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Ashena R.,Petroleum University of Technology of Iran | Moghadasi J.,PUT | Ghalambor A.,University of Louisiana at Lafayette | Bataee M.,PUT | And 2 more authors.
Society of Petroleum Engineers - International Oil and Gas Conference and Exhibition in China 2010, IOGCEC | Year: 2010

Two phase flow applications in petroleum industry are so widespread. It is a fact that UBD precise bottomhole pressure maintenance ascertains UBD success. UBD hydraulics design, especially for inclined trajectories, is a real challenge. This is greatly dependent on the pressure drop in the annulus. Two phase flow through annulus is an ambiguous area of study to evaluate the bottomhole pressure. Two phase flow correlations on which most of UBD simulators based on over predict and also make extrapolation risky. Although Mechanistic approaches increase the frequency for designing two phase flow systems in pipes, modeling them through annulus by using the hydraulic diameter concept is not so successful. For this reason, their corresponding errors are not small. Therefore, in this paper, Artificial Neural Network is made use of to evaluate BHP in the inclined annulus using two major Iranian Oil Fields. To compare BHP found by neural network, Naseri et al mechanistic model which is a popular mechanistic model for these two fields is applied. ANN shows to perform much better than Naseri et al mechanistic model. The results show that neural network can estimate bottomhole pressure with an error of less than 20%. This proves that in case of existence of measured BHP while under balanced drilling, it is worth to use ANN to simulate BHP rather than mechanistic modeling or correlations. ANN is highly shown to be useful for solving the non-straightforward problem of two phase flow in annulus. Few jobs have been done to prove the superiority of ANN to mechanistic modeling and correlations in terms of pressure prediction especially in under balanced drilling. Copyright 2010, Society of Petroleum Engineers.

Ahmadi M.,Rock Mechanics Group | Tarbiat Modares U.,Islamic Azad U Omidieh Branch Young Research Club | Ashena R.,Islamic Azad U Omidieh Branch Young Research Club | Ashena R.,PUT | And 4 more authors.
Society of Petroleum Engineers - IADC/SPE Asia Pacific Drilling Technology Conference 2010 | Year: 2010

High power lasers when applied to drilling is potentially capable of reducing the drilling time, improving well performance and exemption from the necessity to remove the cuttings. In this paper, Rate of Penetration (ROP) and the specific energy (SE) required to remove the rock from Carbonate reservoir rock, Ahvaz#383-9 is measured using the Nd.YAG pulsed laser to identify the prospective laser application for drilling in South of Iran. The three samples selected from each depth and formation were the dry, water and oil saturated. The petrography studies of the rock samples were performed before and after the laser test to analyze any changes in the rock mineralogy and properties. SE was measured with different operational parameters comprising the laser beam and rock properties to detect their effect. This would help us to spot the optimum operational beam parameters with fixed rock properties to be adjusted to obtain minimum SE. The results show SE increases with increasing laser radiation time and drilling depth non-linearly. SE corresponding to water saturated samples were higher than that of oil saturated and the SE of oil saturated were higher than that of the dry samples. ROP and SE showed to have a nonlinearly inverse relationship. The optimum operational parameters determined, can help optimize the laser application in regards to obtaining the minimum SE. Future laser rock mechanical laser simulation softwares can be developed based on the experimental approach. Copyright 2010, IADC/SPE Asia Pacific Drilling Technology Conference and Exhibition.

Mavaddat M.,University of Tehran | Soleimani A.,Schulumberger | Rasaei M.R.,University of Tehran | Mavaddat Y.,PUT | Momeni A.,University of Tehran
Proceedings of the SPE/IADC Middle East Drilling Technology Conference and Exhibition | Year: 2011

Horizontal wells with multiple fractures are becoming more prevalent in the Industry. They can especially beneficial in gas condensate reservoirs to minimize the pressure drop in order to reduce liquid drop-out and reduce the severe loss of well productivity and therefore lower gas recovery. Reliable evaluations of stimulation performance are required for field development planning. As such, pressure transients are often used, and can be successful, to observe and define the various impacting factors of stimulation, such as fracture length, conductivity, orientation, etc. This project investigates the modeling and interpretation of pressure transient responses of multiple hydraulic fractured horizontal wells in gas condensate reservoirs using a numerical reservoir model with a focus on the existence of different mobility zone due to condensate dropout. Derivative shapes expected from hydraulic fractured horizontal well-test data are obtained using a 3D fully compositional model in gas condensate reservoirs below the dew point under various conditions. The numerical model is validated using an analytical solution and applied to a simple reservoir model. Complex reservoirs are then simulated and pressure transient response signatures are obtained. Sensitivity studies of important reservoir, well and fracture properties are performed and a result of each case is presented. It was found that condensate dropout near the wellbore yields a well-test composite behavior; similar to what is found in hydraulically fractured vertical wells, but superimposed on a horizontal well behavior, which makes it much more complex. Furthermore a higher gas production will be achieved in a horizontal well with optimum number of fractures, fractures conductivity and fracture half length which may depend on formation and hydrocarbon characteristics. Copyright 2011, SPE/IADC Middle East Drilling Technology Conference and Exhibition.

