bluuebunny/crossref_metadata_2025 huggingface dataset:
The Single-Lift Vessel "Pieter Schelte": Honoring the Past, Shaping the Future
Authors: Heerema Edward P.
Published: June 2014

This paper describes the building of a ship for single-lifting of very large topsides of offshore platforms.

The ship's layout and functioning was described in an earlier OTC paper (Heerema, E.P. 2012).

The paper covered in detail the significance of a motion compensation system for rough seas, and the benefits of single-lifting by removing the need to build up or remove topsides module by module. The paper also described the installation and removal methods for jackets, as well as the vessel's pipelay system for application in the periods when there is insufficient heavy lifting work.

This paper deals with the next step, the actual building of the vessel and her equipment, taking place largely over the past two and a half years; the commissioning is planned to be completed by the end of 2014.

The concept behind Pieter Schelte is entirely novel, and such is the scale of the ship and her equipment that the building is a major challenge, but one that the shipyard and suppliers are presently coping with well. Proven equipment is used in all elements, but the method of functioning is unprecedented.

Pieter Schelte will have a topsides lifting capacity of 53,000 short tons (48,000 metric tons) and a jacket lifting capacity of 27,500 short tons (25,000 metric tons) (see figures 1 and 2).

Her length will be 1253 feet (382 m) excluding lifting equipment protruding overboard, and her width will be 406 feet (124 m). For moving in around platform substructures, the width of the bow slot will be 193 feet (59 m) (see figure 3).

She will also be a pipelayer with a tensioner capacity of 2200 short tons (2000 metric tons), enabling her to lay heavy pipelines in shallow and deep water (see figure 4).
Mini to Mega LNG: An Independent's Perspective
Authors: Khurana Sandeep , Gallon Steve
Published: June 2014

Independent Oil Companies have found large gas resources globally, onshore and offshore. With relatively low value attributed to gas resources due to either limited or highly competitive markets within its vicinity, companies are facing a dilemma on how to strategize gas to LNG effectively to improve return on investment. Gas to LNG requires understanding of integration and/or interface across various business segments for value creation. The options are numerous and challenging ranging from partnership with established players to entering into new business streams. The paper will address commercial and technical challenges as well as above ground risks such as Government policies and regulatory authorities.

The paper will analyze various business aspects for gas to LNG such as entering into a large LNG plant ownership and operations, effectively being a part of transportation and marketing, moving to new technology such as Floating LNG, or starting small with mini-LNG plants for onshore gas resources.

The paper will illustrate risks and rewards along with capital exposure in various business segments. The amount of integration and commercial innovation required to secure the value of gas resources will be contemplated for various scenarios with case studies.
Li-Ion Batteries for Energy Storage and Hybrid Power: Safety and Suitability Considerations for Offshore Applications
Authors: Hill Davion M. , Agarwal Arun , Gully Benjamin
Published: June 2014

With new battery technologies available and impending emissions control areas (ECA) in the US continental shelf, and NOx enforcement mechanisms in the North Sea and elsewhere, there is a need to reduce emissions and improve efficiency of oil and gas exploration and production. It has been stated that ECA regulations will require NOx reductions by 80% by 2020. This reduction can be achieved in part with hybrid power systems. In addition, the movement toward subsea systems will introduce new power requirements. Transmission to ultra deepwater assets will be costly, and a need to downsize transmission lines and cables can be met with subsea battery systems which buffer transients and reduce the maximum capacity for cables. The challenge that the oil and gas industry faces is to decide when and where hybrid power systems provide the most value for operations, how they should be implemented, what technologies are acceptable, what safety considerations there may be, and how these technologies can improve the bottom line. There is a wealth of information on lithium ion batteries though it is not all consistent; cost data is unclear, lifetime and energy density considerations vary under different conditions, and ruggedness and application to harsh environments is a large uncertainty.
The Past and Future of Floating LNG
Authors: Eisbrenner Kathleen , Srinivasan Vivek , Davison Shaun , van Vliet René , Eisbrenner Ray , Puga Alfonso
Published: June 2014

The Floating Liquefied Natural Gas (FLNG) solution is gaining recognition as an effective means for economic monetization of stranded offshore gas reserves, or in specific cases, near shore/onshore reserves with insufficient local or regional markets. It is also being considered as an efficient and economic alternative to mid size (2 – 4 MTPA), and smaller (0.5 – 1.0 MTPA) land based liquefaction facilities. Significant inefficiencies in natural gas pricing across the world due to supply/demand imbalances, combined with recent finds of additional stranded offshore gas reserves as well as shale gas discoveries could help FLNG solutions capture a key portion of the natural gas value chain. The market for FLNGs over the next ten years is expected to follow a growth trajectory set by the downstream equivalent of FLNG; the floating storage and regasification unit (FSRU) industry over the last decade. The comfort and acceptance of floating LNG technology, and the economic advantages to many of the world's developing natural gas markets in the FSRU space suggest equal acceptance and opportunity for the FLNG upstream segment. The FLNG market in the next decade presents, strategic developers and financial investors, under the right circumstances, an opportunity to participate and create value, in this new energy infrastructure segment.
Gas Hydrate Deposits of Krishna Godavari Basin, India: Issues and Potentiality in Exploration and Commercial Production
Authors: Sahay Vinay K. , Johnson Arthur H.
Published: June 2014

