bluuebunny/crossref_metadata_2025_split huggingface dataset:
Placental site trophoblastic tumor: a case report and review of the literature
Authors: Lucas Rita , Cunha Teresa Margarida , Santos Filipa Batista 
Published: April 2015

We present a case of a gravida 1 para 1 woman, who presented with an 11-month history of amenorrhea after cesarean delivery. The patient was taking birth control pills at the time of presentation. She was observed with a slight elevation of serum ?-hCG level, an enlarged heterogeneous uterus and hematometra. A biopsy was performed, and the patient was diagnosed with placental site trophoblastic tumor; the patient then underwent surgery. Placental site trophoblastic tumor is the rarest form of gestational trophoblastic disease, derived from intermediate trophoblast cells. It does not have a pathognomonic appearance; therefore, correlation with medical history, as well as results of laboratory tests and pathological analysis is mandatory. It is a relatively chemoresistant tumor, posing considerable therapeutic challenges; patients with localized disease are managed with surgery and those with metastatic disease require additional chemotherapy. Herein, we review the main features of this entity and top differential diagnosis, as the rarity of this tumor is associated with imaging and pathological pitfalls, reinforcing the need for further experience in this field.
SS Delta House Project - Riser Interface and Pull-in Procedure
Authors: Authement Glen , DaSilva Otto , Bare Tom , Gi Lee Jung , Cooley Bruce 
Published: April 2015

Abstract
This paper explains the riser hang-off concept as implemented on the "Delta House" floating production system (FPS). A unique riser pull-in procedure is outlined in which the FPS' ballast system is used to align the riser's end fitting with its adapter rather than by an array of tugger winches commonly used. Finally, the paper describes an important capability of this riser hang-off concept, namely the installation of additional risers years after installation of the FPS.
Use of the FPS' ballast system for pull-in of the risers has the potential to create a "step change" in installation time and cost, as well as in safety of operation.
The riser porches and adapter are precision manufactured structures that ensure proper load distribution into the hull. The riser adapters with their conical, open section, heavy wall stress joint bushings are likewise simple structures but also deceptively complex to design and manufacture due to the steel catenary riser (SCR) stress joint/adapter requirement of precise angles of declination and azimuth for each individual riser. The resulting product is easy to install, robust, reliable and fatigue-resistant.
Unconventional Forecasting Method for Brown Field on Primary Depletion - An Example of a Naturally Fractured Reservoir
Authors: Maricic N. , Zuluaga E. , Somasundaran S. , Manzoor A. , Bungo E. , Saeedi A. 
Published: April 2015

A novel in-house technique has been developed for infill well production forecasting for brown fields on primary depletion as an alternative method to forecast production when reservoir simulation models are not available. The paper demonstrates the use of an unconventional approach to forecast infill well performance for a complex carbonate reservoir with fractures and vuggy porosity on primary depletion.
The flow equation was used to determine the initial rates of new development wells and to address expected pressure depletion while a new methodology was developed to take into account well interference. The interference equation takes into account five factors classified as main contributors to well production interference: distance to nearby producers, years on production of existing wells and respective initial rates, presence of faults and density of natural fractures. A correlation between these factors and lost oil volume was established based on historical production data and used to predict the interference of new development wells taking into account their locations. The statistical analysis factored all combinations of potential outcomes for new wells based on historical data and built probabilistic cumulative distribution curve to predict performance of new wells, generating a P10/P50/P90 range of production forecast. Also, a methodology was developed to account for gas and water production, which is also described in the paper.
Understanding Gas Hydrate Growth in Partially Dispersed and Water Continuous Systems from Flowloop Tests
Authors: Vijayamohan P. , Majid A. , Chaudhari P. , Sum A. K. , Koh C.A. , Dellacase E. , Volk M. 
Published: April 2015

