bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Powerful Nonparametric Statistical Framework for Family-Based Association Analyses
Authors: Li Ming , He Zihuai , Schaid Daniel J , Cleves Mario A , Nick Todd G , Lu Qing 
Published: March 2015

Abstract
Family-based study design is commonly used in genetic research. It has many ideal features, including being robust to population stratification (PS). With the advance of high-throughput technologies and ever-decreasing genotyping cost, it has become common for family studies to examine a large number of variants for their associations with disease phenotypes. The yield from the analysis of these family-based genetic data can be enhanced by adopting computationally efficient and powerful statistical methods. We propose a general framework of a family-based U-statistic, referred to as family-U, for family-based association studies. Unlike existing parametric-based methods, the proposed method makes no assumption of the underlying disease models and can be applied to various phenotypes (e.g., binary and quantitative phenotypes) and pedigree structures (e.g., nuclear families and extended pedigrees). By using only within-family information, it can offer robust protection against PS. In the absence of PS, it can also utilize additional information (i.e., between-family information) for power improvement. Through simulations, we demonstrated that family-U attained higher power over a commonly used method, family-based association tests, under various disease scenarios. We further illustrated the new method with an application to large-scale family data from the Framingham Heart Study. By utilizing additional information (i.e., between-family information), family-U confirmed a previous association of CHRNA5 with nicotine dependence.
Fabrication Of Carbon Nanoribbons Via Chemical Treatment Of Carbon Nanotubes And Their Self-Assembling.
Authors: Guillén P. Y. Arquieta , Casas Ortiz Edgar de , Kharissova Oxana 
Published: March 2015

ABSTRACTSome potential applications of the nanoribbons and nanorods occur in the medical field, using gold nanoribbon therapies against cancer cells because they have absorption in the near infrared region. In this paper, the nanoribbons were obtained by physical-chemical method based on multilayer carbon nanotubes functionalized with carboxylic radical groups (-COOH). The obtained material was characterized by Scanning Transmission Electron Microscopy (STEM) and Infrared Spectroscopy (FTIR). The obtained nanoribbons have a diameter of 320 nm with preferably 126° angle in their morphology.
The Impact of Adding High pH Fluid to Sea Water on The Sandstone Rock Charge During EOR Process
Authors: Attia M. , Mahmoud M.A. 
Published: March 2015

Abstract
Many researchers investigated the effect of the ionic strength and the chemistry of the injected water on the oil recovery from sandstone reservoirs. They concluded that as the salinity of the injected water decreased the oil recovery increased. They studied the effect of changing the salinity of the injected water on the zeta potential. The Zeta potential decreased in case of aquifer water compared to the sea water. The new application that we used has the ability to do better than the low salinity water flooding in increasing the oil recovery from sandstone reservoirs without diluting the sea water. Sea water dilution is a costly process, the cost of the new fluid system is low and in terms of recovery it will do better than the low salinity waterflooding. The new EOR fluid system will remove the damage caused by the low salinity water and sea water flooding and also it will prevent the formation damage.
In this paper we will study the effect of adding high pH fluid (chelating agent) to sea water on the sandstone rock charge. Zeta potential was measured for Berea sandstone rock with different fluids and different concentrations of the chelating agent which was added to sea water. Also the effect of the chelating agent on the surface tension and oil recovery was evaluated.
The results of zeta potential showed that adding high pH chelating agent to sea water decreased the value to -33 mV less than the low salinity water (5,767 ppm) which changed the zeta value to -12mV. In addition, the zeta potential of sandstone rock will be affected by the iron concentration in the fluid. Low salinity water with 1000 ppm iron changed the value to 7 mV. But, in case of adding the chelating agent to the same fluid the effect of iron did not appear and the charge decreased to -24mV. The decrease in zeta potential value indicates more water wet rock surface and in turn, high oil recovery will be achieved. The chelating agent diluted in sea water yielded lower surface tension compared to sea water and low salinity water. The oil recovery increased by 30% after sea waterflooding when we used 5 wt% of Na4EDTA chelating agent diluted from initial concentration of 40 wt% using sea water. The recovery increase can be attributed to the change in the rock surface charge, rock dissolution, IFT reduction mechanisms.
Design Optimization of Electric Centrifugal Pump by Multiple Surrogate Models
Authors: Adhav R. , Samad A. , Kenyery F. 
Published: March 2015

