bluuebunny/crossref_metadata_2025 huggingface dataset:
Smart Cement Performance Enhancement with NanoAl2O3 for Real Time Monitoring Applications Using Vipulanandan Models
Authors: Vipulanandan C. , Mohammed A. , Ganpatye A. S.
Published: April 2018

Nano aluminum oxide (NanoAl2O3) up to 1% was added to the smart cement with a water-to-cement ratio of 0.38 to investigate the effects on the sensing properties and compressive strength. Series of physical, curing and compressive loading experiments evaluated the smart cement behavior with and without NanoAl2O3 up to 28 days of curing. The addition of 0.5% and 1% NanoAl2O3 increased the initial sensing property (electrical resistivity) of the smart cement by 10% and 30% respectively. In a one day of curing, the maximum change in the electrical resistivity (RI24hr) for the smart cement without NanoAl2O3 was 375%. The RI24hr for the smart cement with NanoAl2O3 increased with the amount of NanoAl2O3. Addition of 1% NanoAl2O3 increased the compressive strength of the smart cement by 14% and 42% after 1 day and 28 days of curing respectively. The nonlinear Vipulanandan p-q curing model was used to predict the changes in electrical resistivity with curing time. The piezoresistivity of smart cement with the addition of NanoAl2O3 was over 500 times (50,000%) higher than the regular cement depending on the curing time and NanoAl2O3 content. Also a gage factor correlation model was used to relate the strain to the resistivity changes under compressive loading. The Vipulanandan p-q stress-strain and the piezoresistivity models also predicted the experimental results very well. A linear correlation was obtained between the RI24hr and the compressive strength of the modified smart cement based on the curing time.
Reliability Analysis of Buried Offshore Pipelines in Sand Subject to Upheaval Buckling
Authors: Ismail S. , Najjar S. S. , Sadek S.
Published: April 2018

In this paper, the sources of uncertainty in the design of buried offshore pipelines against upheaval buckling in cohesionless seabed soils are combined and propagated within a reliability-based framework. The objective of this effort was to assess the inherent risk for pipelines that are designed as per standard practice, which is based on semi-empirical approaches that assume vertical or inclined slip line models within the overlying soil mass. A comprehensive database that consists of 143 laboratory experiments involving uplift of pipes through sand beds was compiled to assess the model uncertainty. The statistics describing the model uncertainty could be used by researchers and practitioners when assessing the risk of upheaval buckling of pipelines in cohesionless seabed soils. Results of the model uncertainty analysis indicate that the models of Schaminee et al. (1990) and Bransby et al. (2002) result in predicted soil uplift resistances that are on average 21% and 41% smaller than the resistances measured in the laboratory tests, respectively. The two methods also exhibit large model uncertainties with respective coefficients of variation (COV) of 0.39 and 0.37 for the ratio of measured to predicted resistance. The methods by White et al. (2001) and DNV (2007) are less conservative and less uncertain, with average under-predictions on the order of 2% and 9%, respectively and COVs on the order of 0.30 and 0.32. The reliability analysis results indicate that the probabilities of failure are sensitive to the design factor of safety, with probabilities of failure decreasing from around 1% to 0.001% as the factor of safety is increased from 2 to 3. For any given factor of safety, the probability of failure was found to be sensitive to the method used to predict the uplift resistance, and insensitive to the relative density and the temperature and pressure values adopted.
Expediting Deepwater Subsea Development with a Batch Drilling and Completion Strategy: Lessons Learned Offshore Angola
Authors: Piemontese M. , Tassone G. , Sita F. J. , Bertoldi L. , Taleballah E. Y. , Zhao G. , Crawford N.
Published: April 2018

Batch drilling and completion improve field development efficiency in deepwater subsea environments, but well completion operations may be suspended for a long time while waiting for a subsea production system to be installed.

An Angola deepwater field development plan called for five oil producers, two water injectors, and two water-alternate-gas injectors. Using a fast-track approach, the drilling campaign started in parallel with the subsea production system manufacturing. Seven of the nine wells were drilled and completed with reservoir isolation valves (RIVs) that were expected to suspend the wellbore for several months and then remotely open the wellbore without intervention. However, the RIV remote opening mechanism was compromised due to well conditions and compatibility issue in two wells, prompting contingency operations including coiled tubing and electric-line interventions and a redesign of the upper completions for the remaining wells.

The lower completion strings were designed to be isolated with an RIV equipped with a remote opening system based on a nitrogen precharged spring chamber and tubing-applied pressure cycles. After pressure cycles not trigging the remote opening mechanism to reopen the valves in two wells, root cause analysis determined that the combination of bottomhole temperature (120°C), fluid (CaCl2 brine), and long suspension time (12 to 22 months) prematurely aged the RIV elastomers, causing the nitrogen section to loose pressure integrity. As a contingency, intervention operations were performed in the two wells with compromised nitrogen section RIVs, and engineering designs were modified to optimize the upper completion strategy for the five remaining wells. The RIVs in the first two wells were successfully opened using coiled tubing milling (first well) and electric-line mechanical shifting intervention (second well)—the first such operations in the world for the full-ball type of RIV. The paper explains the tool selection and testing processes for the intervention operations, compares the economics of the different intervention approaches, and describes how engineers optimized the new completion design on the remaining wells.

