bluuebunny/crossref_metadata_2025 huggingface dataset:
Mooring Integrity Management through Digital Twin and Standardized Inspection Data
Authors: Matsumoto Shunsaku , Jaiswal Vivek , Sugimura Tadashi , Honjo Shintaro , Szalewski Piotr
Published: August 2021

This paper presents a concept of a mooring digital twin frameworkand a standardized inspection datatemplate to enable digital twin. The mooring digital twin framework supports real-time and/or on-demand decision making in mooring integrity management, which minimizes the failure risk while reducing operation and maintenance cost by efficient inspection, monitoring, repair, and strengthening. An industry survey conducted through the DeepStar project 18403 identified a standard template for recording inspection data as a high priority item to enable application of the digital twins for integrity management. Further, mooring chain was selected as a critical mooring component for which a standard inspection template was needed. The characteristics of damage/performance prediction with the proposed mooring digital twin framework are (i) to utilize surrogates and/or reduced-order models trained by high-fidelity physics simulation models, (ii) to combine all available lifecycle data about the mooring system, (iii) to evaluate current and future asset conditions in a systematic way based on the concept of uncertainty quantification (UQ). The general and mooring-specific digital twin development workflows are described with the identified essential data, physics models, and several UQ methodologies such as surrogate modeling, local and global sensitivity analyses, Bayesian prediction etc. Also, the proposed digital twin system architecture is summarized to illustrate the dataflow in digital twin development andutilization. The prototype of mooring digital twin dashboard, web-based risk visualization and advisory system, is developed to demonstrate the capability to visualize the system health diagnosis and prognosis and suggest possible measures/solutions for the high-risk components as a digital twin's insight.
18 3/4" 15000 Psi Shear Anything KBOS for Subsea Well Applications
Authors: Gallagher Bobby J , Dupal Ken , Jones Reese E
Published: August 2021

Kinetic Pressure Control has developed the 18 ¾" 15000 psi blowout stopper (KBOS) system for applications on all subsea well activities. The 18 ¾" 15000 psi systems builds upon the successful development of the 5-1/8" 15000 psi KBOS system for surface BOP applications[5]. The system can be configured within the existing subsea BOP, by replacing a casing shear ram or blind shear ram, or can be configured as a shut-in device below the BOP. The KBOS system provides a significant improvement over existing shear ram technology, providing the ability to shear/seal any items in the wellbore, which reduces the likelihood of a blowout, resulting in an improved risk profile.

The KBOS is a proprietary design which uses a pyro-technical, electrically initiated process the actuate the shearing process. The system has been designed and tested to actuate and shear/seal in milliseconds, under full wellbore flowing conditions and meets NACE/ISO sour service requirements without exemptions. The control system includes real-time monitoring and function testing capabilities, and requires minimal in-service maintenance, as the working components are isolated from the wellbore fluids. A computational predictive model has been developed, with a test regime conducted to validate the model results. A full qualification program, with 3rd party certification, has been completed to industry standards.

Shearing tests have been conducted for a large range of tubulars which have been challenging to shear with existing technology. These include: 9 ½" drill collars, combinations of large OD casing and inner strings, high strength drill pipe and tool joints, wireline, and production tubing. A subsea test of the system was successfully performed in 2019 to shear large OD casing and inner string.

The KBOS system utilizes technology from other industries (ballistics, military, automotive) to provide improved shearing and sealing capabilities for all well activities (drilling, completion, intervention). The improved shearing/sealing capacity and reduced time enable a reduced likelihood of a blowout and improved risk profile
Buzios FPSO Experience: Standardization and Perspectives for Our Next Generation of Pre-Salt FPSOs
Authors: Padua Mattoso Marcio de , Goulart Pimenta Maiza
Published: August 2021

The purpose of this article is to present a set of experiences and challenges related to the current Buzios FPSOs and the perspectives offered by these related experiences, which should drive further enhancements for next generations of pre-salt production units.