Gas hydrate, is an important energy resource, occurring in sediments on the continental margin of the India Ocean. Quite significant scientific and commercial interest has been generated in India with a 130 m thick gas hydrate discovery in shale in Krishna Godavari Basin. This paper presents the evaluation results of seismic, logging while drilling, and core data in the context of exploring those issues which are relevant in the commercial production of gas hydrate deposits of Krishna Godavari Basin. Apart from this, we discuss the scientific and technological issues and potentialities in commercial exploitation of Krishna Godavari gas hydrate deposits.

Evaluation of logging-while-drilling (LWD) sonic log data of Krishna Godavari Basin shows an increase of relative velocity in the gas hydrate bearing zone. Apart from this, the LWD density log data also shows a relative increase of density in gas hydrate bearing zone in Krishna Godavari Basin. Increase in relative velocity and density of the zone under evaluation may be ascribed due to presence of gas hydrate (as a solid mass, increasing overall cohesiveness of hosting lithology shale, present within the depth boundary of gas hydrate stability zone). The sonic and density log validates their use as an important tool in demarcation of gas hydrate bearing zones and gas hydrate reserve estimations, calibrating and integrating with core-based gas hydrate saturation data. Evaluation of seismic sections, however, does not show the BSR (Bottom Simulating Reflector) as a full proof and conclusive proxy for the presence/absence of gas hydrates as has been observed from the data of KG Basin. Precaution should have to be exercised while utilizing BSR, in seismic data evaluation and interpretation, in the identification of gas hydrate.

Investigation and evaluation of the data of the Krishna Godavari Basin gas hydrate deposits indicate the potential for commercial production utilizing presently available knowledge of science and technology for finding viable accumulations of gas hydrates. Apart from the above discussed aspects, the paper also provides some suggestions which can be utilized and integrated with the National Gas Hydrate Program, India to resolve many issues.
Fatigue Strength Investigation of Drill Pipe for Challenging Scientific Deep Drilling and Utilization of Drilling Data to Estimate Cumulative Fatigue
Authors: Inoue Tomoya , Kyo Masanori , Sakura Koji , Fukui Toshihiko
Published: June 2014

The scientific drilling vessel Chikyu is performing challenging deep drilling activities, such as the Japan Trench Fast Drilling Program (JFAST), for conducting research on the Tohoku earthquake, which accompanied the tsunami that devastated northern Japan in March 2011. Generally, the fatigue strength of a drill pipe is a critical factor governing the performance of challenging deep drillings. This study therefore focused on the fatigue failure of a drill pipe, which is caused by an axial dynamic tension resulting from ship motion and drilling operation under the condition that a bending stress is exerted, in challenging deep drilling or drilling operations in harsh environments. Fatigue tests of actual drill pipes were conducted to acquire the actual fatigue curve. Further, the bending stress distribution of a drill pipe, which refers to the maximum locus of the bending stress during the drilling operation, was analyzed considering interference of the drill string with the structure or drilling equipment. The occurrence probability of ship inclination due to ship motions and ocean current, the occurrence probability of the bending stresses, and the axial dynamic stress and its occurrence probability were analyzed. Consequently, the cumulative damage ratio and the possible duration of operation were obtained. From the results, we confirmed how severe the deep drillings of JFAST are. Another important issue is to estimate the actual fatigue accumulated in drilling operations for further usage of the drill pipe. We therefore attempted to estimate the fatigue that accumulated during operations by using the abovementioned fatigue analysis along with drilling data acquired during the operation.
Wave Energy Research, Development and Testing Including Testing of Materials and Technologies for Bio-Fouling and Corrosion Prevention
Authors: von Jouanne Annette , Baker Josh , Yim Solomon , Amon Ean , Moran Sean , Lettenmaier Terry , Bunn Malachi , Yokochi Alex
Published: June 2014

This paper illustrates opportunities for ocean wave power to become a new, reliable and clean source of renewable energy. Presented are the activities of the Northwest National Marine Renewable Energy Center (NNMREC), a Department of Energy sponsored partnership between Oregon State University and the University of Washington (UW). NNMREC performs fundamental technological, social, and environmental research on marine renewables, in addition to providing unique testing facilities including a wave energy linear test bed, 2D and 3D wave tanks, and an Ocean Sentinel mobile ocean test berth instrumentation buoy to facilitate ocean testing. This paper includes the ongoing research and testing with the Ocean Sentinel instrumentation buoy, in addition to the developing cable-to-shore testing facility, which would be the first utility scale, grid-connected wave energy test site in the US. Finally, this paper presents the ongoing research and testing of materials and technologies for bio-fouling and corrosion prevention in the marine environment.
Development of Turbine Driven Coring System for Hard Rock Sampling
Authors: Miyazaki Eigo , Shinmoto Yuichi , Kyo Masanori , Suzuki Tomoaki , Hayashi Masamoto , Sumitani Nobuyoshi
Published: June 2014

