bluuebunny/crossref_metadata_2025 huggingface dataset:
Increasing Role of Marine Support in Arctic Offshore Exploration Drilling
Authors: Connelly Don , Brovkin Alexander
Published: June 2014

The remoteness of Arctic well sites, lack of infrastructure and severe environmental conditions dictate a high level of self-sufficiency in an offshore exploration drilling project.

Chevron employs the concept of an Arctic Drilling System that, in addition to the appropriate Arctic Mobile Offshore Drilling Unit (MODU), will comprise of a number of marine vessels providing multi-functional support for drilling operations. The recent Macondo incident in the Gulf of Mexico has significantly impacted the conventional view on the multiple functionality of Arctic marine support by adding an in-field independent well containment capability that also has many functions.

This paper will look into the range of functions and tasks that are expected of muti-purpose vessels supporting an Arctic offshore exploration drilling project and will demonstrate the major considerations that need to be taken into account when compiling a highly effective marine support fleet.

The scarse supply of existing Arctic multi-support vessels versus expected industry demand will be demonstrated to emphasize the requirement for new designs and new construction.
Development of Icebreaking Ships
Authors: Wilkman Göran , Mattsson Tom
Published: June 2014

After Columbus has sailed to the West Indies also the search for the northern alternative to reach India became attractive. Over four hundred years ago Dutch Willem Barentz started to sail the North East passage towards east, but he did not get very far. After mapping Spitsbergen and Frantz Josef land he stranded on Novaya Zemilya. After this it took awhile until next expeditions became true, and even in the 19th century, nobody understood the northern environment and its challenges to people and equipment. Today we know perhaps too much. Today nobody would go and risk his life without having a heavily strengthened vessel around him. We have moved all the way from wooden sailing ships to nuclear powered vessels and year-round navigation. Part of this is due to climate change but also because the search for oil is moving further north. This paper brings us back from history to modern times and discusses the recent history what we have accomplished during the last decades and also tries to give some future views.
Arctic Sea Ice Thickness Observed by Moored Sonars
Authors: Hansen Edmond , Spreen Gunnar
Published: June 2014

Time series of sea ice thickness observed by moored sonars in the Transpolar Drift in Fram Strait show significant thinning during the 1990–2011 period. The thickness of old level ice is reduced by 25 %, while the fraction of (ridged) ice thicker than 5 m is reduced by 50 %. The combined effect on the mean ice thickness is a reduction from an annual average of 3.0 m during the 1990s to 2.2 m at the end of the record. Due to the steady advection of ice from many sites across the Arctic, the ice observed in Fram Strait carries an integrated signal of Arctic change. The thickness of old level ice is approaching values more typical for seasonal ice. While such low thicknesses prevail, larger areas of sea ice can melt away during the melt season. Hence conditions favorable to melt (or favorable winds) will result in new summers of very low sea ice extent. It is an important implication that the sea ice extent then depends more on the actual weather each melt season than previously. A relatively warm summer may remove much larger areas of ice than a slightly colder summer. This is exemplified through the relatively cold summer of 2013, which featured a sea ice extent nearly 50 % higher than the preceeding warm summer of 2012. This, again, implies that one may expect larger year to year variability in summer sea ice extent in the coming years, with the ramifications this has on human activity in the Arctic. In addition to this general reflection of the state of the Arctic sea ice cover, the Fram Strait ice thickness observations are of particular relevance to development of offshore petroleum fields on the North East Greenland shelf just downstream of the monitoring site. Most relevant design parameters may be deduced from this data set, such as level ice thickness and frequency and depth of pressure ridges.
Cluster Development of The Barents and Kara Seas HC Mega Basins From the Novaya Zemlya Archipelago
Authors: Efimov Yaroslav , Zolotukhin Anatoly , Gudmestad Ove Tobias , Kornishin Konstantin
Published: June 2014

The region of the Barents and the Kara seas is considered to be extremely rich for energy resources, primary gas. Nowadays this area is divided between two Russian majors – Gazprom and Rosneft. These companies have several projects with their foreign partners: Statoil and Eni in the Barents, ExxonMobil in the Kara Sea. All of these projects are in their early stages (feasibility study, exploration works) but both the experts and the management of the companies agree that production from this region requires enormous investments at a potential high-risk level. This is due to very harsh environmental conditions that put limits on usage of the earlier proved technologies and techniques, personnel, etc.

Moreover some of the regions might not be developed by means of only one company and to be bold enough to state it by the means of one country.

One of the very promising areas is the well-known Barents Sea with its unique fields like the Shtokman and others. Unfortunately the investment decision for the Shtokman project is regularly put off and there are certain reasons for it. Another area, which is now under active exploration, is the Kara Sea. It's not a secret that this sea is even more severe than the Barents – tremendous ice cover, icebergs, and challenging meteorological conditions.

