Temperature prediction model of gas wells for deep-water production in South China Sea

A temperature prediction model was established to analyze gas temperature distribution for deep water production in South China Sea. The model was established by mass, momentum, and energy conservation equations and was solved by the fourth-order Runge-Kutta method. The validity of the model has been verified by field production temperature data from South China Sea. The gas temperature distribution in the production pipe for deep water production in South China Sea was simulated. The influence of gas production rate, production time, geothermal gradient, drilling riser thickness, production pipe type and surface sea water temperature on gas temperature distribution of production pipe in deep water production are also discussed. Results indicate that gas temperature decreases as well depth decreases from down hole to flow head. Gas temperature in the production pipe increases with the increasing gas production rate, production time and geothermal gradient. Meanwhile, the inflection point in the mudline becomes less apparent with the increasing gas production rate and gas temperature in the production pipe has almost no increase with the production time increasing to some extent. The variation of surface sea water only slightly influences the gas temperature in the production pipe within the water depth of 200 m, and the gas temperature in the production pipe increases with the increasing surface water temperature. Gas temperature in the production pipe decreases with the increasing drilling riser thickness. The gas temperature in the production pipe with the outer diameter of 0.114 m and inner diameter of 0.095 m is higher than that with the outer diameter of 0.0733 m and inner diameter of 0.062 m. The results of this study may serve as a reference for deep water production engineers.