bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamics of Production Decline from Shale Gas Reservoirs: Mechanistic or Empirical Models?
Authors: Mishra Srikanta , Kelley Mark , Makwana Kishan 
Published: October 2014

Abstract
Application of decline curve analysis in shale gas reservoirs is known to produce reserve estimates that are unphysical and/or unrealistic. It has been suggested that the assumptions inherent to these models may not always be valid in shale gas wells. For example, the boundary dominated flow period that leads to exponential decline may take years to develop in unconventional gas fields. Also, the impact of matrix adsorption/desorption processes on decline curve model parameters has not been fully investigated. To this end, we use a numerical simulator to understand key factors affecting production decline in shale gas reservoirs, and examine the appropriateness of decline curve based forecasting to model long-term flow behavior.
A numerical model was constructed to simulate production from a horizontal well in a hydraulically fractured shale reservoir. Parameters varied in the evaluation include: (a) reservoir properties, (b) hydraulic fracture properties, (c) well properties, and (d) operational parameters. Ranges in values considered for the model parameters were obtained from published data on major shale-gas plays. Simulated gas production rate time histories were evaluated using standard decline curve analysis techniques.
Our results indicate that long-term production estimates are most sensitive to hydraulic fracture and well characteristics, average pressure and permeability in the stimulated reservoir volume, and to a lesser degree on matrix flow and adsorption processes. Fitted decline curve model parameters generally exhibit time dependence, which affects the accuracy of ultimate recovery estimates with limited production data. The findings from this study suggest that although decline curve based reserve estimates may be appropriate under some conditions, it would be useful to apply a mechanistic (physics based) model for history matching production data and verify the results of decline curve analysis.
Eco-Friendly Biodegradable Materials For Zonal Isolation Of Multiple Perforation Clusters During Refracturing Of a Horizontal Well: Case History From Marcellus Shale Hydraulic Fracturing
Authors: Arnold David , Boulis Anastasios , Fragachan Francisco 
Published: October 2014

Abstract
For some time now the industry has been concentrating on horizontal wells in shale formations which require multi-stage fracturing operations to tap their production potential. Several different techniques have been developed for performing these operations each with their own advantages and drawbacks; however, when it comes to performing re-fracs the isolation of zones to be treated presents some major problems in logistics and operating costs no matter the initial fracturing operation method used.
A key characteristic in unconventional reservoirs development is that they need massive hydraulic fracturing to create high permeability conduits to connect the reservoir to the wellbore and assure appropriate flow rates to make the development economical. In general, production performance for this type of reservoirs show an early high inflow followed by a steep decline. Refracture jobs have been a common practice to mitigate the flow rate decline and revitalize wells productivity. In the cases where infill refracturing is used, the isolation of the existing perforations is imperative, to mitigate the loss of fluids during the refracturing process.
One approach involves the use of mechanical diverters, such as perforation balls, rock salts etc., which may be useful for one stage; however, cessation of pumping operations results in them falling out of the perforations or dissolving. In this paper, a new approach is presented using degradable materials. These materials can be tailored to plug perforations on a temporary basis but degrade over time, depending on formation temperature, to re-open them. This method has applications in initial fracturing operations as an alternative to the often used "plug and perf." method and can be extremely advantageous in refracturing operations in plugging off the existing, productive perforations and exposing the unproductive ones for treatment. It also provides similar advantages in wells with existing perforations, where additional perforations are added and need to be treated.
Moreover, a case study is used to show the application of these degradable materials in a refracturing job in a shale gas well in the Marcellus Shale. Based on the results, the sealing agents successfully bridged off the existing perforations, diverting the refracturing fluid to the new clusters. In this paper the author will discuss the evolution of fracturing methods and describe the development of degradable materials which can degrade over time for a range of bottom hole temperatures. He will continue to present a case study of its' use in a refracturing treatment in a well with 26 sets of existing perforations and 24 sets of recently perforated clusters, with the intent to seal the older clusters and begin accessing the new clusters.
Unique System for Underbalanced Drilling Using Air in the Marcellus Shale
Authors: Maranuk Chris , Rodriguez Ali , Trapasso Joe , Watson Joshua 
Published: October 2014

