bluuebunny/crossref_metadata_2025_split huggingface dataset:
Production Data Analysis of Shale Gas Wells with Abrupt Gas Rate or Pressure Changes
Authors: Pang Wei , Du Juan , Zhang Tongyi 
Published: March 2019

Abstract
Production data analysis (PDA) by using rate normalized pressure (RNP) and rate normalized pressure derivative (RNP’) is useful for transient rate and pressure analysis of shale gas wells with constant or smooth changing gas rate and pressure. However, some reasons may cause abrupt changes, fluctuation, or even loss of production data. The existing PDA methods can not well address this kind of issue.
The paper analyzes the reasons that cause big changes of shale gas production rate and pressure. The reasons include well-interference, well shut-ins, and converting production from casing to tubing. Typical shale gas well cases in China are described.
Three methods are proposed to address the non-smooth production data issue. For shale gas wells with severe well-interference from neighbouring fracturing wells or production wells, the segmented production data before well-interference is suggested as well-interference is like an imposed negative or positive force from outside, and this force disturbs the normal production performance only rely on the well's own energy. For wells with frequent shut-ins, a virtual equivalent time method is referenced. The process for this method firstly calculates the formation pressure distributions and the average formation pressures within the SRV area; sencondly, calculate the virtual equivalent time by use of the average formation pressure; thirdly, divided the whole production data into several interconnected segments by rearrange the vitual euivalent time into the actual time axis, and finally do the analysis by using the log-log plot of pressure and pressure derivate vs material balance time. For shale gas wells with converting production from casing to tubing, as there are abrupt rate and pressure changes at the converting point, the material balance time may be no more monotonically increasing with production time. We proposed the average material balance time method to solve this problem. For this method, we use average material balance time instead of the material balance time in the log-log plot of pressure and pressure derivative.
Results shows that severe well-interference cause big disturblance and only data before well-interference is suggested for PDA. Both the PDA with average material balance time and PDA with virtual equivalent time can get much better match of production history and log-log plot of pressure and pressure derivative then the exsiting PDA method.
Reservoir Depletion-Induced Proppant Embedment and Dynamic Fracture Closure
Authors: Huang Jian , Safari Reza , Perez Oswaldo , Fragachan Francisco E. 
Published: March 2019

Abstract
An optimized stimulation design not only achieves high productivity during early times, but also necessitates maintaining conductive flow paths during the life of a well. Because of proppant settling and bridging, proppants are not uniformly distributed within developed fracture networks. Moreover, no fractures retain original conductivity during long term depletion, due to proppant embedment and crushing. This paper introduces a model that analytically predicts the proppant deformation and fracture closure behavior, and forecasts production performance.
This model is based on contact mechanics to simulate the mechanical interaction between the proppant pack and formation rock. The fracture aperture can be calculated and updated by taking into account the proppant concentration, non-uniform proppant distribution and in-situ stress conditions. The proppant pack permeability is analytically modelled according to its mechanical properties (size and density) and effective normal stress acting on the fracture surface. In this way, the fracture conductive variation caused by reservoir depletion can be quantified and imported into a reservoir model to forecast production.
This paper presents a new analytical model to describe dynamic fracture closure and its impact on production performance, which varies significantly with the proppant mechanical properties, proppant concentration, proppant distribution, stress condition and formation types. Under different conditions, conductivity evolution of propped fractures can be obtained from the presented model and matched well with multiple experimental tests. Sensitivity of proppant properties, reservoir attributes, and operational parameters are discussed in this study. Production results from these sensitivity analyses can be used to compare and contrast different design scenarios.
This model enables an efficient and reliable prediction of the fracture dynamic closure behavior and identification of controlling parameters to mitigate premature fracture closure. This model honors heterogeneous proppant distribution and related fracture closure, and hence captures more realistic reservoir performance. By integrating stress-dependent fracture conductivity and production analysis in this model, an operational guideline can be provided to maximize the productivity of fractured formations.
A Novel Approach for Formulating CO2 Foam Based Fracturing Fluid by Synthesized Grafting Copolymerization to Enhance its Stability for HPHT Shale Reservoirs
Authors: Chaudhary Sahil , Singh Sandeep , Singh Vikas Kumar 
Published: March 2019

