bluuebunny/crossref_metadata_2025_split huggingface dataset:
Efficient Semi-Analytical Engine for Performance Prediction of Unconventional Reservoirs
Authors: Olalotiti-Lawal Feyi , Friedel Torsten 
Published: October 2015

Abstract
Reliable and fast prediction of fractured well performance is vital for asset evaluation and prudent field development decision making in unconventional, low permeability oil and gas reservoirs. Simple low cost techniques such as decline curve analysis are ill suited of properly accounting for extended transient flow regimes. Numerical simulation techniques on the other hand are unrivaled in capturing geological details and high accuracy in fluid flow description. However, they suffer from high computational expense and often too little relevant data is available. Our objective is to develop an efficient semi-analytical solution that combines the advantages of speed and accuracy from both techniques for forecasts on single well, pad and even field level.
Contrary to conventional oil and gas reservoirs, the tight reservoir characteristics allow for the application of analytical solutions to predict the behavior of fractured wells. The depth of investigation is small with spatial property variations having limited influence considering the large local pressure gradients. Fluid flow is mainly of transient nature and less dominated by multi-phase flow effects within the reservoir. Moreover, the typical configuration of an individual well with multiple fracture stage, entire pads with multiple wells or even entire assets allow the application of the superposition in space, providing a cheap means for accurate solution for multi-well problems.
This paper presents a transient semi-analytical model based on a tri-linear formulation. It accurately captures fluid flow to a single or multiple fractured wells over the entire life cycle of production, from early linear flow to pseudo-steady boundary driven flow. It is applicable to oil or gas reservoirs with permeabilities ranging from nano-Darcies to approximately one milli-Darcy. It is capable of handling both the vertical and horizontal well type, with either single or multiple fracture stages respectively. Well-bore, stage and pad configurations can be freely parametrized. A tubing head pressure boundary condition is incorporated to model production from those wells more realistically. For shale type reservoirs, a desorption process is incorporated.
The model is particularly suitable for quantitative evaluation of field development alternatives involving a large number of fractured wells. The accuracy compared to a high resolution numerical simulation model generally exceeds 90% with a computation speedup factor in the order of one hundred or more. Besides conventional benchmarking with a numerical reservoir simulator, actual field production data from the Marcellus and Eagleford shale wells shows the utility of the new solution. Being both fast and accurate, the technique presented in this paper is ideal for supporting high quality, cost efficient decision making which is crucial in the current low oil price environment.
Production Analysis Using Rate Transient Analysis
Authors: Belyadi Hoss , Yuyi Silumesii , Junca-Laplace Jean-Philippe 
Published: October 2015

Abstract
Shale reservoirs have low permeability, high fluid efficiency, and low fluid leak-off making these types of reservoirs ideal for hydraulic fracturing. One of the biggest challenges in analyzing unconventional shale reservoirs is that their flow regimes stay in transient flow for a very long period of time. This aspect of unconventional shale reservoirs makes it very challenging to estimate recoverable resources along with reservoir properties such as fracture half length, permeability, drainage area, and fracture conductivity. Conventional decline curve analysis assumes constant flowing bottom-hole pressure, drainage area, permeability, skin, and existence of boundary dominated flow. Most of these assumptions are no longer valid in unconventional reservoirs. Therefore, it is crucial that not only rate, but also pressure and other reservoir parameters are taken into account to properly evaluate unconventional wells and determine the true flow capacity of their reservoir in linear transient flow.
This study uses rate transient analysis (RTA) which plots pseudo normalized pressure versus material balance square root of time to estimate the productivity of Marcellus Shale wells. Our dataset is limited to a restricted area located in Greene and Washington Counties, Pennsylvania, with similar reservoir properties such as porosity, water saturation, pressure, and temperature. With limited variation in reservoir properties, the slope of the superposition plot used to calculate AK becomes a good metric for well productivity. The y-intercept from the same plot indicates the completions effectiveness of the well. The slope of the line for a well with zero completions damage intersects the origin. Any completions damage (skin damage) caused by poor completions designs or unfavorable reservoir properties will have a higher y-intercept in relation to the origin in the superposition plot. After performing this analysis on operated wells in the study area located in Washington and Greene Counties, the wells with the most successful completions methods were identified. This knowledge can then be applied for future wells in the same area for optimum production enhancements.
Impact of Drilling With Oil Based Mud on Well Control in Horizontal Shale Gas Wells
Authors: Elshehabi Tawfik , Bilgesu Ilkin 
Published: October 2015

