bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Experimental Study for Flow Assurance of the Methane Hydrate Production Test System
Authors: Sakurai S. , Nakatsuka Y. , Edwards T.J. , Hoskin B.J. , Manning D.K. 
Published: June 2014

Abstract
The world's first offshore methane hydrate production test was carried out in March 2013 in the Eastern Nankai Trough. The dissociation of methane hydrates in sediments was produced by depressurization. In this situation, flow assurance (FA) and prevention of hydrate re-formation in the wellbore is an important issue because water mixed with methane is transported through the well and seabed facilities, and subject to the well bore flowing pressure while being cooled-down by the surrounding seawater (around 4°C near the seabed).
A particular concern results from incomplete downhole gas separation of methane and water: this leads to the methane production line containing a small amount of water, and the water production line containing a small amount of free methane gas. In this water dominant flow line there is then the possibility of flow blockage due to gas hydrate re-formation and accumulation, but knowledge about behavior of hydrates under such water dominant conditions was not well known.
To investigate the potential for hydrate re-formation downstream of the downhole separator (including subsea pipes and equipment), Japan Oil, Gas and Metals National Corporation (JOGMEC) and Oilfield Production Technologies (OPT) developed a unique flow loop maintained at low temperature and high pressure. The flow loop was some 20 m in length. Notably, 6 m of the flow loop was constructed in optically clear cast acrylic, which allowed image capture in horizontal and vertical flow lines, and at flow stagnation points, ofmethane/water flows outside the hydrate regionthe formation, development and flow characteristics of hydrate slurries
In this paper we describe the flow loop design, show images of flow taken by a high speed camera, and our measurements of temperature and pressure in this water dominant system, and the potential of FA problems caused by hydrate re-association. The results and observations were used in the design of the test plan and test procedures implemented in the East Nankai production testing.
Mapping gas Hydrate Systems in the Gulf of Mexico Using Marine CSEM
Authors: Weitemeyer Karen , Constable Steven , Key Kerry 
Published: June 2014

Abstract
An extensive marine controlled source electromagnetic (CSEM) data set was collected in the Gulf of Mexico targeting gas hydrate deposits at four geologically distinct areas within water depths that varied from 900 to 3000 m. The Joint Industry Project 2 drilled two of these locations, Green Canyon 955 and Walker Ridge 313, providing ground truth for the CSEM data. A third survey location, Mississippi Canyon 118 (MC118), is a designated hydrate observatory. We collected both traditional ocean bottom electromagnetic receiver data as well as continuous profiling data using a novel towed three-axis electric field receiver. The towed receiver measured data at a fixed offset of 300 m behind the transmitter, while the ocean bottom receivers recorded data over a range of offsets as the transmitter passed by each receiver. We inverted the CSEM data using a newly developed parallel goal-oriented adaptive finite element-modeling algorithm for efficient 2.5D imaging of the CSEM data. 2D inversions from MC118 are consistent with 1D apparent resistivity pseudosections and reveal resistive areas associated with the carbonate/hydrate mound. An extensive conductive region exists below this, associated with conductive brines sourced from a deeper more resistive salt body. Away from the mound the resistivity structure is a fairly uniform and homogeneous. We present new 2D inversions of the CSEM data that consider electrical anisotropy and constrained inversions that leverage structural control using key seismic horizons along the profiles.
Optimized Riser Architectures for 20 ksi Drilling Operations
Authors: Saeedi N. , Persent E. , Averbuch D. , Guesnon J. 
Published: June 2014

Oil and gas companies are considering drilling operations in offshore locations where high pressure formation is anticipated. To be totally safe, such operations will require the use of a 20,000 psi BOP stack and associated pieces of equipment, such as the drilling riser.
This new requirement brings severe constraints for the riser design, which can currently be solved with existing technologies, only in shallow water depth. The load sharing arrangement being the key to 20 ksi drilling risers, it is important to understand in depth this mechanism and its benefits for the riser architecture.
This paper presents a thorough analysis of the behavior of load-sharing risers. The distribution of the loads and stresses between the main riser pipe and the auxiliary lines have been calculated and analyzed for different combinations of design parameters, including effective tension, pressure and load-sharing configurations.
A number of drilling riser options has been evaluated to withstand internal operating pressures of 20,000 psi within the Choke & Kill lines in a water depth of 10,000 ft with heavy mud. According to the study, the conventional technology is discarded because of the thick-walled pipes, the huge mass of the riser and the amount of buoyancy, that are required to withstand high pressure encountered at great depths.
A new generation of drilling risers is proposed based on a new implementation of the load-sharing technology on the Clip-RiserTM. This technology, currently under development, provides the riser with much higher performances for tension, pressure and dynamics.
The evaluated technologies introduce major improvements in the riser design with respect to the conventional one, including a large reduction of the riser mass and of the required buoyancy for riser joints.
Further benefits in terms of weight savings can be achieved by combining this technology with the previously developed steel/composite hybrid Choke and Kill lines.
Deep Water Pipeline Repair In The Gulf Of Mexico
Authors: Brown Lance , Dayani Adrian , Lazenby Shaun , Miller Jackson 
Published: June 2014