The paper anticipates a new concept that proposes to use the Novay Zemlya archipelago as a cluster base for development of the whole region of the eastern Barents and western Kara seas. In this case the so called "unitization principle" can be implemented that might improve economics of field development due to less overall investments in common infrastructure.

It is proposed to build an LNG plant on the archipelago that will be capable to treat gas from several fields, a pipeline system and a port for LNG takers. The pipeline system should be optimized in order to meet production levels from the fields as well as the capacity of the LNG plant. The paper introduces an approach to the problem of pipeline route optimization which is based on multi criteria principle. Total cost of construction and maintenance of pipeline along certain route is determined as a function of several parameters (water depth, presence of ice/icebergs, soil conditions, slop, etc.) and has to be minimized in this model. The problem of optimum pipeline route is solved with the means of modified algorithms from the graph theory.
Precise GNSS Positioning in Arctic Regions
Authors: de Jong Kees , Goode Matthew , Liu Xianglin , Stone Mark
Published: June 2014

For precise positioning in arctic regions with Global Navigation Satellite Systems (GNSS), such as GPS and Glonass, there are a number of issues to be resolved or taken into account. The most important ones are satellite geometry, ionospheric effects and distribution of correction data.

Precise Point Positioning (PPP) is currently the standard for precise offshore positioning. PPP requires a sparse global network of GNSS reference stations to estimate precise satellite orbit and clock parameters in real-time. These parameters are transmitted to users, who can compute their position with an accuracy of 0.1 m using code and carrier observations. The main disadvantage of PPP is that in general it takes a long time to converge to this accuracy, about 30–45 minutes.

GNSS carrier observations are similar to pseudo ranges, but have an additional bias which needs to be estimated. Under certain conditions, these biases are integer. This property is used in what is generally referred to as Real-Time Kinematic (RTK) positioning, a technique which uses corrections generated at reference stations to make sure these ambiguities are integer. Integer Ambiguity Resolution (IAR) results in RTK accuracies of 0.01–0.03 m or better and short convergence times, ranging from instantaneous to several minutes for long inter-station distances. The disadvantage is the limited area of applicability, because RTK in general does not use precise orbits and clocks.

Current research focuses on the combination of PPP and RTK techniques. The main goal is to achieve cm accuracy with a sparse network of reference stations. Another goal is to reduce convergence time. Applications are in the field of precise real-time offshore positioning in general, and subsidence monitoring and tidal estimation in particular.

Results will be presented from standard PPP and PPP combined with IAR for arctic regions and from a test bed in the Gulf of Mexico. These results, although preliminary, indicate centimeter level accuracy is indeed possible, also in the arctic. We will also look at further improvements, mainly in convergence time, using all operational satellites and signals from current and future navigation systems.
A NRT Approach to Accurate Ice Edge Information
Authors: Debien Annekatrien , Whitaker Paul
Published: June 2014

The melting of the Arctic ice has opened up many areas of interest for oil and gas, fishing and transportation. However, not all ships or rigs in these areas have the capacity to deal with moving ice. They try to avoid ice by staying just outside the ice edge, but ice movements result in damage to vessels and Search and Rescue operations that could have been avoided. Monitoring the ice edge and forecasting its movement is therefore of great importance for these operations.

Kongsberg Satellite Services (KSAT), in cooperation with University of Sheffield, has developed an algorithm to quickly detect the edge between open and safe water, and drifting ice, based on SAR imagery. This information is available in a compact format less than 15 minutes after image acquisition. When taking into account transfer to the ship, the user receives information on the ice edge that is only 30 minutes old. The ice charts created by national ice services are based on information that can be several hours old, and are only updated on a daily basis.

As ships and oil rigs operate near the ice edge, they can rely on this ice edge to get fast, accurate and frequently updated information about its location and movement. The ice edge product has been tested and approved in multiple environments including the Barents Sea, the Fram Strait and the Kara Sea, and has proven to be of use for fishing vessels and oil companies operating in or near the ice edge.

This paper will describe the generation of the ice edge product, and the validation of the ice edge created by KSAT in the Fram Strait, around Svalbard, and near the Kara Sea. The validation has been performed internally, based on statistical comparison of the ice edge product with the Arctic marginal ice zone created by the National Ice Center in the U.S. Further validation will be performed with higher resolution ice charting products from the local meteorological offices.
Managing Offshore Superstructure Icing
Authors: Ryerson C.C. , Tripp S.T.
Published: June 2014

