bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distribution of Surface Elevations in Nonlinear Seas
Authors: Tayfun M. A. , Alkhalidi M. A. 
Published: March 2016

AbstractThe statistical distribution describing nonlinear narrowband waves characterized with second-order nonlinearities is simplified to an explicit closed form amenable to theoretical and practical applications. The approximate form and its salient features are examined and compared with oceanic measurements in deep and shallower water depths. The approximate form developed here provides certain advantages in terms its algebraic simplicity, accuracy and a somewhat wider domain of validity, in particular, relative to a previous approximation derived from the same second-order narrowband model. Comparisons with the oceanic measurements in deep and shallow water depths also yield good agreement with the approximate form over the range of surface elevations where the second-order theory provides a relatively valid representation of nonlinear waves.
Inclined Pull-Out Capacity of Dynamically Installed Anchors in Clay
Authors: Chen Zongrui , Sun Jie , Gu Hai 
Published: March 2016

Abstract
Dynamically Installed Anchors (DIAs) refer to anchors which can embed themselves by free-fall from a specified height above the seabed. They have been widely regarded as the most promising deepwater anchor concept in terms of several advantages over other anchors. First, it is economical because of ease fabrication, quick installation, and no requirement from external source of energy. Second, the installation cost is less depend on the water depth. Finally, the holding capacity is less sensitive to the soil undrained shear strength profile since higher seabed soil shear strength permit less penetration depths and vice versa. However, a degree of uncertainty still exists in relation to predicting the embedment depth and subsequent pull-out capacity especially the inclined pull-out capacity.
The pull-out capacity of DIAs can be dominated by the vertical or horizontal failure mechanisms or a combination of the two. When the combination controls, the DIAs are referred to as being under the inclined pull-out failure. This paper focuses on the inclined pull-out failure of DIAs. A series of finite element analysis on pull-out resistance of DIAs in normally consolidated clay was carried out. First, the numerical results were validated through experimental results and analytical empirical results. A proper method to model the inclined pull-out of DIA is illustrated. Then, a methodology for evaluating the inclined pull-out capacity of DIA is proposed based on the numerical parametric study. This method is capable of predicting pull-out capacity of DIA for various embedment depths and DIA aspect ratios. Finally, the design procedure for DIA is proposed.
Development of a Novel Hybrid AUV System for Pipeline Inspection in Gulf of Thailand
Authors: Hoonsuwan Phakhachon , Tipsuwan Yodyium , Slanvetpan Thana 
Published: March 2016

Abstract
Oil and gas companies are increasingly being forced to conduct their sub-sea pipeline inspections in increasingly more hostile and deeper waters. Typically, Remotely Operated Vehicles (ROV) are used for sub-sea pipeline inspections and these are controlled by experienced ROV operators from a surface support vessel, which tend to make ROV operations costly. Conversely, an Autonomous Underwater Vehicle (AUV) can perform sub-sea pipeline inspections without the need for a human operator. This paper sets-out to describe the development of a novel Hybrid AUV (HAUV) system, composed of two unmanned vehicles and designed specifically for sub-sea pipeline inspection. The first vehicle is a compact Unmanned Surface Vehicle (USV), which tracks a sub-sea pipeline from the sea surface. The second vehicle is a HAUV, which is connected to the USV via a fibre optic tether. Both vehicles operate together to automatically inspect sub-sea pipelines. The complete system is controlled by a remote control station on the surface. At this early stage of development, its capability is limited due to its size and battery power source but lab-scale units have been developed and have undergone field testing. Our team study is ongoing and endeavours to refine the HAUV system-capabilities enabling us to offer a cost-effective approach for sub-sea pipeline inspection in the near future.
Centrifuge Model Study on Inclined Pullout Behavior of Square Plate Anchors in Normally Consolidated Clay
Authors: Chen J. , Leung C. F. , Chow Y. K. 
Published: March 2016