Abstract
Conventional Sources of energy are depleting at an alarming rate which give us unconventional resources as an only option for energy source. Unconventional sources of energy like Shale gas, Tight gas, Coal bed methane are difficult to exploit as compared to the conventional sources of energy. Hydraulic Fracturing is the well stimulation technique used for exploitation and production of these unconventional resources. Foam fracturing is the the most opted stimulation technique for low permeability shallow wells because of its reduced damage potential to reactive and sensitive formations. This research paper discusses about the evaluation of attempt made to develop an eco-friendly CO2 foam based fracturing fluid which can be used at HPHT conditions for shale reservoirs by Grafting Copolymerization. The graft copolymer was developed by free radical polymerization of Gum Acacia (GA) and Lactic acid (LA) by using Potassium Persulphate (KPS) as an initiator and its characterization was done by FESEM and FTIR analysis. Then, the grafted copolymer (GA-g-LA) was processed with CO2 foam based fracturing fluid as an additive. Lecithin is used to emulsify brine and liquid CO2. The effect of graft copolymer was on rheology and stability of the formulated foam based fracturing fluid is evaluated as a function of surfactant concentration. The results are compared with the conventional foam based fracturing fluids. The results showed that grafted copolymer has increased the stability of the formulated fracturing fluid at high temperatures. Use of grafted copolymer results in higher viscosity and proppant carrying capacity which is beneficial for HPHT fracturing conditions. The results of the core flood studies was evaluated on a shale sample to determine its return permeabilty and it was comparable to non-foam based fracturing fluid.
Clean-Up Efficiency of Multiple Fractured Horizontal Wells Enhanced by Reactive Chemicals in Tight Gas Homogeneous & Naturally Fractured Reservoirs
Authors: Vijayvargia Utkarsh , Jamiolahmady Mahmoud , R Nakhli Ayman , Yi Ng Khai 
Published: March 2019

Abstract
Hydraulic fracturing stimulation is considered a successful development technique in tight gas reservoirs. However, these expensive operations sometime underperform due to ineffective fracture fluid (FF) clean-up. This paper concentrates on FF clean-up efficiency for a Multiple Fractured Horizontal Well (MFHW) completed in both homogeneous and naturally fractured (NF) tight gas reservoirs. The emphasis is on NF reservoirs that make up a large percentage of tight gas assets, as their clean-up efficiency has received little attention.
In this study, two numerical simulation models, i.e. a single-porosity single-permeability and a dual porosity-dual permeability model representing a homogeneous and a NF tight gas reservoir respectively, were used. Simulations were conducted on a MFHW with seven hydraulic fractures (HF). The process comprised of injection of FF, then a soaking time (ST) followed by production. The impact of various parameters which includes ST, FF viscosity, pressure drawdown and parameters pertinent to relative permeability and capillary pressure in matrix, hydraulic and natural fractures, were evaluated.
In addition, based on a newly proposed treatment process that generates in-situ pressure and thermal energy that breaks gel viscosity, the effect of resultant viscosity reduction and local pressure increase, for improving the clean-up efficiency was also assessed. In these simulations, and due to uncertainty in its value, NF permeability was varied over a wide range. For conclusive purposes, Gas Production Loss i.e. GPL (%) defined as the difference in total gas production between the completely clean and un-clean cases as a percentage of the clean case, after a specific production period was used. This paper prioritizes the impact of pertinent parameters and highlights the influence of thermochemicals on the clean-up efficiency thereby justifying its commercial practicality. For instance, it is shown that the presence of NFs results initially in higher GPL but then GPL reduces significantly. Reducing the FF viscosity improves clean-up significantly especially for the NF models as NFs are the main contributor to the gas and FF flow from the reservoir to surface via hydraulic fractures. The sometimes non- monotonic trend of GPL variations, depends on the specific combination of NFs’ permeability and FF viscosity which results in the certain fluid invasion profile and mobility in the system.
The paper emphasis is on the impact of thermochemicals and natural fractures on the cleanup up efficiency of hydraulic fracturing stimulations that should be optimized to reduce cost, thereby increasing the profit from these projects.
Modelling Hydraulic Fractures in a Full-Field Dynamic Model Using DPDP Simulation Techniques - An Unconventional Approach Applied in a Tight Carbonate Oil Reservoir, Kuwait, Middle-East
Authors: K. Tiwari Brajesh , Al-Sayegh Saleh , Al-Muraikhi Haifa , Kumar Pranay , Cueille Pierre-Victor , Lislaud Frederic 
Published: March 2019

