Determining Gas Flow Rate and Formation Thermal Conductivity from Pressure and Temperature Profiles in Vertical Well (SPE 152034)

Description The problem of determining the gas rate in the well from temperature and pressure profiles along the column is considered. The model mathematical developed allows determining flow rate and one extra parameter from the temperature and pressure profiles assuming that other coefficients are known. We discuss determining the overall heat exchange coefficient between the well and the reservoir, thermal conductivity of the earth, geothermal gradient in the reservoir and gas-column friction factor. Different field situations where one of these four parameters is chosen as the second unknown parameter are discussed. Application The proposed approach was applied for determination of well gas rate and geothermal gradient from the acquired well pressure and temperature data in 3 well from field A (Australia, Cooper Basin). Results and conclusions The detailed analysis has been performed on the physical effects that influence the flow rate in gas well. The most significant effects are: friction, gravity, thermal expansion and gas-reservoir heat exchange. Solving the inverse problem determines the flow rate and geothermal gradient by matching the gas pressure and temperature distributions with measured profiles. Good agreement between the measured and predicted temperature and pressure profiles along 3 wells has been achieved (field A). Sensitivity study shows that the most important parameters are the friction factor and the overall heat transfer coefficient. The friction factor exposes the higher sensitivity with respect to small perturbations of initial data. Significance Determination of rate profile along the well is important for reservoir characterisation, since it allows distinguishing the production rates from different layers. The temperature and pressure sensors in the well are small and cheap chips, while flow meters are cumbersome and expensive, and affect the flow in the well. The present method shows its significance in prediction the gas rate from temperature and pressure data.