bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improved Geological Model Calibration Through Sparsity-Promoting Ensemble Kalman Filter
Authors: Tarrahi Mohammadali , Afra Sardar 
Published: April 2016

AbstractCalibrating complex subsurface geological models against dynamic well observations yields to a challenging inverse problem which is known as history matching in oil and gas literature. The highly nonlinear nature of interactions and relationships between reservoir model parameters and well responses demand automated, robust and geologically consistent inversion techniques. In the recent years, there has been significant progress in automated history matching methods mostly categorized as gradient-based and ensemble-based techniques. Ensemble-based methods such as ensemble Kalman filter (EnKF) have proved to be successful in adjusting reservoir parameters to match observed dynamic data. To calibrate the reservoir model and update the distributed parameters in geologically robust way it is crucial to utilize a parameterization method. Parameterization techniques also aim to make the inversion process more efficient by reducing the dimension of the model parameter.Recently in the fields of image processing and data mining, sparse parameterization and image reconstruction are gained considerable attention. We propose a novel automated history matching method by employing EnKF along with a sparsity-promoting parameterization technique. To improve the performance of EnKF in capturing complex geological features such as channelized reservoirs, we employ sparse constraints to construct the reservoir model from the observed dynamic well data. For the parameterization purpose we investigate utilizing various basis functions or models such as singular value decomposition (SVD) and discrete cosine transform (DCT). The combination of EnKF analysis equation with sparse reconstruction algorithm such as Matching Pursuit (MP) will enhance the inversion results. We also investigated effects of different geologically trained dictionaries or basis such as K-SVD and also the impact of combining various basis sets.We applied the proposed sparsity-promoting EnKF to several numerical examples to estimate reservoir distributed properties from well production data. The enhanced EnKF method with sparse constrained parameterization showed promising improvement comparing to standard EnKF and also EnKF with standard parameterization. The proposed inversion technique propagates and updates an ensemble of geological models through integration steps and provides more consistent distributed parameter fields with the prior geology of the subsurface formation.The sparsity-promoting EnKF is a derivative free history matching method which is also able to perform uncertainty assessment because of its ensemble based nature. Parameterizations along with sparse selection of basis functions make the calibrated solutions of this method more geologically consistent. This method is especially suitable for resolving more complex geological structures such as channelized formations which are generated with multi-point geostatistics techniques.
Accurate New Solutions for Fluid Sample Contamination Quantification, With Special Focus on Water Sampling in Water-Base Mud
Authors: Gisolf A. , Zuo J. , Achourov V. , Kollien T. , Foyn S. , Wang K. , Jiang L. 
Published: April 2016

Abstract
The role of formation testers has evolved significantly over the past decades. Early versions of this tool focused solely on obtaining pressure measurements and fluid samples. With advances in technology, the ability to measure fluid properties downhole at reservoir pressure and temperature has grown continuously. Today, formation tester downhole fluid analysis (DFA) and pressure measurements are routinely used to characterize fluids and address reservoir connectivity concerns in real time. However, quantitative use of fluid property measurements requires the user to measure—and correct for, as required—fluid contaminants caused by invaded mud filtrates. New measurements are combined with new algorithms to yield a harmonized contamination quantification solution that is applicable to all fluids and mud types.
The quantification of drilling fluid content is at its most challenging when the formation fluids and drilling mud filtrate are fully miscible. Water-base mud (WBM) filtrate contamination measurement in formation water samples is particularly challenging because formation water and WBM filtrate exhibit very similar near-infrared optical spectroscopy signatures and are therefore difficult to differentiate. Native and invaded fluid typically do have measurably different live fluid density or resistivity. However, resistivity measurements should only be used if a temperature correction is applied.
The general workflow for real-time hydrocarbon contamination quantification in oil-base mud (OBM) has been applied to water sampling in WBM, using live fluid density and resistivity measurements. First, a temperature correction is applied to the resistivity measurement and the data are converted to conductivity. Next, density- and temperature-corrected conductivity data are crossplotted and a novel linear relation is generated. The independently determined filtrate and formation water properties (endpoints) should fall on the extrapolated linear relation because this relation is intrinsic to the fluid mixture. Lastly, the fluid mixture measurements and endpoints are entered into mixing rules to calculate contamination. With this new method for quantifying water sample contamination, there is now a complete solution that is applicable to all fluid combinations. Several case studies of water sampling in WBM show the effectiveness of the new mud filtrate contamination quantification method.
Holistic Systems Analysis: A Case Study Demonstrating Simple Models Improving the Reliability of the BOP Control Equipment Ecosystem
Authors: Barker Daniel C. 
Published: April 2016

