bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multidisciplinary Approach for Novel Application of Formation-Pressure-While-Drilling Service in High-Temperature (160 Deg.C) Low Permeability Carbonate
Authors: Bruni Corrado , Odumboni Idowu , Sellami Besma , Turner Marcus , Sanguinetti Marco , Kazmer Jorge 
Published: February 2012

Abstract
The Abiod formation is the principal target in the Miskar field, offshore Tunisia. Consisting of fractured geomechanically stressed carbonate with a measured matrix permeability as low as 0.1 mD. The formation dates from Campanian to lower Maastrichtian and forms a horst structure. The formation has been under production since 1996.
Obtaining formation pressure data was considered critical for determining the magnitude of depletion from production, well-to-well comparisons for vertical and lateral connectivity, forward modeling, completion decisions, and refinement of the field development plan. Historically, this has been a challenge with conventional wireline (WL) formation testers for the following reasons:
Severe depletion and well deviation causing differential sticking High temperatures (150 to 195° C) at the limit of tool electronics Low permeability Fractures and breakouts that can impact seal success
This was overcome with a systematic multidisciplinary approach. After review of historical formation testing data, and influence on seal success with probe vs packer elements, it was decided to apply formation-pressure-while-drilling (FPWD) technology. The key questions with FPWD in this environment are: Can we achieve a good transient profile and what is potential impact of supercharging? These questions were addressed with advanced prejob modeling, which enabled determination of an optimized pretest configuration and testing procedure to minimize potential supercharging effects.
While drilling, stage-in procedures were used, and mud logging total gas data were gathered to identify areas of liberated gas. Pre-run wireline petrophysical data were gathered to characterize the Petrophysic of the reservoir and to calculate an intrinsic permeability profile. Ultrasonic borehole images and caliper data were used to determine the principal horizontal stress directions, fracture frequency, and orientation and to confirm the stratigraphyc dipping of the structure. Combined, this information allowed a focused orientation of the FPWD probe and optimal station selection avoiding fractures and breakouts.
This novel approach resulted in 100% seal success, &gt;50% improvement. Four days of rig time were saved, and the required data were obtained.
Investigating the Effect of the Placement of Permanent Downhole Pressure Gauges in Intelligent Well Systems on Well Productivity: A Field Example
Authors: Anifowoshe Olatunbosun , Osisanya Samuel O. 
Published: February 2012

AbstractIn developing most deepwater fields with limited number of wells, intelligent well systems which consist of many valves and sensors are employed to maximize production capacity under facility constraints. Analysis of sensor data unaffected by wellbore effects allows operators to estimate key reservoir parameters, well capacity and calculate actual flow rates at zonal level. Decisions for operational control is made based on data analysis, the result of which is used to optimize overall field performance and maximize return on investment.Understanding pressure sensors placement issue is important from pressure-transient analyses viewpoint. Pressure gauges should ideally be placed as close to the perforations as possible to ensure the pressure data is unaffected by friction in the tubing between the perforations and pressure gauges but placement of the gauge is dictated by completion hardware configuration and can be located far away from the point of reservoir fluid entry. This may result to potentially erroneous measured pressure data and may lead to the calculation of inaccurate reservoir parameters and an overestimated mechanical skin value from pressure buildup response.One of the main operating constraints in deepwater wells is flux limit which is a practical well surveillance tool used to monitor and operate sand control completions, maintaining each producing interval at a maximum safe operating rate, and also monitoring well impairment to allow for proactive remedial operations. Since the flux limit is a function of mechanical skin, if the mechanical skin is over estimated because frictional losses are not properly accounted for, well production may be unnecessarily constrained.In this paper, analysis was done using a wellbore/reservoir simulator to account for frictional effects in the tubing between the perforations, and the gauge for a field example. Sensitivity analysis was also carried out at different flow rates for each well and simple correlations were developed for predicting frictional effects. Results obtained from calculations showed that pressure gauges placement effect is significant as flow rate and gauge distance from perforations increases. Correcting for this effect increased the flux limit thus increasing production rate on several wells that were previously flux constrained.
Pressure Drawdown Decline Curve Analysis
Authors: Oghena A.. 
Published: February 2012

