A DYNAMIC MODEL FOR CALCULATING THETHERMAL PARAMETERS OF HORIZONTAL WELLS WITH STEAM HUFF AND PUFF

摘要

In the process of thermal recovery of heavy oil,the energy exchanges with its surrounding environment during steam migration in a tube,so as to heat will be lost and the steam enthalpy will decrease gradually.It will seriously affect the steam-simulation effect of heavy oil wells if string structure,horizontal section length,steam injection volume,and steam dryness are not reasonably designed.Therefore,the accurate calculation and forecast of thermodynamic parameters of steam along the wellbore,such as pressure,temperature,and dryness,is the key to evaluate the gas injection effect.It also has great significance for the optimization of steam-simulated parameters.In this paper,a dynamic model for calculating thermal parameters in horizontal wells with steam huff and puff is established based on one-dimensional unsteady heat-transfer theory,in which the characteristics of the variable mass flow in the horizontal segment is considered.The results shows that the maximum relative error between the calculation results and the measured data is less than 5%,which proves the accuracy of the model.The effect of wellhead steam parameters on the distribution of steam thermodynamic parameters in horizontal wellbore is almost consistent.The steam-injection rate is in direct proportion to the horizontal wellbore extension distance.In addition,the influence of steam-injection time on steam temperature,pressure,and dryness can be ignored.