Buzios field is a giant oil discovery located at Brazilian southeast coast and has four production systems already in operation: P-74, P-75, P-76 and P-77. Throughout these projects, Petrobras observed technical and business opportunities that are going to lead improvements for next generation of Buzios field's FPSOs. These include enhancements on high production wells, H2S removal technology, vessel standardization, digital transformation solutions, design procedures improvements and several measures to strength the integration between design, construction, commissioning and operation phases.

During the construction, commissioning and startup period of the Buzios’ current installed units, Petrobras identified technical issues that should be addressed in order to add value to the next generation of Buzios’ FPSOs. These experiences point out to the need of technical design improvements and reviews such as: change in technology of H2S removal from solid bed to membranes; a complete analysis of hull capacities and dimensions and standardization of the vessel; and a set of standardization methods and processes to develop the basic design - including aspects of digital transformation. The result was a standard design project called Reference Project ("Projeto de Referência" in Portuguese) that intends to be a reference for new units to be installed in Buzios field. This design also intends to be the basis to other projects in order to allow faster business decisions.
Monitoring and Calibration of Long Term Mooring System Design Assumptions Through Use of AIS and Weather Data
Authors: Lillestøl Dag Børre , Kårvand Odd Torbjørn , Torstensen Are
Published: August 2021

This paper outlines an approach on how to improve the mooring integrity of existing long term mooring systems by using existing and commercially available data.

It will be demonstrated how the use of AIS and hindcast weather data can be used to increase understanding of mooring systems and to monitor and quantify gaps between "as-designed", "as-installed" and "as-is" of a long term mooring system.

Long term moored units have traditionally suffered from many early failures, caused by damages and errors introduced in the installation phase, and costly and unnecessary "late in life" failures. A fact rated high on the agenda of the underwriters. Numerous papers have been written on this topic, but it is only in recent years the industry have started to ensure that systems are inspected to a sufficient degree with respect to the physical condition, taking these learnings into account. However, the second important element, the calibration of the mooring analysis vs. actual vessel and mooring system behavior/performance, have not yet gotten the attention required.

Deviations from the intended design are introduced in the installation phase of a mooring system. In addition, the design assumptions will never be fully accurate. The gap between the design assumptions and the actual system will increase over time, and the industry today do not focus on mapping and quantifying the effect of this gap sufficiently. The described method explains how one can introduce a pro-active approach, without installing onboard equipment, but rather utilizing algorithms on existing data and design documentation.

This paper focuses on the use of AIS data in combination with historic weather/environmental data and seek to demonstrate how this low-cost method can provide useful information with respect to the mooring system.

To emphasize the mapped importance of such calibrations, the July 2021 Edition of the in-service DNV Class Rules, DNVGL-OS-0300, formally introduces requirements to calibration of design assumptions of long term mooring units through use of survey data, service history and actual mooring system behavior in order to ensure a unit's mooring system condition and performance is known in light of the original design assumptions.
Impact of Rheology Models on Horizontal Well Polymer Flooding in a Heavy Oil Reservoir on Alaska North Slope: A Simulation Study
Authors: Leng Jianqiao , Wei Mingzhen , Bai Baojun , Seright Randall S. , Zhang Yin , Cercone David , Ning Samson
Published: August 2021

Polymer rheology can have either a positive or a negative effect on polymer flooding performance under varied circumstances. Many researchers have studied the effect of polymer rheology in a vertical well, but no field scale studies have been conducted to investigate whether polymer rheology is beneficial to polymer flooding in heavy oil reservoirs developed by horizontal wells. In this paper, we conducted a numerical simulation study to examine the effect of HPAM polymer rheology on a polymer flooding pilot, which is the first-ever project conducted on a heavy oil reservoir from Alaska North Slope (ANS) developed by horizontal wells. Three rheology types were considered in the study including the apparent viscosity measured during coreflooding of using a HPAM polymer, the bulk viscosity measured with a viscometer, and a Newtonian flow model. The results suggest that using the bulk viscosity in simulation underestimates the conformance control and the water-oil-ratio reduction capability of the HPAM polymer solution. When the apparent viscosity is used, the incremental oil and sweep were largely increased, and the optimal recovery period of polymer flooding was extended greatly, especially for the heterogeneous formations. Therefore, the rheology type of polymer plays a significant role in the incremental oil recovery and injection profile of the horizontal well system given the pilot testconditions. This study has provided practical guidance to field operators for the ongoing polymer flooding pilot on ANS and will also provide valuable information for other polymer projects conducted in similar conditions.
Repurposing Oil & Gas Wells and Drilling Operations for Geothermal Energy Production
Authors: Pilko Robert M. , Hart-Wagoner Nicole Rita , Horn Andrew J. Van , Scherer Joseph A.
Published: August 2021