Abstract
The ability to repair pipelines remotely becomes critical as water depths of offshore field developments continue to increase beyond diving limits. While there have been several proposed solutions available, very few repairs have been carried out remotely. In October 2012, a Houston based team comprising of Subsea 7, Quality Connector Systems LLC and Stress Engineering Services, Inc. successfully completed a repair in 3, 200 FSW from a light construction vessel (M/V Grant Candies).
The extent of this operation was to assess the damage to the pipeline, remove pipeline coatings, and to install a QCS diverless repair clamp connector; with the limitation that all work had to be carried out only using work class ROVs. Detailed engineering, planning, ROV tool interfacing and a complete system integration test including equipment trials were critical to minimizing vessel downtime and meeting an aggressive schedule. Repair of the pipeline being critical to the long term integrity, and life expectancy following the discovery of a defect.
This paper reviews the current state of remote intervention based pipeline repair technology and provides an overview of the challenges faced when dealing with regulatory agencies (BSEE/BOEM), lessons learned in implementing this repair and considerations to be able to transfer this technology to greater water depths and harsher environments.
Wind-powered Subsea Water Injection Pumping: Technical and Economic Feasibility
Authors: Slätte Johan , Sandberg Johan , Flach Todd , Dekker Gerben , Sixtensson Carl 
Published: June 2014

Abstract
New technologies and solutions are increasingly more critical in the oil industry to develop marginal fields and maintain the oil production rates of more mature fields. In recent years several successful raw seawater injection systems have been implemented and new subsea water treatment technologies are under development, enhancing the methodologies and techniques used.
This paper describes the potential use of floating wind turbines for powering subsea water injection facilities, stand-alone systems', and discusses these systems' technical and economic feasibility compared to current solutions. High-level indicators of economic and technical performance show an interesting window of opportunity for applications that can tolerate unprocessed seawater for injection in oil fields. Other configurations can also be attractive.
The simplest use case considered for this article is powering a subsea pump with a local, offshore floating wind turbine to inject unprocessed seawater into an oil reservoir. Other related cases for floating wind turbine powered injection pumping are identified and discussed. Recent experience on a subsea water injection project on the Norwegian shelf has demonstrated the technical viability of injecting unprocessed seawater into an oil reservoir with suitable properties. Further, successful floating wind turbine demonstration projects have proven this new technology's feasibility.
In the conventional solution for a subsea injection manifold, the costs associated with connecting a subsea power cable to the host platform, where the electrical power for the subsea injection pump is generated, can be substantial. Under the right circumstances and conditions, it may be possible to reduce costs significantly by powering the subsea pump with 1-2 offshore wind turbines that are placed in close vicinity (in the order of hundreds of meters) of the subsea manifold. The reduced costs of this solution are enabled by the shorter subsea power cable, the elimination of incremental power generation on the host platform and, in the case of Norway, reduced taxes related to the incremental emissions of natural-gas turbine power generation for the subsea injection pump.
A study has been performed where the main technical challenges of the wind-powered subsea injection pump have been considered and are judged to be fully manageable. The most significant of these are related to the intermittency of the wind turbine power generation. Wind turbine output characteristics can be designed to produce power even at low but non-zero wind speeds. The optimization problem statement for choosing a wind turbine for this application is therefore very different to the more common challenge of maximizing energy output from wind turbines installed at a particular onshore site.
Seismic Processing Techniques for Geohazard Identification and Risk Reduction in a Frontier Exploration Area
Authors: Noll Christian , Liu Hui , Poole Alan , Helfrich Cody , Scherschel Craig 
Published: June 2014