Superstructure icing occurs when spray freezes on offshore platforms and ships. Though superstructure ice accumulates fastest on moving vessels that generate bow spray, stationary structures also ice in storms. And ice from atmospheric sources also accumulates, affecting parts of platforms and ships not affected by sea spray. Icing is often accepted as an inconvenience to offshore operators, but that tolerance can reduce safety, operational tempo, and productivity. This report shows how to evaluate the impact of superstructure and atmospheric ice to offshore platform and ship functions and components from work conducted for the Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE), and for the US Coast Guard using questionnaires and observations. The report proposes a risk matrix approach for assessing the relative threat of ice from sea spray, frost, snow, rime and glaze to the safety and functions of platforms and ships, and demonstrates how to identify and prioritize areas requiring ice protection. It also briefly describes available ice protection techniques other than baseball bats and mallets. The goal is to provide a resource for offshore operators with superstructure icing-related safety concerns.
Innovative Kick Detection System for HP/HT Ultradeepwater Wells Using a Section of the BHA
Authors: Trivedi Parth P.
Published: June 2014

We are today moving into deeper seas and more challenging areas for finding oil and as the quest continues we enter more areas with uncertainties and possibilities of greater disasters. Very soon, if the technological advancements lag behind, the price of a crude barrel might not cover for the risk that the explorers take for it. Having said that, there is a very crucial balance that we need to strike in terms of long term investments for better efficiency vs. the cost effectiveness of our systems. Risk especially in regions of exploratory drilling is very high and this paper deals with a technology of downhole mud evaluation for predicting the entrainment of formation fluid into the wellbore.

The innovative kick detection system proposed in the paper uses a small mud rerouting section just above the BHA after the LWD and MWD tool. The small section of the mud into the tool is passed from between two plates (of metal with v.high melting point and definite resistance curves at HPHT conditions) that are separated by a small distance and have a definite known (corrected) potential applied across them. As soon as there is entrainment of formation fluid bubbles/droplets into the flow, the medium between the two plates will undergo alteration (change in absolute mud parameters) which will result in a change in capacitance between the two plates that can be detected immediately using the currently available technology.

This change in potential can be coupled through a coil in order to produce a magnetic impulse that can easily be carried to surface and registered as a ‘count’ of abnormality in fluid. Greater the count more will be entraining fluid and hence a kick can be detected. For very fast flowing fluids, we can incorporate high temperature potential measurement systems that can help us quantify the capacitance between the plates and tell for certain whether or not a kick is present.

The tool can be calibrated for specific mud type used and the fluid behavior at down-hole conditions giving us a more accurate measurement.

Limitations of this technology might lie in the materials used for electronics development and type of transmission system in place for the signal to reach to the top in very deep wells but there is an added benefit of quantitative and definitive measurement.
University and Corporate collaborations: Great Data, Good Science and a Strong Geoscience Workforce for the Future
Authors: Wood Lesli J.
Published: June 2014

Student education today, more than ever is rooted in teaching applied interpretation skills as well as conceptual geoscience ideas. Programs need to produce students who are versed in the software of geoscience interrogation as well as the concepts that will allow rapid, thorough and creative investigation of scientific problems. The ability to train students using the most up to date tools investigating state of-the-art, real-world data sets is a luxury that is only made possible through the generosity of companies who pay millions to build the tools and collect the data that we speak of. Gifts of data and software were once handled with a handshake, most often facilitated through a professor with a relationship to a former student who had access to such data. However, changes in our business and the rise of nationalism in many countries in the past decade have necessitated altering the way we collaborate. No longer is seismic data acquisition done by individual companies. Rather today, most seismic is shot as spec surveys that are used by companies to do their business. This means academic organizations need to build relationships with vendors, or leverage existing relationships between vendors and major customers to encourage release of data to academic institutions. In addition, academic organizations need to build a reputation for research excellence, respect for legal and ownership issues, and be recognized as a strong educator of young people.
CastorOne and FDS 2: Getting Stronger for Laying Deeper
Authors: Faldini Roberto , Marchini Stefano , Oldani Andrea , Pellegrini Roberto
Published: June 2014

Reaching the ultra-deep installation scenarios beyond 2,000m WD means that the new generation of S/J-laying vessels will be capable of applying pipe holding tensions well beyond 500te, which may become twice or three times that value if an unexpected flooding of the pipeline or a wet buckle occurs. To meet the increasing holding tension demand, Saipem adopted two innovative solutions on its new deep-water laying vessels CastorOne and FDS2. The FDS2 J-Lay system has been equipped with new compliant pads. This innovative pad design allows the application of up to 2,000te of holding tension in both normal laying and contingency situations, employing standard friction clamps of relatively small dimensions. In case of a wet buckle or in a contingency flooded pipe scenario, the CastorOne S-Lay vessel has the capability of holding and then abandoning the pipeline in a controlled and safe way by applying a tension of 1,500te through the simultaneous use of the A&R winch, of the three tensioners and of the pipe holding indentation clamp, all rated 750te. Moreover, the CastorOne has been equipped with a next generation articulated stinger capable of being adjusted either in terms of ramp angles and of roller heights in active mode during laying, i.e. with the pipe on top of it. This innovative feature allows to change the stinger configuration in order to suit the different bending radii required when laying in shallow, deep and ultra-deep waters without abandoning the pipeline, therefore saving a considerable amount of time and reducing the risks. These capabilities have been successfully tested in the deep water sea trials that took place before the laying of the Jack St Malo export pipeline. Such innovative technologies and equipment required state-of-the-art control and management software: the Centralized Management System (CMS), the Ramp Management System (RMS) and the Pipe Lay Guidance (PLG) just to mention the most important ones. The ability of the Vessel Management Team (VMT) to remotely control at any moment the instant conditions on the vessel firing line and on the double/triple joint workshop is a unique feature ensuring safe and reliable monitoring of the whole pipe construction cycle onboard. These features make the new CastorOne and the FDS2 unique and distinctive vessels on the pipeline installation market for Steep-S/S/J laying technologies.
Challenges, Benefits And Solutions In Holistic Oil Field Monitoring
Authors: Brandsaeter Helge
Published: June 2014