Japan Agency for Marine-Earth Science and Technology (JAMSTEC) is developing a unique wireline retrievable coring tool for sampling of rocks below the deep sea floor. This tool is mainly composed of a turbine motor, a piston/cylinder, an inner tube. A cutting shoe at the bottom of the inner tube is rotated at high speed by the turbine motor and it trims cores. The advantage of applying the turbine motor is that the coring with high rotating speed and low weight on bit is possible compared with conventional coring and it is expected to be effective to improve the core recovery rate and core quality especially for hard fractured rock or interbedded hard / soft formations. This paper presents outline of this tool and several test results on shore.
In Depth Cost of Energy Analysis of East Coast Offshore Wind Farms
Authors: Drenick Chelsea , Prowell Ian , Dolan Dan
Published: June 2014

As the United States moves closer to constructing its first offshore wind farms, data-based decisions about how to select the most viable project site are crucial. This in-depth study examined both the revenue and costs of three potential wind farms off the East Coast. Multi-year energy time history analyses were performed to determine the energy generation and revenue potential of each site based on local winds and energy pricing. The costs were determined for each site based on characteristics including water depth, distance to shore, and distance from a port. These characteristics formed the basis to estimate the foundation costs, cabling costs, equipment mobilization fees, and other expenses associated with the project. Overall, this study shows that seemingly similar sites can have a very different levelized cost of energy (LCOE) estimates when an in depth analysis is performed.
Estimation of Temporal Probability in Offshore Geohazards Assessment
Authors: Nadim Farrokh , Lacasse Suzanne , Choi Young Jae , Hadley Christopher
Published: June 2014

Risk assessment for sea floor installations exposed to offshore geohazards requires an estimation of the occurrence probability of a hazardous event during a reference time period, for example the annual probability of the installation being impacted by a submarine mass gravity flow. The paper describes the procedures developed in recent offshore geohazards studies for the estimation of the temporal probability in two situations:When there is a clear trigger for initiating the slide that would develop into a mass gravity flow andWhen there is evidence of slide activity, but no obvious trigger for slide initiation.

In the first situation, the assessment of temporal probability requires a probabilistic description of the frequency and intensity of the trigger(s) releasing the submarine slide, a probabilistic model for calculating the response of the slope to the trigger, and a probabilistic model for evaluating the runout of the released mass gravity flow. Using these models, the probability of a mass gravity flow impacting the seafloor installation(s) should then be computed for all relevant scenarios and return periods in order to derive the annual or lifetime probability. However, analyzing all possible scenarios and return periods could be time-consuming and impractical. The paper presents a simplified procedure and demonstrates its application through a case study for earthquake-triggered slides. In the second situation, where it is difficult to identify the trigger(s) initiating the slide, one must rely on the identification and dating of recent (in the geological sense) slide events in the area. The dating results and other relevant geological evidence are then integrated into a Bayesian framework to establish the annual probability of slope instability. The paper also presents the theoretical framework and example calculations for this situation.
Intelligent Casing-Intelligent Formation (ICIF) Design
Authors: Stalford Harold , Ahmed Ramadan
Published: June 2014

Intelligent Casing-Intelligent Formation (ICIF) design is evaluated for ultra deepwater (UDW) applications and for maximizing investments therein. ICIF design is a composite of Intelligent Casing (IC) design and Intelligent Formation (IF) design. The impact of ICIF design on drilling, completion and production technologies is assessed. The benefits and implementation challenges of ICIF design are evaluated in identifying optimal UDW applications. Early detection and early forecasting benefits are identified in evaluating the cost effectiveness of using ICIF design. Early detection and forecasting scenarios are utilized in evaluating ICIF design for its impact on Health, Safety, and Environment (HSE), well control, risk management activities and cost control strategies.

Intelligent Casing (IC) designs are considered that utilize fiber optic based distributive sensing of temperature, pressure, strain, acoustic, and chemical. Fiber optical cable deployment outside the casing is considered in the IC designs for permanent and continuous monitoring of reservoir-performance and wellbore integrity to enhance production and return on investment; multilayered reservoirs and multiphase flows are addressed. ICIF designs are cost-effective as compared to conventional designs. Various issues associated with the installation and operation of IC designs and IF designs are addressed (e.g., perforations for completions). The operation and control of downhole equipment (e.g., submersible pump) and the communication of such operational information to the surface are addressed. The benefits of early detection of wellbore barrier failure and/or water breakthrough issues are highlighted. ICIF designs are compatibility with conventional casing and cementing design and procedures.
Impact on Risers and Flowlines Design of the FPSO Mooring in Deepwater and Ultra Deepwater
Authors: Saint-Marcoux J. , Legras J.
Published: June 2014