Abstract
Owing to their complexity and lack of system level data, subsea BOP control system design has historically focused on the component level design and analysis. When system level design and analysis is considered, it is often performed at assumed steady state conditions and without a detailed knowledge of end-user operating conditions. The interaction of multi-domain dynamically coupled systems can result in unintended system level behavior, including field performance issues and system failure. The timely resolution of these field performance issues is of critical concern as rig non-productive time (NPT) can cost operators of floating rigs in excess of USD 15 thousand per hour [1]. The current approach to resolving field performance issues typically involves replacement of the failed component or over-engineering to improve robustness at the expense of cost, weight, and efficiency. However, as the industry pushes for cost reduction and increased reliability, solutions must meet more than fit, form, and function; a holistic approach to solving field performance issues must be developed to ensure original equipment manufacturers (OEMs) and operators collaborate together to treat not only the "symptoms" of equipment failure, but also address the underlying system "disease". In this work, a case study is presented of a low-order mathematical model of a hydraulic control circuit and its utility as a heuristic for rapidly testing and optimizing solutions to address field performance failures resulting from pressure transients in a real world hydraulic control circuit.
A low-order model of hydraulic control circuit was created using a multi-domain lumped parameter approach and replicated the pressure transients detailed in field performance reports, which caused repeated catastrophic failures, e.g. burst inlet/outlet piping, cracked fittings, etc., of the pressure reducing valve. The model was then subjected to a sensitivity analysis to determine dominating input variables, and through repeated iterations of potential solutions, converged to a high-confidence solution.
The high-confidence solution and technical justification from the model were presented to operators for feedback and implementation, and the field verification results are detailed in this paper. The deep system level understanding provided by the model aided in consensus building between OEM and operator. Additionally, the results of the model yielded insight to system level communication failures at the organizational level between operator and OEM.
Currently, there is a dearth of techniques for analyzing and troubleshooting field performance issues. The case study described here demonstrates the value of new technological tools for understanding system failures and developing solutions to minimize rig NPT.
Lula NE Pilot Project - An Ultra-Deep Success in the Brazilian Pre-Salt
Authors: de Moraes Cruz Rafael Oscar , Rosa Marcelo Becher , Branco Celso Cesar Moreira , de Sant'Anna Pizarro Jorge Oscar , de Souza Silva Celso Tarcisio 
Published: April 2016

This paper presents the successful history of Lula NE Pilot Project, a challenging megaproject with an aggressive time-driven schedule, faster than industry average, that demanded new technology development in a scenario of uncertainty. The area is part of the supergiant Lula field, located in the pre-salt region of Santos Basin, Southeast Brazil, 300 km off the coast of Rio de Janeiro state, in 2000 m water depth. It is a joint venture with Petrobras as the Operator, and BG E&P Brasil and Petrogal Brasil as partners.The project was designed as a Pilot aiming to test some new concepts for the production development in the pre-salt area. In terms of subsea gathering system, an innovative concept was deployed, combining flexible flowlines lying on sea floor, with rigid steel catenary risers (SCR) supported by a buoy positioned 250 m below sea level. The drainage plan considered eight oil producers, some of them with intelligent completion, one gas / CO2 injection well and five water alternating gas (WAG) injectors (two subsea WAG manifolds were also installed). A balanced approach between data acquisition and facilities flexibility made possible to face the many reservoir and production uncertainties. Details of the development concept will be discussed, as well as the main results obtained so far, highlighting the strategies adopted in order to mitigate risks and the influence of the acquired information to the following projects in the area.The chartered FPSO Cidade de Paraty started production in June 2013, with an oil capacity of 120,0 bpd, and a gas plant able to process up to 5 million m3/d of gas with 35% content of CO2. Despite all challenges faced, the project was delivered on time, with plateau attained in September 2014.
An Innovative Approach to Well Intervention and Workover Operations on Platforms With Limited Structural Capacity
Authors: Canny Steven A 
Published: April 2016

