bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hospital care for primary hyperparathyroidism in Italy: a 6-year register-based study
Authors: Cipriani Cristiana , Carnevale Vincenzo , Biamonte Federica , Piemonte Sara , Pepe Jessica , Nieddu Luciano , Bilezikian John P , Minisola Salvatore 
Published: July 2014

ObjectivePrimary hyperparathyroidism (PHPT) is one of the most frequently diagnosed endocrine disorders, but few studies have focused on hospital management of the disease in Europe. We investigated the frequency of hospital admission for diagnosis and surgical treatment of PHPT in Italy.DesignA retrospective study was conducted for investigating the hospital care for PHPT in Italy.MethodsWe retrieved data from the ‘Record of Hospital Discharge’ of the Italian Health Ministry, from 2006 to 2011, and analyzed the codes corresponding to PHPT-related diagnoses and surgical procedures.ResultsOverall, 46 275 hospitalization episodes for PHPT were identified during the entire period (69% in women and 31% in men; mean age 63.3±39.8 years). Patients' mean age significantly increased during the years (P<0.001). The mean length of stay was 8.2±10.5 days (28% of the episodes requiring <3 days of stay). Admissions for surgical procedures were 12 457 accounting for 26.9% of the total hospitalizations. There was a trend to a significant increase in the percentage of surgery (P<0.05). The mean hospitalization rate for PHPT was 12.9/100 000 inhabitants per year and the trend showed a significant decrease during the period of 2006–2011 (P<0.0001). The mean hospitalization rate for PHPT surgery was 3.65/100 000 per year, which significantly increased over time (P<0.001).ConclusionsPHPT considerably influences the Italian Hospital healthcare system. We observed a tendency to a decrease in the frequency of hospitalization during the period of 2006–2011, most probably because of economic issues, a concomitant increased age of patients, and, interestingly, also a progressive increase in the percentage of surgical treatment among patients admitted for PHPT.
Acid Stimulation in Agbami Deepwater- The Innovative Success Story
Authors: Nwaochei Francis , Hackney Dave , Olufemi Bayo , Carrillo Ivan , Obembe Akin 
Published: July 2014

Abstract
Agbami Wells; Agbami A, Agbami B and Agbami C experienced significant production decline. A multi-disciplinary team from the Agbami Asset initiated a study to identify the cause of damage to the wells and the best mitigation strategy. The study confirmed fines migration as the primary cause of sandface impairment and recommended an acid formulation to cure the damage. Risk analysis was undertaken to ascertain the problems associated with flowing the acid back to the production facilities.
An innovative deployment method involving a marine support vessel with dynamic positioning and Remote Operating Vehicle (ROV) was adopted. Utilizing the marine support vessel, a customized dual conduit of coil tubing was employed to bullhead acid into the formation. The acid was allowed to soak in the formation for a few hours and well opened to flow back naturally to surface.
Other critical aspects of the job planning and implementation included ensuring pump rates were achieved, designing appropriate acid volumes and soak duration, proper planning of Site Integration Test (SIT) and coil tubing deployment strategy.
Stimulating Agbami A, Agbami B and Agbami C led to a total incremental gain of 17,500 BOPD with a reduction in skin of over 70%. Productivity Index (PI) increased by over 50% on all the wells.
Lessons Learned include:
Dual coil string provides redundancy in the event of failure of one of the strings Identifying the cause of damage is critical in recommending acid stimulation for remedial work Adequate front end loading and proper stakeholder engagement was critical to ensure success
This technical paper describes the steps involved in implementing a successful rigless acid stimulation operation on deep water wells offshore Nigeria and will be a key resource document for future acid stimulation wellwork.
The Use of Glutamic Diacetic Acid GLDA and Boiling Liquid Expanding Vapour Explosion BLEVE in Tight Gas Recovery
Authors: Obode Elizabeth I. 
Published: July 2014

