bluuebunny/crossref_metadata_2025_split huggingface dataset:
Loop Current Operational Forecasting in 2015: Skill Assessment and Lessons Learned
Authors: Frolov Sergei , Sharma Neha 
Published: April 2016

Abstract
2015 was a year of unprecedented Loop Current (LC) activity. From February to June 2015, the LC and its associated eddies were monitored at a significantly higher rate in southern Walker Ridge in support of current-sensitive offshore operations. A privately operated ocean forecast system for the Northern Gulf of Mexico, a.k.a. the Eddy Forecast System (EFS), was actively employed as an integral part of the currents monitoring program. A total of 38 forecasts were performed with the EFS over this four-month period, more than half of these were dedicated to support of operations in the southern Walker Ridge. In this study, we evaluate the site specific EFS skill by comparing current speed forecasted at the site with observed currents. Despite very complex LC-eddy configurations that presented a major challenge for forecasting and most demanding model skill definition, the EFS demonstrated skill up to 6 days on average for the entire four months period. The average site dependent skill was determined to vary from about 5 days to over 9 days, depending on the location relative to the LC and major eddies. Simple ensembling techniques, i.e. combining multiple forecasts, were shown to improve the EFS skill by 2-3 days. Individual forecast failures over the same time period were also analyzed. An additional operational data collection guided by "crucial uncertainties" identified by the EFS is proposed as an effective method of reducing the number of failed forecasts and improving the overall model skill.
Subsea Compression – Long Term Technology Development
Authors: Ramberg Rune Mode , Hedne Pål Eirik 
Published: April 2016

The paper reviews the way leading up to the Subsea Factory Compressor Stations with focus on important technology step-stones and breakthroughs. A dedicated and long term focus on technology development through R&D has been carried out within a series of disciplines supporting the subsea production application. The development has been along two important axis; multiphase flow and subsea systems.
A comprehensive R&D effort was initiated in the beginning of the eighties resulting in a highly successful and profitable development and implementation on the Norwegian continental shelf, namely the subsea industry. Through a series of successful tie-backs and long distance multiphase flow lines, the ultimate concept was achieved for gas-condensate systems represented by the unprocessed transportation of well stream directly to shore. The first multiphase pumps were installed in the late -90 and in 2000 the first subsea separation station was started up. Today subsea boosting and separation is proven technology. In 2011, building the first subsea gas compression station was initiated, taken the last step to a full subsea factory installation.
To realise subsea compression, the main components have been subject to a systematic technology qualification process. The paper describes how Statoil's large scale laboratory facilities has been mandatory for full scale qualification testing as well as focus on quality to achieve the necessary level of confidence. The Subsea Compression projects solely, have carried out nearly 60 qualification activities, further detailed in the paper.
The paper also looks forward and point out that the subsea processing solutions that have been qualified and implemented can be utilized to achieve cost efficient solutions with low environmental footprint.
Fault Block Migration and Its Impact of Complex Fluid Distributions and Equilibration
Authors: Wang Kang , Kauerauf Armin , Dong Chengli , Elshahawi Hani , Zuo Julian Y. , Mullins Oliver C. 
Published: April 2016

Abstract
Reservoir fluid distributions at the field scale are affected by charging history, fluid dynamics as well as geological events during and after charging. With multiple charges of fluid of different maturities, reservoir fluids are typically not in equilibrium initially. Over geological time, fluids tend to equilibrate through connected sands by diffusive processes and in some cases by convective processes. It has long been established that connected reservoirs are often associated with equilibrated asphaltenes. These issues of reservoir structure and equilibration of different crude oil components are examined in greater detail in this study. Additionally, geological events after fluid charging could lead to complicated fluid property distributions. For example, fault block migration can yield complex fluid gradients; nevertheless, within individual fault blocks, good connectivity and trends to fluid equilibration can prevail. Furthermore, different components of crude oils, such as light end hydrocarbons, asphaltenes, biomarkers, can equilibrate at different rates, which makes fluid distributions more complicated. In this paper, equilibration of reservoir fluids after charging terminates and over geologic time is modeled and compared to actual reservoirs. This modeling is combined with potential geological events of faulting and fault block migrations, and scenarios for reservoir processes are better understood on the fluid distributions today. Here, the modeling incorporates diffusion explicitly; nevertheless, some convective flow is indicated associated with fault block migration with its changing formation geometry and connectivity pattern. These field observations are guiding a broader understanding of reservoir fluid geodynamics.
Seismic Assessment of Tension-Leg Platforms
Authors: Arablouei Amir , Cai Wenyu , Sari Ali 
Published: April 2016