Abstract
The inclined pull-out behavior of square plate anchors embedded in normally consolidated clay is presented in this paper. A series of centrifuge model tests have been performed to simulate plate anchor extraction process. Clay sample was prepared under self-weight during centrifuge spinning, where soil undrained shear strength increases linearly with depth, simulating the typical soil strength profile in offshore environment. Pre-embedded plate anchor was pulled out with displacement and resistance measured. Anchor capacity is quantified and presented in the form of capacity factor. The effect of anchor embedment ratio (the ratio of embedment depth to anchor width) and pullout inclination on capacity factor is investigated.
Advances in Computational Hydrodynamics Applied to Wave-in-Deck
Authors: Chen Yu , Wu Yanling , Bahuguni Anand , Gullman-Strand Johan , Zhang Yali , Stewart Graham , Lv Xin 
Published: March 2016

Abstract
In this study, advanced numerical CFD tools based on OpenFOAM are developed to generate extreme waves for the investigation of wave-in-deck loads on fixed offshore structures. The numerical method employs a Navier-Stokes solver with the free-surface captured by the volume of fluid (VOF) approach. The advantages of numerical simulation through CFD are: 1) full scale simulation of nonlinear phenomena; 2) potentially more accurate prediction as viscous and inertia forces are included whereas a model test based on Froude scaling can only scale the inertia forces; and 3) detailed insight into the flow and resulting loads. The numerical simulations for long-crested extreme waves capture the evolution of impact loads and free surface during the interaction with the platform deck. CFD provides more accurate results than analytical tools and the flow physics can be studied in detail, providing further insight that can lead to improvements in the analytical tools. This study also provides a benchmark set of problems for wave loading on platform decks.
Limitations of Using Smart Wells to Achieve Waterflood Conformance in Stacked Heterogeneous Reservoirs: Case Study from Piltun Field
Authors: Khural Harsimran , Rai Udai Bhan , Kumar Ram , Marpaung Billman , Faulkner Andrew , Kumar Rajan 
Published: March 2016

Abstract
The use of smart completion with downhole fluid control through Inflow Control Valves (ICVs) has been extensively described in the literature for balancing the water injection profile and improving the sweep efficiency in commingled water injection. This paper describes the limitations of such a system in ensuring zonal distribution of water in stacked, highly heterogeneous reservoir systems.
Voidage replacement and pressure maintenance requirements necessitate waterflood under fracturing conditions in the four stacked reservoirs (Zone 1 to Zone 4) in Piltun field, offshore Sakhalin Island, Russia. These reservoirs are heterogeneous with differences in their permeability and fracture gradient. Consequently, smart injectors with four ICVs were planned to maintain the desired injection allocation in these reservoirs. The initial injectivity of these wells was extremely low with all of the injected water going to the deepest zone (Zone 4). An expensive pump upgrade improved the overall injectivity, with drastic changes in the distribution of the injected water amongst the reservoir layers. Contrary to performance prior to pump upgrade, the shallowest zone (Zone 1) emerged as the dominant receiver of injected water. Overall, the zonal distribution of water remained a problem with little success in injecting water in the remaining two zones (Zone 2 and Zone 3). Very limited improvement in the water distribution was obtained by manipulating the ICV valves.
Sector modeling was taken up for the injection wells to understand the injection behavior. Modelling results show that after the pump upgrade, fracturing was initially achieved in all zones, although sustained fracture opening and propagation was only possible in Zone 1, the reservoir with better flow properties and reasonably low fracture gradient. The other zones gradually reverted back to injection under matrix conditions with time. The additional pressure drop created by the flow control device is not sufficient to choke back the major zones and achieve sustained fracture growth and water injection in the minor zones in Piltun field. The results demonstrate that the use of intelligent completion for waterflood conformance can be limited by large stress and permeability contrast.
Mitigation of Pig-induced Slugs by Combination of By-pass Pig and Inlet Separator Dual Control Valves
Authors: Park Sangmin , Kim Minseong , Nydal Ole Jørgen , Lee In-Beum 
Published: March 2016