This paper explores a market solution for Operators’ companies to compound their investments in wells, fields, and infrastructure in a low carbon world by applying improved well design, drilling and completion technologies that are adapted to a new generation of geothermal energy production systems. The paper frames challenges posed to the upstream industry by the movement to a low carbon economy, including the climate transition risks related to societal, regulatory, and capital allocation trends. It then examines the technical challenges and solutions related to repurposing oil and gas fields and wells for geothermal energy production and makes high-level recommendations for Operators interested in accessing this new market for geothermal energy - as well as satisfying Environmental, Social and Corporate Governance (ESG) investors.
Carbon Footprint Minimization for Deepwater Pipelay Construction
Authors: Young Raymond , Kashani Manou
Published: August 2021

With recent oil and gas discoveries in deepwater offshore, these regions have become the hotspots for oil and gas exploration. It is for this reason that major pipelay contractors are developing more advanced construction vessels with high lay tension capacity, payload and high specification dynamic positioning (DP) systems to operate at even deeper water depths. It is shown that at water depths of greater than 1000 m, one of the major construction costs is fuel consumption, which is directly related to the level of thrust and hold back tension the laybarge is required to maintain during pipelay operations. Furthermore, the fuel consumption and the resulting carbon footprint, is shown to increase disproportionally as the laybarge thrust increases at deeper water depths. For example, a deepwater laybarge (DP3 class) with a typical operating power of 40MWe can consume 130 metric tonnes of diesel fuel per day (1.5 kg/s) with carbon dioxide equivalent emissions (CO2e) of 3,200 kg per tonne of fuel. This is a substantial measure of emissions, typical of a pipelay vessel during pipe lay operations. It is for this reason that American and European air pollutant emission inventory guidelines expect environmental impact documents for all marine activities, including construction, to be calculated and submitted to relevant environmental protection agencies. By comparison, a typical car will produce around 4,600 kg of CO2e per year.

Currently, deepwater pipeline engineering and design is based on relevant offshore design codes and standards, e.g. DNV-GL and API. Within the framework of those codes and standards, a design approach is presented within this paper that shows that, by properly combining pipe strength and stiffness characteristics with pipelay construction loads, a unique bending strain limit can be defined that would lead to the most economical solution that minimizes the vessel thrust and thereby radically reduce fuel consumption and associated CO2e emissions during pipelay activities.

This unique design approach would be of interest to operators, pipe manufacturers as well as the pipelay contractors. Because of the construction economy and the minimizing of the carbon footprint, this approach is an attractive design method to all concerned parties, including environmental protection agencies. Since the design approach promotes higher steel grades, it would be very much in the interest of pipe mills to further develop and elevate the use of higher steel grades higher than the present widely used API 5L, X-65. Pipelay contractors will benefit by installing pipe with lower levels of thruster power, resulting in safer and a more reliable station keeping and, most significantly, a lower fuel consumption.
Condition Monitoring of Next Generation Digitized Electric Subsea Actuators
Authors: Winter Tobias , Glaser Markus
Published: August 2021

A detailed knowledge about the health status of the installed assets is the key for continuous production without unexpected events and downtime, which causes production loss. A major aspect is the prediction of the occurrence of a failure before the affected function is demanded. This is one purpose of the Condition Monitoring (CM), Prognostics and Health Management (PHM) and the application of a Digital Twin. The paper presents the result of an ability analysis for a subsea actuator towards its possibilities to increase the availability through a novel and extensive grade of information. The paper presents the resulting architecture and solution to achieve an actuator design, which is capable to provide a high safety, high reliability and a predictive health management which is prepared for a digital twin application. For this purpose, an applied Condition Monitoring concept is described and shown based on the case study.

