مدلسازي رياضي فرايند آشام در مخازن شكافدار نفت سنگين

چكيده انگليسي :

Mathematical Modeling of Imbibition Process in Fractured Heavy Oil Reservoirs Mojgan Ebrahiminejad Hasan Abaadi m ebrahiminejad@ce iut ac ir Date of Submission September 21 2013 Department of Chemical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Mohammad Reza Ehsani mrehsani@cc iut ac ir Abstract A lot of researches have been done to increase production of heavy oil and improve EOR methods Because of increasing global oil demand declining production of light oil reservoirs and increasing oil prices in recent are examining fractured reservoirs for more oil production There are several mechanisms for crude oil recovery from the fractured reservoirs that the Spontaneous imbibition of water into the matrix blocks is the most important mechanism for reservoirs with low permeability This project presented a numerical modeling of spontaneous imbibition process when water was imbibed by capillary forces into an oil saturated cube core for studying effect of capillary forces oil and water relative permeabilities and viscosity In this modeling we assumed that imbibition process was a diffusion process gravity forces were neglected and capillary diffusivity coefficient CDC was a function of water saturation Finite difference implicit method was used to solve the spontaneous and counter current imbibition equations and finally imbibition process was simulated using MATLAB program Accuracy of the modeling was investigated with comparison of the modeling results and the experimental data After validation the proposed model was used for studying the effect of capillary pressure water and oil relative permeabilities and viscosity on the oil recovery In order to examine the effect of capillary pressure three different capillary pressures were used with multiplication in order of 0 1 1 and 10 to the matching result of capillary pressure Capillary pressure was driving force in the spontaneous imbibition process thus oil recovery was increased with increasing the capillary pressure In order to examine the effect of relative permeability on oil recovery three cases of oil and water relative permeabilities curves were used Oil recovery was increased with increasing the oil and water permeabilities significantly but the effect of oil permeability was less In order to examine the effect of viscosity the oil recover curves for three different oil viscosities and three different water viscosities were plotted Oil recovery was increased with decreasing the oil and water viscosity but the effect of oil viscosity was less In order to investigate the sensitivity of gravity on imbibition rate the vertical cube core was modeled by proposed numerical method The capillary and gravity forces were driving forces of water imbibition but each of these forces could act as dominant force to control the imbibition rate According to the matrix property and the position of the matrix and the fracture the dominant force was determined Increasing the height of core increased the effect of gravity and decreased the effect of capillary forces Neglecting the gravity force caused a lot of error in predicting the oil recovery from high reservoirs by imbibition process This project also presented a numerical modeling of imbibition phenomenon into an oil saturated cylindrical core for studying effect of boundary condition and shape factor on spontaneous imbibition By using the proposed model the most effective boundary condition for achieving the maximum oil recovery could be determined The oil recovery was increased with increasing the permeable surfaces in contact with water Keywords mathematical modeling of fractured reservoirs spontaneous imbibition counter current imbibition capillary diffusivity coefficient spontaneous imbibition up scaling PDF created with pdfFactory trial version www pdffactory com

ابراهيمي نژاد، مژگان

مدلسازي رياضي فرايند آشام در مخازن شكافدار نفت سنگين

آشام موئينه , ضريب نفوذ مويينگي , مقياس بندي به ابعاد ميداني