The initial value driver for implementation of field wide monitoring systems is increased recovery, based on seismic techniques. However; recent events with leaks from wells and infrastructure as well as more frequent cap-rock integrity failures having environmental impact, have led to a more holistic approach to monitoring incorporating the reservoir, the cap-rock, the overburden, subsea infrastructure and the water column.

This paper will try summarizing the main challenges related to monitoring. That is; as seen from an increased recovery perspective, reservoir integrity perspective and environmental perspective.

Furthermore, a vision for a way forward building sounder business models for monitoring using an integrated approach with equipment complying with open standards will be outlined.
Lophelia II Shipwreck Component: End Game
Authors: Warren Daniel J. , Church Robert A. , Westrick Robert F.
Published: June 2014

In 2008 the Minerals Management Service, now the Bureau of Ocean Energy Management and Bureau of Safety and Environmental Enforcement BOEM/BSEE in partnership with the National Oceanic and Atmospheric Administration (NOAA) and the National Oceanographic Partnership Program (NOPP), sanctioned a deepwater study in the Gulf of Mexico. Officially designated as the Deepwater Program: Natural and Artificial Hard Bottom Habitats with Emphasis on Coral Communities: Reefs, Rigs and Wrecks "Lophelia II", it is typically referred to as the "Lophelia II" Project. A substantial component of the contract was the examination of several deepwater shipwrecks. The "Wrecks" component of the project called for the archaeological examination of several shipwrecks as a continuation of the 2004 Deepwrecks Study in the Gulf of Mexico. These wrecks covered a broad time period from 19th century wooden sailing vessels to World War II era vessels. Between 2008 and 2010 three field seasons incorporated shipwreck investigation cruises that culminated in an Archaeological Assessment Report submitted as part of the larger Lophelia II Project Draft Report submitted to BOEM/BSEE in 2013. This presentation will provide a final analysis of the Lophelia II shipwreck sites based on data acquired between 2008 and 2010. In addition to the shipwreck findings, it will also present an analysis of the project itself and provide recommendations for future deepwater shipwreck studies of this type.
Successful Hole Enlargement Operations Utilizing Reaming While Drilling Techniques and Combining LWD operations in a Deep Water Drilling Environment
Authors: Takase Koji , Sawada Ikuo , Saruhashi Tomokazu , Hodkin Roger D.
Published: June 2014

Hole enlargement tools are often required in deep water drilling operations because of the necessity of running additional casing strings. At the same time, logging while drilling (LWD) tools are required depending on the drilling purpose even in large hole sections. When LWD and hole enlargement operations are required opening the hole and drilling with LWD at the same time offers an effective solution to save time and drilling costs.

Deepwater drilling, hole enlargement and LWD operations are well established technologies individually. However, it becomes very challenging once these three factors are combined together. The main reasons of complication are hydraulics and vibration issues. Additional factors including deep water, large diameter hole, heavy LWD BHA's and reduction of flow to LWD tools by diversion at hole enlargement tools, may require a higher flow rate and higher pump pressure than the rig is capable of providing. Sonic LWD sensors are also sensitive to noise and vibration which are often caused by hole enlargement tools. In these most challenging of circumstances the operator decided to open the hole to 20? while simultaneously logging with LWD.

This paper describes the procedures used at pre-drilling stage and actual operations such as the positive indication of the hole enlargement tool's activation and comparisons between surface weight on bit (WOB) / torque (TRQ) and downhole WOB / TRQ.

The hole enlargement system selection and hydraulic optimization were the key points at the engineering stage. During the actual operation, it was crucial to monitor various drilling parameters and to keep the hole in good condition because of unstable formations.