The analysis and resulting solution is based on a detailed research towards the state of the art. Different available subsea actuators are analyzed towards the communication interfaces and the ability to allow CM. Therefore, the required status and information of the actuator are shown (e.g. Torque, position, temperature, acceleration, water concentration in oil, humidity, pressure, inclinometer). The required environment information about the actuator are evaluated with the help of a failure mode analysis. The different sensor principles provide the necessary information. The paper evaluates the significance of the sensor information towards the CM concept. The data can be provided on different communication interfaces and protocols. These are analyzed towards the satisfaction of the CM requirements.

The result of the analysis is a detailed architecture of a CM capable subsea electric actuator including the CM concept. The possible interfaces are shown and the provided sensor data by the actuator. The sensors provide the input for the CM model and the remote accessibility and controllability of the actuator.

The result is the novel design of a subsea actuator, which fits perfect in a digitalized subsea environment to increase the availability and controllability including a CM concept.
Longer Tiebacks by Electrification and Remote Power
Authors: Verdeil Julien , Manach Julien
Published: August 2021

Standard field architecture is generally based on topsides production and distribution of power and chemicals necessary to operate equipment in drill centers. The paper will present efficient field architectures adapted to operate remote tie-backs with different combinations of subsea electrical power distribution, remote power generation and storage, and improved ways to mitigate corrosion, hydrates and wax issues for long tie-backs.

Developing remote resources requires several technology bricks that enable a cost effective and reliable technical solution. To reduce the CAPEX, the main objective is to reduce the number of tubes typically with one single heated flowline to avoid a long and costly service line or with one small power cable and local distribution of power to avoid a heavy and expensive large umbilical. Alternatively, power can be generated and stored at drill center location and chemicals can also be managed locally with limited OPEX.

A significant focus was done recently on technology developments enabling long distance tie-back developments. Domain of application and interest of each technology is generally well known and the delivered value is well presented. Looking for the most appropriate combination of technologies on a new field development is now the new challenge to figure out new opportunities. This paper proposes to group the long distance tie-backs fields in three main categories based on extensive studies done for several operators and to present the best architecture for each category. The first category groups very long distance single end tie-backs for which a cold flow system combined with full electrical equipment at drill center location is adapted. The second one is applicable for more consequent development where several drill centers are combined to one long and heated export line; with subsea electrical distribution to power each branch of the remote field and local management of chemicals at each drill center. The third category groups all daisy chain developments for which a heated line gathers the production coming from each fully electrical drill center.

Each field development can generally be categorized in one out of the three categories presented in this paper. Based on this categorization, the right combination of low carbon and reliable new technologies enables valuable development of long tie-backs and then increases utilization area of each existing asset.
Novel Elastomer Materials for Extreme Temperature Operation in Subsea Thermal Insulation Applications at Unlimited Water Depth
Authors: Jackson Adam , Diaz Rodrigo , Svalund Heidi , Hansen Raymond , Hartviksen Grethe
Published: August 2021

Rubber based systems have been used in subsea thermal insulation for many years and have proven themselves to be reliable and cost efficient. Formulations have been changed over the years, pressing the maximum usage temperature upwards and into the realm of 160 to180°C in a hot-wet environment. Until recently there was a need for high temperature along with pressure vessels (autoclaves) for vulcanisation. This has limited the widespread use of such systems. Recent changes have eliminated the need for autoclaves, however the high temperature vulcanisation hasstill been required.

