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Omar Mahmoud

Basic information

Name : Omar Mahmoud
Title: Faculty Member at the Department of Petroleum Engineering
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Personal Info: Omar Saad Ahmed Mahmoud: is currently working as faculty member at the Department of Petroleum Engineering, Faculty of Engineering and Technology, Future University in Egypt (FUE). Previously, he was working as petroleum reservoir engineer with the North American Unconventional Resources (NAUR) Team at Apache Corporation’s San Antonio Region, USA. Before joining Apache Corporation, he worked as graduate research assistant/PhD Candidate for 4 years at the Harold Vance Department of Petroleum Engineering, Texas A&M University, USA. Previously, he worked for 8 years as assistant lecturer and teaching/research assistant at the Faculty of Petroleum and Mining Engineering, Suez University, Egypt. He also served as petroleum engineering intern at Apache Corporation (USA) during the summer of 2017. Mahmoud has a demonstrated history of working in the higher education and research industry in addition to a good industrial experience. His research interests include drilling fluids, rheology, filter cake characterization, nanoparticle applications, oilfield chemistry, formation damage and well stimulation, unconventional resources, reservoir simulation, and pressure transient/production data analysis. Mahmoud has authored/coauthored 21 technical articles and conference proceedings and serves as technical reviewer/editor for the SPE Drilling & Completion, SPE Production & Operations, and ASME Journal of Energy Resources Technology. He received PhD-degree from Texas A&M University, BSc and MSc degrees from Suez University, Egypt, all in petroleum engineering. View More...

Education

Certificate Major University Year
PhD Petroleum Engineering Texas A&M University - U.S.A 2017
Masters Petroleum Engineering Suez University - Faculty of Petroleum and Mining Engineering 2009
Bachelor . Suez University - Faculty of Petroleum and Mining Engineering 2004

Teaching Experience

Name of Organization Position From Date To Date
Apache Corporation, USA Petroleum Engineer 01/01/2018 01/01/2018
Apache Corporation, USA Engineering Intern 01/01/2017 01/01/2017
Texas A&M University, USA Graduate Research Assistant (PhD Candidate) 01/01/2013 01/01/2017
Faculty of Petroleum and Mining Engineering, Suez, Egypt Assistant Lecturer 01/01/2009 01/01/2013
Faculty of Petroleum and Mining Engineering, Suez, Egypt Demonstrator (Teaching/Research Assistant) 01/01/2005 01/01/2009

Researches /Publications

Nanoparticles as Promising Additives to Improve the Drilling of Egyptian Oil and Gas Fields - 01/0

Omar Saad Ahmed Mahmoud

Ahmed Mady, Abdel Sattar Dahab

01/08/2020

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Formation-Damage Assessment and Filter-Cake Characterization of Ca-Bentonite Fluids Enhanced with Nanoparticles - 01/0