Abstract
In this paper, an effort has been made to maximize the efficiency of ESP by using surrogate models for optimization. Inlet and outlet blade angles are selected as design variables. Initially, a pump stage simulation is performed using Navier Stokes solver which include rotating impeller and stationary diffuser. The steps of the simulations are: generate geometry, grid and solve. The surrogate models were response surface approximation, Kriging and radial basis neural network. A hybrid genetic algorithm has been implemented to find optimal design. The multiple surrogate approach was used to reduce uncertainty in optimal point search. The initial CFD generated results were used to generate surrogates and the surrogates were used to give optimal point via genetic algorithm. Design of experiments were used to find the designs and low fidelity based surrogates were constructed to reduce the number of simulation runs. The optimization procedure sufficiently reduces the design time. Hence, the approach shows an optimal design of ESP and selection method of right surrogate for the shortening of computational cost.
A Case Study - Living the HSE Vision and Values - Delivering Success in an Environment of Uncertainty
Authors: Karish John , Siokos George 
Published: March 2015

Abstract
Ensco plc is an international drilling contractor which, has experienced significant growth since its creation only 27 years ago to its current position as the second largest offshore drilling organization worldwide. In 2011/12 it doubled its size through the acquisition of another similarly sized drilling organization.
Despite this significant growth, and while being challenged by many issues from inside such as integration, and from the outside such as having to do business in a difficult market and in many different national cultures, it has achieved acknowledged excellent performance. Ensco plc was voted as the number one performer by a cross section of operators in an independent customer survey in 2010, 2011, 2012 and 2013.
This paper will describe these processes and the leadership that has driven this success. They are not new; what Ensco has done is integrate existing and well known concepts in a way that has led to this success. The processes are multi-faceted and integrated and include: –Creation of a safety culture that emphasis accountability and responsibility for all to create a safe work place.–Safety Systems development with an implementation process focused on consistent implementation across the fleet–Verification on how well they used, noting of lessons learned and application across the fleet–Training and development in critical safety tools and processes–A strong safety leadership development process for leaders in critical positions–A strong and visible senior executive at all safety development programs and through other media–A focus on developing engineering and technical solutions that have common elements across the fleet, making their management easier.
This paper will explore these factors; it will focus on the leadership and people aspect, rather than the technical and engineering solutions.
Underpinning Ensco's safety performance to date has been an unshakeable belief by its leaders and people in its Vision and Core Values.
The very visible leadership of Ensco's leaders is perhaps the most striking of the elements that will be discussed, without which, many of the other factors would be more difficult.
Of note, and key to the paper is that Ensco's journey over a decade has come about at the best of times in the industry as well as the worst. This is important to consider given the current difficult and challenging market in which the oil and gas industry, and drilling in particular, finds itself.
Finally, the paper will provide a brief over-view of some key underpinning theory and principles that have guided Ensco's safety program design and development.
Tandem ESP-Packer Dumpflood Completion – A Successful Alternative to Conventional Encapsulated ESP systems – Field Case Study
Authors: Al-Hajeri Nasser , Anthony Elred , A-Sharhan Ghazi , Jha Ajay 
Published: March 2015

Abstract
Dumpflooding from a strong Aquifer to support pressure to another depletion-drive reservoir is not new to the oil industry, neither to the region. In cases where the natural Aquifer pressure is insufficient to deliver adequate volumes to meet pressure support requirements, or the Injectivity of the target reservoir is relatively low, artificial lift is required. This was the case in the North Kuwait Asset where Injectivity was poor owing to the relatively low natural fracture density of the Carbonate reservoir being flooded.
Since the conventional encapsulated (POD) systems required one (1) seal-bore packer, one (1) encapsulated ESP system, and one (1) ESP-packer, it was decided to test an alternate and simpler system that required only two (2) ESP packers that would achieve the same result.
Deployment of this new tandem-ESP-packer system proved less complex and required less rig time than the encapsulated ESP system. Both packers were set simultaneously in one operation with the ESP function test to surface-pit giving excellent results. After opening the SSD's, the ESP operating parameters, measured at surface, indicated optimum pump performance at expected injection rates.
The Tandem-ESP-Packer Dumpflood completion system provides fewer sealing interfaces than the conventional encapsulated ESP system, and therefore fewer opportunities for leaks. Additionally, it affords a very simple one-trip system for less complex deployment, and retrieval, when necessary. This alternate system also provides easily-deployed, immediate pressure support in areas of the reservoir/field while awaiting the installation and commissioning of major surface Injection facilities.
Managing Wellbore Instability in Horizontal Wells through Integrated Geomechanics Solutions: A Case Study from a Carbonate Reservoir
Authors: Khan Khaqan , Abdulaziz Ahmad Azly , Ahmed Sajjad , Ahmed Mujahed 
Published: March 2015