By sharing lessons learned from root cause analysis, intervention operations, and new completion design, this paper adds critical experience to a relatively limited body of work related to engineering completions and contingencies for long-term well suspension and reentry for completion.
Underwater Free-Space Optical Power Transfer: An Enabling Technology for Remote Underwater Intervention
Authors: Jin Michael H. -C. , Pierce Jonathan M. , Lambiotte Joseph C. , Fite John D. , Marshall Jonathan S. , Huntley Melissa A.
Published: April 2018

This paper describes the research and development of underwater free-space optical power transfer (uFSO-PT) technology at Johns Hopkins University Applied Physics Laboratory (JHU-APL). Smart and autonomous underwater intervention for future, low-cost, safe, ultra-deep offshore operation desires a set of tools that are highly efficient and capable of providing new abilities. For example, resident autonomous underwater vehicles (AUVs) equipped with the optical transmitter would be able (i) to charge batteries of undersea sensors such as wellhead sensors and telemetry of well-monitoring systems and (ii) to turn on and off switches remotely without docking/latching to its target assets. This allows the assets to function for an extended period of time performing power and energy-demanding tasks without requiring expensive services from the water surface during inclement weather for its replacement, recharging, or switching. uFSO-PT technology enables the remote power transfer capability. It can serve as a remote battery charger for AUVs and other underwater assets supported by AUVs as well as currently used remotely operated underwater vehicles (ROVs). The successful bench- top laboratory demonstration of uFSO-PT has been made in this study by charging on-board batteries of a commercial AUV. Off-the-shelf blue light-emitting diodes (LEDs) were assembled to produce a 225W optical power transmitter and a standard optical tranducer was used to convert the optical beam to electrical power necessary to charge the batteries. The transmission distance can reach up to 10 meters and it varies according to the wavelength of the light, the type of seawater, and operational depth. The performance of the technology met the initial expectation and the analysis of the data from the experiment has identified science and technology (S&T) gaps to be filled in order to achieve the full potential of uFSO-PT.
Innovative Subsea Repair of a Leaking Flexible Joint Using Hybrid Gasket and Composite Material
Authors: Assier Ludovic , Byrd Daniel , Furmanowski Yves , Golecha Kartik , Beaumert Baptiste , Marin Olivier
Published: April 2018

During a routine subsea inspection of the Akpo subsea assets, leaks were identified on two of the flexible joints at the top of the water injection steel catenary risers. These leaks were categorised as the highest integrity threats for the district and a task force was formed in order to determine the cause of the leaks and thereby, the most appropriate means to resolve the issue. A phased array UT inspection method has been specially developed to perform underwater inspection of the gasket groove.

The nature of the leak was deemed time-critical. The leak was of relatively high volume (the leak rate was estimated at 5 000 cubic meters per day), was worsening and was inducing structural damages to the flexible joint by cavitation.

A technical solution was studied involving underwater machining using divers. The upper joint surface of the gasket groove was part of a replaceable spool but the lower joint surface was integral to the flexible joint and therefore had to be repaired in-place. After several months of planning and testing, it was determined that the machining tool was not suitable for the operation by divers. With only a few months remaining in the 6-month target delivery, a second solution was proposed using a composite epoxy mastic repair together with a hybrid steel-elastomer gasket. The use of such a solution would be a first-of-its-kind for this application and would involve underwater grit blasting to achieve proper adhesion of the mastic. It would also involve precise bolt torquing and tensioning in very restricted work space around the flexible joint receptacle and ultrasonic acoustic bolt length measurements, in order to measure the stress in the bolts.
Technology Qualification of Deepwater Transport Shuttle Adjustable Buoyancy System
Authors: Gaskill Collin G. , Carlisle Kipp B. , Schroeder Art J. , Chitwood James E. , Gay Tom A. , Zhao Wenhua
Published: April 2018

Qualification of new technology for deepwater offshore oil and gas exploration and production is needed for the industry adoption process of new equipment and methodologies. Comprehensive programs can alleviate numerous risks associated with new technology through the application of appropriate industry practices such as DNVGL-RP-A203: Qualification of New Technology. Once qualified, innovative designs can provide effective sources of required sustained cost reductions for field developments creating new economic viability. The objective of this paper is to describe the systematic approach developed for the qualification of macro buoyancy spheres used in loose configuration as adjustable buoyancy in deepwater transport shuttles for subsea facilities and chemical transport.