Omar Saad Ahmed Mahmoud

Hisham A. Nasr-El-Din

01/07/2020

Invasion of mud filtrate while drilling is considered one of the most common sources of formation damage. Minimizing formation damage, using appropriate drilling-fluid additives that can generate good-quality filter cake, provides one of the key elements for the success of the drilling operation. This study focuses on assessing the effect of using different types of nanoparticles (NPs) with calcium- (Ca-) bentonite on the formation-damage and filter-cake properties under downhole conditions. Four types of oxide NPs were added to a suspension of 7-wt% Ca-bentonite with deionized water: ferric oxide (Fe2O3), magnetic iron oxide (Fe3O4), zinc oxide (ZnO), and silica (SiO2) NPs. The NPs/Ca-bentonite suspensions were then used to conduct the filtration process at a differential pressure of 300 psi and a temperature of 250°F using a high-pressure/high-temperature (HP/HT) American Petroleum Institute (API) filter press. Indiana limestone disks of 1-in. thickness were examined as the filter medium to simulate the formation in the filtration experiments. A computed tomography (CT) scan technique was used to characterize the deposited filter cake and evaluate the formation damage that was caused by using different fluid samples. The results of this study showed that the filtrate invasion is affected by the type of NPs, which is also affecting the disk porosity. Using 0.5-wt% Fe2O3 NPs with the 7-wt% Ca-bentonite fluid showed a greater potential to minimize the amount of damage. The average porosity of the disk was decreased by 1.0%. However, adding 0.5-wt% Fe3O4, SiO2, and ZnO NPs yielded a disk-porosity decrease of 4.7, 13.7, and 30%, respectively. The decrease in the disk porosity after filtration is directly proportional to the volume of the invaded filtrate. Compared with that of the base fluid, the best decrease in the filtrate invasion was achieved when adding 0.5 wt% Fe2O3 and Fe3O4 NPs by 42.5 and 23%, respectively. The results revealed that Fe2O3 and Fe3O4 NPs can build a better Ca-bentonite platelet structure and thus a good-quality filter cake. This is because of their positive surface charge and stability in suspensions, as demonstrated by zeta-potential measurements, which can minimize formation damage. Increasing the concentration of Fe3O4 NPs from 0.5% to 1.5 wt% showed an insignificant variation in the filtrate invasion, spurt loss, and filter cake permeability; however, an increase in the filter-cake thickness and amount of damage created was observed. The 1.5-wt% ZnO NPs showed better performance compared with the case having 0.5-wt% ZnO NPs, but in the meanwhile, it showed the lowest efficiency compared with the other types of NPs. This could be because of their surface charge and suspension instability. Results of this work are useful in evaluating the drilling applications using Ca-bentonite-based fluids modified with NPs as an alternative to the commonly used Na-bentonite. In addition, it might help in understanding the NPs/Ca-bentonite interaction for providing more efficient drilling operations and less formation damage.

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Nanoparticle-Based Drilling Fluids as Promising Solutions to Enhance Drilling Performance in Egyptian Oil and Gas Fields - 01/0

Omar Saad Ahmed Mahmoud

Ahmed Mady, Abdel Sattar Dahab

01/06/2020

Over the years, the discovery of petroleum in various regions of the world has led to the development of different techniques and equipment to enhance and optimize the drilling and production operations in this vital industry. Egypt is both one of the major oil-producing non-OPEC countries and one of the oldest energy producers in the Middle East. Recently, the Egyptian government have signed several agreements for the exploration of oil and gas in several provinces/regions including; the Mediterranean, the Western desert, the Nile Delta, and the Gulf of Suez. Petroleum companies have given great attention to Egypt’s new discoveries such as Zohr Gas Field, and Nour exploration prospect. Successful drilling operations to reach the oil and gas targets depends strongly on the effectiveness of the drilling fluids. Drilling fluids can be considered as the heart of the drilling process. They are used to fulfil several functions, such as controlling pressure, carrying cuttings and cooling bit and drill strings, stabilizing wellbore as well as controlling fluid losses. Drilling fluid technology is one of the most targeted and developed technologies worldwide. Several studies have examined the use of various types of nanoparticles (NPs) as additives to enhance the properties and improve the performance of the drilling fluid to mitigate the drilling problems. NPs can be defined as a simplest structure with a size in the range of nanometers. The effectiveness of NPs can be accredited to their small sizes and thus, high surface-area-to-volume ratio. NPs were also showed promising enhancements on the rheological and filtration characteristics of the drilling fluid (mud). Additionally, swelling and collapse of shale formations is expected under drilling with water-based mud, which might result in complicating the drilling operation. Adding NPs to the drilling mud was found to minimize the shale permeability and thus, promote the wellbore stability. This research paper discusses the latest applications and presents the most valuable findings concerning the efficient use of NPs in the drilling fluid industry. Based on that, different recommendations are stated. This might help researchers to better understand NPs’ functionality in this area of application and promote using NPs-based drilling muds as cost-effective and environmental-friendly fluids to drill the Egyptian oil and gas wells.

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Estimating Ultimate Recoveries of Unconventional Reservoirs: Knowledge Gained from the Developments Worldwide and Egyptian Challenges - 01/0