Abstract
For the determination of the design basis of the inlet separator in the offshore oil and gas plant, one of the most crucial factors is the liquid surge volume generated mainly by the transient phenomena such as riser slugging and pig-induced slugging. In particular, pig-induced slugging frequently brings about the most serious slug problems. In the study, a combination of a by-pass pig and an inlet- separator dual control valve scheme is introduced for the application, of which pigging operation is not possible by a conventional method because it causes inlet separator flooding. First, for the purpose of the estimation of the simulation accuracy, the stability map generated from an S-shaped riser experiment is compared with the prediction of OLGA simulation. And then, it is demonstrated that a combination of a by-pass pig and and inlet separator dual control scheme makes it possible to operate stable pigging, even though a conventional pigging is not available due to the excessive pig-induced slugging.
Actively Managing Hydrates Without Compromising on Production and Safety Will Reduce OPEX
Authors: Ahmed S. , Azhar M. A. , Hagag A. M. , Torky A. N. 
Published: March 2016

Abstract
Hydrates have been a constant threat to subsea deepwater operations since pipelines were first used to transport multiphase fluids. Hydrate blockages in pipelines and processing equipment can cause deferment of production and as a result can cause millions of dollars in losses.
The extensiveness and complexities of subsea production systems and deepwater developments such as West Delta Deep Marine (WDDM) in Egypt pose huge challenges in implementing hydrate management strategies. In the past, unplanned strategies were implemented in WDDM due to a lack of Flow Assurance (FA) awareness and understanding, resulting in production deferment caused by hydrate formation or blockages. Operational Expenditures (OPEX) on hydrate inhibitors such as Mono Ethylene Glycol (MEG) and Methanol (MeOH) have been increasing significantly.
Since the implementation of Flow Assurance in WDDM, work has focused on key areas of the development that were hydrate prone, by making use of in-house software and industry good practice. A holistic view of WDDM including equipment and instrumentation was taken, along with the chemistry behind why hydrates form.
To minimise the deferment to production, hydrate monitoring, previously based on a single pressure reading in the flowline, was challenged and changed to the current technique which is based on flowline pressure drop across multiple elements such as flowline, infield line and valves. This has been made possible by implementing a monitoring system based on Pi linked to the control room, allowing engineers throughout the organisation to review a wide range of actual data in real time. As a result of continuous monitoring and optimisation, hydrates are no longer seen as a threat to WDDM production.
Various achievements and lessons learnt in managing hydrates in WDDM over the past 12 years, specifically in hydrate prevention, monitoring, and remediation plan has been compiled. As a result, a "WDDM Hydrate Management Strategy" has been introduced for the operation and future development of WDDM. This paper will share the significant lessons accumulated in WDDM from actual experience of operating the field.
Nanofluids for Enhanced Oil Recovery Processes: Wettability Alteration Using Zirconium Oxide
Authors: Nwidee Lezorgia. N. , Al-Anssari Sarmad , Barifcani Ahmed , Sarmadivaleh Mohammad , Iglauer Stefan 
Published: March 2016

AbstractUltimate oil recovery and displacement efficiency at the pore-scale are controlled by the rock wettability thus there is a growing interest in the wetting behaviour of reservoir rocks as production from fractured oil-wet or mixed-wet limestone formations have remained a key challenge. Conventional waterflooding methods are inefficient in such formation due to poor spontaneous imbibition of water into the oil-wet rock capillaries. However, altering the wettability to water-wet could yield recovery of significant amounts of additional oil thus this study investigates the influence of nanoparticles on wettability alteration. The efficiency of various formulated zirconium-oxide (ZrO2) based nanofluids at different nanoparticle concentrations (0-0.05 wt. %) was assessed through contact angle measurements. Results from the experiments showed ZrO2 nanofluid have great potentials in changing oil-wet limestone towards strongly water-wet condition. The best performance was observed at 0.05wt% ZrO2 nanoparticle concentration which changed an originally strongly oil-wet (152°) calcite substrate towards a strongly water-wet (44°) state thus we conclude that ZrO2 is a good agent for enhanced oil recovery.
Sustainability Through the Use of Unmanned Aerial Vehicle for Aerial Plant Inspection
Authors: Kridsada L. , Chatchai La. , Manop C. , Thana S. 
Published: March 2016