Abstract
Underbalanced drilling offers significant advantages in terms of increased rate of penetration (ROP), less formation damage, reduced lost circulation material, decreased cost of cuttings disposal, and increased production. Underbalanced drilling injects gas into a mud column to lower the overall equivalent mud weight to create a drilling environment where the pressure in the wellbore is kept lower than the fluid pressure in the formation being drilled. Air is the ultimate underbalanced fluid, but diminishes the efficiencies of mud motors, and prevents the use of mud pulse telemetry MWD tools due to the lack of an incompressible fluid. With air drilling, the only fluid injected into the well is a small amount of oil needed to prevent corrosion. Downhole mechanical forces are usually more violent due to the lack of a fluid column for dampening as well as the higher air volumes going through the bottom hole assembly (BHA) for cuttings flow. Common drilling technologies to address air drilling include Electromagnetic Telemetry (EM), mud motors, and downhole air hammers, but reliability issues are particularly prevalent, especially for the EM MWD tools and downhole mud motors.
Air drilling has become popular especially in the Marcellus and Utica shale reservoirs in the Northeast United States because of higher ROP and less formation damage. As an example, of the 111 rigs drilling in the Marcellus Shale, 27 rigs are drilling underbalanced and 23 are being drilled with air. A unique drilling system incorporating the use of downhole mud motors, EM MWD, and air hammers has been specifically designed and ruggedized to address downhole shock and vibration encountered in air drilling. Use of this system has resulted in significant reduction of non-productive time (NPT) while drilling with air.
This paper will describe how air drilling is being successfully utilized in the unconventional reservoir of the Marcellus shale in the Northeast United States. Drilling fluids and their affect on various pressure regimes will be discussed. The new drilling system will be described and drilling parameters highlighting the differences between mud and air drilling will be provided. Modifications to the BHA to increase reliability will be discussed, and success metrics presented.
Friction Reducers Fresh Rheological Insights Married to Performance
Authors: Aften Carl W. 
Published: October 2014

Abstract
Rheological experiments have been conducted with commercial and experimental friction reducers indicating certain profiles are advantageous for performance. In these profiles the factors of time and concentration are important in predicting the maximum performance window. These windows become apparent without the use of sophisticated rheological instrumentation.
The viscosity profile of a friction reducer is dependent on factors such as polymer charge, charge distribution, molecular weight, polymer concentration, solvent properties, specific shear rate and time. Often it is difficult to measure properties such as molecular weight and viscosity, both quite sensitive to the specific test method and many assumptions are made. In this study, the viscosity of the system depends on the shear history, concentration, and time of measurement. Most traditional viscosity methods assume a thermodynamic definition of polymer configuration. This assumption is valid for measurement of friction reduction after significant duration. However, in a hydraulic fracture, this time may not be realized during the volumetric transfer of the fluid from the pumps to the perforations. In a recirculating friction loop measurement, the friction reduction performance of an ideal candidate rapidly increases and then sometimes diminishes with recirculation time. A possible correspondence between this phenomenon can be linked to the measurement conducted in this study.
Shear rate sweeps were conducted on a variety of synthetic polymers with a Couette rheometer and a microchip rheometer. Variables studied were polymer type, concentration, shear history, time, solvent, make-down procedure, and atmosphere. Both inverse emulsion and dry friction reducers were studied. Friction reduction was measured on a once through system.
From this study, ideal friction reducer candidates can be selected by simply and rapidly examining the rheological profile and rheological nuances realized when conducting the measurements. When choosing an ideal friction reducer, it must perform rapidly and maintain the necessary friction reduction required for the time frame needed.
Improving Drilling Performance through Deployment of 12-Project Management Critical Success Factors: An Empirical Investigation
Authors: Alagba Tonye J. 
Published: October 2014

