Research On Nonlinear Heat Transfer Law And Annulus Pressure In Foam Drilling

Foam drilling can preferably solve problems such as mud loss, oil layer pollution and productivity, etc., which is greatly beneficial to protect, find and evaluate oil and gas resources. Foam drilling technology has a obvious efficency in the detailed exploratory wells and step-out wells in low pressure oil and gas zone, which will be used widely.When calculating the annulus pressure in foam drilling, temperature is one of the most important physical parameter. Linear fluid temperature model is used in traditional theory, in which temperature of annulus fluid is equal to that of formation in the same depth. So the premise of this model is to assume that heat capacity of foam is poor, and the heat is transfer-ed fully. But due to the high flow speed of annulus fluid, heat exchange between circulating fluid in annular and formation is not full, at the same time, there are other factors affecting wellbore fluid temperature. Linear fluid temperature model is a kind of ideal one, but the actual temperature distribution is not so simple.On the basis of previous research, this paper bases on fluid mechanics, heat transfer, solid-liquid two-phase flow, computational fluid dynamics and stable foam theory, considering the foam physical parameters changes with temperature, combining nonlinear heat transfer model and the traditional temperature calculation mode, the temperature calculation model in annular of foam drilling is established. Newton iteration method is applied to solve the model. The influence of different liquid flow, gas flow, well backpressure and foam injection temperature on temperature is analyzed. Finally, the effect of wellbore heat transfer to annulus pressure is researched.