Ten years back the choice between turret-moored FPSO and spread-moored FPSOs was primarily dictated by local met ocean conditions: spread moored FPSO in West Africa, soft-(DICAS) mooring FPSO in Brazil, and turret-moored FPSO elsewhere. Over the recent years West Africa is turning to turret-moored FPSOs (internal and external), and Brazil has installed spread-moored FPSOs. Whereas spread moored FPSOs prevail in larger sizes (about 2MB), new built, turret-moored, FPSOs are usually smaller in size (1MB) with external-turret offering cost and schedule benefits to the operators over internal-turrets. This paper presents the impact of this new trend in FPSO mooring on the design of the flow lines and risers and related impact to field layout. The orientation of a spread-mooring is governed by the local met ocean conditions and may not be optimal for the routing of the flowlines; also compromises may have to be done with regards to flow assurance constraints. Turret-moored FPSO allow possibly a better use of the seafloor space especially in deeper water where the seafloor slope is gentler, and result in shorter flowlines. Risers for spread-moored FPSOs are decoupled unless they can be a small number and limited to the central part of the hull. For turret-moored FPSO, decoupled risers allow larger FPSO offset movements and are compatible with both internal and external turret. In the case of SHR or HRT, safety rules impose a significantly longer jumper lines to protect the FPSO from accidental buoyancy tank release. SCRs may also be feasible but highly insulated risers are very light and prone to fatigue in-service. Examples are being provided to evaluate the impact of the various FPSO mooring options.
An Environmentally Friendly Method to Evaluate Gravel and Frac Packed Intervals Using a New Non-Radioactive Tracer Technology
Authors: Han Xiaogang , Duenckel Robert , Smith Harry , Smith Harry D.
Published: June 2014

Recently a new non-radioactive tracer (NRT) technology has become available to locate proppant in induced fractures that offers a viable alternative to the prior technology which utilizes radioactive (R/A) tracers, thereby eliminating the environmental, safety, and regulatory concerns associated with the R/A materials. This new non-radioactive tracer technique also has application in evaluating gravel packs and frac packs. The new technology employs a non-radioactive ceramic proppant containing a high thermal neutron capture compound (HTNCC). This compound is inseparably incorporated into each ceramic proppant grain during manufacturing in sufficiently low concentration that it does not affect any proppant properties. This tagged proppant can also be used as, or mixed with, conventional gravel or frac packing materials prior to downhole placement. The NRT taggant is detected using standard pulsed neutron capture (PNC) logging tools, with detection based on the high thermal neutron absorptive properties and/or capture gamma ray spectral properties of the tagged pack material relative to other downhole constituents. The tagged pack material is indicated from:decreases in after-pack PNC detector count rates relative to corresponding before-pack count rates,increases in PNC formation and borehole component capture cross-sections (Sfm and Sbh), and/orincreases in the computed elemental yield of the neutron-absorbing tag material, derived from the observed PNC capture gamma ray energy spectra.

In many frac-packing situations, combining Sfm and Sbh data permits identification of fracture height behind casing. In some applications, enhancements to these methods have also been developed to eliminate the requirement for the before-pack log. In this paper, log examples illustrate the effective detection of HTNCC tagged proppant placement in fractures and cement, and Monte Carlo modeling illustrates the viability of the detection/evaluation of gravel packs and frac packs using HTNCC tagged pack material. The modeling data and logs indicate the applicability of this effective, safe, and environmentally friendly logging technique to locate the placement of non-radioactively tagged downhole pack material in both gravel pack and frac pack evaluation.
Numerical Study on Eastern Nankai Trough gas Hydrate Production Test
Authors: Zhou Mingliang , Soga Kenichi , Xu Ermao , Uchida Shun , Yamamoto Koji
Published: June 2014

The fully coupled methane hydrate model developed in Cambridge was adopted in this numerical study on gas production trial at the Eastern Nankai Trough, Japan 2013. Based on the provided experimental data of hydrate soil core samples, the soil parameters at Eastern Nankai Trough were successfully calibrated. With calibrated soil parameters and site geometry, a 50 days gas production trail was numerically simulated using the fully coupled simulator CMHGS (Cambridge Methane Hydrate Geomechanics Simulator). The geomechanical behavior of hydrate bearing sediments and production history results under 3 different depressurization strategies were explored and discussed. With the latest gas production site data, several input parameters for the numerical study were calibrated and an updated numerical simulation of the gas production test was carried out. The comparison of gas production history and vertical displacement along the wellbore between the updated simulation and the previous simulation results suggest large discrepancy, which highlights the importance of parametric study for numerical simulation of the gas hydrate production test. Therefore, parameter sensitivity of production history and vertical displacement were investigated and concluded the relative permeability curve; temperature profile, sea water salinity and permeability anisotropy all influence production results and mechanical responses.
The Application of Noise Attenuation Method Based on Frequency and Amplitude in China's Bohai Bay
Authors: Dong Shuili , Fan Baocang , Wang Zheng , Qu Chaoyin
Published: June 2014