Although the hole enlargement service and LWD service providers were selected from different companies, detailed engineering and close communications were achieved for the common goal. The challenge ended successfully with hole enlargement to 20? while acquiring satisfactory LWD data for over a 1,100m section.
Development and Qualification of a High-Pressure, High-Temperature Chemical Injection Valve
Authors: He Peter , Yuan Kun , Rees Robert , Hughes Baker
Published: June 2014

As conventional oil and gas resources decline, interest in unexplored or underdeveloped areas has grown steadily in recent years. High-pressures and/or high-temperatures (HPHT) are the new normal when exploring these territories, posing tremendous challenges on almost all aspects from drilling to completion and production. One of these challenges is developing chemical injection systems with high integrity and reliability specifically for HPHT applications. The chemical injection systems provide precise wellbore chemistry management by pumping down chemicals via dedicated injection lines. Working principles of chemical injection systems for HPHT applications are not significantly different from those used under less-demanding well conditions; however, challenges remain due to harsh HPHT conditions that affect material and equipment performance.

This paper presents the development and qualification of an HPHT chemical injection valve that is the key flow control device in a chemical injection system. The valve contains a pressure differential valve design that creates a "bubble-tight" seal between wellbore fluids and the surface, provides a constant flow rate, and eliminates valve cavitations. The valve was thoroughly tested at various temperatures, pressures and flow rates, and it withstood conditions representative of the most severe well environments. The design cycle was also shortened by integrating computational fluid dynamics (CFD) simulations into the design process and good agreement was achieved between the simulations and the experiments.
An Innovating Premium Tubular Solution For Umbilical's Applications
Authors: Wagner O. , Thevenet G. , Peultier J. , Roques JP. , Romazzotti H.
Published: June 2014

Offshore and deep offshore applications are coming more and more demanding regarding number of functionalities and water depth for umbilicals and especially regarding tubing. Oriented to new resources, the future developments (i.e. ultra deep offshore or abrupt margins) will be more difficult to operate leading to more and more stringent requirements for tubes. Thanks to its high mechanical properties and appropriate corrosion performances, super duplex stainless steel (SDSS) grade 2507 is already commonly adopted by main players of the O&G industry for a wide range of conditions. With a strong collaboration with one of the Majors, an innovative SDSS seam welded tube solution has been developed, exceeding the standards characteristics and opening new perspectives.

An extensive program of qualification, here presented, has been built in collaboration between Oil Companies, Umbilical manufacturers and the tube supplier, to confirm the expected potentialities of the product. Based on more than 11000 results, this paper is presenting the performance of the product in terms of mechanical and corrosion properties. The associated innovative and robust process, here described, is able to guarantee tight manufacturing tolerances combined with a high quality level, offering attractive potential cost savings.
LWD Sonic Data Analysis and Applicability in South China Sea
Authors: Cai Jun , Zhen Lingxia , Han Shim Yen , YiMing Jiang
Published: June 2014

Many drilling risks are met during exploration and evaluation stage in South China Sea, China. The narrow mud weight window and presence of high pressure formation are two main challenges in this area. Generally, geomechanics study will be carried out using information obtained from nearby wells together with the surface seismic data before drilling the well. Sonic measurement is one of the most important input data in the geomechanics analysis to provide an estimate for mud weight window and drilling risks evaluation. What's more, the real-time LWD sonic is critical to improve the accuracy of the safe mud window by calibrating the initial geomechanics model to reduce the associated drilling risks. The real-time LWD sonic data together with the pre-drill geomechanics model calibration is our solution for those challenges.

Based on our experience, the former LWD sonic tool delivers good memory data but the real-time data quality is not very consistent depending on drilling noise, borehole condition, formation properties as well as other operation restrictions. In such cases, the sonic memory data was used to calibrate the mechanical earth model, the updated model will then be used as reference to drill the subsequence well. However, with unstable real-time sonic data makes it difficult to perform real-time evaluation.

Having a reliable real-time sonic measurement is very important for offshore operation, especially in High Pressure High Temperature (HPHT) environment to reduce the drilling risks and save rig time. It is vital to get good quality and accurate real-time sonic data to meet our requirements. With the latest LWD sonic tool, good quality of LWD sonic data was obtained for both real-time and memory. The real-time slowness acquired matches the memory slowness very well which give us more confidence to perform real-time geomechanics analysis in the coming HPHT deep water project.

This paper focuses on data quality comparison between the two generation of LWD sonic tools tested in this area, challenges and methodology in real-time data quality control as well as the applicability of the LWD sonic in South China Sea. With the confidence of the real-time measurement data quality shown in these examples, this will significantly reduce the drilling risks in our next HPHT project. This assurance also enables us to explore additional applications in our projects.
Blended Source Ocean Bottom Seismic Acquisition
Authors: Walker C D T , Monk D J , Hays D B
Published: June 2014

"Blended" or simultaneous source seismic acquisition has had a dramatic impact on the quality and productivity of land seismic acquisition but its application offshore has been comparatively limited to date.