Abstract
With the advent of downhole permanent gauge reliable gathering of flowing bottomhole pressure is on the rise. This essential bottomhole reservoir data is subtracted from the reservoir average pressure to calculate pressure drawdown. The resulting drawdown is commonly used to estimate well productivity index. In this paper we demonstrate how drawdown can be used to generate a decline curve which is extrapolated to estimate future recovery potential.
We show in detail how this method is used to estimate future production performance by linearization of drawdown-time curve and drawdown-cumulative curve and thereafter extrapolate the resulting straight-lines into the future.
Liner Cemented with Lightweight Slurry Allows Gas Production from Depleted Zone, A Case History
Authors: Shaaban Sherif , Salazar Luis , Hughes Baker , Livingstone Bob 
Published: February 2012

Abstract
The use of lightweight materials (ceramic or glass beads) is not new in our industry. But mainly, they have been used to control shallow water/gas flows. There are very few documented cases where lightweight slurries have been pumped across gas producing zones (normally deeper than the previous ones).
British Gas' offshore Scarb Field was producing from the 8.5" open-hole gravel pack completion, below the 9-5/8" casing, until this pay zone was depleted. The plan was then to plug and abandon this zone, side track from the 9-5/8" casing and run a 7" Production Liner to 1,900 mMD approximately. In this depleted field, each well was expected to produce around 60 MMscf of gas. Scarb Field is mainly a gas field, producing considerable amount of gas from the 1,600 – 1,900 meters interval. The pore pressure is between 2,000 – 3,000 psi at the zone of interest.
The dynamic gradient at the shoe depth was limited to 0.65 psi/ft, and the maximum allowed differential pressure over the zones to be cemented was restricted to 500 psi (fracture gradient around 0.7 psi/ft). To overcome this challenging scenario, 12.5 ppg cement slurry (based on ceramic beads) was proposed. As any slurry to be placed across a production zone, this had zero Free Fluid, low Fluid Loss and high Compressive Strength.
The other obvious concern was the quality of the cement bond. Due to the small volume involved, the slurry was batch mixed and all the basic good cementing practices followed.
This paper summarizes how the first two jobs were executed and the results obtained from the CBL/VDL logs.
Selection of Demulsifiers for Produced Crude Oil Emulsions
Authors: Graham David E. , Stockwell Alan 
Published: February 2012

Abstract
A conventional method of treating produced crude oil emulsions is by demulsifier injection; these demulsifiers are usually selected for specific crude oils using the well-known bottle test. It is the purpose of this paper to discuss a physicochemical aspect of the bottle test procedure highlighting a pitfall that has been accepted, and indeed used, for many years by both oil industries and service companies. The main problem is centred around the mode of demulsifier injection. Many demulsifiers are insoluble in crude oil and consequently have poor efficacies when injected in a neat form. In contrast, the performance of demulsifiers previously diluted in organic solvents can be either inhibited or enhanced. The reasons for this are highlighted. The interfacial pressure adsorption isotherms obtained for a given demulsifier in different solvents adsorbing to a crude oil-water interface, coupled to the demulsifier aggregation behaviour in these solvents, show the effect of solvency power on demulsifier interfacial activity. The consequences of this behaviour are demonstrated in the laboratory bottle test and also on the model dehydrating rig for a demulsifier which only poorly resolved an emulsion of water-in-a North Sea crude oil when added neat. We describe how the bottle test can be carried out to effectively and reproducibly screen demulsifiers.
Computer Assisted Gas Production Operations Offshore the Netherlands
Authors: Van der Male Jack , Geurtsen Maarten J. W. , Van Rosse Jaap , Weegink Eef J. 
Published: February 2012

