bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enzymatic Synthesis of Polyaniline/Graphite Oxide Nanocomposites
Authors: Guerrero-Bermea C. , Sepulveda-Guzman S. , Cruz-Silva R. 
Published: October 2012

ABSTRACTIn this work, we prepared graphite oxide (GO)/polyaniline nanocomposites by enzymatic polymerization of aniline in an aqueous dispersion of graphite oxide. Two GO dispersions with sheets having an average lateral size of 12.50 μm and 247 nm were used. The enzymatic polymerization was carried out in aqueous acidic medium using toluenesulfonic acid (TSA) as doping agent, horseradish peroxide (HRP) as catalyst, and hydrogen peroxide as oxidizer. The polymerization reaction was studied using 1.0, 2.5 and 5 wt % of GO and nGO dispersions. No changes were observed in the catalytic activity of the peroxidase during the enzymatic synthesis due to the additionof GO sheets. Scanning electron microscopy images show that PANI colloids were attached on GO sheets. The PANI-GO colloids were characterized by ultraviolet–visible spectroscopy and Fourier transformed infrared spectroscopy, whereas their colloidal stability was evaluated at different pHs. The UV-vis spectroscopy study revealed that GO affects the electronic conjugation of PANI modifying its absorption spectrum.
SERS Biotags (SBTs) for the Quantitative Ratiometric Discrimination between Noncancerous and Cancerous Prostate Cells
Authors: Pallaoro Alessia , Braun Gary , Moskovits Martin 
Published: October 2012

ABSTRACTWe report on a multiplexed, ratiometric method that can confidently distinguish between cancerous and non-cancerous epithelial prostate cells in vitro, as demonstrated by a double blind experiment. The technique is based on bright SERRS biotags (SBTs) infused with unique Raman reporter molecules, and carrying cell-specific peptides. Two sets of SERRS biotags were used. One targets the neuropilin-1 (NRP) receptors of cancer cells through the RPARPAR peptide. The other functions as a positive control (PC) and binds to both non-cancerous and cancer cells through the HIV derived TAT peptide. Averaging the SERRS signal over a given cell yielded an NRP/PC ratio from which a robust quantitative measure of the overexpression of the NRP-1 by the cancer cell line was extracted. The use of a local, on-cell reference produces quantitative, statistically robust measures of overexpression independent of such sources of uncertainty such as variations in the location of the focal plane, the local cell concentration and turbidity.
Hydraulic Fracturing Design and Optimization: A Modification to Zipper Frac
Authors: Rafiee M. , Soliman M. Y. , Pirayesh E. 
Published: October 2012

Abstract
In recent years, new fracturing designs and techniques have been developed to enhance production of trapped hydrocarbons. The new techniques focus on reducing stress contrast during fracture propagation while enhancing far field complexity and maximizing the stimulated reservoir volume. Zipper frac is one of these techniques, which involves simultaneous stimulation of two parallel horizontal wells from toe to heel. In this technique, created fractures in each cluster propagate toward each other so that the induced stresses near the tips force fracture propagation to a direction perpendicular to the main fracture. The effectiveness of zipper frac has been approved by the industry; however, the treatment's optimization is still under discussion.
In this paper, we present a new design to optimize fracturing of two laterals from both rock mechanic and fluid production aspects. The new design is a modification to zipper frac, where fractures are initiated in a staggered pattern. The effect of well spacing on the changes in normal stress has been evaluated analytically to optimize the design. Results demonstrate that the modified zipper frac improves the performance of fracturing treatment when compared to the original zipper frac by means of increasing contact area and eventually enhancing fluid production.
Using Magneto-Rheological Fluids to Improve Mud Displacement Efficiency in Eccentric Annuli
Authors: Ermila Mansur , Eustes Alfred W. , Mokhtari Mehdi 
Published: October 2012