Abstract
Oil and gas drilling projects are the primary means by which oil companies recover large volumes of commercially available hydrocarbons from deep reservoirs. These types of projects are complex in nature, involving management of multiple stakeholder interfaces, multidisciplinary personnel, complex contractor relationships, and turbulent environmental and market conditions, necessitating the application of proven project management best practices and critical success factors (CSFs) to achieve success. Whereas there is a CSF approach to managing complex projects in construction, manufacturing, and even R&D, there is no empirically verified project management CSF approach to implementing (complex) oil and gas drilling projects. Additionally, the literature has reported alarming rates of oil and gas drilling project failure, which is attributable not to technical factors but to failure of project management. The aim of this two-part quantitative correlational study therefore, was to discover an empirically verified list of project management CSFs, which consistent application leads to successful implementation of drilling projects. The study collected survey data online, from two randomly derived samples of oil and gas drilling personnel: Members of LinkedIn's online community "Drilling Supervisors, Managers, and Engineers". A total of 219 Drilling Personnel (Drilling Engineers/Superintendents, Drilling Supervisors, and Drilling Managers) participated in the study, including 127 partcipants in the initial study and 92 in the follow-up study. The results of the study indicated that 12 project management critical success factors are individually related to success of oil and gas drilling projects. These 12 project management CSFs, are namely; Clarity of project goals & objectives, Top management support, Front-end project planning, Integrated stakeholder & supplier management, High caliber project personnel/Project team integration, Use of appropriate tools & technology, Integrated change control, Shared success criteria, Iterative monitoring & control, Communication, Use of realistic estimates, and Iterative risk management. In addition, the study found that the relationship between the 12 CSFs and drilling project success is unaffected by, and generalizable beyond participant and project demographics, namely; role designation of project personnel, project location, and project type (onshore or offshore). The significance of these findings is both practical, and theoretical. Practically, application of an empirically verified CSFs list to oil and gas drilling projects could help oil companies improve the performance of their drilling projects. Theoretically, the study's findings have helped to bridge a gap in the project management CSFs literature, and added to the general project management body of knowledge.
Use of Natural Tracer Data in Well Placement Optimization
Authors: Hutahaean Junko 
Published: October 2014

Abstract
Determining an optimal location and configuration of well to be drilled is a critical reservoir development decisions as it can cost millions of dollars and determine the volume of hydrocarbons being produced. This is a very challenging task due to large number of decision variables involved. One important factor to consider in field development is scale deposition. It can cause production problem and reduce hydrocarbons recovered. In the extreme case, it can cause a production well to be abandoned as a result of formation damage in the near wellbore or narrowing of the production tubing. Due to the potential high cost of scale management, scale risk deposition would be an important issue.
The aim of the paper is to optimize the placement of new wells in a field development accounting for the risk of sulphate scale deposition. This scale is formed when sulphate rich seawater, usually used as injection fluid to maintain reservoir pressure, mixes with barium rich formation brines. Multi-Objective Optimization (MOO) is used to find a range of solutions by maximizing oil recovery and minimizing scale risk. Scale risk deposition is modelled by tracking the injected seawater concentration, which acts as a natural tracer, in the produced water from each well. Penalty parameter is introduced in the optimization workflow and quantified by relating the scale risk impact in the reservoir production to scale treatment (bullhead-squeeze) as the mitigation. The study used a modified version of the benchmark reservoir model, PUNQ-S3; the model was adapted to be developed using seawater flooding, and as a result sulphate scale deposition is of a major concern. Particle Swarm Optimization (PSO), a stochastic population-based and gradient-free optimization algorithm, is applied to search over the new well locations and their completion zones in the presence of potential scale deposition risk.
The paper compares a conventional field optimization with objective only to maximize oil production to the one with accounting scale risk as extra information. The paper demonstrates that multi-objective optimization allows us to identify well locations and completion zones with high recovery and yet low scale risk, leading to significant economic benefit in a number of field development scenarios.
Simulation of Shale Mechanical Properties in PFC2d and Calibration of Them Against Lab Results for Tensile, Uni-axial and Confined Compression Tests
Authors: Fatahi Hassan 
Published: October 2014