Omar Saad Ahmed Mahmoud

Sarah Elnekhaily, and Gehad Hegazy

01/01/2020

Supertight oil and gas reservoirs have always been considered uneconomical. Their high stimulation costs, forecasting the future production and estimating the ultimate recovery (EUR), have long been problematic. They should be constantly updated during the lifetime of a reservoir, besides; their accuracy depends on the amount of available data and the adopted method. However, after the enormous production in North America, exploring and developing unconventional hydrocarbon resources are gaining more interest worldwide. Nowadays, the Egyptian government is targeting tight layers/zones, in the western desert, to increase the high domestic energy demand and hence, increase the annual production of the conventional – high permeability – reservoirs. Several zones within Khatatba source rock in the Shoushan basin as well as in the Abu Gharadig basin are now being studied and evaluated to maximize their productivity and identify the optimal technology for future developments. In the present work, various approaches, used in predicting the performance of unconventional reservoirs, are investigated and compared through their forecasting future production and their estimated ultimate recovery (EUR). Traditional Arps’ decline, for low permeability reservoirs, over-forecasts reserves. Power-law exponential decline (PLED), stretched-exponential decline (SEPD), logistic-growth model (LGM), and Duong’s method have been used to represent the rate/time production data for the standard well completion in a multiple-fractured horizontal well in a shale play. These methods provide different forecasts as they are based on different equation forms. Unfortunately, previously mentioned methods are not satisfactorily adequate to forecast production for all unconventional reservoirs. The rate transient analytical (RTA) models require certain modifications of the reservoir and fracture parameters to provide optimistic EURs when compared to the numerical simulation. In this research, based on the production forecast and EUR prediction, different models for forecasting unconventional well data have been reviewed and compared. Production data has been used to validate the accuracy of the models, show the similarity of reserves estimation, and reveal the relationship to the reservoir theory. This work might help the Egyptian operating companies to better understand the production dynamics of unconventional reservoirs and suggest a more reliable model EUR’s estimation.

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Can Nanoparticles Improve the Characteristics of Drilling Fluids? - 01/1

Omar Saad Ahmed Mahmoud

Ahmed Mady, Abdel Sattar Dahab

01/10/2019

The present work discusses the latest applications of nanoparticles (NPs) in the oil and gas industry, especially their implementations to improve the properties of drilling fluids. Successful drilling operations depend strongly on the effectiveness of the drilling fluids. Over the last few years, several researchers have examined the use of various types of NPs as additives with the drilling fluids. NPs can be defined as the simplest structure with a size in the range of nm. Physically, any collection of atoms bounded together as structure with any dimension in the range of less than 100 nm is considered as NPs. The effectiveness of NPs can be accredited to their small sizes and thus, high surface-area-to-volume ratio. Different types of NPs have been investigated to enhance the performance of the drilling fluid to mitigate the drilling problems, particularly at high pressure and high temperature (HP/HT). A thin filter cake and less filtrate invasion can be produced at these conditions when using NPs, which might help in reducing the differential pipe sticking and formation damage problems. In different investigations, NPs were also showed promising enhancements on the rheological characteristics of the drilling fluids. Another application when drilling shale formations using water-based drilling fluids. Swelling and collapse of shale is expected at these conditions, which might result in complicating the drilling operation. Adding NPs to the drilling fluid was found to minimize the shale permeability by physically plugging the nano-size pores. This can provide a potential solution for environmentally-sensitive areas where the oil-based mud is commonly used. This research paper presents a brief review of the most valuable findings in the literature regarding the efficient use of NPs in the field of drilling fluid. Additionally, different recommendations are stated, which might help researchers to better understand NPs' functionality and dynamics in this area of application.

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Effect of Ferric Oxide Nanoparticles on the Properties of Filter Cake Formed by Calcium Bentonite-Based Drilling Muds - 01/0