Abstract
Tension-leg-platforms (TLPs) are becoming increasingly popular for offshore drilling at deep-water sites. Seismic response of TLPs is of significant importance in the design or assessment of these platforms since seismic excitations, especially the vertical component, can directly affect the total tensile force of tendons. This paper focuses on the impact of seismic ground motions on the TLPs, especially on tendons. The first part of this paper discusses the development of an advanced methodology for seismic assessment of TLP structure considering the following effects; pile-soil interaction, soil radiation damping, soil degradation due to cyclic loading, current effects, hydrodynamic damping, and marine growth. The second part of the paper presents a case study to demonstrate application of the developed methodology. Two types of analyses are carried out; response spectrum analysis for extreme level earthquake (ELE) and dynamic nonlinear analysis for abnormal level earthquake (ALE). The response spectrum analysis is carried out using SACS and the time history simulations are performed using nonlinear dynamic structural analysis program, CAPFOS. Multiple interactions among soil, fluid and platform is numerically quantified in this study, providing insights into the response of TLPs under complicated dynamic loading conditions.
CO2 Enhanced Oil Recovery for Offshore Oil Reservoirs
Authors: Kuuskraa Vello A. , Malone Taylor 
Published: April 2016

This paper presents the results of a recent analysis of applying carbon dioxide enhanced oil recovery (CO2-EOR) to oil reservoirs in the offshore Gulf of Mexico (GOM). The study started with a data base from the Bureau of Ocean Energy Management (BOEM) that contained 531 oil fields with a total original oil in-place (OOIP) of 69 billion barrels. The study excluded 391 of these oil fields, representing 35% of the OOIP, as not being amenable to CO2-EOR based on their size, minimum miscibility pressure, and residual oil saturation. The study then evaluated the remaining 140 GOM offshore oil fields, containing 696 individual reservoirs, for their technical and economic viability for CO2-EOR.
Crude oil production and CO2 injection profiles were calculated for each reservoir using a stream-tube finite-difference simulator. The calculation of economic viability was based on a crude oil price of $90/bbl, a CO2 price of $1.59/Mscf ($30 $/MtCO2) at the capture facility plant gate, an 18.75% royalty, and a minimum 20% rate of return, before taxes. With Current CO2-EOR Technology, the economically recoverable resource (ERR) from the GOM offshore is 0.8 billion barrels, a small fraction of the technically recoverable resource (TRR) of 23.5 billion barrels. With Next Generation CO2-EOR Technology, the ERR increases significantly to 14.9 billion barrels.
Qualification and Implementation of a Subsea Wet Gas Compressor Solution
Authors: Hjelmeland Mads , Torkildsen Bernt Helge 
Published: April 2016

The challenge of increased recovery in development of subsea fields has driven the advancement of subsea processing technologies, in particular within the subsea boosting domain. The successful operation of large subsea boosting systems on a global scale, coupled with significant added value of pre-compression systems in gas fields, has driven the next technology step; subsea multiphase compression. The application of the multiphase compressor in a subsea environment simplifies a subsea compression system significantly, as there is no need for pre-processing. This enables development of simplified subsea systems at lower capital expenditure and field development costs.
This paper will provide an overview of the Technology Qualification Program (TQP) completed for Statoil's Gullfaks Subsea Compression (GSC) project, as well as present the WGC4000 compressor performance characteristics and mechanical design. Experiences from the GSC project, as well as deployment and commissioning of the subsea compression system in second half of 2015, will also be described.
Loop Current Hyperactivity: Analysis of In Situ Measurements in the Gulf of Mexico
Authors: Sharma Neha , Storie Jill S. , Obenour Kelsey M. , Leber Michael J. , Srinivasan Ashwanth 
Published: April 2016

Abstract
Starting in June 2014, ocean currents in the Gulf of Mexico became uncharacteristically detrimental to offshore operations. An unprecedented event of extreme Loop Current activity, not only in spatial and temporal extent but also in current intensity and vertical structure, was observed and documented for a year and half. The unusual activity was attributed to either increased inflow from the Caribbean Sea through the Yucatan Channel or amplification caused by local frontal cyclonic eddies. Anticyclonic eddies that shed from the Loop Current during this ongoing event maintained relatively large structures following their initial detachments and exhibited reconnections with the Loop Current within days to weeks of separation. This process was repeated by several eddies more than twice. In situ measurements indicated frequently reoccurring ocean current intensities upwards of 3.0 knots sustained for several weeks at a time with peak observed amplitudes over 4.0 knots. In this study, we present data collected from ADCP measurements and an extensive network of drifting buoys in correlation with daily frontal analyses based on all available in situ data and satellite imagery – both public and proprietary. The Loop Current and each eddy shed during this period is discussed with emphasis on structure, intensity, and migration pattern. Investigation was made into a possible link to El Niño and/or other large-scale air-sea phenomena and teleconnections; however, the root cause(s) for the circulation hyperactivity in the Gulf, if any, remains unknown. The study concludes with lessons learned and a brief description of long-term forecast modeling efforts to mitigate risk and enhance safety and efficiency in offshore operations.
Parameters Influencing Seismic Assessment of Subsea Structural Systems
Authors: Sari Ali , Azimov Umid , Nguyen Hieu 
Published: April 2016