Abstract
The Nederlandse Aardolie Maatschappij B.V. (NAM) is the operator of some 50 large and small gas and oil fields in the Netherlands, both offshore and on land (the latter of which includes the well-known Groningen gas field).
By the end of 1979 NAM's offshore production operations comprised five production platforms producing from four gas fields, into one pipeline to Den Helder onshore. It is expected that by 1986 these will have expanded to 15 platforms in 11 gas fields.
It is the intention to have the offshore production operations ‘unattended’, i.e. no regular staff will be on board for supervision and control of routine production operations. Staff will only be located offshore as and when required for specific tasks like well testing, adjustments, maintenance, repairs, etc. In order to enable such ‘unattended’ and ‘remote control’ production operations in a safe and responsible mode, a computer assisted (CAO – Computer Assisted Operations) tele-information/operations system has been selected. This system has been operational since late 1978 – early 1979 when the gas fields came on stream.
The CAO system comprises onsite metering, transmission to shore and subsequently data capture and data processing in computer facilities onshore (CAO-computer). As a tele-information/operation tool it provides the operator with full status information on offshore operations and enables him to control process variables Selected production data are sent automatically each 24 hours in a batch mode to another computer system in the Netherlands, for reporting and planning purposes.
The paper will highlight the various functions and tasks of the CAO-system and summarise the experience gained so far especially from a user standpoint.
An Appreciation of Middle Brent Sand Reservoir Features by Analogy with Yorkshire Coast Outcrops
Authors: Archer John S. , Hancock Nigel J. 
Published: February 2012

Abstract
This paper shows that many deltaic features of the Middle Brent Sand can be recognised in outcrop sediments along the Yorkshire coast, By visiting convenient outcrops and seeing the extent and often lack of continuity of these reservoir facies we reinforce some of the guidelines for sand body correlation and show their significance in reservoir study calculations.
One of the responsibilities of a reservoir engineer is to understand and predict reservoir performance. Reservoir definition in the Middle Jurassic reservoirs of the North Sea is complicated by complex sedimentary structures and by faulting. The middle part of the Middle Jurassic (Middle Brent Sand) in many North Sea reservoirs was formed by rivers flowing over a delta plain and is characterised by a great variety of facies changes. Understanding and mapping these sand and shale sequences and their relationship with depositional environment is guided significantly by combined sedimentological and reservoir engineering study. A proper understanding by reservoir engineers of the nature and significance of sedimentological descriptions is necessary for the creation of effective reservoir simulation models.
A System for Project Planning and Control
Authors: Clawson Robert M. , Cloughley Terence M. G. 
Published: February 2012

ABSTRACT
A system has been developed for planning and control of a complex North Sea project. The system comprises a network of activities with supporting cost, time and resource data. Together, the network and activity data form the project plan, which subsequently becomes the tool for controlling the project execution. By linking the plan to an economics package, the planned execution is optimized. Other applications of the system became apparent during the course of development and, as a result of using the system, project costs have been reduced and confidence in attainment of schedules has increased. A system of this kind is considered essential for successful execution of future major projects.
Computerized Material Control and its Application to Project Management
Authors: Godliman Bryan , Connew Frederick 
Published: February 2012

ABSTRACT
This paper reviews the development and application of two critical areas of management control data, time and cost, generated by on-going equipment and material progress information.
Quality of information with respect to access, presentation and response times is considered together with the interpretation and use made of data available.
The employment of a common computer based data source with ‘terminal’ interrogation at all important project locations is also discussed with particular respect to the visibility required for effective operational management and the form of data exposure to encourage and promote active participation in control at all levels.
Mental Disorders in Obese Patients with and without Metabolic Syndrome
Authors: Carpiniello B. , Pinna F. , Pili R. , Velluzzi F. , Loviselli A. 
Published: February 2012

Objective: The authors sought to evaluate lifetime prevalence of mental disorders in patients affected by metabolic syndrome compared with patients affected by central obesity alone. Methods: One hundred eighty-six (63.5%) patients affected by central obesity and 107 (36.5%) affected by metabolic syndrome according to ICF criteria were interviewed by means of SCID I and SCID II. Results: Axis I and axis II lifetime prevalence were respectively 53.8% and 30.1% among patients with central obesity, 50.5% and 28% among patients with metabolic syndrome, differences which were not significant. No statistically significant differences were found between groups as far as each single axis I and II diagnostic category was considered. Conclusion: Metabolic syndrome is not associated with a higher risk of mental disorders compared to central obesity alone.
An Initial Study of Modifiable and Non-Modifiable Factors for Late-Life Psychosis
Authors: Onwuameze Obiora E. , Schultz Susan K. , Paradiso Sergio 
Published: February 2012