Omar Saad Ahmed Mahmoud

Hisham A Nasr-El-Din, Zisis Vryzas, Vassilios Kelessidis

01/09/2018

During the past few decades, nanoparticles (NPs) have been investigated as additives to address the challenges of drilling fluids and have shown potential for application. The present work focuses on introducing and investigating a calcium (Ca) bentonite-based drilling fluid with ferric oxide (Fe2O3) NPs. Generating efficient filter cake is an important property of the drilling fluid and can affect the success of the whole drilling operation. This study aims at characterizing the filter cake produced by Ca bentonite-based drilling fluid modified using Fe2O3 NPs. Computed-tomography (CT) scan and scanning electron microscopy energy dispersive spectroscopy (SEM-EDS) were used for filter-cake characterization. The effects of NP concentration and filtration conditions on the filter-cake properties were investigated. A high-pressure/high-temperature (HP/HT) American Petroleum Institute (API) filter press was used to perform static and dynamic filtrations. Indiana limestone disks were used as filter media to simulate formation behavior. The modified Fe2O3 NPs/Ca bentonite fluid showed improved filter-cake and filtration properties in the presence of polymers and other additives. A concentration of less than 1 wt% of NPs is preferred for generating a good-quality filter cake. The best characteristics were obtained when using an NP concentration of 0.3 to 0.5 wt%. The NPs/Ca bentonite-based drilling fluid can withstand conditions up to 500 psi and 350°F and generate filter-cake properties of 0.151-in. thickness, 6.9-cm3/30-min filtrate volume, and 0.449-md permeability. Fe2O3 NPs improved the filter-cake properties under both static and dynamic conditions. SEM-EDS showed a smoother/less-porous filter-cake morphology with less agglomeration when using NPs at optimal concentrations, which confirms that the NPs play a key role in forming a better filter-cake structure. The present work provides an experimental evaluation of the filter cake generated by modified NPs/Ca bentonite-based drilling fluid at downhole conditions, which is an extension of our previous work using a simple NPs/Ca bentonite suspension (Mahmoud et al. 2018). The improved properties of the filter cake confirmed the effectiveness of using Ca bentonite modified with Fe2O3 NPs to formulate a drilling fluid that can effectively be used for drilling practices.

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Study of Cluster Efficiency in Unconventional Reservoirs by Analytical Simulators - 01/0

Omar Saad Ahmed Mahmoud

Mohamed Ibrahim Mohamed ;Yakup Coskuner ; Mohamed Salah Mohamed ; Mazher Ibrahim ; Chester Pieprzica

01/08/2018

Unconventional reservoirs have been defined as formations that cannot be produced at economic flow rates or that do not produce economic volumes of oil and gas without horizontal well with hydraulic fracture treatments. Horizontal well fracturing efficiency in unconventional reservoirs is the main factor for the success of developing unconventional reservoirs. The early focus of the industry was on the operational efficiency and during this period, the geometric spacing of perforation clusters adopted as the preferred completion method. Cipolla et al. (2011) presented a case study on the interpretation of production logs from hundreds of horizontal wells. The results indicated that 60% of perforation clusters contribute to production when completed geometrically and completion cost could reach more than 60% of the total well cost. Recently, numerous studies have been undertaken to understand this phenomenon. Increasing the stimulation effectiveness and maximizing the number of perforation clusters contributing to productivity was an obvious area for improvement to engineer the completion design. The uniform initiation and distribution of fractures in each frac stage is very complex because there are many factors affecting the fracture initiation such as stress orientation, heterogeneity, existing of natural fractures, and completion design. This paper presents sensitivity studies investigating the effect of the formation permeability, fracture spacing, fracture half-length, fracture conductivity, flowing bottom hole pressure, and outer reservoir permeability on the well ultimate recovery efficiency by using analytical simulator.

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Formation Damage Assessment and Filter Cake Characterization of NPs/Ca-Bentonite Fluids for Drilling Harsh Environments Using Computed-Tomography Scan - 01/0