The qualification process is designed to examine macro buoyancy sphere structural stability under representative conditions of offshore transport shuttle loading, storage, and unloading at the surface and at depth. An overview of empirical testing procedures, equipment, and the configurations through which sphere performance will be quantified against application requirements is presented. Macro buoyancy spheres have been used for decades in a number of offshore and subsea buoyancy applications such as drilling riser buoyancy modules on marine drilling risers, mid-water distributed buoyancy on production risers and umbilicals, and installation buoyancy for subsea equipment. Their performance in these applications is well understood with wide acceptance in the market. Mass manufactured from high strength, low density materials, sphere performance specifications can be tightly controlled while still being produced in a very cost-effective manner. Once qualified, under the program described in this paper, these same buoyancy spheres have an innovative re-purposed extension within deepwater transport shuttle delivery systems.

The readily adjustable and controllable nature of this innovative approach with loose buoyancy spheres, versus a fixed buoyancy system, allows a single subsea transport shuttle to be utilized for a wide variety of loads and service conditions. The buoyancy can be adjusted to match specific payload needs, reliably positioned when and where required, then re-used multiple times in a service delivery mode. This patented feature (patents published and provisional US and world-wide) will enable subsea shuttle transport barges to economically convey equipment from the sea's surface to the mudline and vice versa, especially in remote locations for smaller subsea projects where a typical heavy-lift vessel may prove to be cost prohibiting.
Recent Advances in Well Modeling: Axial Interaction Between Structural Casings and Soil Under Cyclic Thermal Loads
Authors: Zhou Hongjie , Amodio Alessandro , Rodriguez Antonio Borges , Boylan Noel , Deeks Andrew
Published: April 2018

During operation, the structural casings of a well experience two types of cyclic loads due to the heating-up and cooling-down of the well, which are: i) cyclic thermal induced forces on the structural casings themselves; and ii) cyclic thermal forces at the top of the structural casings generated due to the expansion and contraction of the inner casings and tubing (against the restraint from the structural casings). Combined with the nonlinear, hysteretic and degradable behavior of the surrounding soil, the interaction between the structural casings and surrounding soil have a significant effect on the overall performance of a well.

This paper presents recent advances in the numerical modeling techniques of the well system, focusing on the axial interaction between the structural casings and surrounding soil under cyclic thermal loading. The complex structural casing – soil interaction under cyclic loading has been successfully modelled by using advanced cyclic t-z springs. The springs are integrated into a structural model representing the multi-string well system and the associated cement. In the model, the soil specific behavior of the t-z spring is accounted for by calibrating the t-z model against laboratory model tests on the particular soils encountered along the structural casings. The developed modeling approach can capture the variation (e.g. degradation) of the casing-soil interface strength under cyclic loading; thus allowing accurate prediction of well head movement, post-cyclic axial capacity of the structural casings, and oscillation and distribution of axial force along the structural casings during cyclic thermal loading. The predicted wellhead movement with thermal cycles is found to be consistent to the field observation. The insights gained from the modeling exercise enhance our understanding of the casing-soil interaction mechanism and could greatly benefit optimization of well design. The developed modeling technique is also equally applicable to conventional and energy pile designs in degradable material, and capable of accounting for the coupling effect between the axial and torsional loads.
Industry Limits Pushed on Cabiunas Gas Export Pipeline Project
Authors: d'Huart Pierre-Emmanuel
Published: April 2018

The Pre-Salt basin offshore Brazil provides lot of challenges in installation of pipelines and risers. As it is an area with very deep waters (>2000m) and relatively harsh wave conditions (Bi-directional waves, of annual average Hs 2m) Petrobras contracted SAIPEM FDS2 to overcome these challenges. This resulted in two records: the vertical pipe laying tension world record, and the installation of the largest, deepest and heaviest Free Standing Hybrid Riser (FSHR).

The first of the two records - on which this paper will focus - was set in December 2014 on the Rota Cabiúnas contract awarded by Petrobras to SAIPEM. For this project, the FDS2 laid the deepest section of a 24" pipeline in the Santos basin, which had a wall thickness ranging from 1.25" to 1.438" at water depths from 1700m to 2240m. A specific ultra-high-tension J-lay configuration, planned, engineered and implemented for the purpose of maximizing vessel operability in harsh environmental conditions, was made possible by the FDS2's high lay tension capabilities which allowed the planning of laying operations even in flooded configuration. The maximum tension recorded on the project of 760mT, which to date represents a vertical pipe laying tension world record, The FDS2's J-Lay Tower was also used to lay five In-Line-Items and the Pipe end assembly safely and efficiently.
Tactical Airborne Oil Spill Remote Sensing: Poseidon, A New Operational Approach
Authors: Vagata Alessandro , Pinho Guilherme , Hengstermann Theo
Published: April 2018

The extensive oil and gas infrastructure system and port systems in the Gulf of Mexico are crucial not only to the Texas economy but also the United States’ economy, with both environmental and national security impacts. The coastal gulf states are particularly exposed to pollution from either accidental or illegal discharge.