Noise attenuation is one of the most important steps in seismic data processing and it directly affects the final imaging quality of seismic data. Traditional de-noising methods can easily eliminate simple noise, such as spike noise or linear noise, but they can't efficiently handle non-linear external noise. That problem can be solved by using technique based on frequency and amplitude. The method detects and attenuates external noise making the most of differences between external noise and primary in sub-bands, and it can protect the primary by establishing threshold factors varying with frequency and time. This method has been successfully applied in the external noise elimination processing of the seismic data in China's Bohai Bay. Processing results showed that the method can remove external noise satisfactorily while the primary is preserved as much as possible. Other tests indicated that this method was also effective for attenuating near-offset multiples.
Planning and Feedback for Deepwater Drilling Riser Operation in High Currents, Typhoons and Cold Front
Authors: Saruhashi T. , Sawada I. , Kyo M. , Miyazaki E. , Yamazaki Y. , Yokoyama T. , Bhalla K. , Stahl M.J. , Ganpatye A. , Han Y. , Gong L.
Published: June 2014

The dynamically positioned drillship, Chikyu, has performed riser drilling operations twice in high-current environments in the Nankai Trough, offshore Japan. The drilling site is located in a water depth of approximately 6, 361 ft (1, 939 m) and regularly experiences the Kuroshio Current. The mean surface current at the site is 3.5 knots, and the 1-year extreme current is 7.0 knots. In addition, the current is not seasonal and typically changes frequently during the day. The Nankai Trough site also experiences intense typhoons during the months of July to October and frequent cold fronts from November to January. Thus, all operational phases need to be analyzed thoroughly to account for these harsh environmental conditions.

The following operational issues need to be carefully considered: riser deployment and retrieval, BOP/LMRP landing approach with vessel drifting, determination of watch circles, typhoon evacuation plans, hang-off operational criteria, evacuation plans for cold fronts, allowable riser tension range, and riser fatigue measurement with vortex-induced vibration (VIV) monitoring.

Assessment of deepwater/high-current riser drilling systems provides a means for identifying critical stages of drilling operations and enables their successful execution. Feedback from two drilling campaigns (2012/2013) conducted in high currents are described in this paper. The actual riser response matched riser analysis results to a significant degree. Extreme operations including typhoon evacuation, drilling operations in up to 5.2 knot currents, BOP landing in 4 knots, and emergency disconnect sequences (EDS) due to a cold front were performed in 2012. VIV fatigue damage was extremely low, with a maximum of 1.5% fatigue damage in the entire riser assembly in 2012. In 2013, operational criteria for cold front events were reviewed again since the number of these weather events experienced in 2012 was 3 to 4 times greater than in a typical year.

General guidelines and associated criteria are provided to evaluate a drilling riser system under high currents and approaching typhoons. This paper focuses and discusses the major operational concerns in these harsh environments. In addition, a riser fatigue monitoring system is described that has been used to track fatigue damage on riser joints both from VIV fatigue and wave loads.
Experimental Study On Compression Indices Of Gas Hydrate-bearing Sediments
Authors: Kim H.S. , Cho G.C.
Published: June 2014

For gas hydrate production, gas hydrate-bearing sediments should be depressurized below the gas hydrate equilibrium pressure. Gas hydrate-bearing sediments are compacted during the depressurization process because additional effective stress evolves due to a decrease in pore pressure. The compaction of a gas hydrate reservoir can lead to several geotechnical problems such as the destabilization of the production well, settlement of the seafloor installation, or slope failure of the production site. Thus, it is important to determine the compression characteristics of gas hydrate-bearing sediments and the geotechnical behavior of gas hydrate-bearing sediments during the gas hydrate dissociation induced by the depressurization. In this study, gas hydrates were synthesized in remolded sediment samples that were originally cored from a hydrate occurrence region in the Ulleung Basin, the East Sea, offshore Korea. The volumetric strain (or change of void ratio) of gas hydrate-bearing sediment samples were measured for different gas hydrate saturations and under different vertical effective stresses. The experimental results reveal the relation between compression (or the slope of a normal consolidation line) of gas hydrate-bearing sediments and gas hydrate saturation. Experimental data for compression indices of gas hydrate-bearing sediments can be applied to numerical modeling for a geotechnical stability analysis of gas hydrate-bearing sediments.
Earthquake Response of Pipelines on Submarine Slopes
Authors: Kaynia Amir M. , Dimmock Paul , Senders Marc
Published: June 2014

With recent trends in the offshore industry to move to deeper water, the response of submarine slopes has become a major geo-hazard issue partly due to the consequences for pipelines traversing the slopes. The dynamic and permanent displacements of the slope can exert axial loads and large bending moments on the pipeline. A fully integrated nonlinear dynamic analysis of pipeline-slope response under earthquake loading is impractical due to the spatial extent of the model and complications of pipe-soil interaction. The objective of this paper is to present a numerical model for this problem by a sub-structuring approach whereby the response of the pipeline is computed in two steps. In the first step, the dynamic response of the slope is computed independently of the pipeline, and in the second step, the interaction of the pipeline with the soil is analyzed using a model of the pipeline on distributed strain-softening soil springs. The input motion in the latter analysis is the asynchronous acceleration time histories computed on the surface of the slope along the pipeline in the first step. The computational model developed for this purpose, Quiver_pipe, is the result of research in the Joint Industry Project (JIP) Earthquake Effects in Deep Water.
Reliability Analysis of Lazy Wave Steel Catenary Riser (LWSCR) Using Real-Time Monitoring Data
Authors: Zhang Libang , Wu Chunfa , Liu Liming , McQueen Mark
Published: June 2014