Omar Saad Ahmed Mahmoud

Hisham Nasr-El-Din

01/06/2018

Invasion of mud filtrate while drilling is considered as one of the most common sources of formation damage. Minimizing formation damage, using appropriate drilling fluid additives that can generate good-quality filter cake, provides one of the key elements for the success of the drilling operation. This study focuses on assessing the effect of using different types of nanoparticles (NPs) with Ca-bentonite on the formation damage and filter cake properties under downhole conditions. Four types of oxide NPs were added to a suspension of 7 wt% of Ca-bentonite with deionized water: ferric oxide (Fe2O3), magnetic iron oxide (Fe3O4), zinc oxide (ZnO), and silica (SiO2) NPs. The NPs/Ca-bentonite suspensions were then used to conduct the filtration process at a differential pressure of 300 psi and 250°F, using a standard filter press. Indiana limestone disks of 1 in. thickness were examined, as the filter medium, to simulate the formation in the filtration experiments. Computed-tomography (CT) scan technique was used to characterize the deposited filter cake and evaluate the formation damage that was caused by using different fluid samples. The results of this study showed that the filtrate invasion is affected by the type of NPs, which is also affecting the disk-porosity. Using 0.5 wt% of Fe2O3 NPs with the 7 wt% Ca-bentonite fluid showed a higher potential to minimize the amount of damage. The average porosity of the disk was reduced by 1.0%. However, adding 0.5 wt% of Fe3O4, SiO2, and ZnO NPs yielded a disk-porosity decrease by 4.7, 13.7, and 30%, respectively. The decrease in the disk-porosity after the filtration is directly proportional to the volume of invaded filtrate. Compared to that of the base fluid, the best reduction in the filtrate invasion was achieved when adding 0.5 wt% of Fe2O3 and Fe3O4 NPs by 42.5 and 23%, respectively. The results revealed that Fe2O3 and Fe3O4 NPs can build better Ca-bentonite-platelet structure and thus, a good-quality filter cake. This is due to their positive surface charge and stability in suspensions, as demonstrated by zeta potential (ζ-potential) measurements, which can minimize formation damage. Increasing the concentration of Fe3O4 NPs from 0.5 to 1.5 wt% showed an insignificant variation in the filtrate invasion, spurt loss, and filter cake permeability; however, an increase in the filter cake thickness as well as the amount of damage created was observed. The 1.5 wt% of ZnO NPs showed a better performance compared to the case having 0.5 wt% of ZnO NPs, but in the meanwhile it showed the lowest efficiency when compared to the other types of NPs. This could be due to their surface charge and suspensions’ instability. Results of this work are useful in evaluating the drilling applications using Ca-bentonite based fluids modified with NPs as an alternative to the commonly used Na-bentonite. Additionally, it might help in understanding the NPs/Ca-bentonite interaction for providing more efficient drilling operations and less formation damage.

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Using Ferric Oxide and Silica Nanoparticles To Develop Modified Calcium Bentonite Drilling Fluids - 01/0

Omar Saad Ahmed Mahmoud

Hisham A Nasr-El-Din, Zisis Vryzas, Vassilios C Kelessidis

01/03/2018

One of the important functions of drilling fluids is to form a filter cake, which minimizes leakoff of drilling fluids into the formation. Drilling-fluid invasion can cause formation damage, but good-quality filter cake can reduce such damage. This research focuses on the laboratory techniques and performance results of testing innovative calcium-bentonite-based drilling fluids containing nanoparticles (NPs) for minimizing formation damage during drilling in harsh environments. A rotational viscometer was used to measure the rheological properties of the tested fluids. Zeta-potential measurements were conducted at different NP concentrations to assess their stability and to investigate the role of charge potential. Indiana limestone outcrop disks were examined as the filter media for both static and dynamic filtration (up to 350°F and 500 psi) using a filter press. The filter cakes were examined using a computed-tomography (CT) scan and scanning-electron-microscopy energy-dispersive spectroscopy (SEM-EDS). Inductively coupled plasma optical-emission spectrometry (ICP-OES) was used to measure the concentrations of key ions in the filtrate fluids. A reduction of 43% in the filtrate-fluid volume was achieved when adding 0.5 wt% of ferric oxide NPs compared with that of the base fluid. However, using silica NPs led to an increase in the filtrate volume and filter-cake thickness. Using 0.5 wt% of ferric oxide NPs provided less agglomeration and reduced the filter-cake permeability. In addition, the SEM-EDS and ICP-OES analysis showed a replacement of the cations dissociated from the bentonite by NPs, which promoted the formation of a rigid clay-platelet structure. The produced filter cakes consisted of two layers, as indicated by the CT-scan analysis. Increasing the concentration of NPs resulted in an increase in the fluid loss and filter-cake thickness. At a higher NP concentration (2.5 wt%), a third layer of NPs was observed, which adversely affected the filter-cake characteristics, as demonstrated by CT-scan analysis and SEM-EDS elemental mapping. Furthermore, the NP-bentonite fluids had stable rheological properties at different temperatures (up to 200°F) and NP concentrations. In addition, aging these fluids at 350°F for 16 hours showed minor changes in the rheological properties. This research work provides an experimental evaluation of improved calcium-bentonite-based fluids using NPs under downhole conditions. The ferric oxide NPs have the potential to enhance the properties of calcium bentonite, as a low-cost alternative, to perform well in an application where the higher-value sodium bentonite is commonly used, which could provide more-efficient drilling operations and less formation damage.