Both recent natural events and accidents have highlighted the urgency of ensuring the best available technology is available to mitigate the risk from hydrocarbon pollution.

Within this context airborne remote sensing is becoming a foundation of the overall strategy to improve the ability to plan and position response resources in the optimal areas to respond to spills. Having the right information at the right time optimizes dramatically the use of all the response resources. And assess the effectiveness of the response and make an accurate natural resources damage assessment is critical and requires as well quantitative and timely information.

In the past the main effort has been directed towards developing airborne sensors with enhanced spill monitoring capability. Recently, more and more attention has been paid to the operational approach and to the automated processing of oil spill data acquired by integrated airborne sensor platforms.

The most relevant features for an effective airborne remote sensing platforms are: multi-sensors system for complementarity and redundancy of information; capability to classify oil targets as Recoverable or Non-recoverable; capability to georeference the targets and track moving oil; real time relay of immediately usable information - for tactical and strategic use; data suitable to support the Common Operating Picture; ability to expand the operating window to low-light conditions.

This paper focuses on advanced data processing and presents ways of improving the usability of airborne multi-sensor oil spill monitoring systems. In this context, is given an overview of currently existing oil spill remote sensing technology like infrared/ultraviolet line scanners, microwave radiometers, laser fluorosensors and radar system. The paper presents Poseidon, a new airborne system for network-based real-time data acquisition, analysis and fusion of multi-sensor data. Also, a method for the distribution of oil spill data and related data products using web-based geographical information systems is described; automated generation of thematic maps of the oil spill scene along with their real-time web-based distribution is becoming more important in marine incident management.
New LWD Technology Provides High-Resolution Images in Oil- and Water-Based Muds for Improved Decision Making in Real Time
Authors: Gillen M. E. , Moody B. , Dymmock S.
Published: April 2018

A recently developed logging-while-drilling (LWD) ultrasonic imaging tool has been field tested and shown to provide high-resolution images that give an early indication of problems during drilling operations. These images are compared to other LWD imaging techniques in oil-based muds to demonstrate the advantages of the new technology.

The new tool employs a system of three equally spaced ultrasonic transducers along the circumference of the tool at the same level. This arrangement provides the high data density needed for the images and enables precise location of the tool in the borehole for accurate borehole corrections to the data, thereby enhancing the overall image quality. The images are used with other real-time LWD and measurement-while-drilling (MWD) measurements such as equivalent circulating density (ECD), and formation pressure tests (FPT), to monitor wellbore stability and other issues that can lead to non-productive time (NPT) during drilling operations.

The new tool has been field tested in a number of wells in different parts of the world. These tests demonstrated the capabilities of the images to identify wellbore stability issues such as breakouts and cavings. The images can also be used to identify geologic features such as fractures and faults that can impact the drilling operation as well as the eventual production of the well. Examples will also be shown that combine the interpretation of the images along with other MWD and LWD measurements to provide a superior technique for wellbore stability management in real time.

The new LWD tool provides high-resolution borehole images in oil-based and water-based mud systems. Previously, high-resolution images from an LWD tool were only available in water-based mud systems using electrical imaging tools. This new technology provides a much clearer image of the borehole that has been available in the past. The techniques developed for using this information in real time reduce the frequency and magnitude of borehole-related NPT events.
Malikai Tension Leg Platform - Drilling Tender Vessel - Top Tension Riser Operations
Authors: Aramanadka Shankar Bhat , Yong Lewis , Kota Ravi , Jamal Sharizal A , Yeap Fabian
Published: April 2018

Malikai Project made a cost-driven decision to adopt the 2-body TLP-DTV configuration to Drill and Complete the Wells offshore. By opting for a Tender Assisted Drilling approach to drill and complete the Well instead of fabricating a permanent rig package, the project could save capital expenditure by building a comparatively smaller TLP. Also cost-driven, for the first time in the industry, the project decided to employ Single-Casing Combo Top-Tensioned Riser (SCTTR) technology as opposed to using the combination of Drilling Risers, and a separate Dual-Casing Production TTR. This is however with a caveat that wear accumulation during drilling needs to be managed and kept to a minimum.

Combining the above, the project team needed to manage TLP-DTV marine operations paying attention to station keeping performance required by the SCTTR whilst ensuring the hardware on TLP-DTV (e.g. hawser lines, mooring lines, Personnel Transfer Bridge etc.) is operating safely within their design limits and maximizing the uptime of the offshore activities.

