bluuebunny/crossref_metadata_2025_split huggingface dataset:
What Factors Control Shale Gas Production Decline Trend: A Comprehensive Analysis and Investigation
Authors: Wang HanYi 
Published: April 2016

Abstract
One of the biggest practical problems with the optimization of shale gas stimulation design is estimating post-fracture production rate, production decline, and ultimate recovery. Without a realistic prediction of the production decline trend resulting from a given completion and reservoir properties, it is impossible to evaluate the economic viability of producing natural gas from shale plays.
Traditionally, decline curve analysis (DCA) is commonly used to predict gas production and its decline trend to determine the estimated ultimate recovery (EUR), but its analysis cannot be used to analyze what factors influence the production decline trend due to lack of underlying support of physics, which make it difficult to guide completion designs or optimize field development.
In this article, we presented a unified shale gas reservoir model, which incorporates real gas transport, nano-flow mechanisms and geomechanics into fractured shale system. This model is used to predict shale gas production under different reservoir scenarios and investigate what factors control its decline trend. The results and analysis presented in the article provide us a better understanding of gas production and decline mechanisms in a shale gas well with certain conditions of the reservoir characteristics. More in-depth knowledge regarding the effects of factors controlling the behavior of the gas production can help us develop more reliable models to forecast shale gas decline trend and ultimate recovery. This article also reveals that some commonly hold beliefs may sound reasonable to infer production decline trend, but may not be true in a coupled reservoir system in reality.
Estimation of Unconventional Well Recoveries and Economics from Tranient Flow Data
Authors: Seidle J. P. , O'Connor L. S. 
Published: April 2016

Abstract
Accurate forecasts of future production and the associated economics for conventional wells are possible with Arps decline curves as these wells attain boundary-dominated flow (BDF) relatively quickly. Unconventional wells completed in low permeability formations can require several years (and several annual evaluations) to reach boundary-dominated flow, often making Arps based production forecasts for these wells unreliable. Application of methods based on production history, such as rate-transient analysis (RTA), may provide reasonable production forecasts but require wellhead or bottomhole pressures in addition to production rates. In contrast, data available for estimation of proved reserves for unconventional wells routinely includes only rate data from transient flow, limiting the utility of both the Arps and most RTA methods. This study addresses the ability of three models which require only production data, the modified Arps, Duong, and stretched exponential decline model (SEDM) methods, to fill this gap by using time-slice data (6 months, 1 year, 3 years) from long-lived unconventional wells. Accuracy of these models in predicting future well performance and the resulting economics based on constant prices and constant operating expenses, and the ability of these reserves estimates to meet the SEC requirement that proved reserves should remain constant or increase over time are considered.
How Corporate-Level Economics Enable Expected Value Thinking
Authors: Adejumo A. , Queen S. , Gama B. , Germain O. R. 
Published: April 2016

Abstract
Decisions made every day at the asset level affect corporate-level profitability, and oftentimes, this big-picture impact is not obvious to those on the front lines. How can exploration and production (E&P) organizations enable frontline managers to make decisions for a particular field within the larger context of the larger corporate portfolio?
A view of the corporate portfolio shows how oil and gas (O&G) assets come together to drive or diminish value. The E&P industry was originally structured in siloed multidisciplinary teams, and this has resulted in inherently suboptimal overall performance for O&G assets. Projects run behind schedule and over budget, reserves are frequently downgraded after final investment decisions, and value winds up destroyed. Juxtaposed with the huge capital expenditure (CAPEX) required to meet long-term global hydrocarbon demand, an increasing need exists to leverage technology and integrate people, processes, and platforms to produce better results.
This paper discusses the decision dynamics of E&P organizations within the context of the lifecycle of a hydrocarbon asset, identifies the weak links in this decision-making process, and suggests ways of achieving a more collaborative process for making value-added decisions. It demonstrates, using a case study of an exploration project and an acquisition target, how organizations can build resilient portfolios by continuously calibrating to rapidly changing technical and market conditions, thus, unlocking "option value" and achieving balance between risks and rewards.
This paper seeks to trigger a new way of thinking in how organizations could leverage an integrated platform to solve the disconnect between underlying technical risks resident in engineering and execution models and the economic risks inherent to the market and its models.
Much like how the integration of point engineering models significantly advanced the utility of the digital oilfield in the early 2000s, the coupling of petrotechnical, operational, and economic models will unlock a new, greater level of upstream optimization. This paper uniquely shows how possible this integration is today and helps progress the adoption of expected value thinking in the industry. Additionally, the paper introduces the effective use of a cloud-enabled integrated solution to evaluate prospects in a timely manner with minimal information and less resources, thereby, delivering results in mere minutes that would have previously taken a team of professionals several months to achieve.
Data Mining and Analysis - Eagle Ford Formation, South Texas
Authors: Romero Dario H. , Poston Steve W. 
Published: April 2016