A novel formulation has been developed to address these shortcomings, so that this class of materials could have wider use. This new material employs freely available materials in a unique blend. The material contains no hydrolysable groups and can operate from −40°C to 180°C continuously in air and in a hot-wet environment and retains its resilience and flexibility; and thus opening for use in both high and low temperature systems. The formulation does not include the use of hollow glass microspheres and is, correspondingly, without water depth limitations. A new, highly reliable vulcanisation chemistry allows for a stable latency time for application, with vulcanisation temperatures reduced to 50°C. This allows for rapid hand application and simultaneous vulcanisation on subsea trees, valves, manifolds, etc. The material is self-agglomerating, merging under gentle pressure, and can be applied at high thickness. As the base material has an intrinsically low thermal conductivity, glass-based fillers are not needed. The material adheres well to painted or primed surfaces and to many other materials typically used in the offshore thermal insulation industry.

The 2-component material is conveniently combined on site, reducing the need for refrigeration during transport and easing mobilisation logistics and is applied using simple hand tools. Extruded profiles can be used directly on complex structures or combined into sheets for ease of application on more regular shapes in order to optimise application rates. Moulds are not required for application, reducing engineering and fabrication cost, while also shortening mobilisation time.

The system has been extensively qualified according to ISO 12736 for continuous use at 180°C. This paper will detail important aspects of the development project along with the results of the qualification testing.
Offshore Urban Extension of the Anse Du Portier In Monaco
Authors: Aristaghes Pierre , Compte David
Published: August 2021

As part of the Monaco offshore urban extension project, Bouygues TP is in charge of design & build a maritime infrastructure as the first step of the six-hectare expansion of the city into the sea. This maritime infrastructure consists of a fill enclosed by a band of trapezoid concrete caissons and will serve as base for construction of the new residential area.

The paper focuses on some of the problems which had to be solved:

optimization of promenade level and wave absorbing chambers in conjunction with minimal reflection and safety related to overtopping, accounting for sea level rise and correlation between extreme waves and water levels. caissons and rubble mound foundation stability related to waves and seism, including extra seismic forces due to buildings considering the high reclamation height and the immediate proximity of building foundations. the way in which caissons representing nearly 80,000 m3 of concrete can be built in a floating and continuous manner via a caisson box (or "caissonnier" in French), within a particularly short time frame presence of a small craft harbor with shops along the quays, whose location was fixed for urbanistic reasons, which requested optimizations in detail of anti-overtopping devices as much as possible integrated in the urban context, need to convert a breakwater caisson into a low crested swimming pool caisson, with plexiglas windows exposed to wave slamming from outside, but also from inside due to overtopping impacts over the swimming pool basin. Ecodesign has been closely associated with hydrodynamic and coastal engineering, based on estimation of wave pressures and induced velocities in the different possible locations (chambers, walls, structures toes …). The eco-friendly development strategy is based on the wide-scale deployment of a range of 11 solutions which will be described (potential for caissons to be colonized, nursery function development, etc…). Moreover, posidonia transplantation has been done via concrete open boxes, whose stability under storm waves has requested CFD calculations to model local velocities and optimize their shape.
Challenges of Engineering the Hottest Subsea Heated Pipeline for the CRISP Project
Authors: Geertsen Christian , Langford Steve , McKinnon Colin , McKinnon Fred , Niesen Vicki , Orberg Frederico , Wang Nick
Published: August 2021

Objectives/Scope

The project was a 2km, electrically heat-traced, subsea pipe-in-pipe (PIP) system for transportation of a bitumen-like material across a shipping channel. Due to the viscosity of the bitumen, it must be transported at a minimum of 160°C; has a normal pipeline operating temperature of 200°C; and a design temperature is 228°C.

Methods, Procedures, Process

Due to the high operating temperature, pre-stressing and backfilling the PIP was required to lock in stresses at an intermediate pre-stressing temperature. The electrical heat-trace wires (installed to heat up the inner pipe and prevent setting of the bitumen during cooldowns) were used to achieve this pre-stressing during the fabrication process. The heating schedule causes high stress levels and require advanced engineering analyses to model the behaviour of the inner and outer pipe during the fabrication, installation, pre-stressing, and operation. The complex loading history of the inner pipe and the expansion spools was included in the global 3D, finite element (FE) models that were used to validate the pipeline profile, backfilling, pre-stressing temperature, and sequence of operations.