To address the specific joint marine operations on TLP and DTV during the Tender Assisted TTR installation, Drilling and Wells Completion phase of the project, an interdisciplinary taskforce comprising the TTR team, Station keeping and Global Performance team, Wells and TLP Operations teams was created for a fully integrated and focused operational procedure. This procedure was aimed atmanaging and assuring TLP-DTV repositioning and station keeping activities which meet the above constraints/objectives, complete with operation decision organization, a clear communication protocol, and comprehensive decision flowcharts to handle all possible scenarios during the operation. An onshore support group located within the well operations team is tasked with monitoring and predicting (based on forecast weather) of the performance of the TLP-TAD system for safe and effective station-keeping performance. The TLP-DTV-TTR operations is built upon the basis that the integrated team is able to plan the TTR installation / Wells construction operations in advance using forecast weather as inputs to continuously simulate numerically TLP-DTV performance - checking against repositioning criteria, as well as the continuous real-time monitoring of TLP-DTV performance against their operating windows using live data obtained from the MIS/MAS system (performed by both the Onshore team and Offshore team). Lastly, to ensure the overall effectiveness and accuracy in executing the operations, the team had created a suite of purpose-designed software to streamline the activities performed by the Onshore and Offshore Team respectively i.e. advanced activity planning via automated continuous forecast simulations of TLP-DTV and TTR performance to indicate operations go/no-go, as well as clear displays of key parameters constantly updated with live real-time data for operations monitoring.
Case Study: Deepwater Design Verification and Validation Testing for Subsurface Safety Valves for HPHT Environments
Authors: Thai Dan , Orzechowski Diana , Pinard Geoffrey , Henry Jason , Kaminski Dennis , Dighe Sourabh
Published: April 2018

The evolution of subsurface safety valve design for HPHT application has created the need for advanced design verification and validation testing to ensure "fit-for-service" application in a HPHT environment. With the release of API 14A 12th edition and the new V-1H validation grade, couple with Annex H for verification and validation requirements for high-pressure, high temperature environment, strenuous validation testing is required. Navigating the requirements can be difficult with the divergence from API 14A 11th Edition, Class 1, 2, 3, & 4 classes of service, to API 14A 12th Edition, V4-1 to V1-H. In addition to the validation grades, specialized Annexes (D, G, H, J, and L) requires collaboration between the Operator, with its functional specifications, and the service company to develop a specific design verification and validation testing program for Subsurface Safety Valves suitable for HPHT application.

This paper specifies a "fit-for-service" verification and validation plan conducted collaboratively by an Operator and Supplier. The validation testing plan outlines the requirement for V1-H validation grade along with required API 14A Annex testing. The paper also includes details on metallic component analysis using finite element analysis (FEA) and current ASME BPVC Section VIII using true-stress true-strain curves for accurate verification of the equipment design. Localized stress discontinuities and plastic localized yielding design criteria were also used to determine adequate protection against these failure modes, or if additional analysis is required.

With increasing regulatory oversight in HPHT technology development, product qualification planning requires in-depth knowledge of the designs and the criticality of the Subsurface Safety Valve as a critical barrier component. The Supplier and an Operator would like to share their experience and lessons-learned with the industry that would enable industry engineers to understand the requirements of design verification and validation testing of Subsurface Safety Valves for "fit-for-service" in a HPHT environment.
Search for MH370: New Geologic Insights Revealed through the Integration of Multiple Geophysical Datasets
Authors: McBee J. , Ingle S. , Gharib J. , McConnell D.
Published: April 2018

During the search for the missing Malaysian Airlines Flight 370 (MH370), Fugro acquired the largest extent of high-resolution bathymetry in the southern Indian Ocean to date. Integration of these recently released multibeam echosounder (MBES) backscatter, bathymetry, water column, and sub-bottom profiler (SBP) data reveal additional insights into the characteristics of the Indian Ocean seafloor and the geologic and oceanographic processes that shaped it.

From June 2014 to February 2017, the M/V Fugro Equator, the M/V Fugro Supporter, and to a lesser extent, others, collected MBES and sub-bottom data over 710,000 square kilometers in the search area and along transit lines using Kongsberg EM122 MBES systems. We use Fledermaus GeoCoder to process backscatter data, and ArcGIS to create mosaics of all survey lines. Kingdom SMT is used to interpret SBP data. Water column data are interpreted in Fledermaus Midwater. Fledermaus is then used to create a 3D representation of the dataset.

In this presentation, we will highlight several prominent regional seafloor features, and illustrate insights gained by integrating MBES backscatter and water column data with bathymetric analyses. Backscatter data to the north of the southern flank of Broken Ridge illustrate the complexity to which sediment has been reworked downslope where intricate patterns of low backscatter intensities are observed. Here, exposed rocks form prominent high backscatter reflectors amid the surrounding low backscatter sediments. The lateral extent of high backscatter intensity reflectors south of the Diamantina reveals the expansiveness of exposed igneous rocks that resulted from seafloor spreading. Volcanic features, including off-axis volcanoes and leaky transforms are also interpreted as high backscatter anomalies in the tectonic spreading fabric to the north of the Geelvinck fracture zone, towards the southern extent of the dataset.

