full paper)
STEP may be used as an economic criterion on a SAGD project when the SAGD performance parameters are provided from numerical simulation results or field performance data. As reservoir parameters such as reservoir thickness, permeability oil saturation, porosity, and other reservoir heterogeneities impact the SAGD performance, it would be valuable to quantify the impact of these reservoir parameters.
There are a few studies regarding the geological parameters impact on thermal process performance. Thimm et al.(4) analyzed the well performance indices with geology for the steam soak phase of the Peace River Expansion Project. Ito and Suzuki (1998) investigated the effect of reservoir parameters on oil production rates in SAGD projects. They found that oil rates are proportional to pay thickness, permeability, movable oil saturation, and porosity. Llaguno et al.(5) proposed a new methodology to determine the potential SAGD application for Venezuela reservoirs. They used an analytical tool to evaluate the impact of the reservoir properties (API gravity, reservoir pressure, thickness, permeability, porosity, oil saturation, oil viscosity) on the SAGD performance. They found that oil rates were mainly affected by pay thickness, porosity, and oil saturation, and SOR was affected by all the properties.