Abstract
This paper highlights an unconventional approach of using DPDP (Dual Porosity Dual permeability) simulation technique for modelling hydraulic fractures in a full field simulation model during the forecast analysis performed on a tight carbonate reservoir in Kuwait. This was a part of integrated study in which ‘multi-stage hydraulic fracturing’ was recommended as the most optimum stimulation technique in order to enhance the productivity of all the proposed horizontal producers. Importance of DPDP model increases multi-fold when contrast between fracture and matrix permeability is in the order of 10 times or more. In the studied case, as average matrix permeability of the reservoir is in the range of 2-3 mD, this contrast is magnified to the order of 1000-10000 times (considering fracture permeability is in Darcies) which further complements the use of DPDP model.
Three different approaches were tried to model the impact of multi-stage hydraulic fracturing in the full field simulation model; 1) ‘Enhance Well PI’ for all the stimulated wells, 2) ‘Enhance Matrix Permeability’ in the vicinity of all the stimulated wells, hereby referred as SPSP (Single Porosity Single Permeability) approach, and 3) build ‘DPDP Model’ by using upscaled fracture porosity and fracture permeability without changing the matrix properties. First two approaches are very common in the industry but most of the times are not able to capture the real impact of hydraulic fracturing on flow behaviour (bi-linear flow), whereas DPDP model is designed to capture the flow through dual medium. In both SPSP and DPDP approaches permeability anisotropy (increased permeability in the direction perpendicular to horizontal section of the well) in the fractured zone was very well captured and was needed to honour the hydraulic fractures direction. Fracture permeability was calculated using the Poiseuille's law; few sensitivity cases were run to address the associated uncertainty.
Field cumulative oil production and recovery factor were analysed for ‘Enhanced Well PI’ case, SPSP cases and DPDP cases. Field oil cumulative production in DPDP cases is 6% more than SPSP cases and around 10% more than ‘Enhanced Well PI’ case. The hypothesis for the higher recovery in DPDP case with respect to other two cases is that bi-linear flow (fractures are getting filled with the matrix fluid and then feeding to well) is better represented in the DPDP model. Impact in this case is more significant due to the big contrast between matrix and fracture permeability.
Low capacity with high conductivity signature of hydraulic fracture is difficult to model in the SPSP or just by enhancing the well PI. Study clearly demonstrated the benefits of DPDP model for modelling hydraulic fractures over the conventional methods.
Myasthenic crisis treated in a neurological intensive care unit: clinical features, mortality, outcomes, and predictors of survival
Authors: Liu Fan , Wang Qiong , Chen Xueping 
Published: March 2019

Abstract
Background

Myasthenic crisis (MC) often requires admission to an intensive care unit (ICU).

Methods

We retrospectively investigated 115 consecutive patients with first MC admitted to the neurological ICU. Patients’ demographic, clinical and other characteristics were examined, as well as therapeutic interventions; mortality and functional outcome.