Abstract
Significant improvements in technology include the development of subsea systems capable of retrieving and pre-processing oil and gas at sites located miles away from the host platform. The use of subsea systems at deep water sites in seismic regions has become increasingly common in recent years due to the growing exploration and continuing advances in the construction, placement and maintenance of subsea systems. Seismic events may impact the operability, stability and safety of subsea structural systems. Thus, the focus of this study is to evaluate the response and vulnerability of subsea structures during a seismic event and provide a quantitative sensitivity assessment for various parameters affecting the analysis.
An analytical parametric study for a subsea structure and connecting pipe system was performed. The structural configurations of the system, surrounding soil conditions and the expected seismic demands along with the intensity and frequency characteristics of the ground motions are crucial for accurately modeling and predicting the expected structural response during earthquakes.
Computer models using non-linear finite element method analysis procedures are developed to assess subsea systems under seismic loads. Sensitivity studies are conducted on parameters such as soil damping, soil-pile interface gapping, and multilevel excitation to simulate the response of subsea structural system. Computer model was generated, and nonlinear seismic response was simulated in CAPFOS software.
In the case study, it was observed that the soil radiation damping effects, pile-soil interface gapping and uniform versus depth-varying seismic load application can have considerable effect on the response of the subsea structural systems. The results of this study show that the response of the subsea structural system is sensitive to parameters considered. Therefore, specific design information for a subsea system is critical in making a final assessment of the expected performance under site specific ground motions. This study may help offshore engineers to gain a quantitative understanding of how different parameters influence the results of seismic response of subsea structural systems.
Plume Modeling in Lake Kivu, Rwanda for a Gas Extraction Facility
Authors: Morse Timothy L. , Ponchaut Nicolas F. , Bigham Gary N. 
Published: April 2016

Abstract
Lake Kivu, located between Rwanda and the Democratic Republic of Congo, is unique among several East African Rift lakes with high concentrations of dissolved carbon dioxide in that it also contains methane, kept in solution by the pressure of the deep water. The gas poses a potential hazard as a vertical disruption of the lake water (due to a landslide or volcanic activity) could cause gas-laden water to be displaced to shallower depths (and lower pressures), allowing the gas to bubble out of solution, triggering a gas eruption. A floating gas extraction facility has been constructed to extract gas-laden water from deep in the lake, separate the methane and some of the carbon dioxide and reinject the degassed water, thus increasing the safety of the lake and simultaneously providing methane, which will be used to generate electricity. This paper explores the computational fluid dynamics technique used to analyze the degassed water discharge plume from that facility and describes the dynamics of the plume.
We used a Reynolds-Averaged Navier Stokes (RANS) model to analyze the dynamics of the degassed water plume. The density of the water, and hence the plume dynamics, is heavily affected by the water temperature and the concentration of methane, carbon dioxide, and salt. Thus the computational method tracked these quantities throughout the simulation. The background conditions in the lake (including mixed zones separated by density gradients) were also included in the model. Lake Kivu is unique in that the water temperature increases with depth. The lake remains stratified because the salt concentration also increases with depth and more than compensates for the effect of water temperature.
Two main concerns were raised with the degassed water plume: (1) could there be recirculation between the water intake risers and the degassed water discharge points? (2) could the dynamics of the plume lead to an overturn of the lake and a catastrophic gas eruption? Our simulations showed that the degassed water plume ultimately stratifies within a density gradient, that recirculation does not occur, and that the discharge plume does not result in uplift or overturn of the lake for the conditions evaluated.
Using Operational Failure Modes and Effects Analysis to Identify Project Top Risks
Authors: Kokosz C. , Engle R. 
Published: April 2016