Abstract
Gas hydrates are crystalline solids that can plug subsea oil and gas flowlines and are considered a major flow assurance problem. The risk of hydrate plug formation is significantly increased when free water is present in the flowline. Transportability of hydrates has a strong dependence on the total amount of liquids (the carrier phase) present, along with the mixture velocity of the fluids. It is also shown that partially dispersed systems (water dispersed in oil and free water) tend to fail at lower hydrate fraction, compared to completely dispersed systems (no free water) for the same set of conditions. This paper presents the results and analyses of flowloop experiments on partially dispersed systems as a function of water volume fraction, velocity, liquid loading, and oil properties.
A mechanistic model for hydrate plugging of flowlines in partially dispersed system is developed based on flowloop data obtained at the University of Tulsa. Once the hydrates form at the water-oil interface, they soak up large amounts of water thereby depleting the system of a carrier phase which makes transportability very difficult. The plugging mechanism for these systems is a combination of various phenomena (wall growth, agglomeration, bedding/settling, etc.). Experimental data indicates that liquid loading and water cut play a very important role when it comes to transportability of hydrates. The data from the tests performed provide the basis for a mechanistic model for hydrate formation and plugging in partially dispersed systems. A correlation is being developed/modified to predict the onset of plugging in terms of easily measurable variables like the oil viscosity, mixture velocity, etc. Preliminary analysis of the results of experiments using different viscosity oils show that viscosity of oil is an important parameter that determines transportability, and higher viscosity oils tend to facilitate better hydrate transportability.
The work resulting from our experiments should be incorporated into flow assurance models and will ultimately help to advance operating company production strategies to reduce hydrate plugging risks in complex multiphase systems.
A Model for Surface Diffusion of Adsorbed Gas in Nanopores of Shale Gas Reservoirs
Authors: Wu Keliu , Li Xiangfang , Wang Chenchen , Yu Wei , Chen Zhangxin 
Published: April 2015

Abstract
Surface diffusion plays a key role in gas mass transfer due to the majority of adsorbed gas with abundant nanopores of organic matter in shale gas reservoirs. Surface diffusion simulation is very complex as a result of high reservoir pressure, surface heterogeneity and non-isothermal desorption in shale gas reservoirs. In this paper, a new model of surface diffusion for adsorbed gas in shale gas reservoirs is established, which is based on a Hwang model derived under low pressure condition and considers the effect of adsorbed gas coverage under high pressure. Additionally, this new model considers the effects of surface heterogeneity, isosteric sorption heat and non-isothermal gas desorption. Results show that: (1) the surface diffusion coefficient increases with pressure and temperature, while it decreases with activation energy and gas molecular weight; (2) contributions of viscous flow, Knudsen diffusion and surface diffusion to the total gas mass transfer are varying during the development of shale gas reservoirs, which are mainly controlled by nanopore-scale and pressure; (3) in micropores (pore radius &lt; 2nm), the contribution of surface diffusion to the gas mass transfer is dominant, up to 92.95%; in macropores (pore radius &gt; 50nm), the contribution is less than 4.39%, which is negligible; in mesopores (2nm &lt; pore radius &lt; 50nm), the contribution is between micropores and macropores.
The Implementation of a Game Changing Imperium Inspection Technology into the Subsea Domain
Authors: Lasser B , Rich D. , Rhodes J , Gair G , Krugel C 
Published: April 2015

Abstract
Imperium and Subsea 7 have been developing the subsea implementation of the proven Imperium acoustic camera for material defect detection and corrosion mapping. The Imperium tool is well established with terrestrial industries and is the primary defect detection tool within the aerospace and petrochemical industries, beginning with advanced composite materials and more recently extending to pipeline and storage tank inspection. The applications of this technology will considerably enhance the ability of subsea asset owners to detect problems, baseline predictive modelling, optimize up time and extend asset life.
The system generates real time two-dimensional images of subsurface anomalies. Internal corrosion and cracks can be simply and quickly imaged without extensive training or setup. A simple calibration procedure allows internal defects to be visualized immediately and provide thickness data. The technique is based on optical practices, using a large area source of ultrasound, a beamsplitter, an acoustic lens set, and a two-dimensional imaging array. The output of the patented approach is high resolution, real time C-scan imagery. These images can be stitched together as the probe is moved over the target under study to map out larger areas if desired.
There are inherent problems in delivering this technology to the subsea environment. These have been addressed resulting in the first phase diver hand held device ultrasound imaging systems, which replace a number of existing tools required for a variety of NDT tasks. These can now all be undertaken with the one device.
This paper describes the technical functionality and output of the acoustic camera, with an outline of the development program. The application, results obtained and considerable benefits will then be detailed.
Optimizations and Tubular Practice from Integrated Packer Stress Analyses during High-Rate, Multiple Acid Jobs in Low-Permeability, HPHT Reservoirs, China
Authors: Fuxiang Zhang , Liangliang Ding , Xiangtong Yang , Rosland Habil Akram 
Published: April 2015