Results

MC patients admitted to neurological ICU had a mortality rate of 24.34%. PCO2 level before intubation and score on Myasthenia Gravis–Activities of Daily Living (MG-ADL) scale at MC onset correlated with duration of ventilation and length of ICU stay. Compared with patients with good functional outcome, patients with intermediate or poor functional outcome were older at first MC onset, had lower pH and PO2, and had higher PCO2 before intubation. Multivariate logistic analysis identified pre-intubation PCO2 level as an independent predictor of survival. Cox regression showed that age at first MC onset requiring ICU management was the factor which significantly influenced the mortality. Conclusions: Our results suggest that PCO2 before intubation and MG-ADL score at MC onset may be useful indicators of more severe disease likely to require extensive respiratory support and ICU management. Higher pre-intubation PCO2 indicates chronic respiratory acidosis that can increase risk of severe disability and death, especially in patients with older age at first MC onset.
Effects of intravenous infusion of lidocaine and dexmedetomidine on inhibiting cough during the tracheal extubation period after thyroid surgery
Authors: Hu Shenghong , Li Yuanhai , Wang Shengbin , Xu Siqi , Ju Xia , Ma Li 
Published: March 2019

Abstract
Background：Intravenous lidocaine and dexmedetomidine treatments have been proposed as methods for inhibiting cough. We compared the efficacy of intravenous lidocaine and dexmedetomidine treatments on inhibiting cough during the tracheal extubation period after thyroid surgery. Methods：One hundred eighty patients undergoing thyroid surgeries were randomly allocated to the LIDO group (received lidocaine 1.5 mg/kg loading, 1.5 mg/kg/h infusion), the DEX group (received dexmedetomidine 0.5 µg/kg loading, 0.4 µg/kg/h infusion) and the CON group (received saline), with 60 cases in each group. The primary outcomes of cough were recorded. Secondary outcomes included hemodynamic variables, awareness time, volume of drainage, the postoperative visual analogue scale and adverse effects were recorded. Results: The incidence of cough were significantly lower in the LIDO group (28.3%) and the DEX group (31.7%) than that in the CON group (66.7%) (P=0.000). Additionally, both moderate and severe cough were significantly lower in the LIDO group (13.3%) and the DEX group (13.4%) than these in the CON group (43.4%) (P<0.05). Compared with the two treatment groups, both mean arterial blood pressure and heart rate were significantly increased in the CON group during tracheal extubation (P<0.05). Compared with the CON group, the volume of drainage was significantly reduced in the two treatment groups within 48 hours after surgery (P<0.05). compared with the CON group, the postoperative visual analogue scale was significantly lower in groups LIDO and DEX after surgery(P<0.05). Compared with the LIDO group and the CON group, the time to awareness was longer in the DEX group (P<0.05). In the DEX group, bradycardia was noted in 35 patients, while no bradycardia was noted in LIDO group and CON group. Conclusion: Compared with intravenous infusions of normal saline, both lidocaine and dexmedetomidine had equal effectiveness in attenuating cough and hemodynamic changes during the tracheal extubation period after thyroid surgery, and both of these treatments were able to reduce the volume of postoperative bleeding and provide better analgesic effect after surgery. But intravenous infusions of dexmedetomidine resulted in bradycardia and delayed time to awareness when compared with lidocaine and normal saline.
Public discourse and government action in a controversial water management project: the damming of the Aposelemis River in Crete, Greece
Authors: Chifos Carla , Doxastakis Zaharias , Romanos Michael C. 
Published: March 2019