These examples show that by integrating the entire suite of data collected by MBES and SBP systems, more detailed interpretations of the geologic processes that shaped the seafloor may be gained than by examination of bathymetry alone.
A New Correlation for Predicting Solid Particle Erosion Caused by Gas-Sand Flow in Elbows
Authors: Parsi Mazdak , Arabnejad Hadi , Al-Sarkhi Abdelsalam , Zahedi Peyman , Vieira Ronald E. , Sharma Partha , McLaury Brenton S.
Published: April 2018

The current work presents a new correlation for estimating solid particle erosion under gas-sand flow conditions in standard elbows. To develop this correlation, in the first step, a dimensional analysis was performed to obtain dimensionless groups that governed the erosion phenomenon in standard elbows. Then, a power-law correlation was established among the extracted governing dimensionless groups. In the next step, effect of target wall material on erosion was investigated to include a material factor in the correlation. In the final step, an empirical factor to account for sand particle shape was included in the correlation.

Dimensionless erosion number was calculated for different flow conditions, sand sizes and densities, and pipe diameters. It was shown that the dimensionless groups and their exponents provide insight into the importance of different parameters on erosion. The resulting erosion ratio (in mm/kg) was compared to experimental data collected from the literature. It was found that the dimensionless erosion number correlation follows the trend of the experimental data, and good agreement between the correlation's predictions and the experimental data was observed.

The proposed correlation is an effective tool that enables the users to estimate erosion under gas-sand flow conditions in just several minutes. More importantly, unlike the existing empirical correlations that do not account for many of the parameters affecting erosion and have been developed based on a limited number of experimental data, the correlation proposed accounts for all flow and particle parameters.
Normalized Modulus Reduction and Damping Ratio Curves for Bay of Campeche Carbonate Sand
Authors: Flores Lopez F. A. , Taboada V. M. , Gonzalez Ramirez Z. X. , Cruz Roque D. , Barrera Nabor P. , Dantal V. S.
Published: April 2018

Predictive equations of normalized shear modulus (G/Gmax) and material damping ratio (D) are presented for calcareous sand, siliceous carbonate sand and carbonate sand of the Bay of Campeche and Tabasco Coastline. This was achieved using a database of 84 resonant column tests and 252 strain-controlled cyclic direct simple shear test that provide data to define the normalized shear modulus, G/Gmax, and material damping ratio, D, versus cyclic shear strain. The range of cyclic shear strains of the database is from 0.0001% to 1%, and the range of carbonate content (Ca2CO3) from 10% to 100%. The curves of normalized modulus reduction and damping ratio were organized in three groups according to the percentage of carbonate content: 1) calcareous sands (10% to 50%), 2) siliceous carbonate sand (50% to 90%) and 3) carbonate sands (90% to 100%). Two independent modified hyperbolic relations for normalized modulus reduction and material damping ratio versus cyclic shear strain were developed for each group. The normalized shear modulus was modeled using two parameters: 1) a reference strain defined as the strain at which G/Gmax is equal to 0.5, and 2) a parameter that controls the curvature of the normalized modulus reduction curve. The material damping ratio was modeled using four parameters: 1) a reference strain γrD defined as the strain at which D/Dmax= 0.5, 2) a curvature parameter αD that controls the curvature of the material damping ratio curve, 3) a maximum material damping ratio Dmax, and 4) a minimum material damping ratio Dmin. The new empirical relationships to predict the normalized modulus reduction and material damping ratio curves as a function of effective confining pressure are easy to apply in practice and can be used when site-specific dynamic laboratory testing is not available. The curves of G/Gmax-γ and D-γ, are similar between silica sand and calcareous sand. The curves of siliceous carbonate sand and carbonate sand are very similar, but show a different shape and width than the curves of silica sand and calcareous sand. This indicates that when the carbonate content is smaller than 50% there is a small effect on the curves of G/Gmax-γ and D-γ, and a considerable effect when the carbonate content is greater than 50%.
Cost Optimized Solutions for Near Shore FLNG
Authors: Kim CN , Hwang HW , Kim SE , Park SM , Park JS , Kim TJ , Kim YR , Kim YH
Published: April 2018

Offshore development project are facing significant challenges from current market environment. Due to current low price of oil and gas, the development of natural reservoirs on offshore may not be attractive. However, the demand of natural gas will gradually increase because natural gas is relatively clean source comparing to the other fossil fuels and the demand of clean energy is growing due to environmental change.

In this regards, Near Shore FLNG is becoming one of the most economical solutions as the unit is equipped with essential liquefaction process, storage as well as offloading facility. That is, comparing to typical deepwater FLNG application, expensive components are not required such as the turret, complex pre-treatment system and self-generation of utilities, plus logistics such as refrigerant supply are better.