Abstract
As global demand for energy rises and more nations turn towards environmental friendly energy sources, attention is shifted to cleaner and economically viable energy sources. Natural gas, with 43% and 30% lesser carbon emission than coal and oil respectively, is among these sources. However, most of the natural gas reserves –including tight gas which this paper focuses on- are present in impermeable rock formations, and the extraction processes used sometimes raises concerns over the impact on the environment and fresh water reserves. These often times increases regulatory scrutiny and delay in exploitation. This paper explores the enhancement of reservoir permeability through first acidizing with Glutamic Diacetic Acid (GLDA), an organic substance with low corrosion potential and increased effectiveness with increasing temperature, and then using a Boiling Liquid Expanding Vapour Explosion (BLEVE) –specifically liquefied nitrogen in ceramic globes. This combination will not only achieve maximum permeability, but will also ensure that propants-ceramic splinters- are strategically placed within the wormholes formed and consequently improve gas recovery. This method supersedes conventional ones by being more environmentally friendly; nitrogen is already a component of air and is easily gotten and dispelled into the atmosphere; and in its capacity as a BLEV, significantly reduces the use of fresh water for fracturing. GLDA as a chelating agent forms unreactive complexes with regards to the environment and eliminates the need for iron control agents. The fast spending and high corrosion potential associated with mud acid is removed – well tubulars last longer, and this method is consequently more cost effective.
Shale Oil and Gas Revolution: Implications on Energy Market Outlook and Politics
Authors: Oyekunle A. A. 
Published: July 2014

Abstract
In 2000, shale gas was 1% of domestic gas production in the United States. In 2013, it had risen to 32% and it is expected to account for half of total US domestic gas supply in two decades from now. The US who is the second largest energy consumer in the world after China has seen a decline in her net import of energy since 2007.
In Europe, a recent report in the UK suggests that Shale gas in Northern England could meet Britain's gas need for 40 years.
Though lagging behind shale gas, shale oil development has already begun in some countries.
With the abundance of shale oil and gas around the world and the increasing interest in their development, this paper intends to look at the fast changing trend in the energy mix and hypothesize the effects on energy prices, energy demands and energy politics in different regions and across the world.
Managing HSE in the Turn Around Maintenance of a Deepwater Asset in the Gulf of Guinea
Authors: Awonusi Samuel , Oamen Christopher 
Published: July 2014

Abstract
Oil and Gas exploration and production activities are increasing by the day in the deepwater zone of the Gulf of Guinea (GoG). The assets are situated over 100 kilometers away from the continental shore.
To maintain asset integrity and comply with statutory regulations of government, the assets are taken through periodic Turn Around Maintenance (TAM). During the TAM of such remotely located facilities, resources such as vessels for the transportation of procured equipment and floating hotel for accommodating additional human resources in excess of the facility's class approved personnel on board are mobilized offshore. The workforce for the execution of the identified and approved scope is also mobilized to the field. Several concurrent activities such as water transportation, lifting and hoisting of heavy spools, fabricated equipment, demolition and installation of spools, diving and vessel/tank cleaning are executed simultaneously thereby increasing HSE risks exposures.
Local content drive of national governments in the GoG has increased the participation of local contractors in the delivery of TAM of oil and gas facilities. This comes with its attendant challenges in the area of competence of local contractors and high attrition rate of competent work force.
Though the facility is brought to a static state i.e. complete shutdown, the workforce would have to intrusively work on pipings, vessels and other components of the facility thereby increasing the risk levels.
Through the combination of various strategies, the challenges were safely managed in the execution of TAM of a Floating, Production, Storage and Offloading facility in the deep water zone of Nigeria. The operator's aspiration of achieving goal zero which implies no harm to people, environment, FPSO and the operator's reputation was fully achieved.
Enhancing the Production Performance of Dual Completed Gaslifted Wells Using the Nova Venturi Orifice Valves
Authors: Nkilika Grace Nwadike , Ifeanyichukwu Jude Ofia , Uwem Udom Essien , Benjamin Uduak Obong , Trost Amos , Enoto Udo Oton , Adoghe Sheri 
Published: July 2014