Abstract
Shale oil and gas reserves became an important source of energy and their development can increase fossil fuel source. The shale exploration activities have been growing very fast worldwide. However, shale oil and gas production differs from conventional reservoirs in many ways due to its underlying complexities associated with reservoir rock and petro-physical properties as well as extremely low permeability. While massive hydraulic fracturing through horizontal well completion for commercial production of shale oil and gas is paramount, there are many development challenges in regards to understanding of hydraulic fracture propagation behaviour, and its potential impact on fluid flow as required to accurately assess the production performance. The principle mechanism of hydraulic fracture propagation behaviours in shale formation is not well documented. In addition the shale formation is very heterogonous in nature, especially in vertical direction.
The fracture propagation behaviour of rock strongly depends on rock mechanical properties, far field stress state and orientation and anisotropies present in the formations such as bedding.
This paper presents results of numerical simulation, where shale rock samples are subjected to tensile, uni-axial compression and confined compression tests; and their behaviour are studied. In the first stage, mechanical properties of the simulated samples are calibrated against mechanical properties of two oil shales considered from western US to get micro-mechanical properties that define the samples in the PFC2D. In the second stage these micro-mechanical properties are used to simulate two kinds of rock, one of which has a vertical heterogeneity and the other has lateral heterogeneity to study the effect of fissility on mechanical properties measured in different directions.
Pore-Network Modeling of Carbonate Acidization
Authors: Tansey Joseph 
Published: October 2014

Abstract
Carbonate reservoirs represent a significant portion of global hydrocarbon reserves. Injecting strong acids around the wellbore of carbonate wells can significantly increase near-wellbore permeability. A pore-network model is developed to capture permeability response of carbonates to acid stimulation. A novel pore-scale mass-transfer coefficient and pore-merging criterion are developed using finite element simulations. Preliminary results are able to reproduce the expected trends in permeability increase and capture the gamut of different dissolution regimes. Future work will focus primarily on using advanced subdomain coupling techniques to simulate much larger domain sizes to investigate the effects of domain size and determine a representative elementary volume.
NMR Investigation of Pore Structure in Gas Shales
Authors: Gannaway Gregory 
Published: October 2014

Abstract
In shales, the wettability contrast between water wet pores located between clay particles, oil wet organic pores and mixed wettability pores located at the interface between clays and organic matter, can be exploited to quantify the porosity associated with each pore system.
In order to quantify the different types of porosity, the NMR T2 spectra of 5 Barnett shale samples have been acquired, both in their native state, after dodecane saturation at 3000 psia, and after immersion in a 65% MnCl2 aqueous solution. These NMR spectra were acquired with Tau = 57 μsec on a 2MHz instrument. 65% MnCl2 aqueous solution has been found to exhibit no NMR signal and it does not mix with dodecane.
All the samples displayed a unimodal T2 distribution in their native state with a peak around 0.2 ms. This NMR peak is generally associated with clay pores. After dodecane saturation the development of a second peak around 5 ms forms. These two NMR peaks decreased after immersion in the MnCl2 solution. MnCl2 imbibition decreases the NMR water signal as it diffuses into the existing water in clay-dominated pores, and decreases the mixed pore system signal by a displacement process. The true organic pores are not affected by the MnCl2 solution because an aqueous, water-based solution cannot displace dodecane by simple imbibition in an oil-wet pore. After 30 days of MnCl2 imbibition the signal remaining on the peak at 5 ms is due to true organic pores. Also, this organic pore system displayed a positive relationship with the TOC of each sample.
Upon placing samples in both a vacuum = 4x10-6 mTorr and 150°C for 2 weeks, the remaining NMR peak around 0.2 ms reached a threshold beyond which it could not be reduced. These NMR results mimicked the results achieved chemically by using a 65% MnCl2 aqueous solution for the same NMR peak. These two experimental results, in conjunction with an understanding that the NMR peak around 0.2 ms represents clay dominated pores, yield support to the notion that the remaining peak around 0.2 ms (after 1 month of MnCl2 aqueous solution imbibition) represents clay-bound water.
Ultimately, this study allows for the quantification of effective porosity, inorganic porosity, organic porosity, the porosity at the inorganic-organic interface and clay-bound water.
Performance and the Gendered Body in Jamaica Kincaid's “Girl” and Oonya Kempadoo's Buxton Spice
Authors: Bailey Carol 
Published: October 2014