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New Magnetite Nanoparticles Allow Smart Drilling Fluids with Superior Properties - 01/1

Omar Saad Ahmed Mahmoud

Chris Carpenter (JPT Technology Editor)

01/11/2017

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 18731, “A Comprehensive Approach for the Development of New Magnetite Nanoparticles Giving Smart Drilling Fluids With Superior Properties for HP/HT Applications,” by Z. Vryzas, Texas A&M University at Qatar; V. Zaspalis, Aristotle University of Thessaloniki; L. Nalbantian, Centre for Research and Technology Hellas; O. Mahmoud and H.A. Nasr-El-Din, Texas A&M University; and V.C. Kelessidis, Texas A&M University at Qatar, prepared for the 2016 International Petroleum Technology Conference, Bangkok, Thailand, 14–16 November. The paper has not been peer reviewed. Copyright 2016 International Petroleum Technology Conference. Reproduced by permission. This work focuses on using custom-made (CM) magnetite (Fe3O4) nanoparticles (NPs) to improve the properties of bentonite-based fluids. The microstructure qualities and modes of interaction have been identified, helping to optimize the rheological and fluid-loss properties of these drilling fluids. The better performance of the CM Fe3O4 NPs can be attributed to their extremely small size, which leads to stability in suspensions and effective linking with the bentonite particles, thus allowing the formation of a rigid microstructure network.

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Development of Novel Drilling-Fluids Nanoparticles for Enhanced Drilling Operations - 01/1

Omar Saad Ahmed Mahmoud

Chris Carpenter

01/11/2016

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 18381, “Development and Testing of Novel Drilling Fluids Using Fe2O3 and SiO2 Nanoparticles for Enhanced-Drilling Operations,” by Zisis Vryzas, Texas A&M University at Qatar; Omar Mahmoud and Hisham A. Nasr-El-Din, Texas A&M University; and Vassilios C. Kelessidis, Texas A&M University at Qatar, prepared for the 2015 International Petroleum Technology Conference, Doha, Qatar, 7–9 December. The paper has not been peer reviewed. Copyright 2015 International Petroleum Technology Conference. Reproduced by permission. This work focuses on the laboratory techniques for developing, assessing, and analyzing innovative water-based drilling fluids containing iron oxide (Fe2O3) and silica (SiO2) nanoparticles. The examined nanoparticles have the potential to significantly improve the characteristics of the filter cakes at both low-pressure/low-temperature (LP/LT) and high-pressure/high-temperature (HP/HT) conditions. They also have the ability to maintain optimal rheological properties so that many drilling problems can be mitigated efficiently. Introduction Drilling-fluid loss is considered the major source of capital expenditure during drilling operations. Nanoparticles have proved to be more effective in reducing the filtrate losses than conventional fluid-loss reducers. Because they exhibit different adsorption and transportation behavior in different porous media, nanoparticles have been used successfully as stabilizers in emulsions and foams, as rheology modifiers, and as fluid-loss additives in surfactant/polymer or water-based drilling fluids. Addition of Fe2O3 and SiO2 nanoparticles can improve or at least maintain fluid properties even at high temperatures. This work aims to find the optimal concentration of such nanoparticles.

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Studying the Combined Effect of Wellbore Storage and Skin on Well Testing Using Simulation and Analytical Solutions - 01/0

Omar Saad Ahmed Mahmoud

Omar Mahmoud, Mazher Ibrahim, Attia M. Attia, Shouhdi Shalaby

01/01/2008

Well testing is an important tool for reservoir evaluation and characterization. The goals of a well test are to obtain sufficient data to meet the stated objectives and to accomplish these tasks in a less time and inexpensive manner. For that, designing of a test plan is too important before starting that test. Reservoir simulation is widely used to solve research problems as well as actual field problems. This is due to the limitation of analytical solutions to deal with the heterogeneity of the reservoirs and non-linearity of the diffusivity equations (i.e., for gases, properties changing with pressure). Another reason is its ability to be used in predictive methods for reservoir management purposes. This paper discusses the design of well testing models using conventional reservoir simulator, GASSIM, to simulate the combined effect of wellbore storage and skin. Both oil and gas cases, with radial and areal grids are designed. The simulated pressure-transient behavior model results matched well the analytical solutions (having the same wellbore storage and skin parameters within a well test software) which illustrate its accuracy. These models are used to study the effect of wellbore storage and skin on a pressure-transient test. The results illustrate its agreement with any actual reservoir behavior, so its ability to be used, without the need to modify the simulator, in simulating and designing pressure-transient tests.

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