Abstract
The politics and practices of decision-making in a large dam project on the Greek island of Crete is investigated through the case study of the Aposelemis Dam, a European Union (EU)-funded development project to supply drinking water to three urban centers and major tourist destinations. Our study employs a modified version of the World Commission on Dams (WCD) evaluation framework. We compare the processes used in Greece with the best practices suggested by the WCD framework. Our study reveals three areas of weakness in this project. First, the political decision to build the dam took place in the absence of reliable hydrological studies and in the face of strong opposition from the residents, local governments, and professional organizations. Second, during the stages of planning, design, implementation, and operation of the project, the Greek government failed to follow transparent procedures in its deliberations. Affected residents and local governments in all the stages of the project were disregarded and mitigation of negative effects was negligible. And, third, the comprehensive sustainable regional development goals of the EU funding were never materialized.
Recent Development in Indole Derivatives as Anticancer Agents for Breast Cancer
Authors: Kaur Kamalpreet , Jaitak Vikas 
Published: March 2019

Background:Breast Cancer (BC) is the second most common cause of cancer related deaths in women. Due to severe side effects and multidrug resistance, current therapies like hormonal therapy, surgery, radiotherapy and chemotherapy become ineffective. Also, the existing drugs for BC treatment are associated with several drawbacks such as poor oral bioavailability, non-selectivity and poor pharmacodynamics properties. Therefore, there is an urgent need for the development of more effective and safer anti BC agents.Objective:This article explored in detail the possibilities of indole-based heterocyclic compounds as anticancer agents with breast cancer as their major target.Methods:Recent literature related to indole derivatives endowed with encouraging anti BC potential is reviewed. With special focus on BC, this review offers a detailed account of multiple mechanisms of action of various indole derivatives: aromatase inhibitor, tubulin inhibitor, microtubule inhibitor, targeting estrogen receptor, DNA-binding mechanism, induction of apoptosis, inhibition of PI3K/AkT/NFkB/mTOR, and HDAC inhibitors, by which these derivatives have shown promising anticancer potential.Results:Exhaustive literature survey indicated that indole derivatives are associated with properties of inducing apoptosis and disturbing tubulin assembly. Indoles are also associated with the inhibition of NFkB/mTOR/PI3K/AkT and regulation of estrogen-mediated activity. Furthermore, indole derivatives have been found to modulate critical targets such as topoisomerase and HDAC. These derivatives have shown significant activity against breast cancer cells.Conclusion:In BC, indole derivatives seem to be quite competent and act through various mechanisms that are well established in case of BC. This review has shown that indole derivatives can further be explored for the betterment of BC chemotherapy. A lot of potential is still hidden which demands to be discovered for upgrading BC chemotherapy.
Inflammatory Bowel Disease Therapies Adversely Affect Fertility in Men- A Systematic Review and Meta-analysis
Authors: Banerjee Antara , Scarpa Marco , Pathak Surajit , Burra Patrizia , Sturniolo Giacomo C. , Russo Francesco P. , Murugesan Ram , D'Incá Renata 
Published: March 2019

Background and Aims:
Sexual functions are sometimes adversely affected by the therapeutic
drugs delivered for treating IBD. Much attention has been focused on pregnancy/sexual issues in
women. Relatively less attention has been poured in to address this issue in men. This systematic review
assesses the drugs having potential detrimental effects on fertility in men.

Methods:
Three databases were searched by two researchers independently for potentially relevant
publications between 1964 to 2015 and 249 papers were retrieved. Studies that dealt with sexual problems
after IBD drugs administration were included in the purview of this review.

Results:
Fourteen studies with 327 human patients and 110 animals were analysed. Sulphasalazine
treated patients had lower spermatozoa count, lower sperm motility and higher risk of oligospermia
compared to mesalazine treated ones. Biologics seem to be safe to use while attempting to conceive
however, proper clinical studies reporting male fertility problems in IBD patients are lacking. Azathioprine
caused oligospermia but a meta-analytical approach was not possible due to heterogeneity in
studies. Some animal studies showed methotrexate affects abnormal testis structure and spermatogenesis.

Conclusion:
This study summarises the current literature and safety issues affecting fertility parameters
in men and animals treated with IBD therapeutic drugs, which can further assist clinicians in better
management of adult male IBD patients.