Abstract
Jamaica Kincaid's compact and succinct story “Girl,” the lead story in the collection At the Bottom of the River (1983), has been lauded as one of the premier works in Kincaid's corpus, particularly her discourse on the making of “woman” in postcolonial Caribbean contexts. The text is essentially a set of instructions offered by an adult (assumed to be a mother), laying out the script for the performance of womanhood in the fictional society in which the female child is expected to live and perform her gender. “Girl”'s emphasis on performative acts reiterates the inextricable link between gender and performance. Undoubtedly, this landmark Kincaid story is in dialogue with Butler's theorization of the centrality of stylized acts in the creating and crafting of gendered selves. Less well known is Oonya Kempadoo's debut novel Buxton Spice (1999). Buxton Spice chronicles the experiences of four pubescent girls in 1970s Guyana as they learn about, participate in, and challenge some gender expectations of their immediate and wider communities. The story is told from the point of view of Lula, who keenly observes the ways in which gender roles are enacted and how these roles may be re-enacted. Her observations alert the reader to the novel's preoccupation with uncovering, or perhaps reconfiguring, how gender roles might be at once imagined and played out in contemporary Caribbean societies. Both texts illustrate how the tensions and contradictions surrounding the constructions of womanhood, and in Buxton Spice, manhood, are engaged through performative acts, some of which ostensibly conform to prescribed gender roles but that actually undermine them.
Excerpts from the Voices of Feminism Oral History Project
Authors: Saika Peggy , Ross Loretta 
Published: October 2014

Abstract
In this oral history, Saika underscores the lasting impact of the internment experience as a call to vigilance and action. She traces her political involvements from pan-Asian student activism in the late 1960s forward, marking her journey through various forms of organizing: direct service, civil rights, community organizing, and philanthropy. The interview offers a general outline of Saika's path as a postwar progressive who embraces her generation's challenge to build an ethnic movement that affirms Asian American identity and rights while it also advances a broad anti-racist, feminist, class-conscious social justice agenda.
Recurrent lacrimal abscess in infant
Authors: Mondal Monojit , Biswas Biswajit , Laha Sumanta , Roy Atanu , Barik Kanai Lal , Datta Asok Kumar , Bose Sayan , Biswas Tanmoy 
Published: October 2014

Acute dacryocystitis at or shortly after birth is uncommon and its main complication, formation of lacrimal sac abscess, is rare. Uniform and standard treatment protocol for this condition has not been established till date. We report on a 2 month old infant with an abscess of the lacrimal sac. He was treated for similar condition on day 6 of his life by incision and drainage; unfortunately, the condition recurs. This time, he was managed with incision and drainage under systemic antibiotic cover; and an early probing of the nasolacrimal duct (NLD) was done on 7th post-operative day. The patient was followed up for a period of one year without any further recurrence and complication. Pathophysiology of the condition and possible treatment options in children have been discussed.DOI: http://dx.doi.org/10.3126/ajms.v6i2.10458Asian Journal of Medical Sciences Vol.6(2) 2015 121-123