bluuebunny/crossref_metadata_2025_split huggingface dataset:
CFD Investigation on Scale and Damping Effects for Vortex Induced Motions of a Semi-Submersible Floater
Authors: Koop A. , Rijken O. , Vaz G. , Maximiano A. , Rosetti G. 
Published: April 2016

Abstract
Available field measurements of semisubmersibles indicate that the Vortex Induced Motion (VIM) response is typically found to be smaller than what is predicted in model tests. Reductions of as much as 50% seem to be occurring in the field compared to the response found in model tests. Several variations in the model test setup have been made in the past to achieve a better agreement between field observations and model test results, but no conclusive results have been obtained so far to explain the reason for those differences.
MARIN and the University of Sao Paulo (USP) initiated the VIM JIP with the primary objective to enhance the understanding of possible differences between field measurements and model test observations. In this JIP the effects of waves, current inflow conditions, external damping, mass ratios and Reynolds number are investigated using CFD and model tests. Some of these effects are examined using CFD, some experimentally and some by both CFD and model tests.
In this paper the CFD results are presented to examine the effects due to Reynolds number and external damping. The basic step of the JIP is the comparison of the model-scale CFD results to experimental results. Extensive verification steps are undertaken to improve the confidence in both model-scale and full-scale CFD results. The model-scale CFD results show VIM response very similar to behavior observed in model tests. Then, the CFD model is applied to full-scale Reynolds number to investigate the effects of Reynolds number on the VIM response. Furthermore, the effects of external damping are examined as well, both at model-scale and full-scale Reynolds number.
The CFD simulations at full-scale Reynolds number presented in this paper show a shift in the response curve to lower reduced velocities, but no significant reduction in normalized VIM amplitude is observed. Thus, Reynolds scale effects seem not to be the main reason for the difference between model tests and field observations. However, a significant reduction of VIM amplitude is observed when increasing the external damping in the CFD calculations.
According to these observations the importance of external damping on the VIM response is identified. Further investigation is recommended to assess the damping from riser and mooring configurations which occurs at prototype semisubmersibles, so that the correct VIM response can be considered in the design phase.
An Historical Perspective of Loop Activity from Nov. 2014 to Oct. 2015
Authors: Cooper C. , Yang X. , Danmeier D. , Stear J. 
Published: April 2016

Abstract
This paper compares the Loop activity during a one-year period beginning November 1, 2014 to the historical record derived from the Gulf Eddy Model (GEM) which covers 27 yrs. During our Study period, five anticyclones were generated (Lazarus, Michael, Nautilus I, Nautilus II, and Olympus) or one eddy every two months, far exceeding the 10-month shedding frequency observed in the historical data. Histograms describing the percent occurrence and intensity of ocean currents observed over the Study period are compared to historical statistics at sites in Walker Ridge, Mississippi Canyon, and Green Canyon and show Loop or Eddy (LCE) currents occurred at roughly twice the average historical frequency. At the two sites in Walker Ridge, the peak observed speed was near the 100-yr extreme calculated from GEM. At the Shell Stones site, observed currents exceeded the 100-yr GEM calculation by about 10% when the site was impacted by the combined currents of the Loop and a strong associated cyclone. GEM does not include cyclones so it is not too surprising that it could underestimate the currents in these situations.
Practical Guidelines for the Diagnosis and Remediation of Pipeline Blockages
Authors: Bukkaraju Sampath K. , Osorio Nelson F. , Annadorai Karthik M. , Garduño Jorge L. , Golden Nathan K. 
Published: April 2016

One of the primary flow assurance challenges in the production of hydrocarbons is the prevention of pipeline blockages. Blockages can occur from a combination of improper system design, improper selection of piping and insulation materials, production chemistry aspects, inadequate or improper commissioning, startup and operating procedures, deviation from the proven operating procedures, changes in the operating conditions, intervention operations and improper maintenance procedures. The nature of the blockages can vary from "not-so-severe" to "hard-to-remediate" depending on the type of blockage.
While prevention is the best strategy, pipeline blockages do occur and it is very important to identify the cause and nature of the blockage along with its location to a reasonable level of accuracy and the operating limitations dictating the best suited remediation strategy. The criticality of blockage resolution largely depends on proper identification of the type and location of the blockage/s.
A Self-Walking Vertical Mining System Concept Using DTH for Seafloor Mining and Its Preliminary Design
Authors: Watanabe Yoshiyasu , Watanabe Keisuke , Yuasa Fumio , Nazuka Tatsuki 
Published: April 2016

