Prediction of key points of water-oil relative permeability curves using the linear regression technique

Relative permeability is among the most critical parameters in reservoir performance evaluation and EOR projects. It reflects the ease of movement and trapping of different phases and affects the production rate and ultimate recovery from reservoirs. Experimental measurement of relative permeability curves is complicated, costly, time consuming, and the results can easily be influenced by test conditions and interpretation methods. Empirical correlations are alternative approaches that are based on existing experimentally measured relative permeability curves and rock and fluid properties. The authors used 260 relative permeability curves from Iranian carbonate and sandstone reservoirs. Six key points for each set of water-oil relative permeability were determined, which fully characterize these curves. Using linear regression technique, new correlations were proposed to predict these key points. Having this done, it is then easy and straightforward to construct unnormalized/real water-oil relative permeability curves.R. Roghanian, M. Reza Rasaei and M. Haghigh

PREVALENCE OF GENOMIC ISLAND PAPI-1 IN CLINICAL ISOLATES OF PSEUDOMONAS AERUGINOSA IN IRAN

Pseudomonas aeruginosa, a gram-negative rod-shaped bacterium, is an opportunistic pathogen, which causes various serious diseases in humans and animals. The aims of this study were to evaluate of the presence of genomic island PAPI-1 in Pseudomonas aeruginosa isolated from Reference Laboratory of Ilam, Milad Hospital and Emam Khomeini Hospital, Iran and to study the frequency of extended spectrum beta-lactamases (ESBLs) among isolates. Forty-eight clinical isolates of P. aeruginosa were obtained during April to September 2010, and were evaluated for ESBLs by screening and confirmatory disk diffusion methods and PAPI-1 by PCR. Fifteen of 48 P. aeruginosa isolates were positive for ESBLs and 17 isolates positive for PAPI-1. This was first study of the prevalence of PAPI-1 in clinical isolates of P. aeruginosa in Iran, showing that most of PAPI-1 positive strains had high levels of antibiotic resistance and produced ESBLs

Upscaled unstructured computational grids for efficient simulation of flow in fractured porous media

First published online in 2009Discrete fracture modeling (DFM) is currently the most promising approach for modeling of naturally fractured reservoirs and simulation of multiphase fluid flow therein. In contrast with the classical double-porosity/double permeability models, in the DFM approach all the interactions and fluid flow in and between the fractures and within the matrix are modeled in a unified manner, using the same computational grid. There is no need for computing the shape factors, which are crucial to the accuracy of the double-porosity models. We have exploited this concept in order to develop a new method for the generation of unstructured computational grids. In the new approach the geological model (GM) of the reservoir is first generated, using square or cubic grid blocks. The GM is then upscaled using a method based on the multiresolution wavelet transformations that we recently developed. The upscaled grid contains a distribution of the square or cubic blocks of various sizes. A map of the blocks’ centers is then used with an optimized Delauney triangulation method and the advancing-front technique, in order to generate the final unstructured triangulated grid suitable for use in any general reservoir simulator with any number of fluid phases. The new method also includes an algorithm for generating fractures that, contrary to the previous methods, does not require modifying their paths due to the complexities that may arise in spatial distribution of the grid blocks. It also includes an effective partitioning of the simulation domain that results in large savings in the computation times. The speed-up in the computations with the new upscaled unstructured grid is about three orders of magnitude over that for the initial GM. Simulation of waterflooding indicates that the agreement between the results obtained with the GM and the upscaled unstructured grid is excellent. The method is equally applicable to the simulations of multiphase flow in unfractured, but highly heterogeneous, reservoirs.Muhammad Sahimi, R. Darvishi, Manouchehr Haghighi and M. Reza Rasae