Abstract
The paper applies commonly available public information to outline well behavior for productive trend modeling within a chosen area of the Eagle Ford shale in South Texas. Public records are often thought to contain qualitatively insufficient information to provide a reasonable analysis of well and producing character trend characteristics. They –Public records- contain both static and dynamic well data. Static information consists of completion histories, locations, deviations surveys, core analyses, and well property maps while oil, gas and water production records comprise dynamic records. Too often, this freely available information is not utilized for regional studies because pressure, porosity, permeability profiles are not included in these files. More descriptive data are usually only available in individual company well files. This means for most cases, rate – time data represent the only information available to the public.
The study of monthly production records involving multiple ownership properties can highlight regions of no additional interest but also can highlight areas of potential additional economic value. Property value could be increased by well cleanouts, workovers, and re-fracturing or new drill locations to increase recovery from these high productivity areas. In any case, a seemingly intractable data problem could be reduced to a rather straightforward procedure by the study of well records.
Cumulative production, remaining reserves or initial production rate estimates plotted on available property maps could highlight areas for further review or in the majority of cases exhausted areas of no additional interest.
Transforming production data is only the first step of the process, a comprehensive interpretation of the results must follow. Property and maps obtained from public records provide a basis for plotting production trends for a particular well set. Analysis of well tickets coupled with the oil, gas and water production history supply considerable insight into interpreting a well history since erratic production changes are numerous in the Eagle Ford trend.
Recovery estimates can only be determined after the data are plotted and studied to select the proper production segment to analyze. Selection of transient and boundary dominated segments is of paramount importance for interpreting Eagle Ford wells. Smoothing techniques such as material balance time and normalized production can be applied if necessary. The "goodness" of the fracture system can be estimated from the transient portion of the curve while estimated reserves from the boundary side. Of course, the process will not apply if discrete systems cannot be identified. These results are plotted on a property maps and interpreted.
A particular area within the south Texas area is identified and each well subjected to the data mining process. The result of this study should help identify maturely developed areas and highlights areas of interest.
A Strategy for Low Cost Development of Incremental Oil in Legacy Reservoirs
Authors: Attanasi Emil D. 
Published: April 2016

Abstract
The precipitous decline in oil prices during 2015 has forced operators to search for ways to develop low-cost and low-risk oil reserves. This study examines strategies to low cost development of legacy reservoirs, particularly those which have already implemented a carbon dioxide enhanced oil recovery (CO2 EOR) program. Initially the study examines the occurrence and nature of the distribution of the oil resources that are targets for miscible and near-miscible CO2 EOR programs. The analysis then examines determinants of technical recovery through the analysis of representative clastic and carbonate reservoirs. The economic analysis focusses on delineating the dominant components of investment and operational costs. The concluding sections describe options to maximize the value of assets that the operator of such a legacy reservoir may have that include incremental expansion within the same producing zone and to producing zones that are laterally or stratigraphically near main producing zones. The analysis identified the CO2 recycle plant as the dominant investment cost item and purchased CO2 and liquids management as a dominant operational cost items. Strategies to utilize recycle plants for processing CO2 from multiple producing zones and multiple reservoir units can significantly reduce costs. Industrial sources for CO2 should be investigated as a possibly less costly way of meeting EOR requirements. Implementation of tapered water alternating gas injection schemes can partially mitigate increases in fluid lifting costs.
Operating EOR Projects: The Experience of an Independent Energy Company
Authors: Covey F. D. , Craig F. F. 
Published: April 2016