Abstract
This paper presents various case studies that were performed on an HPHT gas well located in the Tarim Basin, China, with a primary focus on well completion, string design, and technique in response to packer-seal failure resulting from the interconnection of production casing pressure when conducting staged acid jobs with a straddle-packer string. After tripping out, it was discovered that the upper packer mandrel was broken. This paper discusses the factors that led to the broken mandrel and packer-seal failure and provides a unique solution to these challenges during staged acid jobs.
Based on a detailed investigation conducted at the scene and further post-mortem studies using an advanced wellbore temperature simulator that integrates with tubing and packer-stress analyses, it is believed that acid jobs using a heavy-duty pump under high pump pressures have resulted in a rapid temperature drop inside the wellbore, causing possible liquid contraction within the enclosed space between the straddle packers and, subsequently, decreasing the pressure. High differential pressure between the upper and lower packer, as well as inside and outside of the enclosed space, can lead to a broken mandrel and packer-seal failure.
This paper discusses the failures that were analyzed using a comprehensive model that integrates with tubing and packer-stress analyses by implementing multiple iterations and conditions with variations in pressure that were established between the packers during acid jobs. In addition, the string mechanical-analysis method was used for the staged acid jobs. Based on case studies on the different methods for mitigating string challenges, a method was selected as the primary measure for improving string safety during staged acid jobs for high-pressure wells, which has been successfully applied in staged acid-job operations for two wells in this field.
Various models for tubing and packer mechanical analysis for staged acid jobs were established, providing a better understanding of pressure with change in temperature within the enclosed space between packers. The results were able to explain the causes of packer failure from the string mechanical point of view, which identifies the effect of various parameters on pressures within the enclosed space and the effect of pressure change to the packer and tubing stresses. The results were supported by a detailed investigation conducted at the wellsite.
The thesis of this paper introduces various methods for improving the safety of packers and strings, including increasing the temperature of injected fluid, tapping on the string between packers, and optimizing string design. Based on analysis and field study, tapping on the string between packers has been the best measure for improving string safety during staged acid jobs for high-pressure wells in this field.
Well Testing Technique for HPHT Sour Gas Wells in China
Authors: Wei Pang , Juan Du , Tongyi Zhang , Zhiguo Qiao , Gang Lu 
Published: April 2015

Abstract
Yuanba Gas Field is one of the most difficult fields categorized as Super-deep and high-pressure high-temperature (HPHT) reservoirs to develop not only in China but also in the world. It's buried in vertical depth (TVD) of nearlly 7000 m, and with pressure as high as 70 MPa while temperature from 149.5°C to 157.4°C, meanwhile, the average concentration of hydrogen sulfide (H2S) and carbon dioxide (CO2) are 5.14% and 7.5%. In order to successfully exploit this gas field, many problems must be solved in well testing tecniques.
In this paper, we review the most common failures of HPHT sour gas well testing tools and tubular and generalized three major failure types based on analysis of more than 80 wells*times, meanwhile, the potential reasons related to each kind of failures are analyzed. Improvements on tools and operation techniques are conducted. The mandrel of the testing packer is optimized on the basis of axial force simulation and tensile strength is increased from 383 to 618 kN. Three kinds of well testing string assembly are formed to accommodate different well types, different combination operations (i.e., combination of perforation and well testing, combination of perforation-acid stimulating-testing). Well killing and pluging techniques are improve to guarantee the succesful ratio of well testing operations.
The research reviewd field experience and proposes development techniques for well testing of HPHT sour gas field. It can also be taken as a reference for economic and safety development of other reservoirs in extremely harsh environment.
A Value of Information Demonstration for Geohazard and Georisk Assessments
Authors: Trainor-Guitton Whitney 
Published: April 2015

Abstract
Value of information (VOI) is a metric that can be used to determine if a particular data type should be purchased. The VOI analysis is based on how the information or data (used interchangeably here) could influence a decision taken, and consequently, improve the outcome. VOI has been used extensively for engineering applications related to product design and safety. VOI has also been used for geoscience applications related to groundwater remediation and oil exploration. The distinction of recent VOI work as applied to geoscience applications has been to include the spatial aspect of both pieces of the VOI framework: the decision and the data. Spatial uncertainty has not been previously included in many VOI calculations. This paper provides an example that demonstrates how VOI could be applied to deep-water geohazard investigations. Future work could be to extend the recent advances of spatial VOI to the deepwater application.
Measurement of Wellhead Fatigue
Authors: Howells Hugh , Baker Richard , Rimmer Alex 
Published: April 2015