Abstract
The challenge faced when identifying and planning the requirement for intervention and workover operations on small platforms or single caissons is significant. Typically drilled via a jack up rig, there are limited opportunities to install hardware to the platform directly. With an increasing well stock reaching maturity, there is a requirement to perform operations at a reduced cost on wells with increasing deviation and complexity. This scenario would typically be addressed by a jack up rig being installed over the well site, or with a HWU (Hydraulic Workover Unit) being installed if there are capping beams/availability to install them. Each has its merits; however, they also have cost and safety implications respectively. To address the market of platforms with limited structural capacity, a new WHWOU (Wellhead Mounted Workover Unit) has been developed to facilitate intervention, workover and abandonment operations in a safe and efficient manner on platforms with structural limitations.
This paper describes the market challenges facing mature basins and assesses the opportunities arising to perform intervention and workover operations on the ageing well stock to stimulate well production. It also presents key design parameters driving the new technology, principally: Safety, Efficiency and Cost reductions. Each is achieved through lessons learned allied with a novel approach to the use of new technology. Operational flexibility facilitates wireline, coiled tubing, pumping and fishing operations for example to aid wellbore stimulation activities. It also facilitates heavy workover such as re-completion, re-perforation, and whipstock setting in preparation for multilateral well development. Plugging and Abandonment operations are achievable with section milling, primary isolation plug setting, and tubular recovery through the design.
The operational capability is supplemented by a flexible philosophy - deployment through appropriate well control equipment to the surface wellhead. Further, the ability to be installed on light beams or by cantilever beams from a lift barge or boat gives the end client numerous scenarios for a campaign and platform stock. The WHWOU will allow operators to successfully conduct operations on a wide range of platforms from single wells to downgraded structures with multiple well slots and active process facilities.
Dual RFID Activated Reamers Reduce Vibration in Deepwater Well
Authors: Goodwin Alex , Salminen Chuck , Valverde Eddie 
Published: April 2016

Abstract
Simultaneous drilling and enlargement is common in deepwater Gulf of Mexico projects. It controls equivalent circulating density, manages pore pressure anomalies, and ensures that casing strings and liners reach total depth (TD). Common hole-enlargement-while-drilling (HEWD) bottomhole assemblies (BHAs) place a concentric hydraulic underreamer above the rotary steerable system (RSS) and measurement-while-drilling/logging-while-drilling (MWD/LWD) package. Although this placement is effective, it could leave up to 200 ft (61 m) of under gauge rathole at TD, which often leads to a dedicated trip to eliminate the rathole. This underreamer placement with the bit off bottom also has limited underreaming capabilities because of vibration caused by drill string instability. These vibrations typically make underreaming an existing pilot hole more difficult than simultaneous drilling and reaming.
On a job for a sidetracked well in the Gulf of Mexico, a drilling team had challenges in a 12 1/4- × 14 1/2-in. section. The team encountered significant vibration and torque when underreaming 423 ft (129 m) of an existing 12 1/4-in. pilot hole in a salt section. After this operation proved unsuccessful, due to low rate of penetration (ROP) caused by severe torque spikes and high shocks and vibrations, the team opted for an alternative solution to achieve the section objectives.
The team designed a unique BHA that included two intelligent underreamers. The first placed above the MWD assembly, and the second placed below the MWD assembly. Historically, placing underreamers below the MWD package and near the bit creates problems because the inside diameter (ID) of the MWD/LWD tools restricts balls that activate the underreamer, and flow-operated underreamers can prematurely activate or fail to activate.
In the new dual-reamer design, radio-frequency identification (RFID) technology provided the capability of activating and opening each underreamer and underreaming with both simultaneously. Wiring through the underreamer below the MWD package connected the rotary-steerable and MWD tools for communication.
The team ran the RFID underreamer below the MWD/LWD package and activated the cutter blocks at the correct depth. The team used both reamers concurrently to ream the 423-ft (129-m) section and then tripped into the hole using the upper reamer to continue drilling the below-salt formation. The operation continued as planned until 500 ft (152 m) before the planned well depth. At that point, downhole problems resulted in losing the BHA in the hole, cementing the openhole interval, and sidetracking the well.
The innovative dual-reamer design delivered a stable BHA to enlarge a wellbore section in one run, which could not have been done using a conventional ball-drop underreamer and BHA design. The drill string operated at 15,000 ft-lb (20,337 N·m) less torque spikes than with the previous design.
Marital Status and Survival in Patients with Carcinoid Tumors
Authors: Greenleaf Erin K. , Cooper Amanda B. , Hollenbeak Christopher S. 
Published: April 2016

Background Marital status is a known prognostic factor in overall and disease-specific survival in several types of cancer. The impact of marital status on survival in patients with carcinoid tumors remains unknown. We hypothesized that married patients have higher rates of survival than similar unmarried patients with carcinoid tumors. Methods Using the Surveillance, Epidemiology, and End Results database, we identified 23,126 people diagnosed with a carcinoid tumor between 2000 and 2011 and stratified them according to marital status. Univariate and multivariable analyses were performed to compare the characteristics and outcomes between patient cohorts. Overall and cancer-related survival were analyzed using the Kaplan–Meier method. Multivariable survival analyses were performed using Cox proportional hazards models (hazards ratio [HR]), controlling for demographics and tumor-related and treatment-related variables. Propensity score analysis was performed to determine surgical intervention distributions among married and unmarried (ie, single, separated, divorced, widowed) patients. Results Marital status was significantly related to both overall and cancer-related survival in patients with carcinoid tumors. Divorced and widowed patients had worse overall survival (HR, 1.33 [95% confidence interval {CI}, 1.08–1.33] and 1.34 [95% CI, 1.22–1.46], respectively) and cancer-related survival (HR, 1.15 [95% CI, 1.00–1.31] and 1.15 [95% CI, 1.03–1.29], respectively) than married patients over five years. Single and separated patients had worse overall survival (HR, 1.20 [95% CI, 1.08–1.33] and 1.62 [95% CI, 1.25–2.11], respectively) than married patients over five years, but not worse cancer-related survival. Unmarried patients were more likely than matched married patients to undergo definitive surgical intervention (62.67% vs 53.11%, respectively, P < 0.0001). Conclusions Even after controlling for other prognostic factors, married patients have a survival advantage after diagnosis of any carcinoid tumor, potentially reflecting better social support and financial means than patients without partners.
Secularisatie, een gelaagd begrip
Authors: Latré Stijn , Vanheeswijck Guido 
Published: April 2016