Abstract
The main objective of Geohazard Investigation is to reduce operational risk in Drilling and Developments. While this is paramount during all operations, it is especially so for exploration drilling in frontier areas where only sparse data are available. Geohazard analysis is often carried out using conventional exploration 3D seismic data on a standalone basis. As these data are primarily acquired and processed to image deeper targets, they do not contain the high frequency content in the shallow section that would be achieved by high-resolution 2D or 3D acquisition.
To ensure operational integrity in areas where there is poor well control, and, or, where geologic complexity is high, it is necessary to pursue techniques beyond the traditional evaluation of available data to deliver high quality risk assessments.
Application of processing and analysis techniques to gain additional insight to conditions, by extracting additional attributes from existing geophysical data are, therefore, attractive. These techniques can be used to build a more robust geologic model, to understand the complexities of the geological system, in the absence of direct sampling, and are even more useful when complemented by ground-truthing.
This paper describes how exploration 3D seismic data were reprocessed into a "high-resolution" 3D seismic volume. The reprocessing was carried out to improve frequency content by focusing on the shallow section for use in site investigation. Work was undertaken to deliver improved understanding of the shallow velocity field by generating a Full Waveform Inversion velocity model. This was then used as the starting model for a pre-stack Kirchhoff depth migration which was able to provide further improved stratigraphic and structural imaging to allow an even more accurate interpretation.
Having delivered an improved seismic volume, advanced coherency algorithms were applied to understand discontinuities, at multiple scales, and spectral decomposition analysis was performed to better understand the distribution of seafloor and subsurface lithologies.
The combined effect of the application of these processing and analysis steps lead to a better understanding of the geologic complexities of the area and how these might translate to potential geohazards, allowing them to either be directly avoided, or mitigated, through engineering design prior to the start of drilling operations.
Underwater monitoring network: Using the deep-sea Drill MARUM-MeBo for installing Subseafloor Sensor Systems for monitoring Seafloor Intervention Operations
Authors: Waldmann Christoph , Freudenthal Tim , Kopf Achim 
Published: June 2014

Abstract
Any intervention into the seafloor will have an impact on the structural integrity of the material in the affected region and will hence result in variation in stress, pore water pressure, and temperature. As a consequence fluids maybe mobilized and may in turn affect the intervention process. To closely track such processes or monitor safe operations in areas of e.g. hydrocarbon exploitation, seafloor mining or marine renewables, new measuring strategies have to be developed to allow a spatio-temporal coverage via a sensor network. With the deep-sea drill MARUM-MeBo that has been developed at the University of Bremen/MARUM new opportunities are opened up to deploy sensors in shallow boreholes (&lt;80 m sub-seafloor depth). MeBo is characterized by its versatility and high mobility with deployments down to water depths of 2000 m. Materials recovered via wire-line coring technique included both soft sediments and hard rocks. After drilling a 2.35 m section the core is recovered using a wire that is latched to the inner core barrel with an overshot. The outer drill string stays in the drilled hole during the entire drilling process. Recently, simple self-contained borehole instruments were developed that are placed in the hole, in which the outer drill string serves as casing. We propose to employ MeBo to deploy a network of instrumented boreholes in the region of deep-sea interventions to monitor the environmental conditions continuously over long time intervals. Data can be exchanged via acoustic modems and may serve to archive time series and use in hazard assessment and early warning.
Future Changes in Gulf of Mexico Hurricane Wave Climatology
Authors: Done James M. , Ge Ming , Holland Greg J. , Bruyère Cindy L 
Published: June 2014

Abstract
Meeting industry demand for assessments of future changes in Gulf of Mexico hurricane impacts is a challenge that extends well beyond simply improving climate prediction. Once the climate predictions have been made, there remains a huge gap regarding how this affects industry. The National Center for Atmospheric Research is actively engaged in a collaborative project with the Research Partnership to Secure Energy for America, Chevron Energy Technology Company and Willis Re to align the latest climate research with the requirements of industry.
This paper explores methods to simulate and predict future changes in hurricane impacts on the offshore energy industry. We first expand the concept of the Saffir-Simpson hurricane categorical scale to include important characteristics of the wind field for damage including maximum wind speed, storm translation speed and size, in a new Cyclone Damage Potential index. The index is applied to simulated current and future hurricanes to assess future changes in hurricane damage potential.
Loading on structures in the Gulf of Mexico is a complex function of not only characteristics of the wind field but also ocean characteristics including currents and waves. Simple empirical relationships between wind, wave and current miss some of the essential physics, particularly for extreme events. To improve upon the damage potential assessments we need to account for the full physical interactions between wind, wave and current. This paper explores the ability of fully coupled atmosphere-ocean dynamical simulations to capture metocean hurricane conditions through a case study simulation of Hurricane Katrina. This preliminary case study simulation establishes the simulation technology that will then be used to build robust assessments of the 100-year load and its future change using a combined theoretical and dynamical-statistical approach.
A Pressure Coring Operation and On-board Analyses of Methane Hydrate-bearing Samples
Authors: Yamamoto Koji , Inada Norihito , Kubo Satoshi , Fujii Tesuya , Suzuki Kiyofumi , Nakatsuka Yoshihiro , Ikawa Terumichi , Seki Makoto , Konno Yoshihiro , Yoneda Jun , Nagao Jiro , Mizuguchi Yasuhiko 
Published: June 2014