Abstract
Saudi Aramco is one of the pioneers in optimizing hydrocarbon production and reducing development cost using latest technologies aimed to increase gas production and enhance gas recovery. The case study discussed here shows results from an integrated approach used to drill wells in the minimum horizontal stress direction to create multiple transverse fractures during stimulation that helps enhancing production. The real challenge involved in drilling such horizontal wells is to maintain wellbore stability (especially in a transition zone from high porosity to low porosity and vice versa) mainly due to wellbore breakouts and differential sticking. Due to variably depleted reservoir pressures together with geological and structural complexities, pre-drill geomechanical models need to be updated in real-time, which require extra vigilance, in terms of optimizing mud weight while drilling, to address both formation breakouts and risk of differential sticking. If these problems are not addressed in a timely manner, initial signs of wellbore instability can aggravate with time leading to stuck pipe and loss of tool downhole.
To address above issues, an integrated approach was applied during well planning and execution phases using prior drilling experience in conjunction with a geomechanical analysis to make recommendations for the planned well. While drilling, potential uncertainties in the geomechanical model due to formation heterogeneity and varying in-situ stresses, were further addressed by updating the model using real-time logging while drilling (LWD) data along with real-time drilling geomechanics (RTDG) support and advanced mud logging technology. In addition, advanced cutting return-monitoring technology was implemented which helped monitor proper hole cleaning and minimize the risk of stuck pipe due to compressional formation failure at the wellbore. Based on this analysis, revised drilling practices and recommendations were made to address the wellbore instability issues. The case study presents results from a challenging well using this integrated approach showing significant improvement in well safe delivery within planned drilling time and achieved the planned target gas rate.
Horizontal Drilling in Kuwait for Development of a Complex Carbonate Reservoir
Authors: Zaidi Salman , Pathak Ashok Kumar , Al-Hamadi Hajer Bader 
Published: March 2015

Abstract
Approximately 75% of the proven conventional oil reserves in the Middle East occur in carbonate reservoirs like Mauddud in North Kuwait. Today, this reservoir is the focus of aggressive development through drilling of horizontal wells.
Mauddud in North Kuwait is heterogeneous with varying rock and fluid properties between crest and periphery. A major challenge in its development is the presence of high permeability streaks that are random, inconsistent and unpredictable. Though typical of carbonates this causes early breakthrough into producers and cycling of injection water into patterns resulting in poor sweep efficiency and oil recovery. The reservoir is under active water flood for over 10 years.
Horizontal wells is not something new to KOC yet their objective, completion and integration with development plan is more holistic now than before. Mauddud today is at a point where its character, quality and condition favors development by horizontal and multi-lateral wells. The objective of drilling new horizontal wells is to have large contact area of the reservoir and the good news is that, despite early mixed results, we are beginning to see their positive impact. Modeling studies have indicated that a combination of pattern and peripheral water flood would help maintain reservoir pressure and achieve reasonable oil recovery.
Encouraging production results from recent horizontal completions at the periphery of Mauddud structure, where rock quality is not good, is the beginning of a new phase of development in the life of this reservoir. The incremental production benefit is expected to be around 2-2.5 times the vertical.
The paper discusses the typical design considerations, problems in drilling, lessons learnt, their benefit over offset vertical wells and test results of some of these wells drilled in Mauddud Reservoir.
Numerical Modeling of Flow and Temperature Distribution in Heterogeneous Wellbore Medium
Authors: Irawan Sonny , Bathaee Mahmood 
Published: March 2015

Abstract
The mathematical model for flow and temperature distribution for the water alternating gas (WAG) process had been developed. Water alternating gas (WAG) injection has been a popular method for commercial gas injection projects worldwide. The injection of water and gas alternatively offers better mobility control of gas and hence, improves the volumetric sweep efficiency.
The model is generated for the injection well with one cycle of water and one cycle of injected gas. There are some considerations for the three phases modeling in this study. The scope of the model is to develop the flow model for cylindrical, gravity segregation, turbulency effect due to the high injection rate, incompressible water, slightly compressible oil, compressible gas, IMPES method and with ignoring the tangential flow. The energy balance equation for the three phases could be expanded after the saturations from the flow part had been obtained. These are the conditions for solving the equation for temperature distribution: Cylindrical, implicit method, convection and conduction with ignoring tangential temperature gradient.
In order to solve the governing equations, an analytical method had been used for the two and three phase systems around the wellbore; then a program had developed to do the iteration for implicit parts. The water, gas and oil pressures and saturations had been obtained in addition with the system temperature for homogeneous and heterogeneous media.
Improving the Accuracy of Cement Bond Evaluation by Improving the Borehole Fluid Impedance Measurement in Ultrasonic Scanner Tools
Authors: Tello Lucio N. , Azuaje Dimas C. 
Published: March 2015