Abstract
A major producer of natural gas and natural gas liquids, Mitchell Energy Corporation also produces 5,200 barrels per day of crude oil and condensate, 15 percent due to secondary (waterflood) operations and 16 percent due to tertiary (enhanced) operations.
This presentation examines Mitchell's Enhanced Oil Recovery (EOR) philosophy and commitment and the role EOR plays in Corporate operations. Manpower size and capabilities are discussed, along with Corporate efforts to keep personnel technically up-to-date in the rapidly changing EOR environment. The independent's advantages and limitations with regard to EOR operations are highlighted by describing the development chronology of Mitchell's Alvord South (Caddo) Unit, a full-field carbone miscible flood located near Fort Worth, Texas. The impact of Corporate innovations, such as development of a patented carbon dioxide tracer system and the application of hand-held computers to data gathering and reporting, as well as the impact of industry-wide events, such as the end of the DOE's Tertiary Front-end Recoupment Program and the 1986 collapse of oil prices, are continuing to play a major role in the technical and economic outcome of the Alvord South (Caddo) project. Mitchell's view of the EOR potential for independents under current conditions is also reviewed.
Comparison of Phosphorus Fertilization Diagnostic Methods of Potato in Mollisols
Authors: Zamuner E. C. , Lloveras J. , Echeverria H. 
Published: April 2016

The aim of this research was to provide tools for the profitable and environmentally friendly P fertilization of potato (Solanum tuberosum L.) crops. The objectives were: (i) to examine the relationships between the available soil phosphorus index (Pav), as determined by Bray1, Mehlich 3, Olsen, and CaCl2 in Mollisols, and potato yields and (ii) to identify the P fertilization rates required to obtain the maximum agronomic yields, considering the environmental risk of P loss. The study was conducted from 2005 to 2014 in soils with a wide range of initial available P levels (8.6–50.0 mg kg−1 Bray1; from a depth of 0 to 20 cm in which irrigated potato crops fertilized with P were cultivated. The linear‐plateau, quadratic‐plateau, and Cate–Nelson models were used to analyze crop responses to P and to determine the phosphorus threshold (Pt) required to identify soils with positive responses to P fertilization. The Pt was 32 mg kg−1 for Bray1 and Mehlich 3, 11 mg kg−1 for Olsen and 2.8 mg kg−1 for CaCl2. Recommended P rates were defined based on the initial soil Pav index, the quantity of P removed by the crop for a specific yield, the P required to increase the initial soil P to the Pt, and the environmental Pt. Soil Bray1 determined postharvest confirmed that the P fertilizer recommendation was appropriate in Mollisols soils.Core Ideas

The relationships between potato yield responses and available soil P were examined.
The available soil P threshold was determined with the Bray1, Mehlich 3, Olsen, and CaCl2 tests.
The P rate required to maximize the potato yield while avoiding environmental pollution was defined based on empirical information.
Enhancing Speaking Ability of EFL Students through Debate and Peer Assessment
Authors: Fauzan Umar 
Published: April 2016

The objective of the study was to implement the debate technique and peer assessment to improve the third semester student’s speaking ability. This study employed classroom action research and it was done in two cycles. There were four meetings in each cycle; three meetings was for the implementation of debate in the teaching of speaking and one meeting was for conducting speaking test. The instruments used to collect the data were: (1) observation checklist, (2) field-note, (3) score sheet, and (4) questionnaire. The result of the research showed that the criteria of success had been reached in cycle 2. There were two aspects determined as the success criteria; score improvement and classroom atmosphere. The result of speaking test showed that the students had made some progress, the average scores raised from 60 in pre-test, 69 in cycle 1 and 75 in cycle 2. These scores indicated that there is an increasing ability from being ‘fair’ to being ‘good’. The classroom atmospheres were also increasing positively. The result shows that the students gradually could express their thought and opinions in debate practice. This activity encouraged the students’ creativity to explore the language, since they were asked to develop their arguments from certain motions. The motions were made familiar to them so that they found it easy to speak on the topics. By practicing speaking in the debate practice, they improved their fluency as well as their confidence.
Book Reviews
Authors: Plum Catherine , Berghahn Klaus , Smulewicz-Zucker Gregory , Freis David , Eckel Matthew , Pehl Malte 
Published: April 2016

