F. Hormozzade; M. Baniassadi; F. Sahabi; H. Izadi; H. Memarian
Abstract
The determination of Petrophysical rock properties has always been an important part of geological modeling and also is used in reservoir engineering studies. Permeability (k) is one of the most important properties of porous media which is the measure of a porous material to allow fluids to pass through ...
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The determination of Petrophysical rock properties has always been an important part of geological modeling and also is used in reservoir engineering studies. Permeability (k) is one of the most important properties of porous media which is the measure of a porous material to allow fluids to pass through it. Permeability can be determined from both experimental tests and numerical simulations. Numerical simulations should be performed on geometries determined from advanced imaging techniques. Digital rock physics (DRP) is an approach for studying rocks nondestructively. In this paper, 10 carbonate rock plugs from the oil fields in South-West of Iran were imaged by medical CT scan and the outputs were used for image processing and permeability determination. We evaluated the use of Navier-Stokes equations to perform fluid flow simulation through the pore spaces geometry. The permeability of the samples were calculated and compared with laboratory-derived values. The results indicated a trend between the permeability values reported by the laboratory and medical CT images with R2=90%.
M.A Sarparandeh; B Mehrgini; A Mollajan; F Sahabi; G.H Norouzi; G Jozanikohan
Abstract
In evaluating the quality of the reservoir sandstone facies, clay usually has significant effect in reducing reservoir effective porosity, permeability as well as calculation accuracy of formation fluids saturation. There are several methods for identifying and measuring the amount of clay. In sandstone ...
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In evaluating the quality of the reservoir sandstone facies, clay usually has significant effect in reducing reservoir effective porosity, permeability as well as calculation accuracy of formation fluids saturation. There are several methods for identifying and measuring the amount of clay. In sandstone reservoirs, diversity of type and amount of clay minerals may change the capacity of cation exchange (CEC) measured in the reservoir rocks. The last parameter (i.e. CEC) can be an important criterion for zoning of reservoir based on the type of clay minerals. Cation Exchange Capacity (CEC) measurement is used as one of the subsidiary clay typing methods. This parameter is the ability of clay to absorb and release of cations in the surrounding solution, which has a specified range for each clay mineral. In cases of clay mixtures, CEC values tend toward the range of the dominant clay type of sample. In this study, cation exchange capacity of the clay minerals has been calculated in two wells of the Gonbadli Gas Field in the Shurijeh sandstone reservoir. First, CEC of 20 samples has been measured using Bower method and employing intelligent estimator based on neural network as well. Based on the petrophysical logs and laboratory results, an appropriate model was fitted to estimate this parameter in well interval. According to the CEC values of clay minerals, existing data classified into five categories including clean zone and zones of clay containing kaolinite, chlorite-illite, halloysite with two water molecules and montmorillonite. For this purpose Bayesian, Parzn and K- nearest neighbor (KNN) classifiers were used. Finally, the obtained results in comparison with the results of X-ray diffraction experiments (XRD) showed good agreement.
G Jozanikohan; F Sahabi; G.H Norouzi; H Memarian
Abstract
Clay minerals reduce the reservoir quality in different ways. They may cause mechanical problems in drilling and lead to petrophysicalmisinterpretations.Therefore,Clay typing is necessary for upstream petroleum exploration and production industry. In this paper, type, amount and distribution patterns ...
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Clay minerals reduce the reservoir quality in different ways. They may cause mechanical problems in drilling and lead to petrophysicalmisinterpretations.Therefore,Clay typing is necessary for upstream petroleum exploration and production industry. In this paper, type, amount and distribution patterns of different clay minerals in 76 core samples from two producing and non- producing wells inthe ShurijehFormation, aging early cretaceous,were identifiedby six different instrumental analytical methods such as X-Ray diffraction (XRD), X- Ray fluorescence, thin section studies, thermal analysis (DTA-TGA), scanning electron microscopy (SEM) and measuring the cation exchange capacity (CEC). The results proved that the dominant clay minerals are illite, magnesium rich chlorite andkaolinite. The minor clays are glauconite (in the both wells), montmorillonite (in producing well) and mixed layers of illite-montmorillonite and chlorite-montmorillonite. The average amount of each clay minerals in non-producing well is more than producing one. Then clay minerals were classified on the percentage basis into five classes (less than 10%, 10-15%, 15-20%, 20-25% and more than 25%).According to quantityof samples in each class, the producing and non-producing wells were recognized as clean and shaly sand respectively. An increase in glauconite and Illite amounts and also an increase in illite and chlorite layers of mixed-layered clayswith increasing burial depth and temperature is an obvious sign of burial diagenesis in this formation. The best correlation was observed between percentages of clay minerals and iron, aluminum, potassium and magnesium.The clay minerals in the ShurijehFormation are diagenetic alteration of rock fragments, plagioclase and alkali feldspar in origin and in some cases they originate from outside with layered distribution. Distribution pattern of the autogenic clays are pore filling, pore coating and pore bridging, which cause the porosity and permeability reduction in this formation.