Abstract
Fatigue loading on subsea wellheads has been increasing in recent years through the use of larger and heavier BOP stacks and the longer drilling durations needed for deeper wells and to extend production lives. This challenge has prompted the widespread implementation of monitoring systems to confirm predictions of wellhead fatigue and ensure well operations are conducted safely. Monitoring system design requirements, data processing and evaluation of field measurements from a number of wells are described.
Monitoring systems for measurement of wellhead fatigue require careful planning. Considerations include what to measure, instrument accuracy, power, data transmission, methods of attachment, data processing and data storage. The evaluation will determine the suitability of off-the-shelf equipment or the need for application specific devices. An example assessment of the requirements of measurement devices from which wellhead fatigue can be derived is given that demonstrates the importance of integrated consideration of instruments, resolution and data processing methods in the selection and design of the system. The assessment presented here has widespread application across subsea wellhead systems worldwide.
A variety of different approaches to monitoring wellhead system fatigue have been attempted. These include motion measurement, using devices located in varying positions along the wellhead and BOP, to strain measurement of the conductor pipe. Examples of real systems used in different geographical locations and the wellhead system fatigue damage derived from the data are presented. The improved understanding of wellhead behaviour and modelling improvements that can be made from the use of the data obtained are demonstrated. Finally, comparisons of response measurements from different devices demonstrate the importance of instrument positioning. This finding provides a driver for the design of future instrumentation systems and an important pointer for verification of wellhead fatigue damage derived from previous monitoring programs.
The work presented here provides a systematic basis for design and implementation of wellhead fatigue monitoring systems. Furthermore, the field measurements obtained demonstrate some potential pitfalls to be avoided and how to get maximum value from the data obtained.
The Risk of Cryogenic Liquid Release Could Have Been a Show Stopper for the FLNG Market: How Did the Industry Respond?
Authors: Wade R 
Published: April 2015

Abstract
Liquid natural gas (LNG) at atmospheric pressure, remains as a liquid at -162°C. As the temperature increases, gas is evolved which is flammable and under certain mixtures with air is explosive when in the presence of an ignition source.
As designers have looked more at the risks posed by accidental release of Cryogenic Liquids onboard FLNG assets, it has become more apparent that the steel structures used for these facilities could be prone to brittle fracture. This could potentially lead to structural failure. If fire ensues soon after this cryogenic release then further escalation may occur, particularly if the passive fire protection does not function as expected.
The need for effective, tried and tested solutions to mitigate the risks posed by cryogenic liquid gas exposure was identified nearly 20 years ago. In the last 10 years, as the FLNG industry has accelerated, development has intensified for cryogenic spill protection (CSP) systems. Indeed construction of a leading FLNG asset was nearly stopped due to the lack of an effective solution. In response, owners have initiated studies into the most effective CSP materials to ensure progression of these projects.
Since then, the industry has developed a better understanding of the risks posed by these LNG liquefaction assets and the consequences of not addressing these risks appropriately. Working closely with owners and design engineers to address these project specific risks and to develop robust solutions, has therefore become of paramount importance in developing this appropriate response.
This paper covers the initial requirements of protection against cryogenic spill. It considers the solutions developed to meet all the industry expectations (and where appropriate conformance to standards) and describes those finally adopted by the first FLNGs under construction.
More Improvements to Deepwater Subsea Measurement - Overview
Authors: Letton W. , Pappas J.M. , Shen J. 
Published: April 2015

Abstract
Since the beginning of the last decade efforts have been underway to develop new measurement technologies for ultra-deepwater oil and gas production. Though initial R&D activities were carried out by individual companies, after a few years interested parties began to pool their efforts.
The first such endeavor was a project sponsored by the DeepStar consortium, Improved Multiphase Metering for Subsea Tiebacks, performed in 2006 and 2007. Beginning at the end of 2008 a larger effort – Improvements to Deepwater Subsea Measurement – was initiated by the U.S. Department of Energy's National Energy Technology Laboratory under the Research Partnership to Secure Energy for America (RPSEA). RPSEA was a product of the U.S. Energy Policy Act of 2005, and was aimed at encouraging technology development in oilfield exploration and production, of which ultra-deepwater was a major element. Key to the project's success was the active support of a JIP sponsored by seven deepwater operating companies: BHP, BP, Chevron, ConocoPhillips, Shell, Statoil, and Total. After the first project was completed in 2011, RPSEA approved a Phase 2 effort to extend the results that had been achieved in the first project.
The new project – More Improvements to Deepwater Subsea Measurement – has addressed those gaps that were viewed as the most pressing for multiphase flow measurement by the new JIP (Chevron, ConocoPhillips, GE, Statoil, and Total): Deepwater Fluid SamplingDeepwater Meter Verification TechnologyEarly Kick DetectionDownhole Differential Pressure Sensor DevelopmentVirtual Flow Meter EvaluationDetection of Meter Fouling
These technology developments are significant due to the increasing global importance of subsea production. Improved recovery from deepwater reservoirs could yield millions of barrels of additional reserves, but to achieve this goal requires better, more reliable measurement at the sea floor. Equally important is insuring that royalty assessment and production allocation are precise and equitable.
However, a noteworthy application for these new measurement technologies is in the areas of drilling operations. Better, more extensive measurement can be pivotal in preventing the loss of well control. Certain aspects of this new measurement project aim at this goal, as will be explained in the companion papers and presentations to this one.
This paper and presentation will provide an overview of these areas of development, with details of the achievements in each of the target areas described in the six papers/presentations that follow.