Mike Dennis and Norman LaPorte, State and Minorities in Communist East Germany (Berghahn: New York, 2013)
Reviewed by Catherine Plum Florian Illies, 1913. Der Sommer des Jahrhunderts (Fischer: Frankfurt/Main, 2012)
Reviewed by Klaus BerghahnHoward Eiland and Michael W. Jennings, Walter Benjamin: A Critical Life (Cambridge: The Belknap Press of Harvard University Press, 2014)
Reviewed by Gregory Smulewicz-ZuckerHelmut Schmitz and Annette Seidel-Arpacı, ed., Narratives of Trauma: Discourses of German Wartime Suffering in National and International Perspective (Amsterdam: Rodopi, 2011)
Reviewed by David FreisTriadafilos Triadafilopoulos, Becoming Multicultural: Immigration and the Politics of Membership in Canada and Germany (Vancouver: University of British Columbia Press, 2012)
Reviewed by Matthew EckelFrank Trommler. Kulturmacht ohne Kompass – Deutsche auswärtige Kulturbeziehungen im 20. Jahrhundert (Cologne: Böhlau Verlag, 2014).
Reviewed by Malte Pehl
The use of thebe-passive in academic Englishes: localversusglobal usage in an international language
Authors: Hundt Marianne , Schneider Gerold , Seoane Elena 
Published: April 2016

In this paper, we examine the diffusion of a syntactic change in a specialised text type in different World Englishes – in particular, the use of be-passives in academic discourse in nine contact varieties of English and six English as a Native Language (ENL) varieties. The Zürich-parsed International Corpus of English (ICE) makes it possible to retrieve automatically, for the first time, the two variants in the envelope of variation: active transitive constructions and be-passives. We apply regression analysis in order to gauge the effect of potential external factors that play a role in the choice between them: regional variety (with potential influence from the substrate in the contact varieties) and academic sub-discipline. The use of the passive has undergone change in the twentieth century (see, for example, Leech et al., 2009 ). As a necessary backdrop for variation found in the ICE corpora, we therefore use historical data from the extended Brown family of corpora, which have also been parsed at the University of Zürich.The results of our analysis show that regional variety is less important than academic sub-discipline: with the sole exception of American English, be-passives are about equally frequent in both ENL and contact varieties; moreover, they are distributed similarly across all varieties according to academic sub-discipline (humanities, social sciences, natural sciences and technology).
TRANSIT TIMING VARIATIONS FOR PLANETS NEAR ECCENTRICITY-TYPE MEAN MOTION RESONANCES
Authors: Deck Katherine M. , Agol Eric 
Published: April 2016

ABSTRACT
We derive the transit timing variations (TTVs) of two planets near a second-order mean motion resonance (MMR) on nearly circular orbits. We show that the TTVs of each planet are given by sinusoids with a frequency of

jn

2

−

(
j
−
2
)

n

1

, where

j
≥
3

is an integer characterizing the resonance and n
2 and n
1 are the mean motions of the outer and inner planets, respectively. The amplitude of the TTV depends on the mass of the perturbing planet, relative to the mass of the star, and on both the eccentricities and longitudes of pericenter of each planet. The TTVs of the two planets are approximated anti-correlated, with phases of ϕ and