Abstract
Long-term zonal isolation provided by cement is a crucial task in the life of oil and gas wells. However, significant number of primary cementing jobs experience problems; particularly in highly deviated wells, extended reach wells, and wells prone to severe washouts. Primary cementing efficiency has attracted more attention since the development of shale gas industry and the Macondo Blowout in the Gulf of Mexico. Sustained casing pressure reported in some of the wells in Marcellus shale play and the root of several blowouts is attributed to cementing job performance. Therefore, studies on the performance of cementing operations are essential in restoring the public opinion on petroleum industry by addressing problems that have major social, environmental and economical consequences besides the technical interest.
Casing is prone to deviate toward the bottom of the well especially in horizontal wells. This eccentric annular space leads to annular velocity disturbance in favor of wider region of the annulus. Finally, part of the narrow section of annulus would be left un-cemented. The bypassed mud is potential path for the formation fluid communication with other formations or to the surface. Poor cementing can affect the hydraulic fracturing job as well.
This paper is part of a comprehensive three-dimensional time-dependent computational fluid dynamics (CFD) model developed to account for dominant parameters affecting the mud displacement process in horizontal wells. Parameters such as casing eccentricity, cement yield strength, cement plastic viscosity, the density difference between mud and cement, pumping rate and washout are studied. The effects of the first three parameters are addressed in this paper.
Current best cementing practices have deficiencies in providing excellent cementing efficiency. Therefore, a novel technique, using Magneto-Rheological fluid, is also proposed to improve the displacement efficiency. Magneto-Rheological fluid can act as a plug in the wider region of annulus under magnetic field applied through the casing. Consequently, flow will be directed to the narrower annular region that could not be cemented or cleaned otherwise. The results are appealing and further study on application of Magneto-Rheological fluid in petroleum industry is suggested.
Effectiveness of Self-Healing Cement Additives Based on Test Methodology Using Simulated Cement Sheath Cracks
Authors: Browning Robert , Duffy Marcus , Gaugler Drew , Jones Paul 
Published: October 2012

Abstract
A testing methodology was developed to examine the effectiveness of oil-swellable additives in cement slurries by evaluating the capability to shut off hydrocarbon fluid flow through a crack initiated in the cement. An open-loop testing fixture was used to investigate the effect of oil-swellable additive concentration and environmental temperature, using Kaydol mineral oil as a test fluid. Under a pressure differential of approximately 2 psi/in., test results indicated that a concentration of 10% by volume of additive relative to a 15.5 lbm/gal Class G slurry was sufficient to significantly reduce hydrocarbon flow in a crack in cement at a temperature of 160°F in an average time span of 48 hr and in shorter time spans with an increase in temperature.
A New Approach to Reserves Estimation in Shale Gas Reservoirs Using Multiple Decline Curve Analysis Models
Authors: Mishra Srikanta 
Published: October 2012

Abstract
Recent interest in the development of Marcellus and Utica plays has renewed attention on the problem of reliable estimation of recoverable reserves from low-permeability shale gas formations. Over-optimistic results obtained from the commonly used Arps hyperbolic model has led to the development of alternative decline curve analysis models based on empirical considerations (e.g., Duong's power law model) or mechanistic considerations (e.g., Valko's SEDM). This work addresses the practical difficulty of discriminating between such models (including a new mechanistic model proposed for decline curve analysis based on the Weibull growth curve) from limited production data. The paper also presents a new approach to aggregating estimated ultimate recovery (EUR) forecasts from multiple plausible models using the Generalized Likelihood Uncertainty Estimation (GLUE) methodology.
Two field examples are presented to demonstrate the performance of Hyperbolic, SEDM, Duong and Weibull models. Model parameters are estimated via nonlinear regression using Excel-SOLVER, from which 30-year EUR estimates are generated. The GLUE procedure is then used for determining the likelihood of each model by weighting the results with [1/RMSE^2], and computing the weighted mean and standard deviation for the 30-year EUR. For the first example (with 15 years of data), excellent visual fits are obtained for both rate and cumulative production with all four models. However, 30-year EUR estimates from the Arps and Duong models are on the high side and the SEDM and Weibull models are on the low side. The uncertainty in the mean amounts to only ~2%. For the second example (with 52 months of data), the trends are very similar, albeit with greater separation in the 30-year EUR forecasts and a higher uncertainty in the mean EUR (~7%).
These results reinforce earlier findings that multiple alternative models can provide equally good fits to limited-duration production data, but yield very different 30-year EUR forecasts. The GLUE approach provides a robust methodology for aggregating such analyses and quantifying the uncertainty of the EUR forecast.
Flow Isolation Tube for Milling and Sand Jet Perforating
Authors: Dotson Thomas , Farr Jim , Tucker Barrett 
Published: October 2012

Abstract
Sand jet perforating (SJP) is currently gaining acceptance in unconventional resource plays where horizontal development has shown the need for methods to perforate these formations. This paper examines a new design for a tool assembly that allows fluid to flow through the sand jet perforator while operating a PDM (Positive Displacement Motor) with a mill or cutting tool. In multi-stage fracturing operations where through tubing mills are often used for cleanout runs prior to perforating, the flow isolation tube assembly can be added to the tool string to achieve cleanout in conjunction with perforating in one trip. The design allows an operator to isolate the SJP tool, which is resident in the work string and perforate casing and formation, then restore flow to the PDM to continue operations such as milling or further well cleanout-all in a single trip.
Discussion of the assembly design process and laboratory testing results are included as a part of the paper and will analyze the effectiveness of the technology and tools as well as the economic impact of this type of program. Economics includes process costs as well as cost savings from support equipment that is gained by the combination of operations. The program’s translation to other shale plays like the Marcellus, Bakken, and Haynesville are also discussed.
Shale plays dominate domestic drilling as well as production today and being able to combine completion operations to save both time and money is of interest to all producers. Using the flow isolation tube assembly will save cost and wear for coil tubing units as well as costs for other surface support equipment. Finally, safety is increased and the quality of the perforations is improved with SJP; giving a better perforating job for a lower cost.
Computational Modeling of Drilling Fluids Dynamics in Casing Drilling
Authors: Mokhtari Mehdi , Ermila Mansur , Tutuncu Azra N. , Karimi Moji 
Published: October 2012