For towed streamer operations the principle benefit is to improve data quality by increasing the fold of the acquired data by reducing the shot spacing. There is little, if any, reduction in data acquisition time and hence no reduction in costs. For ocean bottom seismic applications, however, the situation is very different - survey durations can be almost halved with a very modest increase in costs by firing more than one source into the receiver spread "simultaneously."

In this paper we will describe the acquisition of what is believed to be the world's largest ocean bottom survey, more than 2200 square km, using two blended sources and a very large receiver spread - more than 4200 ocean bottom receiver nodes. By firing each source wholly independently on a pseudo-random distance basis not only is blended source residual noise reduced but also operational efficiency is improved since downtime on one source vessel has no impact on the other. Since ocean bottom data are extensively used for production and development applications to provide wide azimuth data in congested producing fields the usability of blended sources for 4D or timelapse is critical and this will be examined in the presentation.
Implications Of New Code Versions To Pile Fatigue Assessment
Authors: Chung Jean , Wallerand Régis
Published: June 2014

The aim of this paper is to present the methodology currently followed in the offshore industry for the prediction of the pile fatigue induced by pile hammering during installation. A few decades ago piles were thicker, of lower yield stress and hammers were less efficient. Today, to be cost effective, it is common to use high strength steel resulting in lower pile thickness and increased driving stress together with better hammer efficiency to reduce installation time. Hence fatigue damages are more important. Evaluation of fatigue damages depend on various parameters such as applied stresses, number of blows, Stress Concentration Factor (SCF) and S-N curves. It is shown how fatigue damages are dependant on the choice of the values used for the SCF and S-N curves and also on applied stresses by the hammer, and in the end the impact of these parameters on the residual available fatigue life for the in-place conditions.
Subsea Field Inspection of the Future
Authors: Gair George , Ferguson Hugh , Jamieson James
Published: June 2014

The latest advances in sensor and autonomous technology provide the opportunity to change the way that future inspection and condition assessment of the subsea infrastructure is carried out. The potential for smart sensors to be an integral or retrofit able part of the infrastructure and the increasing capability of autonomous vehicles is already promoting discussions. Recent work by standards groups is producing new and robust methods of harvesting sensor data; subsea hardware suppliers are looking at increased in-suite equipment monitoring and intervention methods; the oceanographic community has developed remote seabed environmental monitoring systems. These are all significant indicators that show a general trend is towards smarter systems. Some of the more significant challenges that remain in the subsea inspection arena are changing methods and practices that have been evolved over many years. It is only to be expected that the introduction of new technology will change the norms and will need to be managed. Key decision making parameters can be identified by revisiting the type and format of the measurements required to make an acceptable assessment of subsea infrastructure. Early engaging with operators, service providers, sensor manufacturer and standards groups will be essential. This paper aims to set out the key benefits that can be achieved by embracing the technology and provide a look ahead to show what future services might look like.
New Deepwater Constructin Equipment Update 2014
Authors: Wilson Mike
Published: June 2014

Ecosse's SCAR Plough system has been developed to deliver an all-in-one or one-part solution to support trenching and pipe/cable lay operations. The SCAR system has the capacity to work in deep water, both near shore and onshore, and can be deployed dry for shore approaches or can be launched and recovered over the stern roller of an Anchor Handler with no A-frame required. SCAR is inherently simple and robust, offering reduced downtime and low maintenance time/costs.
A Modular Subsea DC Electrical Power System
Authors: Lai Rixin , Zhang Di , Dong Dong , Song Chi , Harfman Todorovic Maja , Ranjan Gupta , Garces Luis , Gunturi Satish , Datta Rajib , Wijekoon Thiwanka , Sihler Christof , Rocke Svend Erik , Elgsaas Kristin Moe , Savarit Elise , Arungalai Anbarasu , Song-manguelle Joseph , Pappas James Marcus
Published: June 2014

Subsea processing has been increasingly accepted by the offshore oil and gas industry as a solution to boost the production and reduce cost. Accordingly, the subsea power demand is growing in order to support the various processing loads including pumps and compressors. Depending on the application, the power rating of a field ranges from tens of kW to tens of MW. A reliable subsea electrical power system which is suitable for subsea deployment is desired.

The hostile and remote subsea environment has imposed significant technical challenges on the electrical system. Due to the extremely limited accessibility, the electrical system needs to be very reliable and require minimum regular maintenance in its lifetime. The system should be able to detect and isolate local faults without shutting down the whole system in order to maximize the availability and avoid unplanned stops. The electrical system should also be as compact as possible and modularized, so that they can be installed and retrieved without heavy vessels and lifts which have very limited availability.

