Sharif Digital Repository

Accurate estimation of the reservoir parameters is crucial to predict the future reservoir behavior. Well testing is a dynamic method used to estimate the petro-physical reservoir parameters through imposing a rate disturbance at the wellhead and recording the pressure data in the wellbore. However, an accurate estimation of the reservoir parameters from well-test data is vulnerable to the noise at the recorded data, the non-uniqueness of the obtained match, and the accuracy of the optimization algorithm. Different stochastic optimization methods have been applied to this address problem in the literature. In this study, we apply the recently developed iterative ensemble Kalman filter in the... 

Accurate estimation of the reservoir parameters is crucial to predict the future reservoir behavior. Well testing is a dynamic method used to estimate the petro-physical reservoir parameters through imposing a rate disturbance at the wellhead and recording the pressure data in the wellbore. However, an accurate estimation of the reservoir parameters from well-test data is vulnerable to the noise at the recorded data, the non-uniqueness of the obtained match, and the accuracy of the optimization algorithm. Different stochastic optimization methods have been applied to this address problem in the literature. In this study, we apply the recently developed iterative ensemble Kalman filter in the... 

Capacitance-Resistive Model (CRM), as a fast yet efficient proxy model, suffers from some limitations in modeling relatively complex reservoirs. Some current improvements on this proxy made it a more powerful simulator with updating parameters over time. However, the model's intrinsic uncertainty arisen from simplifying fluid-flow modeling by some limited number of constant parameters is not addressed yet. In this study, this structural limitation of CRM has been addressed by introducing a time-correlated model error, including stochastic and non-stochastic parameters, embedded into this proxy's formulation. The error term's non-stochastic parameters have been tuned to be used in forecasting... 

Using the original form of Capacitance-Resistance Model (CRM), as a waterflooding performance prediction tool, for modeling real reservoirs makes some unavoidable errors. Combination of this model with available data assimilation methods yields more powerful simulation tool with updating parameters over time. However, the inherent uncertainty arisen by modeling complex reservoirs with only a limited number of CRM parameters is not addressed yet. In this study, the model error behavior has been simulated through a physically-based dynamical system in which it has been correlated with the original model parameters. The ensemble-based Kalman filter (EnKF) data assimilation method has been... 

The bulk samples of GdBa2Cu3-xCrxO7-δ with x = 0-0.3 have been prepared by the conventional solid-state reaction method. Structural phases were determined by powder X-ray diffraction. The XRD and the unit cell parameters were obtained through Rietveld refinement of the XRD data. By increasing the doping, the c parameter decreases and the a parameter increases, and by the nearly fixed b parameter, the orthorhombic phase approaches to the tetragonal phase. The resistivity measurements show a strong effect of doping on suppression of Tc. At the first doping step of x = 0.05, Tc decreases abruptly to 57 K, but by increasing the doping, this rate slows down and becomes nearly linear for higher... 

Capacitance-Resistive Model (CRM), as a fast yet efficient proxy model, suffers from some limitations in modeling relatively complex reservoirs. Some current improvements on this proxy made it a more powerful simulator with updating parameters over time. However, the model's intrinsic uncertainty arisen from simplifying fluid-flow modeling by some limited number of constant parameters is not addressed yet. In this study, this structural limitation of CRM has been addressed by introducing a time-correlated model error, including stochastic and non-stochastic parameters, embedded into this proxy's formulation. The error term's non-stochastic parameters have been tuned to be used in forecasting... 

We present a novel method in which a phase mask is used to modulate a beam in order to produce a large extension in the focal depth at the focus of a lens. © 2005 Optical Society of America  

This article introduces a novel duty-cycle control circuit (DCC) preceding a delay-locked loop (DLL)-based clock frequency multiplier preventing the output duty-cycle over process, supply voltage and temperature (PVT) variations. However, the proposed DCC eliminates the effect of input duty-cycle variation and, hence, decreases the sensitivity to the input jitter and distortion. The circuit realisation in 0.5-μm CMOS technology shows that the duty-cycle variation at the output clock is less than 2.7%, while driving the digital section of a CODEC chip and also test pads. The analysis, confirmed by measurements, shows a stable and accurate response for the proposed clock generation unit (CGU).... 

Whole level of the erosion and the resistance of rocks which were composed closured have been studied, besides, the impact of temperature and laser irradiation for more investigation about this issue has been involved before all. This subject more reveals the matter which laser absorption on the laboratory scale using laser to what extent can cause the augment of the relative permeability and secondary porosity of reservoir rock, that of the vertical and horizontal useful connectivity and eventually that of the positive transferability. This research has been carried out in the form of case study on one of Iranian south west formations in north east of Behbahan city in Iran, either the rate... 

The capability level of rotary as well as first generation drilling operation could not be matched for deeply drilling programs. To reach that deep, the increasing in drill string length could also cause an additional constraint on hydraulic performance. The operation of slim hole drilling has significant potential to reduce well costs. This cost might be savings are especially important with increased demand for reduced capital finance under current economic conditions in the Iranian oil and gas industry. This savings achievement could be caused by use of smaller drilling rigs, work over rigs, reduced casing size, reducing requirement for drilling consumables and other costs associated with... 

Designing a successful acidizing treatment requires understanding the chemical interactions between reactive fluid and reservoir rock. The rotating disk experiment is a common approach in the energy industry to study the kinetics of the reactions occurring in chemically reactive systems. The analytical solution of Levich—also known as the Levich equation—has been widely used to calculate the rate constants based on the dissolution rates measured by the rotating disk experiment. However, this equation might fail to produce correct results due to its simplifying assumptions. Ignoring species interactions, intra-aqueous reactions, energy transfer, two-phase flow, and the behavior of...