پيش بيني پارامترهاي موثر در فرآيند VAPEX

چكيده انگليسي :

Prediction of the Effective Parameters in the VAPEX Process Morteza Sabeti m sabeti68@yahoo com Date of Submission 2013 06 01 Department of Chemical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree Master of Science Language Persian Supervisor M R Ehsani ehsanimr@cc iut ac irAbstract According to the almost all Middle East reservoirs with high depth carbonated and fractured characteristics a model is required to estimate heavy oil recovery from low permeability low porosity and low thermalconductivity of such reservoirs So a non thermal recovery technique seems to be more successful than athermal technique in some situations One of the cold recovery methods is vapor extraction called VAPEX VAPEX is the solvent analogue of the steam assisted gravity drainage SAGD process and uses essentiallythe same well configuration A solvent vapor is injected instead of steam and the viscosity reduction occursdue to the dissolution of the solvent in the oil In the VAPEX process tow horizontal wells are drilled insidereservoirs for solvent injection and oil production The main mechanism of VAPEX is governed by masstransfer of the solvent into heavy oil and consequent oil viscosity reduction and gravity drainage Theobjective of this research was to develop a semi analytical and numerical method to predict the effects of themain parameters in the VAPEX process The semi analytical method bases on the solvent chamber growth ofVAPEX under unsteady state constant pressure and isothermal conditions In this method the oil and solventinterface was divided into a number of segments and oil drainage for each time step was calculated Theother method bases on the compositional simulation in the VAPEX process Therefore a two dimensional three phase numerical model reservoirs with formulation details numerical solution method andcomputational results was described for simulation of VAPEX process in heavy oil The model included theeffects of three phase relative permeability and pressure dependent fluid properties and also interphase masstransfer of solvent in heavy oil was considered The three phase mass balance equations were solvedsequentially using finite difference method hence it was able to simulate VAPEX with different diffusionand dispersion coefficients Predictions of the two models were validated against experimental data and otheravailable models After this the presented models were used for extraction of heavy oil from an Iranianreservoir according to the reservoir characteristics and several cases were run in order to study the effects ofsolvent bed permeability initial oil viscosity bed height and diffusion coefficient on the oil production rate Finally it was concluded that for the stabilized stage of production oil rate is a function of bed height to thepower of 0 6847 and the stabilized production rate is proportional to the square root of the matrixpermeability moreover the horizontal interface movement with lower permeability will have a more uniformvelocity Comprehensive and comparative studies together with extensive sensitivity analysis from 0 0178 to0 00178 cc s as solvent injection rates were conducted to specify the dependency of the oil recovery breakthrough time and SOR to injection rate On contrary of general opinion the increasing of diffusion valuedoesn t always cause significant effects on production rate At the end of study a proper plan was suggestedsuch that a high solvent rate is injected at the beginning of the process afterward it is reduced to decrease therequirement of solvent and eventually makes the operation be more economical Keywords VAPEX heavy oil numerical modeling reservoir simulation oil recovery solvent injection diffusion

ثابتي، مرتضي

پيش بيني پارامترهاي موثر در فرآيند VAPEX

استخراج با بخار هيدروكربني , نفت سنگين , مدلسازي عددي , شبيه سازي مخازن , برداشت نفت , تزريق حلال , نفوذ