In the traditional concept of subsea mining field development, a subsea crawler generally has a big drill and scrapes the mineral deposit horizontally. In this "Horizontal Mining System (HMS)", ores vary in size and large chunks should be crushed into transportable particles. So a Subsea Crushing and Feeding Unit (SCFU) must be required for efficient slurry transportation to use the traditional riser system.
The vertical mining system (VMS) introduced in the previous paper1) consisted of a Down-The-Hole Drill (DTH) unit with a moving beam mounted on a jack up platform. The whole mining system consisted of the VMS, an Installation and Relocation Vessel (IRV), a subsea separator with pump, a riser and a mining support storage offloading (MSSO). The VMS had various merits but had a demerit that its relocation was executed by the IRV, which increased the project cost and period.
This paper introduces the concept and preliminary design of a Self-Walking Vertical Mining system (SW-VMS) that eliminates the use of the IRV and reduces the project cost and period. The SW-VMS consists of an upper jack up platform (UP) where the DTH drill unit and a moving beam are mounted, a middle frame (MF) and a lower jack up platform (LP). Each jack up platform has four legs and the platforms and the frame slide with each other. With alternately landing the four legs of each platform on the seafloor, the slides between the UP and the MF make the SW-VMS walk in one direction and the slides between the LP and the MF make the SW-VMS walk in the other direction. Thus the SW-VMS becomes capable of walking two-dimensionally on the seafloor.
Understanding Fluid Complexity and Reservoir Connectivity Using Downhole Fluid Analysis in Wilcox Formation Gulf of Mexico
Authors: Betancourt Soraya.S. , Mishra Vinay. K. , Clinch Simon , Guo Genliang , Malik Mayank , Cañas Jesus A. , Chen Li , Mullins Oliver C. 
Published: April 2016

Abstract
The development of the Wilcox formation in the Gulf of Mexico is constantly pushing technical boundaries in the oil industry. Here, ultra-deepwater wells are needed to target ultra-high pressure sub-salt reservoirs that are up to 32,000 ft below sea level. Innovative evaluation techniques and processes that could reduce reservoir uncertainties are key from prospect evaluation through field appraisal and development. In particular, detailed description of reservoir properties, fluid characterization and connectivity assessment in this challenging environment are extremely valuable.
An operator is extensively utilizing wireline formation tester measurements and downhole fluid analysis (DFA), and has implemented a workflow to assess reservoir connectivity using DFA data, asphaltene nanoscience, and geochemistry in a multi-well context. The coupling of vertical and lateral fluid gradient measurements from DFA and thermodynamic equilibrium analysis of the reservoir fluids represents a powerful new method for connectivity assessment. This includes use of novel asphaltene science and the Flory-Huggins-Zuo equation of state to model equilibrium asphaltene concentration gradients in petroleum reservoirs.
The workflow has been successfully implemented in all the operator's Wilcox fields to appraise both vertical connectivity of reservoir sands within individual wells and lateral connectivity throughout the field, and identify potential production challenges associated with non-equilibrated fluids. These workflows hinge on the application of the latest formation testing technology to help acquire the nearly pristine formation fluid samples required for such DFA field studies and real-time decision-making in characterizing reservoirs.
Electrically Trace Heated Pipe in Pipe: Technology Upgrade for Extended Application Range
Authors: Gooris François , Ansart Bruno , Rageot Olivier , Kaye David 
Published: April 2016

The benefits of active heating of subsea pipelines in terms of operability and flow assurance have been demonstrated, in particular for deepwater and/or remote fields with complex production conditions (hydrate formation risk, wax deposit, gelling issues, short production plateau…).
Electrical Trace Heating was developed to reduce significantly field developments CAPEX by simplifying subsea architectures and topside equipment, and OPEX through a low power consumption, and a drastic reduction in the use of chemicals.
After the first deployment of Electrically Trace Heated Pipe in Pipe (ETH-PiP) in reel-lay on Islay Field (North Sea, 2012), a development programme was launched in 2012, supported by major Operators to upgrade and qualify ETH-PiP technology for long tie-backs and higher power for production or export lines. This paper presents the maturity of all components of the ETH-PiP system. In a second part, the paper emphasizes on tracing cables design, production and validation testing phases as a critical aspect of the overall qualification process.
Drilling for the Next Generation of Multilateral Completion Systems
Authors: Abuahmad Yousif , Saleh Rami , Bouldin Brett , Turner Robert , Ali Bin Al-Sheikh 
Published: April 2016