Abstract
Casing drilling is used as an alternative to conventional drilling with drillpipe in order to reduce non-productive time. The smaller annular space in casing drilling elevates the annular pressure loss considerably at similar flow rates in conventional drilling. Consequently, the Equivalent Circulating Density (ECD) is more affected by annular drilling fluid dynamics in casing drilling than the conventional drilling. The higher ECD experienced in casing drilling brings concerns about exceeding fracture gradient which can lead to induced lost circulation. However, several field observations demonstrate successful application of casing drilling in combating lost circulation and strengthening the wellbore.
Smearing effect theory backed by smaller cuttings at the shale shaker, eccentric casing wear, and discrepancy between analytical and field measurements are three main evidences for potential significant eccentricity in casing drilling operations. This paper demonstrates the inherent eccentricity of casing drilling as one of the parameters that controls the annular pressure losses. Eccentricity reduces the velocity in the narrow section of annulus. Similarly, it reduces the annular pressure losses considerably. In addition, controlling the fluid rheological properties as well as the flow rate are recommended to manage the casing drilling hydraulics. This comprehensive study of pressure loss and velocity profile at various annular sizes can help analyzing several field observations and designing the hydraulics of drilling operations.
Method of Using KUTT Radiometric Data to Prospect for Oil and Gas
Authors: Mulkern Mark E. 
Published: October 2012

Abstract
A method of using surface acquired radiation data has proven successful in Kentucky's shallow oil reservoirs of the southern Illinois Basin. The theory adhered to is that measured surface radiation shows characteristic low activity above petroleum deposits when compared to surrounding areas. Mapping measured potassium data layered with total radiation data can aid in identifying pooled hydrocarbon deposits as well as the area and extent of these deposits.
An overview of proper field acquisition operations is given as well as an analysis of three radiometric surveys taken in Kentucky.
Short Bit-To-Bend Motors and Horizontal Drilling
Authors: Greer John , Ide Russell 
Published: October 2012

Abstract
Thrust bearings used in mud lubricated drilling motors have to handle high loads, abrasive drilling mud, and large impacts, all of which reduce bearing life. In bent housing motors used for directional drilling, these adverse operating conditions are amplified and generally result in severely shortened bearing life and reliability. When drilling the lateral section with a bent housing motor a shorter "bit-to-bend" length is a great advantage because it reduces the loads on many of the motor components. Through the use of a resiliently-mounted stacked ceramic bearing design, the thrust bearing length can be reduced while retaining the capability to handle the increasing thrust and impact loads and withstand the erosion from abrasive drilling muds, thus increasing life expectancy and reliability.
The patented ceramic stack bearing has been designed to replace ball and PDC bearings in mud lubricated drilling motors. Although the bearing can be used in any drilling motor, a significant advantage is realized from using the shorter bearing design for short bit-to-bend motors. The increasing demand for short bit-to-bend motors has led manufacturers to reduce the length of their bearing section, and thus the life and load capacity of the thrust bearing. A shorter conventional thrust bearing stack means the load is carried by fewer bearing components and thus the load-per-bearing stage is increased, reducing the life expectancy of the bearing and, in turn, limiting the drilling hours a motor can continuously operate.
With the increasing number of directional wells being drilled, short bit-to-bend motors have become more desireable; more drilling companies are requesting them and more motor manufacturers are designing them. Using the improved bearing technology, combined with short bit-to-bend mud motors, directional drillers are able to drill curved and lateral sections of wells with one motor. This eliminates tripping out of the well to change the motor / BHA (Bottom Hole Assembly). Deep wells in the Eagleford formation have saved days of drilling time by operating motors in excess of 280 hours continuously with this resiliently mounted ceramic thrust bearing assembly.
An Investigation of Ancient Geological Events and Localized Fracturing on Current Bakken Trends
Authors: Borglum Scyller J. , Todd Burt J. 
Published: October 2012