Abstract
Efficient gas lift optimization and sustained steady state production performance in dual-completion gas lifted wells has remained an industry challenge as a result of the inherent legacy well configuration in which two strings of a dual completion well share a common gas injection annulus. Common well symptoms include, but are not limited to, surging, instability as a result of fluctuations in casing and tubing pressure, gas deprivation to one arm of the dual completion, low productivity, and, in extreme cases, inability to concurrently produce both arms of the dual completion.
A deep investigation into the identified problems of instability, gas sharing, and gas deprivation revealed that optimal gas allocation to the respective arms of the dual completion was influenced by the surface injection pressures, fluctuations in tubing pressure, and inability to attain critical flow using the traditional square-edge orifice valve installed in most of the wells under review.
The existing conventional square-edge orifice valve typically would require approximately 56% pressure1 differential between upstream and downstream to attain critical flow; this contrasts with the NOVA venturi orifice valve, which requires barely 10% pressure differential. This pressure differential is rarely achieved in the traditional square-edge orifice valve. Consequently, slugging, suboptimal gas injection, unstable production, and sometimes total loss of production are evident.
Whilst industry research is on-going to identify optimal management of this class of wells, the NOVA venturi orifice valves deployed in some carefully screened candidate wells using established criteria have addressed, to a large extent, some of the challenges inherent with the current well configuration.
The NOVA venturi valve uses a venturi-type mechanism and overcomes the limitation of the square-edge orifice valve to achieve critical flow and stabilize the gas injection rate through the orifice by minimizing the pressure drop across the valve to as low as 10%.
A pilot trial of the NOVA venturi orifice valves in the restoration and stabilization of five candidate wells in two brownfields located in the Niger Delta resulted in recommendations for optimal use of the NOVA venturi orifice valves.
Optimal Gas Production Design in Gas Condensate Reservoir
Authors: Izuwa Nkemakolam Chinedu , Obah Boniface , Appah Dulu 
Published: July 2014

Abstract
Optimal production of gas from gas condensate reservoirs have been a major concern to the petroleum industry. Enormous liquid dropout lost to the reservoir during depletion process has been found to restrict the flow of gas near the wellbore, thereby reducing wellbore productivity. The search for the optimal production strategy to produce gas and even the condensed liquid has resulted to the use of enhanced production technique such as gas cycling, water flooding or wettability alteration. Gas cycling is used in gas condensate reservoirs to improve permeability to gas by evaporating the condensed liquid. Where the cycling is commenced early It may defer the dew point pressure. The challenge is the choice of the best production strategy to effectively recover gas trapped by the condensed liquid hydrocarbon and the condensed liquid hence enhancing the productivity of gas condensate reservoirs. In this study, technical and economic approaches are combined to evaluate the potentials of different production strategies using various injection rate and pressures. In the study dynamic uncertainty parameters that influence recovery of gas, condensate and production profile determination are considered. Model that can predict the recovery of gas was developed by the integration of experimental design, fluid characterization and reservoir compositional simulation. The research investigated a range of production strategies in gas cycling project using the predictive model to assess the effects of the reservoir and production parameters on recovery of gas and condensate. The best strategy was established from the optimal injection rate and the effective injective pressure. The work concluded that cycling is best started above dew point pressure. It also established the minimum injection pressure below which gas cycling is uneconomical.
Distinct Value Realisation from Pulsed Neutron Spectroscopy (PNS) and Subsurface Integration in a Mature Niger Delta field
Authors: Nduka Ezechukwu , Chinedu Anijekwu , Linus Nwoke , Nkonyeasua Oghene , Ezeike Emeka , Olayinka David 
Published: July 2014