The objective of drilling a well is to accommodate the completion string designed to optimize reservoir production. Streamlining a completion design for a mature field maximizes the chances of achieving the well objective with minimal drilling challenges. Therefore, introducing a new completion technology requires reevaluating the drilling procedures and practices to accommodate for the modified completion, and this is more true when running new completion designs into the open hole as opposed to cased hole completions. The Saudi Aramco drilling team were faced with the challenge of executing a multi-lateral well plan that will allow for running three open hole completions that will segment the open hole laterals and provide active control and monitoring capabilities for each segment. Such a completion requires a complex power and telemetry system that can energize all the segmented lateral completions including the ones that are deployed through the windows. The open hole laterals must be conditioned properly to successfully run the completion components in the open hole without restriction, and land the completions at the pre-planned target depths.
The main power supply and telemetry conduit between the upper completion and the open hole completions is a cable cemented behind the 7 in. liner. This presented several challenges such as running and cementing the liner and milling the windows without intersecting the cable, which would jeopardize the success of the entire completion. The team addressed the challenges by developing procedures to properly execute the mentioned operations while maintaining the integrity of the power system and land the completions at depth. This was confirmed by conducting tests at various stages throughout the implementation process.
An integrated project such as this requires focused collaboration between the drilling and completion teams because the traditional practice is to drill to total depth then complete the well, although this unique completion design requires a drill-complete-drill-complete sequence as the well progresses.
In addition to highlighting the key factors in managing and implementing such a well construction project where various disciplines are interdependent and require continuous coordination, the paper will summarize the modifications applied to the drilling procedures to achieve the objective of the subject well. The emphasis will mainly be on three operations: Under-reaming while drilling the 8-1/2 x 9 in. hole section, hole preparation prior to running the open hole completion, and the implementation of a unique cable avoidance procedure during conventional window milling operations.
Innovative Methods for Methane Leakage Monitoring Near Oil and Gas Installations
Authors: Waarum I-K. , Sparrevik P. , Kvistedal Y. , Hayes S. , Hale S. , Cornelissen G. , Eek E. 
Published: April 2016

In recent years, there has been an increased focus on environmental issues near oil and gas production sites and pipelines. The trend is likely to continue as future oil and gas production is commencing in environmentally vulnerable areas, and farther north near the polar ice cap. The exploration in more remote areas implies that online in situ monitoring has great advantages over expedition based monitoring.
The Norwegian Geotechnical Institute (NGI) is an independent research and consultancy foundation having over 40 years of worldwide offshore instrumentation experience. NGI has recently launched a research initiative to develop new methods for in situ and on line environmental monitoring offshore. In 2012, NGI designed and installed an integrated environmental monitoring system for subsea leakage detection. It was installed on the seabed beneath an operating oil and gas platform in the North Sea. We give here an overview of the instrumentation system and the motivation for the different design choices. The system is an example of an integrated monitoring system, where different types of sensors complement each other and gives a more thorough understanding of methane transport at the site of interest. After installation, NGI has analyzed monitoring data and provided decision support to operator personnel. Nearly two years of production site data collection represents a unique data set that enables a comprehensive analysis of methane transport.
From the operator side, the motivation for environmental monitoring usually arises from the need to answer clearly defined questions such as ‘Is there a gas leakage in the production system? Where is it? How large is the leakage?’ The leakage detection system is expected to answer these questions, preferrably in an unambiguous manner. However, natural gas can be released to the water phase from several sources e.g. organic matter on the seabed. If the leakage detection monitoring data shall be interpreted in a control room that operates with alarm states, these sources of background noise must be identified and separated from a real leak situation. We look at which circumstances to be aware of and how to maximize the operational value of a leakage detection system.
Lessons Learnt From Pre-Commissioning of Large Diameter Pipeline Using Coiled Tubing in Ultra-Deep Water Offshore Brazil
Authors: Lirola F. , Perreau E. , Dubois A. , Roubertie C. 
Published: April 2016