Lazy Wave Steel Catenary Riser (LWSCR) is a relatively new type of configuration through the introduction of buoyancy modules for a certain length of the suspended riser for deep-water application. The benefits of this configuration includes the lowering of riser stress and fatigue at the top end and touch down area, making this an attractive concept. However, reliability analysis of LWSCR is scarce due to its very short application history and it is the purpose of this paper to investigate:Use of real-time monitoring field data from the Gulf of Mexico (GoM) in 2012, combined with a Finite Element Method (FEM) tool to calculate the reliability of the LWSCR;other conventional reliability methods, such as Monte Carlo simulation; andthe implication/impact of real time monitoring for assessing the riser integrity.The method proposed in this paper creatively integrates the concepts of Response Surface Method (RSM), FEM, and First Order Reliability Method (FORM). In general, the reliability analysis of nonlinear risers in the time domain is very challenging. Since the limit state function of a nonlinear dynamic riser system is implicit, RSM is used to approximate the limit state function and FORM used to calculate the corresponding reliability index, coordinates of the design point, and the sensitivity indexes for the random variables involved in the problem.The reliability estimation procedure is given in a form that will allow the basic ideas of the 1st and 2nd order reliability methods to be demonstrated. Using these methods allows variable sensitivity estimates for low computational cost to be made. The proposed procedure show good agreement over a range of probability distributions for the input random variables and for various complexities of the limit state functions.
How Waves can Significantly Impact Performance of Amine Unit Installed on a FLNG?
Authors: Weiss C. , Huguet E. , Magné-Drisch J. , Alix P. , Perdu Gauthier , White G.
Published: June 2014

To conquer the current FLNG challenge, experts have to answer the question " What effect does the movement of the ship have on the amine process?". It is necessary to rely on accurate knowledge of the impact of the floating support movement on the towers operation, to first secure then optimize the design of the process units. Indeed both flooding and internals efficiency will significantly impact the towers sizing (diameter and height) and thus the whole FLNG project.

It is a complex problem to be able to take into account the multitude of factors such as liquid viscosity, height of packing, diameter of column, acceleration, liquid/gas flowrate, type of packing, and motions imposed on the system. After first years of work when they completed an extensive review of bibliographic data to build an early model of maldistribution based on a theoretical approach, Total, Prosernat and IFPEN have now performed more than one year research and development at Heriot-Watt University to model mass transfer and hydraulics of a tilting, moving tower. To assess the impact of experimental column diameter and to be in position to scale-up the results, two columns have been used and will be described.

The program has included both static and motion tests with varying periods and angles, at different liquid loads to map the distortion of liquid distribution at adjustable heights of packing. The data now acquired has shown, depending on operating conditions, a significant impact on liquid distribution in the packing bed, leading to differentiated wetted zones, including dry and overloaded areas. Some examples will be given to illustrate the impact on tower efficiency and the corresponding tower oversizing based on the results of test campaign.
Corrosion Testing of Deepwater Tubing Materials under Extreme Pressure and Temperature Conditions
Authors: Huang J. , Guraieb P. , Yan C. , Contreras E. , Tomson M. , Tomson R.
Published: June 2014

Prediction and prevention of scale and corrosion at extreme high pressure and temperature (xHPHT) is important to reduce environmental risk, improve human safety, and for production security for Gulf of Mexico (GOM) ultra deepwater (UDW) oil and gas production. In order to develop the methodology and prediction models needed for xHPHT corrosion, scale formation, inhibition, and the next generation of fluid modeling, this research was funded by RPSEA to study corrosion and scale at extreme pressure and temperature.

This paper presents the corrosion experimental work conducted at xHPHT and high total dissolved solids (TDS) conditions in both a static autoclave reactor and a flow-through apparatus. The corrosion behavior of different alloys used for deepwater production tubing in two types of synthetic brines which simulated two UDW well conditions were studied.

Reliable and feasible apparatus and procedures were developed for the corrosion study at extreme pressure, temperature and TDS conditions. Vertical scanning interferometry (VSI) was explored and found to be a powerful tool for localized corrosion analysis of different surface shapes (e.g., flat or curved).
Deepwater Reverse-Circulation Primary Cementing: Applicability and Technical Path Forward for Implementation
Authors: Wreden C. , Watters J.T. , Giroux R. , Nikolaou M. , Macfarlan K. , Richardson D.A.
Published: June 2014

A two-year government funded project is being conducted to evaluate the viability and applicability of Reverse-Circulation Primary Cementing (RCPC) in deepwater wells. This project focuses on the identification of technical issues that must be addressed before routine RCPC operations can occur in deepwater wells, and a recommended path forward to full evaluation of the viability of this placement technique in deepwater. Analysis includes numerical models and simulations, mechanical placement controls, cementing materials, and operational challenges.

