CALCULATION OF ESTIMATED OIL RECOVERY USING CARTER TYPE CURVES

Abstract

The focus of this research is to calculate the Estimated Ultimate Recovery (EUR) of shale wells for a diverse range of fluid types using Carter (1985) type curves. The Carter (1985) type curve is a plot of flow rate versus time in dimensionless form and originally developed for dry gas and under-saturated black oil reservoirs. One of the key advantages of the Carter (1985) type curves is that it accounts for different flow regimes such as transient, infinite-acting flow and boundary-dominated flow as well as fluid properties such as viscosity and compressibility. However, because it relies on the use of well-defined and pressure-sensitive fluid properties such as viscosity and compressibility, the Carter (1985) type curves cannot easily generalized to multiphase flow or flow of more complex fluid types. In this thesis, I extend the use of Carter (1985) type curves to wet gas, gas-condensate and volatile oil reservoirs for flow above and below their respective saturation pressures. This is achieved by determining an effective viscosity-compressibility product that can be used in the Carter (1985) type curves. This viscosity-compressibility product is then correlated against fluid C7+ fractions so that the practicing reservoir engineer can easily look-up the appropriate viscosity-compressibility product values for use in EUR calculations using Carter (1985) type curves.