≈
ϕ
+
π

, where the phase ϕ also depends on the eccentricities and longitudes of pericenter. Therefore, the TTVs caused by proximity to a second-order MMR do not in general uniquely determine both planet masses, eccentricities, and pericenters. This is completely analogous to the case of TTVs induced by two planets near a first-order MMR. We explore how other TTV signals, such as the short-period synodic TTV or a first-order resonant TTV, in combination with the second-order resonant TTV, can break degeneracies. Finally, we derive approximate formulae for the TTVs of planets near any order eccentricity-type MMR; this shows that the same basic sinusoidal TTV structure holds for all eccentricity-type resonances. Our general formula reduces to previously derived results near first-order MMRs.
ON THE RADIO DETECTION OF MULTIPLE-EXOMOON SYSTEMS DUE TO PLASMA TORUS SHARING
Authors: Noyola J. P. , Satyal S. , Musielak Z. E. 
Published: April 2016

ABSTRACT
The idea of single exomoon detection due to the radio emissions caused by its interaction with the host exoplanet is extended to multiple-exomoon systems. The characteristic radio emissions are made possible in part by plasma from the exomoon’s own ionosphere. In this work, it is demonstrated that neighboring exomoons and the exoplanetary magnetosphere could also provide enough plasma to generate a detectable signal. In particular, the plasma-torus-sharing phenomenon is found to be particularly well suited to facilitate the radio detection of plasma-deficient exomoons. The efficiency of this process is evaluated, and the predicted power and frequency of the resulting radio signals are presented.
ELECTRON ACCELERATION BY LANGMUIR WAVES PRODUCED BY A DECAY CASCADE
Authors: Krafft C. , Volokitin A. S. 
Published: April 2016

ABSTRACT
It was recently reported that a significant part of the Langmuir waveforms observed by the STEREO satellite during type III solar radio bursts are likely consistent with the occurrence of electrostatic decay instabilities, when a Langmuir wave



resonantly interacts with another Langmuir wave


′

and an ion sound wave


′

through the decay channel


→

′
+

′
.

Usually such wave–wave interactions occur in regions of the solar wind where the presence of electron beams can drive Langmuir turbulence to levels allowing waves



to decay. Moreover, such solar wind plasmas can present long-wavelength, randomly fluctuating density inhomogeneities or monotonic density gradients which can significantly modify the development of such resonant instabilities. If some conditions are met, the waves can encounter a second decay cascade (SDC) according to


′
→

″
+

″

. Analytical estimates and observations based on numerical simulations show that the Langmuir waves


″

produced by this SDC can accelerate beam particles up to velocities and kinetic energies exceeding two times the beam drift velocity v

b
and half the initial beam energy, respectively. Moreover, this process can be particularly efficient if the scattering effects of waves on the background plasma inhomogeneities have already accelerated a sufficient amount of beam electrons up to the velocity range where the phase velocities of the


″

waves are lying. The paper shows that the conditions necessary for such process to occur can be easily met in solar wind plasmas if the beam velocities do not exceed around 35 times the plasma thermal velocity.
The Opportunity To Eradicate Peste des Petits Ruminants
Authors: Mariner Jeffrey C. , Jones Bryony A. , Rich Karl M. , Thevasagayam Samuel , Anderson John , Jeggo Martyn , Cai Yi , Peters Andrew R. , Roeder Peter L. 
Published: April 2016

AbstractPeste des petits ruminants (PPR) is a highly infectious disease of sheep and goats that is caused by PPR virus, a member of the genus Morbillivirus that includes the viruses that cause rinderpest (RP) in cattle. RP was the first animal disease to be globally eradicated in 2011 and is only the second disease, after smallpox, to have ever been eradicated. PPR is one of the principal constraints to small ruminant production in Africa, Asia, and the Middle East. The epidemiology of PPR and RP as well as the technologies available for their diagnosis and control are similar. The conditions that favored the eradication of RP are also largely present for PPR. In this work, we outline the evolving strategy for eradication in light of current opportunities and challenges, as well as the lessons from other eradication programs in animal and human health. The global PPR situation and technology for its control are summarized. A strategy based on the lessons from previous eradication efforts that integrate epidemiology, social science, and economics as tools to target and motivate vaccination is summarized. Major aspects of the cost and benefit-cost analysis of the indicated program are presented. The overall undiscounted cost of eradication was estimated as $3.1 billion, and the benefit-cost ratio for the most likely scenario was estimated at 33.8. We close with a discussion of the possible next steps.