A wellbore heat transfer model for steam injection as enhanced oil recovery method

Increasing of viscosity in heavy oil reservoir lessens oil production capacity. Therefore, it is necessary to decrease the oil viscosity in order to increase the production capacity. For this purpose, steam injection method is one of the most important techniques which are used to enhance the heavy oil production capacity. The accurate estimation regarded the heat loss from steam to geological structure surrounding the well is of utmost importance for design of such a thermal system. In this thesis, thermal analysis for the thermal system consisting of a surface transmission line and a wellbore well is performed. Formulations for the heat losses along the steam distribution line and wellbore during steam injection, and some parameters are expressed in this analysis. A computer program in EES (Engineering Equation Solver) based on the formulations is prepared to see effects of thermophysical properties of the geological structure surrounding the well on the performance parameters of the system. The performance parameters such as steam quality, temperatures and pressures of the steam, and heat loss from the wellbore are computed by using the program for both conditions of steam injection and steam with the non-condensable gas CO2. Results obtained from the computations are given as figures and discussed in this study. Finally, statistical analyses by using General Linear Model (GLM), Analysis of Variance (ANOVA) and analytical modeling through multiple linear regression technique are carried out. The analyses are used to obtain simple mathematical formulations for calibrating some significant parameters such as line length, outside radius of pipe, wellbore depth, properties of insulation materials and steam injection time in order to evaluate the steam injection system.