While RCPC has been used on land and on a few shallow water offshore wells, it has not yet been fully evaluated for use in a challenging deepwater environment. The application of RCPC to deepwater wells is expected to reduce bottom-hole circulating pressures and prevent lost circulation during cementing, as well as increase safety, environmental sustainability, zonal isolation, and improve cement seals.

Standard commercially available software packages are unable to directly model the flow path through the complex configuration of a deepwater reverse-circulation cementing process. A multi-physics finite-element software package has been used to develop a model to predict temperatures and pressures during the reverse-circulation cementing process. Evaluation of mechanical placement controls has found that a major challenge will be the development of a switchable crossover between a conventional and reverse flow path, and the modification of float equipment. Also, with the application of RCPC it is anticipated that the design methodology of cementing fluids may be affected by changing the placement method.

One major challenge in deepwater cementing is the narrow formation fracture gradient, so the application of RCPC has clear beneficial potential. By lowering the Equivalent Circulation Densities (ECDs) during the job, the risk of fracturing the formation and lost-circulation is decreased. Less fluid lost to the formation during placement can potentially lead to higher tops of cement (TOC) and improved cement bonding and zonal isolation.
Characterization of the Slope-destabilizing Effects of Gas-charged Sediment via Seismic Surveys
Authors: Morgan Eugene , Vanneste Maarten , Vardy Mark
Published: June 2014

Finneidfjord, Norway has a history of submarine slope failure and hosts areas of buried, gas-charged sediment. Using shipboard seismic survey data from Finneidfjord, we illustrate how novel seismic data processing techniques can yield estimates of geotechnical properties of this gas-charged sediment: gas saturation (concentration) and excess pore pressure as well as their uncertainty. This data processing involves two steps:estimate the amount of seismic attenuation that a gas-bearing layer creates, andfit a wave attenuation model to the observed attenuation. We accomplish the first step using a wavelet-based spectral ratio approach, and find the seismic quality factor (inversely related to attenuation) from the change in amplitude spectra across the gas layer. The novelty of this paper really comes in the second step, where we create a Bayesian hierarchical model that combines a wave attenuation model with a spatial random (Gaussian) process model. The advantage of this combination is that our estimates of the gas properties not only must conform to the observations of attenuation (quality factor), but must also smoothly vary over space, as one would expect of any natural process. Ultimately, we end up with posterior distributions of gas properties at points throughout our gas-bearing layer, which give us estimates of parameter values and a sense of uncertainty about these estimates. We find good performance and agreeable values for gas saturation, but the model shows weak sensitivity to pressure, leaving large uncertainty in any excess pore pressure estimates. Implications for slope stability at Finneidfjord are discussed.
Significant ageing effects for axially loaded piles in sand and clay verified by new field load tests
Authors: Karlsrud Kjell , Jensen Tor Georg , Lied Ellen Katrine Wensaas , Nowacki Fritz , Simonsen Arne Schram
Published: June 2014

The paper describes key results from a series of new load tests to verify the impact of time or ageing on the axial bearing capacity of driven tubular steel piles. Load tests in two different sand deposits (a silty fine loose sand deposit and a medium dense, medium sand deposit), and four different clay deposits (low and medium plastic normally consolidated clay, over consolidated glacial clay, and a very highly plastic and over consolidated clay) were undertaken. Six tubular test piles were driven at each test site, with diameter 400 to 500 mm and length around 20 m. The piles were loaded to failure typically 1, 3, 6, 12 and 24 months after pile driving. At both sand sites, the shaft friction approximately doubled from the 1 month to the 12 months tests, but tended to level off after that. The ageing effect for piles in clay vary with the clay type, and comes in addition to the normal set-up due to dissipation of excess pore pressures. After 2 years, the gain in capacity range from a factor of about 1.1 to 2.0 compared to the capacity after full re-consolidation. The tests in the low-plastic low-OCR clay deposit showed the largest gain, and the tests in the highly plastic high OCR clay deposit the smallest. The study also revealed that repeated load testing on the same pile to failure can give both lower and higher capacity than first time testing, and therefore, can lead to misleading interpretation of ageing effects. One pile at each test site, was subjected to sustained loading at 60 % of the assumed failure load before being loaded to failure after 2 years. The impact of such sustained loading was generally to increase ageing effects for piles in clay, and reduce ageing effects for piles in sand. The overall results confirms that ageing effects are a significant positive factor to account for in future pile design practice.
SS: Donation of Petrotechnical Data to Universities, Paper: Geohazards And Fluid Seepage Assessment On The Mad Dog Field Using Bathymetry, Ultra-high-resolution Seismic And Satellite Seepage Slick Data
Authors: Cope N.R.G. , Huuse M.
Published: June 2014