Abstract
ROBOTS in Oil & Gas production! No, this is not science-fiction it is a reality. Robots have served in various industries for many years, but now the science of robots, or should we say "Robotics", is developing at such a rapid pace that robots have become far more diverse, infinitely smarter and are being used in ways that we would not have dreamt possible a few years ago, especially in the E&P and Petrochemical industries. In keeping with modern trends, PTTEP engineers have developed a multi-purpose Unmanned Aerial Vehicle (UAV), complete with "Plug and Play" imagery options, to perform a wide range of aerial monitoring and inspection applications. We call it a "Multipurpose Plant Inspection Octocopter" (MPIO). The MPIO project focuses on areas that are considered high-risk for human intervention and subsequently financially high-cost too. The MPIO has been designed and tested to perform various kinds of plant inspection; from offshore riser platform storage tank roofs to cooling tower observations, to name a few. But, in order to put the MPIO to the ultimate challenge and prove its viability, our engineers have been utilizing it to perform live flare-stack inspections, where radiated heat and turbulent air-conditions prevail.
To date, there have been many successful demonstrations providing quality high resolution pictures and proving the techniques applied. However, knowledge gained and ongoing development-effort will ultimately lead to the next step, a "Fully Automated MPIO" that will include; Auto Take-off, Auto Flight Control, Auto Landing, etc.
Vertical Cable Seismic (VCS) Survey for Buried Hydrothermal Sulfide Deposit
Authors: Asakawa Eiichi , Tara Kenji , Murakami Fumitoshi , Tsukaraha Hitoshi , Mizohata Shigeharu 
Published: March 2016

Abstract
In the Seafloor Massive Sulfide (SMS) exploration, the buried sulfide deposits without hydrothermal activity are important for mining development. We had proposed Vertical Cable Seismic (VCS) for exploration of SMS and found out it could reveal the buried deposit through surveys. The conventional VCS data processing gave us the large-scale 3D structure. We re-examined the data processing to focus on the very shallow part so that the detailed structure of the buried sulfide deposit could be recognized.
We adopted the Three-dimensional Pre-Stack Depth Migration (3D-PSDM) method that did not assume a horizontal structure since the hydrothermal area has a complex structure. In order to focus on the shallow part, we used a high-density gridded velocity model to achieve high accurate travel time calculation. Grid spacing is about one-tenth shorter than that of normal oil/gas exploration case. Velocity model is not complex but a two-layer model consisted of the seawater and sub-seafloor. The water velocity is adjusted to match the migrated ocean bottom reflection to ship-born multi-beam bathymetry.
The first VCS survey with GI-gun in 2011 and the second one with high-voltage sparker in 2013 in Izena Hole, Okinawa Trough, gave the high-resolution 3D PSDM volumes of 500m x 200m x 200m and 400m x 200m x 200m respectively. These results successfully delineated the top interfaces of the buried sulfide ore deposit that are consistent with the geological model provided by Japan Oil, Gas and Metals National Corporation (JOGMEC) using the core data of their intensive drilling. In addition, the existence of the high velocity zone was suggested beneath the seafloor by the estimation of velocity structure by Common Reflection Point (CRP) gather analysis. We consider the high velocity anomaly implies the existence of buried sulfide ore deposit.
These results suggest that VCS can reveal the distribution of buried sulfide ore deposits. We are developing a detailed velocity analysis method to reveal the velocity anomaly caused by the buried deposits. Furthermore, it is important to estimate other geophysical properties using EM, magnetic and gravity surveys. To confirm the distribution of the buried deposits represented by the VCS data, it is necessary to compare the VCS results and drilling cores by JOGMEC directly.
Pre-flush Design for Extended Scale Inhibitor Squeeze lifetime in Limestone Reservoir – Laboratory Investigations and Cost Benefit Analysis
Authors: Ghosh Bisweswar , Alklih Mohamad Yousef , Li Xin 
Published: March 2016

