Abstract: When steam flows in horizontal wellbore,the mass flow rate will decrease with steam draining into the formation.Acceleration pressure drop will cause the change of steam physical parameters,which play an important role in the distribution of steam properties.Based on the rules of mass conservation and energy conservation,a model for steam quality variation along with the horizontal section length is built.Pressure drop and temperature distribution of injected steam along horizontal wellbore are deduced by using the principle of momentum conservation,and some models such as work done by friction,density of wet steam mixture,amount of steam absorption and the heat transfer calculation model between wellbore and formation are built,and the models are solved by the method of pressure increment iteration.The comparison between examplebased calculation results and reservoir numerical simulator shows that the new model has a higher accuracy.

Key words: steam stimulation, horizontal well production, steam quality distribution, wellbore pressure distribution, wellbore temperature distribution