Abstract
Combining the Mission Support Equipment (MSE) Failure Modes & Effects Analysis (FMEA), Project Installation Methodology and the customer's Risk Management Plan produces a project oriented customized ranking of the risks resulting from MSE failures modes. Identifying the Project Top Risks (PTR) allows the customer to prioritize equipment verification and project specific maintenance prior to the customer's project readiness review.
The FMEAs provided by the MSE's Original Equipment Manufacturer (OEM) typically focus on the risks posed to the MSE, not to the customer's project. The MSE operational FMEA can be written at the most reasonable level of repair/replacement of the equipment. Each operational FMEA is then assessed against the project installation methodology and the risk management plan providing a likelihood, severity and risk ranking score for each failure mode.
As a result of the operational FMEA, the project top risks are identified. The project manager uses the PTR to prioritize project specific inspections and verifications, project specific maintenance, assess the need for additional spares and identifying operational workarounds for problems that may arise during the project. These analytical techniques provide a focused view of the MSE failure mode risks and possible mitigations in order to avoid costly effects and downtime.
The FMEA can also be used to quickly build Fault Trees which can be used as an aid to determine the most probable cause of a failure should a failure occur.
Use of a Good-Enough Strategy to Reduce Costs of Development of Deep Offshore Brown-Field Marginal Infill Reservoir
Authors: Shukla Shashank 
Published: April 2016

Girassol Miocene M14 project, a Brown Field subsea tie-back to Girassol FPSO on Block17 in Angola, was suspended after pre-project/FEED studies to give priority to more profitable developments. In a permanent attempt to develop the upside reserves of TOTAL Angola portfolio at the best costs, an alternative development scenario was envisaged early 2015 considering the use of stock drilling tubular, completion equipment as well as SPS equipment, the reuse of existing XTs recovered from depleted Girassol wells, the selection of minimum functionalities system.
This paper presents how a "good-enough" strategy has been used to generate real cost savings and schedule optimization for the project. All together, this is a first-of-a-kind for deepwater fields in TOTAL.
Lessons Learned from HPHT Equipment Verification and Validation Process
Authors: Patel Harish N. , Ji Jing , Lin Jessie , Raghunathan Varun 
Published: April 2016

The industry is looking to drill in reservoirs exceeding the current limitations of associated equipment with pressures greater than 15,000 psi and/or temperatures greater than 350°F. This paper will discuss the design verification and validation efforts, integration assessment, and safety analysis for equipment with increased boundary limits to be utilized for High Pressure and High Temperature (HPHT) applications. It will also address the general areas of concern during prototype testing. The test procedures developed from the design validation process will incorporate the suggestions, recommendations, and optimizations from the design verification efforts. The created testing procedures will then assist in validating the design of the increased limits of components of drilling equipment for HPHT environments. The on-going projects that ABS is working on will be used in development of HPHT equipment design, production, and testing requirements. This paper will summarize the challenges in validation and verification that HPHT technology faces at the early stages of development and provide lessons learned for future projects and new technologies.
This paper will discuss in detail the obstacles experienced during design verification, material selection, risk study, and validation programs that have been set up to perform technology qualification and satisfy newly developed regulatory requirements. Discussion about material qualification testing, prototype testing, and findings based on experienced gained on the project will be presented. The lessons learned during this project will help to establish a baseline for standardizing the certification process of HPHT drilling equipment and new technology systems for global applications. The knowledge gained also will be instrumental for the development of various codes and standards associated for HPHT technology. Class and certification can provide greater confidence to offshore operators in order to commission drilling equipment and systems capable of delivering safer, more dependably drilled wells, some of which may be considered un-drillable with the limitations of existing equipment.
Lessons Learned During Manufacture, Installation, Deployment and Operation of a Managed Pressure Drilling System on Classed Drilling Units in Gulf of Mexico
Authors: Bruton Jay , Patel Harish N. , Mohammed Sohail , Lin Jessie 
Published: April 2016

Managed Pressure Drilling (MPD) has been used on land and offshore units with surface blowout preventers (BOP). More Deepwater projects around the world are adopting this innovative technique due to the advantages offered by this technology. The industry is facing several challenges, such as reliability, barriers, offshore environments, limited space, riser gas management (RGM), general riser interface issues, training and regulatory requirements. The primary focus of this paper will be on the system that utilizes a Rotating Control Device (RCD) and surface choke system equipment. The objective of this paper is to discuss and address lessons learned and challenges faced during the classification of the first MPD System deployment in Gulf of Mexico (GOM) on Deepwater drilling units and based on ABS experience gained from past and on-going various MPD projects.
Details on key focus areas, obstacles, and areas of improvements faced during the design review, risk assessment, testing, installation, and integration and commissioning of an MPD system in GOM for Deepwater operation will be provided. Lessons learned from under performance, failures, unplanned issues, and mitigation measures taken during project execution will be discussed. Key findings from the various risk studies that assisted in improving system safety will be discussed.
Based on past project experiences, ABS has determined that additional improvements are needed to most effectively meet class and regulatory requirements. This paper summarizes major concerns to be addressed and provides necessary mitigation measures to eliminate unscheduled events, and help minimize delay in classification. These efforts establish a baseline for classification of MPD drilling equipment and system for operations in Gulf of Mexico by providing major steps in achieving Classification along with providing information on the regulatory involvement in MPD Operations in Gulf of Mexico.