AbstractScale inhibitor (SI) squeeze treatment is an established practice in offshore fields to prevent inorganic scale deposition in the wellbore and near wellbore formation. Squeeze lifetime is measured by the duration for which the concentration of the chemical is released at a concentration above the required minimum inhibitor concentration (MIC). Hence, maximizing SI adsorption to the pore surfaces may proportionately enhance squeeze lifetime. However, most oil-field squeeze scale inhibitors being aqueous-based, it is unlikely to get optimum adsorption on an oil-wet formation due to unfavorable rock surface condition. This work is targeted towards optimum formation conditioning through an intelligently designed pre-flush treatment; so that the adsorption and lifetime of SI in an oil-wet carbonate reservoir are significantly improved.Eco-friendly APG surfactants are evaluated with and without alkali and co-surfactants to design the pre-flush composition. A series of coreflood experiments are conducted in simulated reservoir conditions, using data and materials from a high temperature carbonate oil reservoir from the Middle-East. The results are evaluated in light of IFT and phase behavior and changes of rock wettability due to pre-flush treatment.The results show that SI squeeze lifetime can be enhanced by as much as 240% when compared to conventional treatment and it has a direct correlation with wettability index and IFT. Anionic surfactant may look more attractive than nonionic surfactant due to favorable wettability alteration and highly reduced IFT, however they may not be the right choice for carbonate formation due to higher adsorption and competition with scale inhibitor molecules. Cost benefit analysis evince that introduction of the newly designed pre-flush treatment would results in improved economics through reduced treatment frequency, leading to minimized well intervention and consequent production loss.Not enough attention is given on the design/optimization of pre-flush and conditioning of the formation to be used as adsorbent/storehouse of the inhibiting chemical in preferentially oil wet carbonate formations. The applicability of surfactant-alkaline has been long established as means of EOR mechanism but they are rarely investigated for near wellbore treatments to maximize chemical storage and placement; which is what this work has studied.
Microbial Controlling Strategy for Upstream Oilfield Process System
Authors: Afizza I. M. , Muhd-Faizul H. A. H. , Mohd-Fadly Y. , Ngau-Uvang J. , Mohd-Hazriq S. I. S. 
Published: March 2016

Abstract
Continuous & effective bio-corrosion monitoring task is highly critical for fast & direct detection of microbial-induce corrosion growth risk pattern within an upstream processing system. This might due to changes in fluid characteristic by time. Failure in detecting such risk changes might trigger for occurrences of serious corrosion-related issue. This study incorporated new detection using AccucountTM energy-based detection kits into monitoring task along with conventional API RB38 SRB test vials & Kitagawa Hydrogen Sulfide gas test. Besides focusing on pipeline microbial growth risk, the monitoring are extended throughout the processing stages to identify the potential & direct microbial risk. The test are carried out at three different sampling time frame; one week after previous treatment, two weeks after treatment & after newly established treatment. The results offer valuable information on the weak point of established treatment program which has previously been overlooked by conventional methods; medium-risk growth in stagnant point, medium risk well-pools & potential solid sedimentation in stagnant point. Time kill test shows high effectiveness of current biocide that been applied into system. Besides, internal corrosion inspection of production separator identified twelve pitting formations. Developing microbial controlling strategy for offshore platform may varies by locations. Accurate and rapid process monitoring leads to correct and well-targeted solutions to potentially detrimental problem. A complete assessment with different set of viewpoints are highly critical in order for a cost effectiveness and further optimize the mitigation method.