Abstract

Secularization, A Multi-Layered Concept. On the Vicissitudes of Sociological and Philosophical Theories of Secularization

This article focuses on the historical evolution of the concept of ‘secularization’ in sociology and philosophy. It does not include a description of political systems and their approach to religion and secularity. The authors dwell on the classic secularization thesis and explain how this thesis was questioned in sociology and philosophy alike. The secularization debate nowadays counts many participants reflecting diverging normative positions. Despite this multitude of positions and nuances, the debate is likely to continue in the future along two particular strands: first, discussions on the use of concepts as secular/post-secular and the tenability of the religious/secular divide; second, discussions that will revolve around western modernity/multiple modernities, or ‘the West versus the rest’.
Wat is de rol van mentale beeldvorming in de waarneming?
Authors: Veldeman Johan 
Published: April 2016

Abstract

What is the Role of Mental Imagery in Perception? A Defense of the Continuity Thesis

What is the nature of the mental image, and which role does mental imagery play in perception? According to David Hume and Immanuel Kant, the capacity to form images lends a constitutive contribution to our perception of the world. Both philosophers portray the imagination as a unifying power that connects perceptions of different objects of the same kind, and that connects different perceptions of the same object. I shall call this view the continuity thesis. Since the beginning of the 20th century the continuity thesis is heavily under attack. Jean-Paul Sartre and Ludwig Wittgenstein emphasize the conceptual and phenomenological distinction between perception and mental imagery. These philosophers are sceptical about the important psychological and epistemological role that is traditionally attributed to imagery. The central target of critique against the continuity thesis is primarily the Humean view that mental images, however complex, can be traced back to pictures or ‘copies’ of sense impressions. It will be argued that the sceptics about mental imagery, even though they justifiably attack pictorialism, have no grounds to dismiss the continuity thesis. Then I shall discuss the reassessment of the mental image with the rise of cognitive science since the 1970s, and I shall argue that the continuity thesis is supported by the so-called ‘enactive’ theory of mental imagery.
Ware liefde zonder uniciteit: goede redenen voor romantische liefde
Authors: Hindriks Frank 
Published: April 2016

Abstract

True Love Without Uniqueness: Good Reasons for Romantic Love

Love involves emotions, and emotions are things that happen to us. So how can love be true? Love can be true only if people can have reasons for loving someone. I explore the tension between these two thoughts and propose a way of resolving it. I argue that reasons for romantic love are not limited to the other person’s properties, not even when relational properties such as a common sense of humour are included. A full-blown romantic relation provides relation-dependent reasons that derive from the values that are realized within the relationship. These include trust, vulnerability and intimacy. True love is justified in part by such relation-dependent reasons. How this is consistent with the emotional dimension of love becomes clear once it is appreciated that people can have reasons for the emotions they experience. As this is not always recognized, the mystery of love is sometimes overrated. I end by discussing whether true love must be unique in the sense of being limited to one particular person. I argue that true love need not be combined with the norms of monogamy, but is consistent with those of polyamory.
Eros bij Plato
Authors: Hupperts Charles 
Published: April 2016

Abstract

Plato on eros

What is love for Plato, and why, after his analysis of eros in Symposium, did Plato take up the subject again, some ten years later, in Phaedrus? This article describes a transtition in Plato’s thinking about eros. In the Symposium, eros is a desire for immortality and a creative power, and it is is elicited by a beautiful person. In the homoerotic case, the lover’s soul is pregnant, and his eros produces the good in the form of poems, laws, philosophical ideas, and virtue. But the philosopher has to gradually outgrow his love for a beautiful body, and turn towards the realm of abstract ideas. In the Phaedrus, by contrast, the beauty of a boy can straightforwardly connect the philosopher to the divine, i.e., perfect and timeless reality. Here, the philosopher does not leave his love for the person behind. On the contrary, the friendship is forever, and it is the conversation between the friends that generates knowledge.