For gas-lifted wells in the Permian basin, there can be big differences in the operating casing pressure, depending on which temperature models are used for the design.
Empirical data was collected from fiber optic and temperature surveys in flowing wells in the Midland and Delaware basins. Comparisons were then made to the standard enthalpy balance equation, Beggs and Shiu's correlation, and the Hassan & Kabir (2007) correlation. From these comparisons the model providing the best match to measured data was identified.
Geothermal temperature varies widely throughout the Permian basin – even between benches. This poses a challenge for predicting gas-lift operating pressures in this area, since the majority of the gas-lifted wells in the Permian basin use an IPO (injection pressure operated) type of gas-lift valve. An IPO valve has a dome that is nitrogen-charged, but nitrogen is sensitive to temperature, which makes proper flowing temperature modeling a critical element of the design process. When a temperature model has not yet been defined for an area, it is common to use a conservative safety factor, but this can result in a low operating casing pressure, which wastes the energy of the compressed gas.
This paper identifies a method for determing the best flowing temperature model and includes a model, not typical to the gas lift industry, for use in creating gas-lift designs in the Permian Basin. The proper model allows the design engineer the ability to predict operating parameters without fear of locking gas-lift valves out because of temperature, enabling them to use maximum available operating casing pressure for better lift.