The purpose of this paper is to introduce the optimized process of Nearshore FLNG system comparing typical FLNG. To illustrate the optimized process, at first, target area is defined as North America. The reason why North America is selected is because of the potential of future projects and shale gas revolution. The gas composition is defined by reviewing 1,200 shale gas reservoirs in North America and considering the hydrocarbon gas is typical pipeline gas which needs to meet Pipeline Gas Spec requirement. Topside process is reviewed to find optimized options and process model has been built to check feasibility. Analysis is made on several technical optimized options as below. Optimized Liquefaction systemOptimized Condensate SystemRemove Deethanizer and Ethane make up columnOptimized Heating Medium systemOptimized Produced Water Treatment System

Finally, this paper provides several options with reducing several facilities and optimizing process which will reduce CAPEX/OPEX.
Preventing Unexpected Walking Induced by Interaction Between Acceptable Uncontrolled Buckles And Spans
Authors: Verdeil Julien , Mourad Romain
Published: April 2018

The design of a long gas flowline laid on a rough seabed and in which HP/HT gas is circulating shows that the numerous spans along the line were all acceptable and that some acceptable lateral buckles will occur at some key features (crests).

A long section of the line was expected to be anchored preventing any walking. A first analysis with the steepest P/T transients showed no walking behaviour of the line. However it was observed that, when the line is gradually heated to the highest HT/HP profiles, unacceptable walking is observed at hot end. This paper will present how this line was designed and how an effective mitigation design was performed to prevent unacceptable walking and how that was implemented at the appropriate time in the overall design process.

Design activities were performed with non-linear finite-element software able to model the pipeline and its interaction with the rough seabed. The standard design activities were done, specifically; on-bottom roughness, lateral buckling analyses and their conclusions combined at the end of the design process into a global model built to simulate potential interaction between buckles and spans. This is a stepped process that should be followed in any pipeline design activities.

All spans and all potential rogue buckles were found acceptable, and the steepest HP/HT transients did not induce walking behaviour, as per conclusions from preliminary engineering studies. However, combining the most severe HP/HT scenario (corresponding to restart of the wells one after another) found spans along the line and the most probable scenario for locations of buckles led to unacceptable walking at hot end. This phenomenon is explained by the interaction between buckles and spans, as they evolve with the applied loadings. Mitigating this walking was achieved by integrating a padeye in the end structure. This particular padeye was linked by a chain to a single suction pile installed nearby. The integration of the mitigating padeye was done without any interruption to the overall schedule. This was achieved by an effective design process which listed the Key Interface Datas (KIDs) which in turn defines the important milestones between engineering disciplines (pipeline, structure, installation, fabrication).

There is no one single scenario that can lead to pipeline walking, particularly for lines laid on rough seabed with many spans and buckles. It is recommended to always study a case where several cycles of maximum operational profiles are applied. The overall design process should also list the Key Interface Datas in the overall schedule in order to ease the interfaces between engineering disciplines.
Malikai TLP - Superlift and Integration of Topside with Hull
Authors: Sinha S. K. , Zin Chuah Siak , Lim John , Walters Paul
Published: April 2018

Lifting a heavy topside (superlift) for the integration with the Hull has always been a challenge for any mega project. Methods of lifting, skidding, lowering down for integration and final load distribution must be carefully studied before selecting the best possible method. Once the method has been determined, and the relevant procedures have been developed, the execution must then be strictly done in accordance of the procedures to meet the set objectives for the selected method.

The superlift and integration method must be determined at an early stage of the project, considering all aspects of engineering, procurement, installation, construction, post installation removal, contingencies, safety, scheduling, etc. for the project. This decision of selection is often a challenge, which will be discussed in this paper. All aspects including the above and the risks involved in each of them must be considered and mitigated.

This paper presents the super lift and integration method used for the Malikai Tension Leg Platform (TLP), highlighting the salient engineering characteristics of the specific method used.

For superlifting the Malikai TLP Topside, the Hull was completely integrated and both the Hull and the Topside were weighed. The Topside was then moved close to Hull, superlifted and then skidded above the Hull, alighted to the deck post and then finally lowered, to be integrated with the Hull. The operations involved heavy planning and interface with the superlift subcontractor, engineering, fabrication team, vendors and regulatory bodies. Various challenges were faced where the Topside of approx. 14,000 MT was lifted and integrated with the hull which will be outlined/discussed in the paper.

The superlift and integration which took approximately 9 days, finally resulted in safe integration of the TLP as planned with necessary design, construction and operational contingencies. The method included jacking up the Malikai Topside 40m high, before skidding the Topside 90 m whilst at this elevation - making this the world's highest jack-up and skidding operation performed on this scale.
Hybrid Subsea Foundation for Deepwater FLET: A Case History
Authors: Won Jeong-Yun , Audibert Jean M. E. , Misra Asutosh , Bush Samantha
Published: April 2018