Abstract
To date the most prolifically producing geologic structure in Montana's Bakken formation is the Elm Coulee Field. While the first wells drilled into this structure 35 years ago had some success, significant production did not occur until horizontal wells were drilled starting in 2000. The Bakken Petroleum System consists of three members, the Upper Bakken, shale, the Middle Bakken, silty dolostone, and the lower Bakken, siltstone. Production of the Bakken Petroleum System is extremely difficult to predict with standard reservoir models. Thus, the decision to understand initial production through geologic drivers was made. An investigation of the implications of ancient geology on what is believed to be specific areas of micro-flexures in and around the major geologic structures in Montana's Bakken three-member formation will form the basis for a Bakken production model.
The challenge in modeling the Bakken's production, both initial and subsequent, stems from the unusual history matching problem of either extremely high initial production with an unpredictably low subsequent production or surprisingly low production to begin with. The authors believe this phenomenon is due to broaching a series of micro-flexures and draining them, resulting in high initial production and unsustained subsequent production, or missing these structural flexures all together resulting in low production. This paper will investigate the genesis of Montana's Bakken micro and macro fractures with the ultimate goal of simulating and thus predicting production for wells currently producing in the area.
The Impact of Multistage Fracturing on the Production Performance of the Horizontal Wells in Shale Formations
Authors: Ayers K. L. , Aminian K. , Ameri S. 
Published: October 2012

Abstract
The interest in exploitation of ultra-low permeability formations, such as the Marcellus Shale, has increased in the recent years. Shale formations require massive stimulation treatments to achieve economic production. The recent advances in horizontal drilling and multistage hydraulic fracturing have proved successful in achieving commercial production. However, the parameters that directly affect lifetime production of the wells have not been well established.
The primary objective of this study is to examine the effects of basic stimulation parameters used in hydraulic fracturing of Marcellus Shale wells on production performance. Historical production data and stimulation treatment information have been collected and analyzed for a number of horizontal wells both in West Virginia and Pennsylvania. A commercial reservoir simulator which utilizes a dual porosity model and accounts for adsorbed gas was utilized for history matching and predicting the long term production performance. The impact of the stimulation parameters including number of stages, stage spacing, the volume of water used, and the volume of sand used on production performance was investigated. An understanding of the impact of each stimulation parameter to overall production of a well can be used for the optimization of stimulation treatments.
Impact of Hydraulic Fracture and Subsequent Increased Production Due to In-Situ Stress Changes in the Marcellus Shale
Authors: Wade Adam , Bilgesu H. Ilkin 
Published: October 2012

Abstract
Shale gas reservoirs are quickly becoming an important source for natural gas. Historically, the shale basins were not looked at for economic production because of their very low permeability values. However, with the use of hydraulic fracturing combined with horizontal well completions, shale plays have become economically producible, especially the Marcellus shale. In order for these wells to produce, hydraulic fracturing must be employed. This technique makes production viable, but it also changes the in-situ stress field, through the fracture itself and the increased production that occurs. This change in the stress field can damage the wellbore and compromise the integrity of the casing.
In this study, geomechanic and reservoir models were constructed using commercially available software to study the change of the stress field in the formation. The parameters of the hydraulic fracture were varied to study the effects of the hydraulic fracture half length and the fracture permeability on the stress field, specifically near the wellbore.
Proppant Selection for Hydraulic Fracture Production Optimization in Shale Plays
Authors: Yang Mei , Economides Michael J. 
Published: October 2012

Abstract
Proppants are essential to the success of most hydraulic fractures and often account for the overwhelming cost of the treatment. Both the mass of proppant and the selection of the right type of proppant are important elements in gaining the highest Net Present Value (NPV).
It has been generally believed that in the lower closure stress environment (below 6,000 psi, i.e., shallow reservoirs), natural sands such as Brady and Ottawa are appropriate as proppants and, for the same mesh size, they provide essentially the same permeability. A commonly accepted notion is that manmade proppants (such as ceramics) should be applied at higher closure stress environments, invariably, deeper reservoirs.
The characteristics of most shale plays are very different, mainly as regards to the rock stiffness, exemplified by the Young’s Modulus, stress anisotropy/isotropy and the existence of natural fracture network. Fracture strategies in shale formations are very different. This study presents fracture designs based on three types of proppants for shale formations: Brady sand, Ottawa sand and ceramic. Permeability tests and crush tests under certain pressure range are done to determine experimentally the dimensioned fracture conductivity. A fracture optimization p-3D model is used to maximize well performance by optimizing fracture geometry, including fracture half length, width and height. Reduced proppant pack permeability is compensated by larger width. Non-Darcy effects in the fracture are also considered for gas reservoirs. Post-treatment well performance is then estimated, using the optimized well geometry, leading to cumulative production over the well life. NPV analysis is employed as the criterion to select the best proppant for the job. Finally, the completion and production data from example wells will be analyzed for comparison purpose.
In this work, we try to correct the prejudice that natural sand proppants cannot be applied to deeper reservoirs by showing NPV study results that are superior to those of manmade proppants. Keeping stimulation costs down, natural sands proppants have a much larger range of applicability than previously thought.