Abstract
As a part of the offshore production test program, in June and July of 2012, Japan Oil, Gas and Metals National Corporation (JOGMEC) conducted coring operation in the Eastern Nankai Trough where the first offshore production test of methane hydrates was to be conducted. By using a pressure coring device, Hybrid PCS developed by Japan Agency of Marine Science and Technology (JAMSTEC), Aumann and Associate Inc. (AAI), and JOGMEC, pressure conserved cores were recovered from methane hydrate-bearing sandy formations although some technical difficulties encoutered. The samples were analyzed onboard by Pressure Core Analysis and Transfer System (PCATS, GeoTek). Some samples were sent to onshore laboratories for further analyses. Continuous 60m intervalin a methane hydrate concentrated zone was cored and fairly good core recovery and pressure conservation rates were achieved. The obtained data are used for reservoir characterization of methane hydrate concentrated zone from where gas was produced during the actual production test conducted in March 2013.
Hydrate Modeling & Flow Loop Experiments for Water Continuous & Partially Dispersed Systems
Authors: Vijayamohan P. , Majid A. , Chaudhari P. , Sloan E.D. , Sum A.K. , Koh C.A. , Dellacase E. , Volk M. 
Published: June 2014

Abstract
A major industry concern is to reduce the severe safety risks associated with hydrate plug formation, and significantly extending subsea tieback distances by providing a cost effective flow assurance management/safety tool for mature fields. Developing fundamental understanding of the key mechanistic steps towards hydrate plug formation for different multiphase flow conditions is a key challenge to the flow assurance community. Such understanding can ultimately provide new insight and hydrate management guidelines to diminish the safety risks due to hydrate formation and accumulation in deepwater flowlines and facilities. The transportability of hydrates in pipelines is a function of the operating parameters, such as temperature, pressure, fluid mixture velocity, liquid loading, and fluid system characteristics. Specifically, the hydrate formation rate and plugging onset characteristics can be significantly different for water continuous, oil continuous, and partially dispersed systems. The latter is defined as a system containing oil/gas/water, where the water is present both as free water and partially dispersed in the oil phase (e.g., entrained water in the oil). This paper presents the results and analyses of flowloop experiments on partially dispersed systems as a function of water volume fraction and velocity/mixing. These experiments indicate that the partially dispersed systems tend to be problematic and are more severe cases with respect to flow assurance when compared to systems where the water is completely dispersed in oil. We have found that the partially dispersed systems are distinct, and are not an intermediate case between total water, and totally water-dispersed systems. Instead the experiments indicate that growth of hydrate sheet/deposit on the pipe wall because of the wetting of pipe walls by the free water layer coupled with bedding of the hydrates that are formed in bulk liquid seems to be the governing phenomena for hydrates growth in such systems. The data from the tests performed provide the basis for a mechanistic model for hydrate formation and plugging in partially dispersed systems. Lessons resulting from this work should be incorporated into flow assurance models, as well as operating company production strategies to reduce or mitigate hydrate plugging risks in complex multiphase systems.
Hydrate Deposition Mechanisms on Pipe Walls
Authors: Grasso G.A. , Sloan E.D. , Koh C.A. , Sum* A.K. , Creek J.L. , Kusinski G. 
Published: June 2014

Abstract
As the oil and gas industry moves towards offshore developments in deeper waters, the risk management of plugging pipelines due to hydrate formation increases in difficulty, which may lead to operation/safety hazards (Sloan, 2005). To tackle this challenge, the flow assurance community requires predictive tools to account for hydrate formation in flowlines (Zerpaet al., 2011). Although significant knowledge has been gained from mechanistic models for hydrate plug formation, there are still components missing for a comprehensive model, such as hydrate deposition on pipeline walls. Currently, field and flowloop data suggest the need to include and quantify hydrate deposition in the hydrate formation model (Lachanceet al., 2012). Agglomeration of hydrate particles by itself cannot account for large pressure drop observed during hydrate formation. Because hydrate deposition is difficult to decouple from other hydrate related phenomena (e.g., agglomeration), little to no research has previously been done addressing this phenomenon, particularly in gas-liquid systems. This paper details the initial effort to study hydrate deposition mechanism as part of a DeepStar funded project (CTR11203). Here, we present results that provide insight into hydrate deposition mechanisms based on experimental investigations designed to isolate this phenomenon from other hydrate issues. We have identified that water (hydrate former) reaches the deposition surface by direct contact of water with the surface, by condensation of water on the cold surface, and finally by liquid capillarity. Once the water reaches the deposition surface hydrate deposits form. We have also found that the rate of hydrate deposition increases by decreasing the surface temperature and these results are repeatable. We have shown that hydrate deposition on pipe walls is a key component for hydrate plug formation. The understanding gained with this investigation contributes to the efforts of the flow assurance community to develop a comprehensive hydrate formation model that could account for all the risks pertinent to hydrate formation in multiphase flow systems.