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Tehrān, Iran

Keshavarzi B.,Sharif University of Technology | Keshavarzi B.,MAPSA Co. | Jamshidi S.,Sharif University of Technology | Salehi S.,University of Louisiana at Lafayette
Special Topics and Reviews in Porous Media | Year: 2014

This work concerns simultaneous determination of relative permeability, capillary pressure, pore size distribution (PSD), and residual oil saturation data by optimization of well testing data, and introduces a new capillary pressure relationship, based on the Weibull distribution function, for direct determination of the PSD function from capillary pressure parameters. Three consecutive injection, fall off, and production well tests are performed on a predefined synthetic reservoir through simulation, and an optimization algorithm is used to find the parameters of relative permeability and capillary pressure curves as well as the value of residual oil saturation. The PSD function is also determined from capillary pressure relationship parameters. The result shows successful application of an optimization technique using the well testing data for determination of relative permeability, capillary pressure, and PSD curves. Also, analysis of the well test scenarios shows that the three periods of injection, fall off, and production are required for generation of enough data for a successful optimization. The sensitivity analysis shows more sensitivity of objective function (OF) values for variations encountered with the water exponent in the relative permeability curve (m) and the C parameter of the capillary pressure relationship in comparison to the other parameters. © 2014 by Begell House, Inc.

Ashrafizadeh M.,Sharif University of Technology | Ahmad Ramazani S.A.,Sharif University of Technology | Sadeghnejad S.,MAPSA Co.
Energy Exploration and Exploitation | Year: 2012

The main purpose of this paper is modeling and simulation of in-situ releasing of smart nano-sized core-shell particles at the water-oil interface during polymer flooding. During the polymer flooding process, when these nano-particles reach the water-oil interface, migrate to the oil phase and the hydrophobic layer of them dissolves in this phase. After dissolution of this protective nano-sized layer, the hydrophilic core containing a water-soluble ultra high molecular weight polymer diffuses back into the water phase and with dissolving in this phase, dramatically increases viscosity of flooding water in the neighborhood of the water-oil interface. In this study, two different time-dependent dissolution models are implemented. A swellable-chain disentanglement model with concentration-dependent diffusion coefficient is considered for dissolution of the core polymer into the aqueous phase, whereas, surface chain disentanglement with constant diffusion coefficient is considered for dissolution of the shell polymer in the oil phase. Using finite difference scheme, the governing equations are numerically solved by defining some dimensionless parameters for the main parameters as well as the moving boundaries. In addition, some experimental flooding tests in micromodel were carried out to experimentally investigate the recovery factor of using these particles compared to those of the conventional polymer flooding.

Esrafili-Dizaji B.,University of Tehran | Rahimpour-Bonab H.,University of Tehran | Mehrabi H.,University of Tehran | Afshin S.,MAPSA Co. | And 2 more authors.
Facies | Year: 2015

The Sarvak reservoirs are characterized by thick rudist-dominated intervals in the south and southwest Iran. During the middle Cretaceous, rudistid communities were widely developed on the shallow parts of the Sarvak platform, mainly in the central Zagros and eastern Persian Gulf. Regional distribution and subsequent diagenesis of the rudist-dominated facies were strongly controlled by a number of paleostructures (i.e., fault-related paleohighs and salt domes) in the area. Facies analysis in 16 Sarvak reservoirs reveals the rudistid units can be classified into three main facies groups, developing thick depositional cycles in the Sarvak Formation. Integrated petrographic and geochemical data shows the rudist-dominated facies were subjected to fresh water diagenesis caused by a considerable drop in relative sea level after the deposition. Subsequently, where they were subaerially exposed over the crests and flanks of the paleohighs, the initial porosity of the rudist facies was enhanced by extensive meteoric dissolution (types A and B). Farther away from the paleohighs, same facies have poor reservoir quality, because the porosity was reduced by meteoric and shallow to deep burial cements, and mechanical/chemical compaction (type C). Despite their deep burial depth, significant amounts of porosity (>10 %) are still preserved in the rudist-dominated facies of the Sarvak Formation, especially below disconformity surfaces. Results of this study reveal the controls of early diagenesis on later diagenetic modification and porosity evolution in the Sarvak Formation, as the second important oil-producing reservoir of Iran. © 2015, Springer-Verlag Berlin Heidelberg.

Mehrgini B.,University of Tehran | Eshraghi H.,Pars Oil And Gas Company | Memarian H.,University of Tehran | Ghavidel A.,MAPSA Co. | And 2 more authors.
3rd Sustainable Earth Sciences Conference and Exhibition: Use of the Sub-Surface to Serve the Energy Transition | Year: 2015

Reservoir geomechanical evaluation provides powerful insights to understand and more precisely predict the lifetime behavior of reservoir regarding to the given or desired development plan. Any geomechanical evaluation is directly based on the rock mechanical data which is taken from experimental destructive tests on intact rock samples. However in some situations preparing required undisturbed and intact rock samples is impossible, technically or financially. Investigating the relationship between some microstructural properties and key geomechanical characteristics may lead to develop some models to estimate those geomechanical parameters by thin section studies instead of destructive tests. In this study which is done on 15 carbonate plugs of Iranian gas field, first qualified plugs were chosen based on the CT-Scan images to investigation. Second thin section studies were carried out on each trim of plugs both qualitatively and quantitatively. In the next step, uniaxial compression tests were performed on the samples. Investigations results illustrate that microstructural parameters including porosity, mud percentage and anhydrite cement content are the main affecting features on unconfined compressive strength (UCS) and Young's modulus (E) of studied carbonate samples.

Mehrgini B.,University of Tehran | Memarian H.,University of Tehran | Dusseault M.B.,University of Waterloo | Eshraghi H.,POGC | And 4 more authors.
Journal of Natural Gas Science and Engineering | Year: 2016

Geomechanical characteristics of the reservoir and adjacent formations are important inputs to lifetime evaluation, operation and monitoring of E&P projects. Causes and cures for issues such as well instability and production decline often are found in the geomechanical behavior of the rock. Rock testing usually involves destructive tests on core samples, and it is widely acknowledged that properties should be measured at the representative conditions (T, p, σ) from which samples were taken. In this study of a well in an Iranian gas field, geomechanical units were first defined using well logs and lithological assessment. Then, based on the computed tomography images, intact samples were chosen and prepared for uniaxial and triaxial compression in both ambient (20 °C) and reservoir (90 °C) temperature conditions. The geomechanical properties at both temperatures, including uniaxial compressive strength (UCS), Young's modulus (E), Poisson's ratio (v), friction angle (φ') and cohesion (c') were compared. Porosity is observed as the main factor influencing the geomechanical behavior, and temperature affects UCS and E values of each GMU, in two distinct ways. We noted a transition porosity of 9%; specimens above this porosity respond differently to temperature compared to specimens below this porosity. It is concluded that whenever rock solid components' thermoelastic expansion is compensated by sufficient available free space (high porosity), the rock matrix will be strengthened. Finally, we noted that this range of δT has no significant effect on ν, φ' and c'. © 2016 Elsevier B.V.

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