Abstract
Objective of this study is to shed light to critical well control parameters of horizontal shale gas wells drilled with oil based muds (OBM). This study utilizes an interactive well control simulator to re-evaluate the kick control procedures in water based mud (WBM) and verify its application to oil based mud. Due to gas solubility in OBM a real time drilling and hydraulics data analysis is essential to minimize kick volumes. Therefore, early kick detection and surface warning signs are critical to minimize the influx size and reduce wellbore pressures. Moreover, the impacts of water-to-oil ratio, gas solubility, kick size, influx type and circulation rates on well control are investigated. OBM kick control process in horizontal wells creates additional challenges since the surface pressure and volume are not representative of the bottom-hole conditions. In unconventional shale gas reservoirs, oil and synthetic based drilling fluids are very common. Drilling cost, log interpretation, and environmental impacts are the main drawbacks of OBM. However, wellbore stability, reduction in torque and drag, stability of mud properties at higher temperatures and better drilling performance are the main advantages of OBM. Preliminary results show that dissolved gas in oil is liberated at the bubble point pressure and complicates surface kick handling procedures. Choke adjustment is hard due to the unexpected high volume of gases released and the delay time of choke response. Early detection is a key factor in minimizing the influx size and properly controls the casing shoe and choke pressures. Based on 110 hours of real time interactive simulation, influence of gas solubility on well control in OBM is presented to improve rig and personnel safety and reduce the blowout associated risks.
Production Decline Models: A Comparison Study
Authors: Ali Tariq A. , Sheng James J. 
Published: October 2015

Abstract
Erroneous reserve estimates associated with improper application of Arp's relations has led to the development of alternative rate-time models based on empirical considerations. These models can equally provide good fits for only limited duration production data, but they yield significantly different 30-year-estimated ultimate recovery (EUR).
In our previous work, we extensively demonstrated the reliability of cumulative-production model to analyze the production performance of fractured dominated tight and shale reservoirs.
In this paper, a number of real field examples are used to generate 30-year-EUR estimates using different rate-time models as well as a production-decline model.
Results show that some of rate-time models overestimate EUR with more than 150% compared with the cumulative production-decline model which yields correct estimates in most of the cases.
Experimental Investigation of Geomechanical Impacts on Organic-Rich Shales Matrix-Fracture Characterization
Authors: Zamirian Mehrdad , Aminian Kashy , Ameri Samuel 
Published: October 2015

Abstract
During hydraulic fracturing process, the formation undergoes significant changes in the net stress as a result of the fluid injection and retrieval. These stress changes impact the formation petrophysical properties including permeability, porosity, and the compressibility. In this experimental study, the impact of geomechanical changes on shales petrophysical properties is investigated using a laboratory set-up that was designed and assembled for fast and robust shale core plug porosity and permeability measurements under steady-state conditions. This laboratory set-up is capable of accurately measuring shale core plug ultra-low permeability and porosity because it has a resolution of one millionth standard cubic centimeters per second for gas flow rate and one hundredth cubic centimeters for pore volume measurement. The laboratory set-up allows measurements to be performed under isothermal conditions by automated temperature control. The application of the confining pressure on the shale core plug allows permeability and porosity to be measured under a wide range of net stress.
A sequential set of experiments were performed in this study. During the first set of experiments, the permeability of the core plug was measured by increasing the net stress from 500 psia to 7,900 psia followed by decreasing net stress from 7,900 psia to the initial net stress condition. The next three sets of experiments repeated the same steps as the first set on the same core plug. However, during the third set only the porosity, and during the fourth set only permeability was measured.
The measured porosity and permeability values from the experiments clearly exhibited hysteresis with the net stress changes. The hysteresis was more pronounced for permeability than it was for porosity. Since the permeability changes were non-linear with respect to net stress changes, Walsh method was used to estimate the fracture closure pressure. The results indicate that sequential net stress changes can cause a reduction in fracture closure pressure. This reduction however tends to diminish with increasing number of sequential stress changes. Finally, comparing the porosity and permeability measurements revealed two distinctive behavioral changes for both porosity and permeability that can be contributed to the natural fracture and matrix properties.
Utilizing Cement Bond Logs to Evaluate Wellbore Integrity for Local and Regional Scales
Authors: Haagsma A. , Burchwell A. , Sminchak J. , Gerst J. , Moody M. 
Published: October 2015