A novel modular stacked DC (MSDC) development has been developed to address the above mentioned challenges. The proposed system consists of a number of power converter building blocks connected in series on both the on-shore station and the seabed stations. The dc-link current is controlled to be constant, and the dc-link voltage will vary according to the loading condition. This architecture renders simplified power distribution, fault-tolerant capability and feasibility for field extension.

This paper will focus on fault protection of the MSDC system. A fast bypass circuit is proposed to isolate the faulty equipment in tens of micro-second without affecting the operation of the rest of the system. The concept has been verified by both simulation and experiments. The paper will also cover the cooling concept for the power electronics in the subsea power converter. A phase change approach has been investigated and tested in the lab. Latest testing results will be shown in the paper.
Integration of Horizontal Wells in the Modeling of Carbonates Reservoir. Upscaling and Economical Assessment Challenges
Authors: Ait-Ettajer Taoufik , Fontanelli Laurent , Diaz-Aguado Almudena
Published: June 2014

The integration of horizontal wells during the modeling and the economical assessment of reservoirs is becoming an important task. This is mainly due to the development of horizontal drilling and the improvement of the logging techniques of horizontal wells. However, this integration of horizontal wells creates additional challenges related to the uncertainty generated by the upscaling of the well data from well log scale to reservoir scale. A large number of probable scenarios is required prior to the economical assessment of the reservoir potential in terms of hydrocarbon in place and reservoir performance forecast. In this paper we will present a process for quantifying and modeling the uncertainty of the upscaling of horizontal well logs, then we will discuss the impact of this uncertainty and the pore volume and the economical assessment of the reserves related to the hydrocarbon reservoir.

The process of quantifying, incorporating and modeling the uncertainty introduced by the upscaling of the properties of horizontal wells, can be decomposed into four steps:Defining the optimal geological layering scheme.Quantifying the one dimension uncertainty introduced by the upscaling of the horizontal wells.Modeling the upscaling uncertainty in the three dimension reservoir.Ranking the different scenarios through pore volume calculation and flow simulation processes.

The technique was applied to a tight carbonate reservoir. The study showed that the range of uncertainty, introduced by the integration of horizontal wells into the reservoir model, can significantly impact the accuracy of the reservoir pore volume and the reservoir performance forecast.
Industry Survey of Past Failures, Pre-emptive Replacements and Reported Degradations for Mooring Systems of Floating Production Units
Authors: Fontaine E. , Kilner A. , Carra C. , Washington D. , Ma K.T. , Phadke A. , Laskowski D. , Kusinski G.
Published: June 2014

The results of an industry survey of mooring line failures are presented and analyzed. The failure data presented includes geographic location, mooring line composition, prevalent failure modes and the phase of failure inception. At a component level, cause of failure, location along the line and time to failure are presented. Failure data suggests that the observed increase in the number of failures is proportional to the increase of the FPSO population, with the underlying failure rate per mooring line approximately constant over the last ten years.
The Changing Role and Perception of Archaeology in the Gulf of Mexico Exploration Industry
Authors: Warren Daniel J.
Published: June 2014

Archaeology related to the offshore energy exploration industry has changed significantly over the last 15 years. New regulations, technologies, and discoveries have impacted not only how archaeology related to offshore exploration conducted but also how it is perceived within the industry itself. Additionally, the nature of the exploration taking place in the Gulf of Mexico has affected archaeology. The shift from shallow continental shelf exploration to ever deeper regions of the Gulf of Mexico has taxed to archaeologists adapt to changing technologies used in deepwater exploration. The increasing discoveries in deepwater show that the past perceptions of these portions of the Gulf are mistaken and has forced archaeologists to re-examined the processes affecting shipwrecks in these regions. Numerous deepwater shipwreck discoveries have also led to increased interactions and cooperation between archaeologists and industry operators. These interactions have changed perceptions of both groups and are forming strong mutually beneficial relationships between those involved in exploration and those tasked with protecting our maritime heritage. This paper will discuss how archaeology within the industry has changed, what have been some of the most significant events influencing this change, how archaeologists are interacting with industry now versus the past, and what they perceive the future will bring for archaeologists working in this sector of the industry.
Plug and Abandonment Using Reverse Cement Placement Technique in Deepwater Gulf of Mexico
Authors: Gubanov E. , Nana D. , Bogaerts M. , Moretti F. , Flamant N.C. , Kanahuati A.
Published: June 2014

Four deepwater wells in the Gulf of Mexico were identified for permanent abandonment in accordance with local regulations. The abandonment plan called for multiple cement plugs to isolate the production zones from seabed in each well. The most challenging cement plugs in each well were the ones directly above the production packer isolating the casing-tubing annulus and the production tubing. To avoid cement left in the Christmas tree at seabed and potential plugging off any valves in the manifold, cement plugs could not be placed the direct way, pumping down the production tubing.

