Petroleum Engineering – Reservoir
Mohammad Ashrafi; Seyyed Alireza Tabatabaei-Nezhad; Elnaz Khodapanah
Abstract
Challenges of rock absolute permeability prediction of tiny samples are remarkable when laboratory apparatus is not applicable and there is no pore network modeling. The prediction using the characterization of micro-computed tomography images has been studied in this paper. Twenty series of 2D micro-computed ...
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Challenges of rock absolute permeability prediction of tiny samples are remarkable when laboratory apparatus is not applicable and there is no pore network modeling. The prediction using the characterization of micro-computed tomography images has been studied in this paper. Twenty series of 2D micro-computed tomography rock binary images have been collected, and each was considered a 3D binary image. Their geometric measures in 2D and 3D for measuring image properties have been considered using Minkowski functionals and available functions, developing a regression model; absolute permeabilities have also been evaluated. Some 2D and 3D geometric properties are considered. The area, the perimeter, and the 2D Euler number are 2D binary image properties. The volume, surface area, mean breadth, integral of the mean curvature, and the 3D Euler number are 3D binary image properties. The porosity and number of objects have also been considered parameters of a regression model. Twenty-four parameters were evaluated, and some were chosen to perform linear regression. An equation was proposed based on the extensive study to predict rock permeability. This equation has two sets of parameter coefficients: one set predicts high-permeability rocks (above two Darcy), and the other used for low- and medium-permeability rocks (less than two Darcy) can be employed for carbonated rock. The average absolute relative error for conducted cases is 0.06.
Petroleum Engineering
Nima Hamidian Shoormasti; Seyyedalireza Tabatabaei-Nezhad
Abstract
Shale formations are essential for different disciplines, including wellbore stability studies in petroleum engineering. In shale stability studies, the prediction of transport parameters of water and ions is a significant issue (Farrokhrouz and Asef, 2013). A unique and novel method to address this ...
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Shale formations are essential for different disciplines, including wellbore stability studies in petroleum engineering. In shale stability studies, the prediction of transport parameters of water and ions is a significant issue (Farrokhrouz and Asef, 2013). A unique and novel method to address this subject is the Revil model (Revil et al., 2011), which, unlike previous models, considers physiochemical mechanisms in the pore space and needs a few easily measurable shale properties (Revil et al., 2004). In this paper, for the first time to our knowledge, the Revil model has been extended for salts of multivalent ions. The extended model for water and ion transport through shale has been evaluated against a range of experimental data sets in the literature. The extended Revil model only needs a few shale properties such as cation exchange capacity (CEC), porosity, and grain density, which can be readily measured in the laboratory. Further, in the present work, three parameters ( ) have been considered calibration parameters. In addition to extending the Revil model for multivalent salts, we derived a simplified equation to estimate ion selectivity (IS) and a proof for the conjecture that IS correlates with membrane efficiency (ME). Focusing on the data set of Albazali (2005), a complete matching could be obtained by adjusting calibration parameters for each test data. In the case of adjusting all experiments with only three standard calibration parameters, the prediction was not satisfactory. However, the “intact-anion method” results were more accurate than the “Donnan method”. When multiple sets of ME data in a broader concentration range, including low concentrations, were plotted along with high-concentration data, correlativity was significant (R2 > 0.9). Further, a sensitivity analysis of the model parameters was performed. Our findings pave the way for the appropriate mechanistic approach to investigating and handling practical engineering challenges associated with shale.
Petroleum Engineering
Mehdi Qassamipour; Elnaz Khodapanah; Seyyed Alireza Tabatabaei-Nezhad
Abstract
Net pay thickness is defined as that portion of a reservoir which contains economically producible hydrocarbons with today’s technology, prices, and costs. This thickness is a key parameter of the volumetric calculation of in-place hydrocarbons, well test interpretation, and reservoir characterization. ...
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Net pay thickness is defined as that portion of a reservoir which contains economically producible hydrocarbons with today’s technology, prices, and costs. This thickness is a key parameter of the volumetric calculation of in-place hydrocarbons, well test interpretation, and reservoir characterization. A reservoir interval is considered as net pay when it contains hydrocarbons that can flow at an economic rate. Therefore, to define net pay, cutoffs of hydrocarbon storage properties besides flow properties of reservoir rock are necessary. Frequently, petrophysical log-derived rock storage properties like porosity and water saturation are linked to core measured properties like permeability to find a relation between them. Then, by use of a fixed limiting value for permeability, log-derived properties cutoffs are determined. The basic problem of these methods is related to permeability cutoff, since in most cases there is no knowledge about it, and the permeability cutoff can differ from field to field or even well to well. A new methodology has been developed to find a logical permeability cutoff for gas reservoirs which can differ for different wells and/or fields. This technique is based on gas flow through porous media in tight rocks. Accordingly, a relationship between porosity and permeability is derived as a cutoff value at reservoir pressure and temperature, which is considered as a discriminator plot. Then, the core data of the specified reservoir are added to this plot and the data points reflecting net pay zone are identified. This technique has been applied to four real gas reservoirs in Iran and indicated acceptable results confirmed by the drill stem test (DST) and production data. The results show that the proposed procedure is less dependent on experts’ experiences and acts as a straightforward and powerful tool for the refinement of net pays. In addition, the cutoff values calculated from this method contain a scientific base supporting the main procedure.
Chemical Engineering
Ahmed Zoeir; Alireza Tabatabaei Nejad; Elnaz Khodapanah
Abstract
In sour gas flares, content like any other components in inlet gas influences adiabatic flame temperature, which, in turn, impacts on the pollutant emission. Wherever flame temperature increases, the endothermic reaction between and is accelerated, which means higher emission ...
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In sour gas flares, content like any other components in inlet gas influences adiabatic flame temperature, which, in turn, impacts on the pollutant emission. Wherever flame temperature increases, the endothermic reaction between and is accelerated, which means higher emission to the atmosphere. In this work, we developed an in-house MATLAB code to provide an environment for combustion calculations. Then, this written code was used to perform sensitivity analyses on content, air temperature, and excess air ratio in sour gas flares. We used Environmental Protection Agency (EPA) reports to assign weighting indexes to each air contaminant according to its harmfulness to environment; thereafter, sour gas flaring conditions were optimized for two real field case studies, namely Ahwaz (AMAK) and South Pars, to reach the minimum integrated pollutant concentrations. The results show that each 2% increase in the content of the entrance feed may produce 0.3% additional in the exhaust. The results also confirm that decreases of 20 °F and 50 °F in the oxidant temperature cause emission to reduce by 0.5% to 1% respectively. Finally, to verify and validate our results acquired from the written MATLAB code, FRNC 2012 industrial software was used to duplicate the oxidation results for the two sour flare case studies.