Abstract
Understanding fluid dynamics is key in optimal well and reservoir management practices in brown fields. This is more apparent in strong water drive reservoirs where water shut-off (WSO), zone change, recompletion and work-over drilling are key well intervention activities usually carried out to optimize the production from these fields. Geologically, the structural architecture of these reservoirs makes it difficult to have uniform fluid movement with time as they are produced. In addition, the interpretation of Carbon/Oxygen (C/O) ratios as derived from Pulse Neutron Spectroscopy (PNS) logs in terms of hydrocarbon saturation is such that, a lot of variables can influence the outcome of the result. Water leg calibration, type of completion, and open hole log interpretation are some of the factors that can affect C/O interpretations negatively. PNS logs when combined with extensive subsurface data integration can become very useful in understanding fluid dynamics and optimization of intervention activities. This has been demonstrated recently in the X Field of SPDC.
The two case studies in this paper demonstrate how PNS data and subsurface integration has helped resolve both non-uniform flushing as well as interpretation problems usually associated with PNS logs. Significant cost savings of ca. USD0.5 mln and ca. 2000 bopb have been realized from optimizing the planned well intervention activities on these cases. The result and observation from the study is already being applied to de-risk other similar opportunities in the portfolio while still exploring further understanding to further improve the gains.
Confidence Check from Seal Capacity Analysis for Resource Volumes Estimation
Authors: Poon Becky B. , Itua Osazua J. , Wodu Ebimobowei K. , Horst Peter A. 
Published: July 2014

Abstract
For a green field, estimating fluid contacts can be challenging when there is large uncertainty due to the lack of fluid contact penetration by the appraisal wells, insufficient pressure data in oil or water legs, or ambiguous seismic amplitude shut off. For reserves booking, SEC Rule 4-10(a)(22) states that "In the absence of data on fluid contacts, proved quantities in a reservoir are limited by the lowest known hydrocarbons (LKH) as seen in a well penetration unless Geosciences, Engineering, or performance data and reliable technology establishes a lower contact with reasonable certainty." One way to ensure reasonable certainty conditions are met for contacts beyond LKH and to increase confidence for probable and possible fluid contacts that may be estimated using regional pressure trends is to analyze the seal capacity to check whether the seal would hold the hydrocarbon column associated with the proposed contacts.
There are two methods for testing seal capacity within the framework of a capillary pressure model. One method uses the capillary entry pressure for a sealing layer (Pseal) to compute the maximum hydrocarbon column (Hmax_seal) that a sealing layer (e.g. shale, silt, salt, anhydrite, etc.) can sustain without leaking. However, Pseal data are usually not available since such lab measurements are not typically made with the sealing layers. The other method uses the shale fracture pressure (Pfrac) estimated from a model that incorporates leak of pressure measurements across sealing layer to compute the Hmax_frac that the shale layer above the reservoir can sustain without fracturing.
This presentation is aimed at sharing the approach using fracture pressure to analyze seal capacity, establishing reasonable certainty associated with proposed fluid contacts. Application of this method will be shown using examples from a Deepwater Nigeria field.
Analysis of Injectivity Decline in Some Offshore Water Injectors
Authors: Dambani S. L. , Blunt M. J. , Tendo F. , Lawal K. A. 
Published: July 2014

Abstract
The challenges and risks relating to injectivity decline due to injection of particulate-laden water are well documented in the petroleum industry and elsewhere. Although different theories have been advanced to rationalize this problem, the modeling aspects remain largely unresolved, putting huge investments at risk. By combining the fractional-flow and deep-bed filtration (DBF) theories, this work formulates a new model for describing reservoir impairments due to suspension transport by injection water.
The critical settling velocity of the suspended particulates is determined from fractional-flow theory and used to create a condition at which particle settling will occur, dependent on its size. The particle settling velocity as obtained from Stokes law for laminar flow (NRe ≪1) is compared to the critical settling velocity, which is a function of the residence time of the particles, to obtain the optimum transported particle size profile in the formation. Furthermore, the average size of transportable particulates and their total volumes are then obtained and used to determine the volume of deposits which is in turn used to develop a new injectivity decline model for predicting permeability impairment due to the deposition of suspended particles in the porous media.
The resulting models are validated by analyzing reported dataset from two water injectors offshore Niger Delta. Overall, the results are reasonable as the impairment model rationalized available field dataset satisfactorily. The developed models should find relevance in the following field applications: (1) quantifying formation damage; (2) optimising water treatment facilities design; (3) implementing an effective and safe backflow operation.
Exception Based Monitoring of Oil and Gas pipelines using VTOL type-Unmanned Aerial Vehicles (UAV)
Authors: Idachaba Francis Enejo 
Published: July 2014