Bualoti R.,Polytechnic University of Tirana | Qemali M.,PUT | Hobdari N.,Polytechnic University of Tirana
IET Conference Publications | Year: 2010

The distribution networks are actually growing with complexity, due to the gradual increase of power demand and the existence of customers with more sensitive loads. An interruption has nowadays more severe impact in load equipment than in loads existing a few years ago. This fact combined with the analysis of customer failure statistics, causing also financial loss for utility companies, reinforces the need to be concerned with reliability evaluation of distribution network. An efficient operation of distribution networks can, therefore, be achieved by using reconfiguration techniques. The network reconfiguration is carried out by changing the on/off status of the switches. Obviously, the greater the numbers of remote control switches, the greater are the possibilities for reconfiguration and better are the effects. The automation implementation will be technically advantageous as well as economical for the utilities and the customers, in terms of the variable costs reduction and better service quality. This paper discusses some important aspects related to Optimal Separation Point in distribution network. Some techniques previously studied in the literature are analyzed and a critical evaluation of Optimal Separation Point Approach is presented. The effectiveness of the analyzed methods is demonstrated through numerical studies in test systems.

Cristutiu I.-M.,PUT | Nunes D.L.,PUT | Dogariu A.I.,PUT
Steel and Composite Structures | Year: 2012

Steel structural elements with web-tapered I cross section, are usually made of welded thin plates. Due to the nonrectangular shape of the element, thin web section may be obtained at the maximum cross section height. The buckling strength is directly influenced by lateral restraining, end support and initial imperfections. If no lateral restraints, or when they are not effective enough, the global behaviour of the members is characterized by the lateral torsional mode and interaction with sectional buckling modes may occur. Actual design codes do not provide a practical design approach for this kind of elements. The paper summarizes an experimental study performed by the authors on a relevant number of elements of this type. The purpose of the work was to evaluate the actual behaviour of the web tapered beam-columns when applying different types of lateral restraints and different web thickness.

Prifti V.,PUT | Bala R.,PUT | Tafa I.,PUT | Saatciu D.,PUT | Fejzaj J.,PUT
Proceedings of the 2015 Science and Information Conference, SAI 2015 | Year: 2015

This paper presents an experimental description of how to use OpenMP for achieving high performance from the quicksort algorithm through the parallelization of some key sections of its code. When this work was in process, I was unsure if the time profit I would achieve would be evident, but I think I exceed my expectations in this matter. The only problem I faced was the unpredictability of execution time in some cases for the parallel version. Anyway, even in this case the time profit in comparison with the sequential version was clear and evident. © 2015 IEEE.

Ashena R.,Islamic Azad University at Omidieh | Nabaei M.,Islamic Azad University at Omidieh | Habibnia B.,PUT | Taee B.,National Iranian Oil Company
Society of Petroleum Engineers - Nigeria Annual International Conference and Exhibition 2010, NAICE | Year: 2010

Specific energy is the amount of energy required for a specified volume of rock to be destroyed. This is a normalization method used to compare the efficiency of destruction of rocks. In this study, low power laser beam of Free Electron Laser (FEL) has been used to penetrate different reservoir carbonate rocks and shales in Ahvaz Oil Field. The corresponding specific energies and ROPs are measured. laser beam is shown to be capable of drilling boreholes because of the high energy it can create. Laser is shown to drill shales while preventing the clay swelling problem prevailing when water is in contact with shales. Laser can also increase the accuracy of perforation of casing strings. The core samples tested were taken from Asmari member Sandstone, Asmari limestones and Khami shale. Comparison of different laser modes in terms of specific energy and ROP increase has been investigated which has not been accounted for in many previous works. As the future work, shape and rock type should be considered although there exist many works in literature wherein these parameters have been neglected. © 2010, Society of Petroleum Engineers.

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