This paper reports an environmental assessment of the geohazards and seep phenomena of the Mad Dog field area of the Gulf of Mexico. The Mad Dog block, centered on US GOM block GC782, is located on the Sigsbee Escarpment in the Green Canyon region of the Gulf of Mexico, approximately 310 km south of New Orleans. The study area covers approximately 120 km2 and extends to water depths of 1300 m – 2170 m. The available data included a deep-tow multibeam bathymetry and ultra-high-resolution 2D seismic grid in combination with satellite seepage slick interpretations from the greater Mad Dog area. Hydrocarbon seep phenomena and SAR slick data were cross-examined to determine a relationship; however although some large slicks had been mapped by SAR in the project area, the slick density was lower than anticipated and correlation to sea-bed manifestations was not always well defined. The seabed displayed substantial relief and steep gradients across a salt- related graben structure in the northwest, associated with several potential gas-related seismic wipeout features, and scarps in the central survey area. Substantial geohazards occur in the escarpment region with slope gradients up to 28 degrees and abundant evidence for mass transport deposits. The presence of strong currents that run parallel to the base of the escarpment at up to 1 ms−1 (Bryant et al. 2000) form mega furrows. Associated erosional processes in this current could mask seep phenomena and therefore be lost during bathymetry and subsurface analysis. Eight possible seep structures were observed in the region and one coned shaped mound interpreted as a mud/asphalt volcano. When correlating the locations to SAR slick data it was hard to conclusively establish a relationship between seeps and slicks due to the unknown currents. In order to reduce the uncertainty of slick and seep correlations, sea current data at various depths throughout the water column would be needed at the time of SAR capture, and access to any seafloor cores would help ground truth interpreted seepage phenomena. A better understanding of the plumbing system can only be gained from examining deeper-penetration 3D seismic data that was unavailable for this study.
An Integrated Approach for Numerical Simulation of Earthquake Generated Tsunamis: Modeling Tsunami Generation, Propagation, Inundation and Fragility Analysis of Coastal Structures
Authors: Basu D. , Das K. , Janetzke R. , Dasgupta B. , Stamatakos J.A. , Waiting D.J. , Sewell R.T.
Published: June 2014

The present paper presents an integrated computational approach for earthquake generated tsunami prediction. The computational framework fully integrates the earthquake generated tsunami source, open-sea wave propagation, and wave run-up with inundation and on-shore effects. In addition, preliminary fragility analyses are presented considering the dynamic inelastic (damage) response of simple structures from both hydrostatic and hydrodynamic pressures. A simplified source model is developed based on pertinent local geologic and tectonic processes, observed seismic data, and measured seafloor and land deformations. The source model establishes estimates of the configurations of seafloor deformation that are used for the initial waveform in the tsunami simulations. Well-resolved bathymetric and topographic data are used to generate the computational grid. The FUNWAVE-TVD solver with the nonlinear Boussinesq form of the Navier-Stokes equations is used to numerically simulate tsunami wave propagation and inundation. The coastal impact from the tsunami is represented through the structure fragility curve. The developed integrated approach was used to simulate the 2011 Tohoku-Oki tsunami. The tsunami fragility curve presented in this paper predicts the failure fraction (or probability of failure) as a function of wave amplitude and accounts for the water impact velocity, wave height, and dynamic load history associated with the impacting wave.
Nanostructured metallic materials in extreme environments
Authors: Zhang X. , Yu K.Y. , Chen Y.
Published: June 2014

Severe high pressure, high temperature downhole environment in gas and oil industry, and high dose radiation in nuclear reactors posed significant challenges for the application of metallic materials. In this paper, we will review our recent discovery of nanostructured triphase metallic materials that have extraordinary high temperature thermal stability. These nanostructured metallic materials also have high mechanical strength than their coarse grained counterparts. Metallic multilayers with immiscible layer interface also have the potential for accomplishment of high temperature thermal stability. Furthermore these immiscible multilayers have extraordinary radiation resistance. By using in situ radiation experiments inside a transmission electron microscope, we show that nanostructured multilayers have exceptional radiation tolerance with capability to remove radiation induced dislocation loops. Advanced materials are clearly necessary for their application in various extreme environments. Under this context, nanostructured metallic materials metals have emerged as promising candidates with superior damage tolerance.

The rapid development of numerous energy sectors calls for the design of advanced materials. Taking gas and oil industry as an example, the continuous push towards high temperature and high pressure downhole environment put increasing challenges to sustainability of currently employed metallic materials. In parallel, next generation nuclear reactors are being and designed to provide increasing service lifetime and enhanced safety and reliability. Materials to be employed to construct these reactors needs to withhold higher temperature, much aggressive radiation dose and in many cases corrosive environment. The properties of traditional metallic materials cannot accommodate these requirements. Extensive studies are being performed to search for novel metallic materials with unprecedented advanced properties. In this paper, we will discuss strategies to enhance thermal stability and radiation tolerance of metallic materials. Two examples will be provided to illustrate the ideas.