Abstract
The vast and diverse spread of the oil and gas pipeline infrastructure makes real-time monitoring of the entire network a very costly and impossible task. This topology has provided vandals and crude oil thieves with the opportunity of tapping the pipelines and successfully stealing crude oil from these lines unhindered. Nigeria lost over $11 billion to crude oil theft and pipeline vandalisation over a 4 year period (2007 to 2011). The increase in vandalisation has led to the divestment of assets by some of these oil companies as it is no longer economical to continue operating the assets. Strategies employed by the government and Oil companies to tackle these challenges include the deployment of military personnel to these assets and also along their pipeline right of way. In spite of this attempts, the results show that the deployment of these personnel and the attendant cost have not reduced the quantity and frequency of oil theft as the deployment time to some of these locations also contribute to delay in the response of the security personnel. The deployment of dynamic pipeline pressure profiles of enables the determination of the onset of a leak or a loss of crude oil. This paper presents the deployment plan and communication architecture of the Vertical Take Off and Landing (VTOL) type of Unmanned Air Vehicles for pipeline monitoring. The pipeline network of the company is divided into wide area cells and each cell is controlled from a facility. Low power UAVs with directional antennas and long range zoom cameras are deployed to provide real-time visual monitoring of the pipeline section whenever a pressure drop or any significant third party activity is detected on section of the pipeline. Security personnel can then be deployed to the pipeline section if vandal activity is detected. This solution has the capability of reducing crude oil theft by providing accurate location data in a timely manner to the company with respect to the bunkering activity along its pipeline ROW and also enabling the timely deployment of personnel to contain the situation.
New Records of Lecanora for Bolivia. II
Authors: Śliwa Lucyna , Wilk Karina , Flakus Adam , Rodriguez Flakus Pamela 
Published: July 2014

AbstractMembers of the lichen genus Lecanora Ach. are important but still poorly known components of almost all vegetation types in Bolivia. In this paper, seven species new for Bolivia are presented: Lecanora bicincta Ramond, L. fulvastra Kremp., L. hagenii (Ach.) Ach., L. muralis (Schreb.) Rabenh., L. percrenata H. Magn., L. stramineoalbida Vain. and L. strobilina (Spreng.) Kieff. Their distributions are described and information on their diagnostic characters and chemistry is given
Ecological specialization in Trebouxia (Trebouxiophyceae) photobionts of Ramalina menziesii (Ramalinaceae) across six range‐covering ecoregions of western North America
Authors: Werth Silke , Sork Victoria L. 
Published: July 2014

• Premise of the study: Many lichens exhibit extensive ranges spanning several ecoregions. It has been hypothesized that this wide ecological amplitude is facilitated by fungal association with locally adapted photobiont strains.• Methods: We studied the identity and geographic distribution of photobionts of the widely distributed North American lichen Ramalina menziesii based on rbcL (chloroplast DNA) and nuclear ribosomal ITS DNA sequences. To test for ecological specialization, we associate photobiont genotypes with local climate and phorophyte.• Key results: Of the photobiont lineages of R. menziesii, 94% belong to a clade including Trebouxia decolorans. The remaining are related to T. jamesii. The photobionts showed (1) significant structure according to ecoregion and phorophyte species and (2) genetic associations with phorophyte species and climate.• Conclusions: Geography, climate, and ecological specialization shape genetic differentiation of lichen photobionts. One great advantage of independent dispersal of the fungus is symbiotic association with locally adapted photobiont strains.