Abstract
The installation of flowlines in ever deeper and remote areas requires the usage of specific technologies in order to carry out pre-commissioning operations. As the water depth increases, the weight of the conventional equipment to be deployed to perform the required operations becomes a major issue and alternate solutions are thus required. An option lies in using Coiled Tubing. Coiled Tubing consists of continuous pipe that has been coiled around a reel and can be deployed and recovered according to operational needs.
So far, offshore operation of coiled tubing has been limited to small diameters and to short operational duration. The pre-commissioning operations can require the Coiled Tubing to be deployed several times for durations sometimes exceeding a month, and also requires larger diameters (typically 3.5"). As the duration of operations increases, a suitable way of assessing and mitigating the fatigue of Coiled Tubing is required. To that extent SAIPEM has carried out an extensive testing campaign aiming at better understanding the mechanism underlying plastic and elastic fatigue. Once enough confidence in the models has been gathered, the Coiled Tubing has been deployed offshore for the pre-commissioning operations of several Brazilian projects.
This paper reports the lessons learnt from an innovative pre-commissioning method based on Coiled Tubing that was successfully implemented on four ultra-deep offshore pipelines in 2015. All these projects were located offshore Brazil in water depth around 2200 m. The paper will provide feedback on the engineering and operations associated with the use of large diameter Coiled Tubing for pre-commissioning in deep water. A first section will highlight the specificities of the projects while subsequent sections will provide more details on offshore operations.
Efficient Environmental and Structural Response Analysis by Clustering of Directional Wave Spectra
Authors: Vogel M. , Hanson J. , Fan S. , Forristall G.Z. , Li Y. , Fratantonio R. , Jonathan P. 
Published: April 2016

Abstract
Estimation of environmental and complex structural responses, such as fatigue for risers on deepwater floating production systems, is a critical and generally computationally intensive process. Long term damage estimates require the determination of host vessel motions used for riser stress calculations. In principle, riser stress could be calculated for each of a large number of directional sea states, a considerable computational burden. However, it might be possible to identify a representative subset of directional sea states for vessel motion and subsequent riser stress analysis, such that estimated fatigue characteristics (from the full set of sea states and the subset thereof) were equivalent. This would be advantageous as it would require considerably less computational effort.
In this work we use non hierarchical K-MEANS cluster analysis to partition a large set of directional wave spectra for contiguous sea states at a location offshore Brazil, corresponding to a period of approximately 2 years into a number of clusters. We adopt the set comprised of cluster centroids only as representative sea states for efficient characterization of the environment and structural response.
We demonstrate that the representative sea states provide an efficient basis for estimation of overall sea state bulk, wind sea and swell characteristics. We evaluate the effect of cluster size on the performance of the representative sea states using custom built visualization tools utilizing the Kolmogorov-Smirnov test statistics. The representative sea states are further used as input for a VLCC-class FPSO vessel motion analysis. For heave at the turret, roll motions, and relative vessel heading, distributions of vessel motions from analysis of representative sea states are in excellent agreement with those from analysis of all sea states. Guidelines for the application of the methodology are provided.
Delay P&A Through Improvement in Oil Cut for Mature Offshore Facilities
Authors: Clement B.G. , Karicherla P. , Meling T. , Kozicki K.M. , Veeningen D. 
Published: April 2016

Abstract
Enhanced oil recovery operations are less common offshore in comparison to their mature counterparts onshore. Large inter-well distances, facilities and weight constraints as well as capital expenditure limitations due to declining production greatly restrict choices for tertiary recovery strategies. Moreover, as oil cut continues to fall, maintaining economic production requires processing ever-increasing water volumes eventually requiring plugging and abandonment (P&A), even though typically 45 to 70% of the original oil remains in the formation.
Ideally, the economic life of mature offshore facilities would be extended by incremental oil production at a reduced, per-barrel cost to lower the overall lifting expense. As fluid processing and pumping rates are usually already optimized at maximum rates, an ideal enhanced oil recovery method would, in addition to increasing the oil production, also improve the oil-to-water ratio and reduce the per-barrel operating expenditure, or OPEX.
A biological enhanced oil recovery (EOR) solution initially deployed offshore in the North Sea has been validated with multiple onshore demonstrations and is now available for mature, offshore facilities to promote preferential oil flow in water-flooded sandstone reservoirs. The method makes use of the existing biology in the formation, which is activated from its dormant state by continuous addition of a low-dose (ca. 100 ppm) nutrient solution from a small footprint injection unit. The resulting biological growth reduces interfacial tension (IFT) and mobilizes otherwise trapped oil.
This paper shows the rapid improvements of oil production and oil-water ratios over large injector- producer well distances in as little as 2-4 months following initiation of biological EOR. Recommendations are offered that are relevant for extracting otherwise trapped oil and recovering significantly more of the oil-in-place prior to P&A. Strategies are also offered for field-wide implementation to enhance oil recovery and reduce OPEX with minimal capital investment and equipment installation.