Objective: To determine rates of psychotic symptoms and associated modifiable and non-modifiable factors among elderly long term nursing home residents without prior history of psychiatric illness. Method: A cross-sectional design using the Scale for the Assessment of Positive Symptoms (SAPS) to measure psychotic symptoms, the Folstein's Mini-Mental State Exam (MMSE), and Mattis Dementia Rating Scale (DRS) to evaluate cognitive impairment. Frequency and rates of global psychotic symptoms and hallucinations, delusions, formal thought disorder, and bizarre behavior were calculated. Logistic regression was used to examine modifiable (e.g., medication use) and non-modifiable clinical characteristics (e.g., older age) associated with late-life psychosis. Results: There were 15.9% of subjects reporting delusions and 7.3% reporting hallucinations. History of stroke, poorer cognition, and receiving multiple medications showed significant association with late-life psychosis. Only stroke (OR=9.12; 95% CI: 1.58–52.74) and receiving different classes of medications (benzodiazepines, neuroleptics, and antidepressants) (OR=13.17; 95% CI: 2.10–85.82) remained significantly associated with psychosis after adjusting for Mattis DRS total score. Further analyses excluding subjects with MMSE scores of 24 or lower ( n = 24) showed essentially the same results but subjects with better cognitive function suffered a less severe form of psychosis, essentially constituted by one symptom type (i.e., visual hallucinations). Conclusions: Rates of late-life psychosis in this sample of nursing home residents without previous psychiatric history were high. Simultaneous use of medications including antidepressants, sedatives, and stimulants may be a clinically relevant modifiable factor to be targeted in prevention studies. Severity and type of psychosis is dependent on the severity of cognitive impairment.
The Duke Activity Status Index in Patients with Chronic Kidney Disease
Authors: Ravani Pietro , Kilb Brett , Bedi Harman , Groeneveld Sharon , Yilmaz Serdar , Mustata Stefan 
Published: February 2012

Summary

Background and objectives
Exercise capacity is impaired at a younger age in CKD patients than in the general population. This study examined the reliability of the Duke Activity Status Index (DASI) questionnaire as a measure of exercise capacity in medically stable adults with stage 3–4 CKD (estimated GFR [eGFR], 15–59 ml/min per 1.73 m2).

Design, setting, participants, & measurements
Peak oxygen uptake ([Combining Dot Above]O2peak), estimated from DASI responses and cardiopulmonary exercise test measurements, was obtained at baseline and 6 months in a derivation sample (n=23) and once in a validation sample (n=20). Bland–Altman analysis and linear mixed models were used to estimate bias, concordance correlation coefficients, and intraclass correlation coefficients as the proportion of the variance due to participant (intertest reliability) and method (test–retest reliability).

Results
The two samples were homogeneous with respect to age (mean 60±14 years), eGFR (35.5±15 ml/min per 1.73 m2), male sex (53%), and diabetes (56%). Mean measured [Combining Dot Above]O2peak was 16.5±4 ml/kg per min. The DASI questionnaire overestimated [Combining Dot Above]O2peak by 4.3 ml/kg per min. Intertest reliability was 53% when eGFR was ≥35 ml/min per 1.73 m2 (median) and 60% when eGFR was <35 ml/min per 1.73 m2 (P<0.01). Test–retest reliability was 81% when eGFR was <35 ml/min per 1.73 m2 and 71% when eGFR was ≥35 ml/min per 1.73 m2 (P<0.01).

