Sharif Digital Repository

The permeability is one of the most important reservoir parameters and its accurate prediction is necessary for reservoir management and enhancement. Although many empirical formulas are derived regarding permeability and porosity in sandstone reservoirs [1], these correlations cannot be modified accurately in carbonate reservoir for the wells which are not cored and there is no welltest data. Therefore estimation of these parameters is a challenge in reservoirs with no coring sample and welltest data. One of the most powerful tools to estimate permeability from well logs is Artificial Neural Network (ANN) whose advantages and disadvantages have been discussed by several authors [2]. In this... 

Producing from gas condensate reservoirs under dew-point pressure and at constant temperature shows a complex behavior because of existing liquid condensate around the well. Zones with different mobilities generate three zones as a zone away from the well containing only gas, a zone having liquid around the well and finally a zone containing movable oil and gas. Existence of condensate around wellbore reduces gas relative permeability and as a result productivity index of the well will decrease. In fact, this condensate acts like an additional skin and investigating of this behavior can be difficult because of the complex fluid flow processes. Well test analysis in naturally fractured... 

In this paper, we used echo state networks - a class of recurrent neural networks - for prediction of drought based on remote sensing data. To this end, the drought index was obtained for a number of stations in different clime zones of Iran. For each station, we also extracted the corresponding vegetation indices based on satellite imagery. Our model takes the satellite-based features as input and outputs the severity of drought. One of the major challenges of echo state networks is optimization of the reservoir parameters. Here we used a method based on Kronecker product in order to substantially reduce the parameter space to be optimized. We then used various optimization techniques... 

An integrated model is proposed for simultaneous study of CO2-flood enhanced oil recovery and sequestration in both technical and economic points of view. Based on this model, Green Balance software is developed for quick estimation of performance and profitability of CO2-flood enhanced oil recovery and carbon capture and storage projects. This software benefits users to do sensitivity analyses in extended times, easily and quickly. Several sensitivity analyses were done and effects of reservoir parameters and economic expenditures and taxes were studied. Among all affecting parameters, the role of tax per CO2 emission is the most important one. The use of... 

Top-down in situ combustion (ISC) involves the stable propagation of a combustion front from the top vertical injector to the bottom horizontal producer. With the exception of laboratory studies of conventional sandstones, no application of the process in fractured carbonates has been addressed. The aim of the present work is to study ISC in the presence of a system of networked fractures using a thermal reservoir simulator from the Computer Modeling Group (CMG; Calgary, AB, Canada). The performance of ISC is compared with nonfractured system under similar conditions. To obtain more realistic results, a history-matched and validated combustion model of an Iranian naturally fractured... 

This study presents a novel perspective on pressure-transient analysis (PTA) of downhole-pressure and flow-rate data by use of system-identification (SI) techniques as widely used in advanced process engineering. Key features of the paper are that it considers the classic PTA process from a system-theoretical perspective; derives the causal structure of the flow dynamics; proposes a method to deal with continuously varying pressure and flow-rate signals contaminated with correlated noise, which estimates physical reservoir parameters through a systematic matching procedure in the frequency domain; and can cope with arbitrary (i.e., not necessarily piecewise constant) flow-rate signals. To...