Abstract
Wellbore integrity is a fundamental aspect of site characterization for storage in areas with existing or abandoned oil and gas wells. The condition of well cement and casing structures determine if a well can sustain optimal hydrostatic pressures and prevent leakage. This is a necessary but underappreciated aspect of assessing potential reservoirs when optimal and sustainable pressure conditions are critical for success. Cement bond logs (CBLs), a tool not generally used efficiently, can represent the cement quality around a wellbore and be used to identify intervals of poor cement integrity. A standardized CBL evaluation tool was created to remove inconsistencies in interpretations and used to evaluate 394 CBLs in Michigan and 306 CBLs in Ohio.
700 CBLs were analyzed for six site specific study areas and reviewed regionally across Michigan and Ohio to identify any trends in cement quality and highlight possible fluid migration pathways through wellbores with poor cement integrity. The CBL evaluation tool uses a quantitative bond index method to assign percent bond to wireline log readings based on user defined conditions. Once analyzed, the tool outputs a descriptive statistical dataset. Industry standards were used to categorize wells based on cement quality. Correlations between cement quality and the year and season the well was completed, well depth, cement column thickness, and formations cemented over were explored using basic statistics and graphing methods. As well, a standardized assessment of such a variety of wells and cement conditions allows for the incorporation of these wellbores into subsurface models to identify possible zones of weakness for ideal pressure conditions.
There were no strong correlations on the regional scale between cement quality and year/season well was completed, depth of the well, and cement column thickness. The tool was very useful in providing red flags in the assessment of a site specific study area and in the evaluation of potential confining layers. Within a study area it was easy to identify wells with poor cement quality and determine if the wells posed a risk to a potential storage site. High risk areas for potential confining layers were also mapped and could be used as a guide to determine areas of poor cement bond within a specific formation.
Understanding the Impact of Rock Properties and Completion Parameters on Estimated Ultimate Recovery in Shale
Authors: Javadi Faegheh , Mohaghegh Shahab D. 
Published: October 2015

Abstract
Estimating ultimate recovery (EUR) in shale is a function of rock properties, well, and completion design parameters. The variation associated with these parameters are in source of uncertainty. In this paper the combined decline curve (CDC) approach is used to estimate the EUR of shale wells. CDC is a conservative approach that combines hyperbolic (in early time) and exponential (in later time) declines for production analysis. The major objective of this work is to condition the results of the CDC-EUR of shale wells to rock properties, well characteristics, and completion design parameters in a given shale asset. As the first step CDC-EUR is estimated. In the second step data-driven analytics using artificial neural networks is employed to condition the CDC-EUR to rock properties, well characteristics, and completion design parameters. Then, artificial Intelligence techniques are used in order to extract the nonlinear relationship between well productivity and reservoir characteristics and completion parameters. In this study 168 wells from Marcellus shale asset are examined.
The major rock properties that are studied are porosity, total organic content, net thickness, and water saturation. Moreover, the effect of several design parameters, such as well inclination and azimuth, stimulated lateral length, stage length, number of clusters per stage, and amount of fluid and proppant are studied. A data driven model is developed using AI techniques. Results show that the model is able to find the relationship between the input parameters and EUR. Thus, this model will help petroleum professionals to have a better understanding of the effect of rock properties and design parameters on the future production from shale wells.
Economic Evaluation of Marcellus and Utica Under the Effects of Dynamic Market and Development Conditions
Authors: Ozkan S. , Duman R. 
Published: October 2015

Abstract
The Marcellus and Utica are among the most talked about natural gas plays in the country. In this paper their productivity and economics are examined, along with a production forecast. The type curves for natural gas and oil for different production areas within the Marcellus and Utica are compiled from well-level production data to gauge productivity differences between different parts of the plays. A drilling schedule is applied to the type curves to arrive at a production forecast for the various regions. Using the type curves and processing plant data, a natural gas liquids production forecast is provided as well. The breakeven natural gas prices and internal rates of return for the various production areas are calculated using a discounted cash flow model. These metrics are compared to other plays across the US to understand the competitiveness of the Marcellus and Utica, particularly in natural gas production growth, going forward. The Marcellus already boasts the best natural gas play economics in the country and will continue to be the cheapest source of natural gas production outside of natural gas volumes produced in association with oil-directed drilling. The Utica has great production potential, as can be seen in the impressive initial production rates already observed in certain windows of the Utica. However, the high drilling and completion costs and various operational problems need to be overcome if the play is to mature into the development phase. Both the Marcellus and the Utica will continue to see investment. The Marcellus will attract capital due to its already prolific economics, and the Utica will attract capital due to the high productivity potential that could be unlocked by marching up the learning curve.
The Effectiveness of Corticosteroid Injection for De Quervain’s Stenosing Tenosynovitis (DQST): A Systematic Review and Meta-Analysis
Authors: Rowland Patrick , Phelan Nigel , Gardiner Sean , Linton Kenneth N , Galvin Rose 
Published: October 2015