Conclusions
The DASI questionnaire may be a reliable measure of exercise capacity in CKD patients, especially when eGFR is <35 ml/min per 1.73 m2. Larger prospective studies are needed to determine its prognostic value.
Is Assisted Peritoneal Dialysis Associated with Technique Survival When Competing Events Are Considered?
Authors: Lobbedez Thierry , Verger Christian , Ryckelynck Jean-Philippe , Fabre Emmanuel , Evans David 
Published: February 2012

Summary

Background and objectives
This study assessed whether assisted peritoneal dialysis (PD) was associated with a lower risk for technique failure using methods developed for survival analysis in the presence of competing risks.

Design, setting, participants, & measurements
This retrospective cohort study, based on data from the French Language Peritoneal Dialysis Registry, analyzed 9822 incident patients starting PD between January 2002 and December 2010. The observation period ended on June 1, 2011. Time to transfer to hemodialysis was compared between patients with assisted PD and those undergoing self-care PD.

Results
There were 5286 patients undergoing assisted PD; 4230 of these were assisted by a community nurse and 1056 by family. Assisted PD patients were older and had a higher Charlson comorbidity index than self-care PD patients. There were 7594 events: 3495 deaths, 2464 transfers to hemodialysis, 1489 renal transplantations, and 146 renal function recoveries. According to a Cox model, assistance and center size were associated with a lower risk for technique failure, whereas hemodialysis before PD, early peritonitis, and transplantation failure were associated with a higher risk for transfer to hemodialysis. A Fine and Gray regression model showed that assisted PD was associated with a lower risk for transfer to hemodialysis.

Conclusions
Compared with patients undergoing self-care PD, those with assisted PD had a lower risk for transfer to hemodialysis, a higher risk for death, and a lower risk for transplantation.
Monte Carlo simulations for optimization of neutron shielding concrete
Authors: Piotrowski Tomasz , Tefelski Dariusz , Polański Aleksander , Skubalski Janusz 
Published: February 2012

Abstract
Concrete is one of the main materials used for gamma and neutron shielding. While in case of gamma rays an increase in density is usually efficient enough, protection against neutrons is more complex. The aim of this paper is to show the possibility of using the Monte Carlo codes for evaluation and optimization of concrete mix to reach better neutron shielding. Two codes (MCNPX and SPOT — written by authors) were used to simulate neutron transport through a wall made of different concretes. It is showed that concrete of higher compressive strength attenuates neutrons more effectively. The advantage of heavyweight concrete (with barite aggregate), usually used for gamma shielding, over the ordinary concrete was not so clear. Neutron shielding depends on many factors e.g. neutron energy, barrier thickness and atomic composition. All this makes a proper design of concrete as a very important issue for nuclear power plant safety assurance.
Gangue mineral textures and fluid inclusion characteristics of the Santa Margarita Vein in the Guanajuato Mining District, Mexico
Authors: Moncada Daniel , Bodnar Robert 
Published: February 2012

Abstract
Successful exploration for mineral deposits requires tools that the explorationist can use to distinguish between targets with high potential for mineralization and those with lower economic potential. In this study, we describe a technique based on gangue mineral textures and fluid inclusion characteristics that has been applied to identify an area of high potential for gold-silver mineralization in the epithermal Ag-Au deposits at Guanajuato, Mexico. The Guanajuato mining district in Mexico is one of the largest silver producing districts in the world with continuous mining activity for nearly 500 years. Previous work conducted on the Veta Madre vein system that is located in the central part of this district identified favorable areas for further exploration in the deepest levels that have been developed and explored. The resulting exploration program discovered one of the richest gold-silver veins ever found in the district. This newly discovered vein that runs parallel to the Veta Madre was named the Santa Margarita vein. Selected mineralized samples from this vein contain up to 249 g/t of Au and up to 2,280 g/t Ag. Fluid inclusions in these samples show homogenization temperatures that range from 184 to 300°C and salinities ranging from 0 to 5 wt.% NaCl. Barren samples show the same range in homogenization temperature, but salinities range only up to 3 wt.% NaCl. Evidence of boiling was observed in most of the samples based on fluid inclusions and/or quartz and calcite textures. Liquid-rich inclusions with trapped illite are closely associated with high silver grades. The presence of assemblages of vapor-rich-only fluid inclusions, indicative of intense boiling or “flashing”, shows the best correlation with high gold grades.