An unconventional approach was proposed to address the challenge. It involved reverse placement of cement plugs, which is not common in deepwater even in these days. Using this technique, cement was pumped down the casing-production tubing annulus and, through perforations, back up the production tubing. Risk analysis indicated very low likelihood of plugging off any valves in the tree. However, this configuration did not allow use of mechanical separators between fluids to prevent intermixing. Additional challenges in placing the plug were the high deviation of the section and the completion brine in the wellbore.

Simulation of reverse placement is not possible with existing software. Therefore, the jobs were designed using experimental software, which enabled the design engineer to accurately reconstruct field conditions. Additional attention was given to the job procedure to minimize contamination with the brine and optimize cement placement. Viscous spacer was pumped ahead and behind the slurry to displace the brine. The slurry was designed with low fluid loss to be squeezed through perforations in the production tubing without plugging them off.

A total of seven plugs were placed using the reverse placement technique. Specific requirements with regards to the top of cement and plug integrity had to be met before any of the cement plugs could be accepted by the operator. All plugs were tagged and pressure tested successfully in the annulus as well as inside the production tubing on the first attempt. As a result of the campaign, the four wells were abandoned as per schedule and within budget.
Operation of Subsea Electrical Power Systems
Authors: Askeland Audun Magne , Sølvik Nils Arne
Published: June 2014

Reliable, dependable and cost effective subsea electrical power supply systems have been one of the most important factors in the successful development of the subsea boosting and processing applications and technologies over the last 15 years. This paper will provide an overview of how the system and component parameters and ratings have developed over this period. In the early days of subsea hydrocarbon production, there was a lot of skepticism using high voltage equipment under water - today we know that when the design and qualification is done thoroughly, high availability is achieved on subsea electrical power systems. Further, a focus on what have been the decisive factors for system design, correlation to the end-load and consequently component selection will be offered. An overview of key component qualification methodologies and programs will be described, and finally an overview of operational experience of the existing subsea power systems will be given. The end loads have increased in power rating from some hundred kilowatts to multi-megawatts. This have obviously had a significant impact on the design and utilization of the power components, such as subsea wet mateable connectors, subsea transformers, frequency converters, electrical motors, etc. In parallel to the increase in power rating, and consequently voltage and current, the water depths and environments for installation have changed in this time period and have led to increased requirements to pressure withstanding capabilities, cooling and physical robustness.
Gryphon Alpha FPSO - Experience Gained During Moorings Replacement and Hook-Up
Authors: Toal Fred J. , Martin John G. , Brown Martin G. , Lindsay Ian M. , Sinclair Robert
Published: June 2014

In a North Sea storm during February 2011 the Gryphon Alpha FPSO broke four of her 10 mooring lines and moved partially off station, causing damage to subsea assets. Heading control was re-established using the FPSO's thrusters and in due course the moorings which had parted were re-connected back to the Tentech turret. Following the incident, the FPSO was taken to dry dock for life extension work and to allow replacement of the damaged subsea infrastructure and moorings. The original mooring system was recovered for forensic inspection.

This paper describes the measures which were put in place so that the Gryphon mooring system could be replaced and the FPSO re-connected in accordance with a schedule which would not delay the installation of the subsea infrastructure or first oil. The intention is that this paper should be a useful reference for others engaged in similar work. It was decided to replace the original moorings, apart from the recovered Stevpris anchors that were refurbished. Since the size of the chain into the gypsy wheel fairleads at the turret was fixed, the mooring designers had to optimise their design to meet latest code requirements. This resulted in a 100 m long tri-parallel chain configuration to reduce FPSO mooring loads and excursions, but which also caused some handling issues. High specification Anchor Handling Vessels (AHVs) were needed for the prelay operation, which had after deck chain handling gantries to manipulate safely the heavy chain, delta plates and associated shackles.

A challenging design and procurement exercise was needed to make sure that all the mooring components were delivered on time. The initial mooring sections were pre-laid in February/March of 2012, including anchor proof tensioning, so as to suit the subsea schedule. The mooring lengths had to be adjusted offshore by chain cutting, depending on the final resting place of the chain ends after tensioning. This was to ensure each tri-chain end was correctly located so that the system stiffness would be uniform and the moorings properly balanced. The pre-deployed mooring lines were each buoyed off subsea for later ROV recovery.

The FPSO moorings hook-up took place in September 2012 using the AHVs previously used for the pre-lay. Due to the presence of three Mid Water Arches (MWAs) within the FPSO swing circle, four AHVs were used to hold Gryphon in position during the reconnection operation. The AHVs were positioned two forward and two aft about the FPSO. Adjustment of AHV tow lines enabled the FPSO to be held within just 5 m of the Field Turret Centre (FTC) during the entire reconnection operation. The FPSO also had access to a 3D computation and visualization package which provided real time in-situ position monitoring. This ensured that no mooring chain to subsea assets contact occurred despite the unusually tight installation tolerances.