De Quervain’s stenosing tenosynovitis (DQST) treatments include corticosteroid injection around the tendon sheath; however there is some ambiguity concerning the efficacy of this treatment. The aim of this systematic review and meta-analysis is to examine the totality of evidence relating to the use of corticosteroid injection in DQST when compared to placebo or other active treatments. A systematic literature search was conducted in July 2014. Only randomized control trials (RCTs) were included.Outcome measures included impairment, activity limitation and participation restriction.Five RCTs were identified with165 patients, 88 in the treatment group and 77 in the control group.Patients who received corticosteroid injection (n=142) had a higher rate of resolution of symptoms [RR 2.59, 95% CI: 1.25 to 5.37, p=0.05,I2=62%]. This group reported greater pain relief as assessed by Visual Analogue Scale (VAS) at first assessment [mean difference -2.51, 95% CI: -3.11 to -1.90, p=0.0003,I2=65%] and demonstrated a statistically significant improvement in function (n=78) as measured by the DASH score and Dutch AIMS-HFF score [SMD -0.83, 95% CI: -1.54 to -0.12, p=0.02,I2=48]. This review confirms that corticosteroid injection results in a statistically significant increase in resolution of symptoms, pain relief and increased function in the treatment of DQST.
The Association Between Primary Open Angle Glaucoma and Clustered Components of Metabolic Syndrome
Authors: Rasoulinejad Seyed Ahmad , Kasiri Ali , Montazeri Mahdi , Rashidi Negin , Montazeri Maryam , Montazeri Mohammad , Hedayati Hesam 
Published: October 2015

Purpose :There is conflicting evidence whether components of metabolic syndrome (MetS) increase or decrease the risk of primary open-angle glaucoma (POAG). The aim of the present study was to determine the association between metabolic syndrome and primary open-angle glaucoma.Methods :A total of 200 participants comprising 100 controls and 100 patients with POAG documented by clinical tests and examined by an experienced ophthalmologist using standard ophthalmologic equipment were included in the study. MetS was defined and based on ATP III criteria and POAG was defined by the criteria of the International Society of Geographic and Epidemiological Ophthalmology (ISGEO). The data were entered into the SPSS software and analyzed.Results :The prevalence of MetS in the glaucoma group was 53% in comparison to 38% in the control group (p=0.037). MetS was associated with an increased odds ratio for an IOP higher than 21 mmHg (OR: 1.72; 95% CI 1.03-2.79; p=0.034). The mean IOP was 24.91±4.29 mmHg in the patients without MetS, and 27.23±4.81 mmHg in those with MetS (p=0.027). The mean values of CCT were 603.64±63.16 µm in MetS patients and 579.27±72.87 µm in controls (p=0.018).Conclusion :Data showed an increased prevalence of components of metabolic syndrome in patients with glaucoma. The mechanisms underlying these associations need to be established in future studies. Our results support the recommendation that patients with metabolic syndrome undergo regular ophthalmological exams to monitor for the onset or progression of glaucoma.
Faster extubation time with more stable hemodynamics during extubation and shorter total surgical suite time after propofol-based total intravenous anesthesia compared with desflurane anesthesia in lengthy lumbar spine surgery
Authors: Lu Chueng-He , Wu Zhi-Fu , Lin Bo-Feng , Lee Meei-Shyuan , Lin Chin , Huang Yuan-Shiou , Huang Yi-Hsuan 
Published: October 2015

OBJECT
Anesthesia techniques can contribute to the reduction of anesthesia-controlled time and may therefore improve operating room efficiency. However, little is known about the difference in anesthesia-controlled time between propofol-based total intravenous anesthesia (TIVA) and desflurane (DES) anesthesia techniques for prolonged lumbar spine surgery under general anesthesia.

METHODS
A retrospective analysis was conducted using hospital databases to compare the anesthesia-controlled time of lengthy (surgical time > 180 minutes) lumbar spine surgery in patients receiving either TIVA via target-controlled infusion (TCI) with propofol/fentanyl or DES/fentanyl-based anesthesia, between January 2009 and December 2011. A variety of time intervals (surgical time, anesthesia time, extubation time, time in the operating room, postanesthesia care unit [PACU] length of stay, and total surgical suite time) comprising perioperative hemodynamic variables were compared between the 2 anesthesia techniques.

RESULTS
Data from 581 patients were included in the analysis; 307 patients received TIVA and 274 received DES anesthesia. The extubation time was faster (12.4 ± 5.3 vs 7.0 ± 4.5 minutes, p < 0.001), and the time in operating room and total surgical suite time was shorter in the TIVA group than in the DES group (326.5 ± 57.2 vs 338.4 ± 69.4 minutes, p = 0.025; and 402.6 ± 60.2 vs 414.4 ± 71.7 minutes, p = 0.033, respectively). However, there was no statistically significant difference in PACU length of stay between the groups. Heart rate and mean arterial blood pressure were more stable during extubation in the TIVA group than in the DES group.

CONCLUSIONS
Utilization of TIVA reduced the mean time to extubation and total surgical suite time by 5.4 minutes and 11.8 minutes, respectively, and produced more stable hemodynamics during extubation compared with the use of DES anesthesia in lengthy lumbar spine surgery.