In a recent Gulf of Mexico deepwater development project, two hybrid subsea foundations (HSF) were designed, fabricated and successfully installed for two flowline end terminations (FLETs) in approximately 2,170 meter water depth. The HSF is an attractive option when a subsea structure is subjected to substantial lateral loads, vertical loads and overturning moments that cannot be effectively resisted by a typical shallow (mudmat) foundation. A new HSF design methodology was established and a pile head locking system was developed by the project team. This is the first offshore application of the HSF concept utilizing the vertical resistance from the corner piles in addition to their lateral resistance via a custom designed pile head locking system. In configuring the pile head locking system to provide pile head fixity, the gap between the sleeve and the pile became one of the governing factors for design, fabrication and installation of the HSF. This paper presents the case history of the successful project execution covering the detailed design, fabrication and staged installation. Foundation selection during the detailed design stage, description of the pile locking system, preventive measures taken during the fabrication stage, back analysis results from the installation stages and pictures taken by remotely operated vehicles (ROVs) during the FLET HSF installation are presented.
Integrating Completions for a True Spud to First Oil Deepwater Well Manufacturing Machine
Authors: Wijning D. , Adams E.
Published: April 2018

The concept of a deepwater well manufacturing machine, defining the next generation drillship design, provides a blank canvas for the pre-commissioned integration and deployment of complex subsea completion systems. Input from operators and third-party service providers on future deepwater well requirements enables the scientifically driven pre-positioning of the entire completions package, including tubulars, allowing for seamless transition from drilling to completions to safely and predictably reduce well delivery times, from spud to initiation of production.

This paper discusses step-change advances designed in an evolving concept to facilitate efficient running of deepwater completions, including offline handling of subsea completion equipment and XT's, while reducing logistical requirements. The authors will examine the flexible base of design, which comprises a flat and unobstructed work deck on the entire vessel, and replacement of the derrick and substructure with a Dual Multi-Purpose Tower (DMPT), incorporating robotic pipe manipulators and a 1,800ST hoisting system. An examination of current methodologies and future deepwater well designs provides insight into improvement opportunities, including applicable design of new or modified completions equipment.

The robotized DMPT in combination with a large, flat deck empowered the conception of new methodologies for handling and running subsea completion equipment and consumables, including cutting-edge drilling/completion fluid system and delivery capabilities. The modularized tower, robotized pipe grippers, tools, dual rotating setbacks and other unique components can be quickly and safely employed to optimize efficiency and safety throughout the completions process. Tubing can be racked in the setback drums in up to 180-ft stands, while more delicate and non-standard assemblies can be hung off at convenient elevations. The manipulators, with various dedicated tools, allow semi-automated running in hole. Furthermore, with a drill floor flush with the deck and absent V-door limitations, bulky equipment can be rigged up offline and easily skidded to the well center when required. When running tubing, a modular raised and skiddable work floor facilitates attachment of control lines and umbilicals below the hang-off table. Strategically located utility stations on the deck allow plug-and-play connections for power, air, communications and data transfer for third-party equipment, thereby reducing rig-up and rig-down time. Ultimately, these and other advancements have the potential to reduce by 20-30% the days required to complete a deepwater well.

By evaluating future deepwater well requirements, an optimal layout can be achieved at the onset. The vessel can be commissioned with all the proper tie-in points and a deck uncluttered with high-pressure pipe lines, cabling, separate diesel generators and the like. Provisions for ensuring tubulars are hung off so as to remain heave compensated at all times are also conceived and will be presented.
Prediction of Seabed Trench Formation Induced by Anchor Chain Motions
Authors: O'Neill Michael , Erbrich Carl , McNamara Anthony
Published: April 2018

Recently there has been significant interest in the development of seabed trenches associated with anchor chains in front of suction anchors. The issue was first highlighted by Bhattacharjee et al. (2014) in relation to the Serpentina FPSO located offshore Equatorial Guinea. The subsequent implications of the Serpentina experience have been significant, such that the geotechnical design of suction anchors now often includes allowance for the potential formation of an anchor chain trench extending down to the anchor padeye.

Previous publications relating to anchor chain (mooring line) trenching have focussed primarily on observational case histories (e.g. Serpentina FPSO) and analysis of the impact of seabed trench formation on suction anchor in-place holding capacity. Furthermore, recent work by others outlined the results of 1g and centrifuge model anchor chain tests and the use of these results in the preliminary development of a chain model encompassing the progression of erosion and trench wall collapse with time.

This paper describes a new design tool which permits identification of the primary mechanism leading to the formation of seabed trenches running along the embedded section of mooring lines in front of anchors. The model provides a direct approach to estimating the extent of seabed trench formation that may arise from mooring line motions under both normal (operational) and extreme (storm/cyclonic) conditions. As inputs the design tool requires the full mooring line layout/configuration from the fairlead (located at the floating facility) down to the anchor padeye, the range of design loads at any point along the mooring line and the seabed soil properties.

Through an example study the paper demonstrates the ability of the design tool to back-analyse seabed mooring line trench formation at existing installations and predict the extent to which mooring line trenches may develop for new sites. The ability to perform site-specific assessments of trenching risk should in turn allow the industry to move away from including blanket allowances for trenches which, sometimes unnecessarily, mean that much larger anchors are planned than actually required.