Abstract
Ultrasonic scanning tools measure the cement acoustic impedance at higher radial and vertical resolution than radial cement bond and sector tools. The cement impedance measurement is affected by variations of the borehole fluid contained in the well. Until now, ultrasonic tools estimated the value of the fluid impedance by measuring the slowness and multiplying this value by the density which is a constant reading at the surface. Occasionally, the slowness measurement is acquired during a logging down pass. An error is introduced when the fluid changes from one type to another, because both slowness and density change with the fluid; however, density will change in larger percentages than slowness. This causes the estimated fluid impedance to have a substantially different value than the actual one. Not surprisingly, this difference in fluid impedance causes the cement evaluation to differ as well.
In this paper we present the results of the field testing program of the newly developed mud chamber for the ultrasonic radial scanner tool. Instead of calculating the impedance indirectly from the slowness measurement, the mud chamber measures the fluid impedance directly. The tool takes this measurement in situ, during logging, and with greater accuracy than before. In addition, we present the algorithm that computes changes in the cement impedance which are due to variations of the impedance in the fluid column. Observations in laboratory tests and logs obtained during field testing show that the fluid column commonly has variations in the acoustic impedance and its density. Under the new measurement, phantom communicating channels are not displayed and actual channels are correctly detected. The effect is accentuated in instances where stratigraphic fluid columns with different densities are present. The new mud chamber eliminates the uncertainties of small channels by detecting the presence or absence of cement.
Oil Recovery Enhancement in Middle East Heavy Oil Field using Malonic Acid based Deep Eutectic Solvent
Authors: Al-Weheibi I. , Al-Hajri R. , Al-Wahaibi Y. , Jibril B. , Mohsenzadeh A. 
Published: March 2015

Abstract
This study investigates the potential of chemical solvent called deep eutectic solvents (DES) to recover the residual heavy oil left after waterflooding. For the first time to our knowledge, the effectiveness of two DESs - choline chloride-malonic acid of molar ratios 1:1 and 1:0.5 - in enhancing heavy oil recovery was thoroughly investigated. As preliminary investigations, the two solvents were characterized by measuring density, viscosity, conductivity and pH at different temperatures (20 – 80°C). In order to investigate the EOR potential of the solvent, measurements of interfacial tension, wettability alteration, spontaneous water imbibition, emulsification, core flood and formation damage tests were conducted at different temperatures. The core flood test was carried out at reservoir condition (pressure = 1200psi, temperature = 45 - 80 °C) using Berea sandstone core samples and fluids from the field of interest (formation brine and crude oil). Results of the core flood test showed the solvents produced 7-14% of the residual heavy oil after brine flooding as tertiary recovery stage and both DESs displayed better performance in enhancing the oil recovery at higher temperatures. Measurements of absolute permeabilities before and after injection of DESs/brine solutions showed no damage to the formation. Wettability alteration was found to be the dominant mechanisms for the tertiary oil recovery enhancement.
Maximizing Reservoir Exposure in the Thin Limestone of Ahmadi Formation, Bahrain
Authors: Suleiman Sameh , Al-Ansari Yusuf , Shah Razza , AlTawash Feras , Samaroo Rajeev , Al-Alqum Wael , Jawad Waleed 
Published: March 2015

Abstract
Lately, stratigraphically thin reservoirs are being exploited more and more to meet an ever-growing need to increase reservoir recovery. In Bahrain, the AB3 layer of the Ahmadi formation has a true stratigraphic thickness (TST) of 8 to10 ft. Gamma ray and resistivity stand relatively constant at 12gAPI and 45ohm.m, respectively, and there is good conductivity contrast between the Ahmadi limestone and the underling mudstone and overburden shale. The Ahmadi formation is also known to have faults and high dips, contributing to the geological challenge for geosteering wells in the region.
To address the challenges, a bed-boundary mapper (also includes core petrophysical measurements like gamma ray and resistivity) has routinely been incorporated into the bottom-hole assembly (BHA) along with surveying and rotary steerable technology. Given the lean nature of the BHA meant that drilling operations were cost-effective and that measurements were as close to the bit as feasibly possible, ideal for both formation evaluation and well placement.
During drilling, inversion data from the bed-boundary mapper was used to estimate both reservoir thickness and formation dip. These dips correlated with those estimated from the seismic model. The inversion information was also used to estimate the vertical displacement of faults and directed the next geosteering decision for either returning the trajectory to the reservoir or to the reservoir “sweet spot”. Even in this high penetration rate drilling environment (+200 ft./hr), these core measurements, located close to the bit, allowed for quick and efficient well-placement decisions to be taken at the right time.
Using these drilling, evaluation, and geosteering practices, more than 30 horizontal producer wells have been drilled in the Ahmadi formation to date. Reservoir net-to-gross averages 91%, with wellbores typically placed in the middle of these thin reservoir sections. The method has shown to improve reservoir exposure and well productivity when compared to geometric drilling and evaluation methodologies.