Results, Observations, Conclusions

The complex buckling behaviour of the inner pipe is presented and shown to be within DNV GL OS-F- 101 code limits. The end expansion during the various stages of pre-stressing is presented and compared to observed behaviour. The loads and stresses in the bulkheads are presented and shown to be acceptable. The analysis demonstrates that the pipeline system can be safely installed and operated up to the maximum design temperature of 228°C.

Novel/Additive Information

The project used pre-stressing by heating the inner pipe to an intermediate temperature before coupling the inner pipe to the outer pipe. The purpose of the pre-stressing was to manage the high axial stresses making it feasible to achieve the high design temperature of 228°C. Pre-expanding of the expansion spools at either end of the subsea pipelines was also used due to the space limitations. Innovative engineering analysis and construction methods were used to ensure the integrity of the inner pipe during the pre-stressing process and operation.
A New Era: Large Subsea Multiphase Compressor - Driven by Subsea Adjustable Speed Drive
Authors: Lendenmann Heinz , Fløisand John Olav , Vatland Svein
Published: August 2021

The use of subsea processing equipment, which maintains, increases, and accelerates oil and gas production, is now more and more widespread in offshore subsea field developments. Furthermore, there is a strong drive for electrification of offshore fields, both subsea and topside, to lower emissions. To meet the technical challenges, a significant effort is put into research and technology development by academia and the industry. ABB, a specialist in electrical equipment and control systems, and OneSubsea, a specialist in subsea processing, have executed large development programs organized as Joint Industry Projects (JIPs) together with oil and gas operators. In this paper, we discuss how ABB and OneSubsea joined forces in testing and validating their respective subsea technologies as a full subsea system for subsea multiphase gas compression.

This paper presents the world's first full-scale, combined subsea adjustable speed drive (ASD) and multiphase compressor (WGC6000) string test. In spring of 2020, both the ASD, and the WGC6000 reached Technology Readiness Level 4. The string test, with both units concurrently submerged, completed its witness test program in June 2020, with mapping of the WGC6000 speed and power envelope and a subsequent 24 h thermal stability run. The flawless test result confirms the strategic development road map for all the involved partners.

The technologies presented in this paper are now fully qualified and available for commercial use enabling a paradigm shift in subsea oil and gas production.
Vertical to Horizontal - Ultra Deep Azimuthal Resistivity Tool UDAR Service Helping to Maximize Production
Authors: El Sedeq Ahmed Zarroug , Hughes Neal , Oian Tore , Byrski Piotr , Denichou Jean-Michel , Nketah Daniel Ndubuisi , Dahroug Mohamed Saher
Published: August 2021

Dvalin field, discovered in 2010-2012. The location of this field is in the Norwegian Sea, as shown in (Figure 1). Dvalin field is an HPHT gas field in Middle Jurassic sandstone in the Garn and Ile Formations – the former being homogeneous with better reservoir properties, during the later heterogenous with low quality. (DVALIN, 2020)

The well 6507/7-Z-2 H objective is to produce hydrocarbons from the Jurassic reservoir section of the Dvalin field safely and cost-effectively. The well was planned to be drilled near vertical in the reservoir section and TD'ed at a maximum depth corresponding to the Garn Formation base.

After the productivity results from Z-3-H well came in at the low end of expectations, it was evaluated and decided to change the well profile of the Z-2-H well from vertical reservoir penetration to a horizontal profile; to have two penetrations with a minimum of 150m MD separation in the upper high permeable streak and then drop to penetrate lower high permeable streak. This decision was conducted only three days before starting the 17.5-inch section on the subject well. One Team culture was the key to achieving this significant change successfully.

The decision to change the well-profile was conducted after a thorough engineering evaluation, including offset well analysis, which was very limited as the closest horizontal well was more than 40 km away.

As the well was not planned as a horizontal well, departure between the surface location and Target Easting & Northing was minimal. Therefore, a high turn and deeper inclination build were required, which added some complexity to the well design.

One of the additional primary risks related to this change of trajectory design is deploying a more complex BHA design in the reservoir section with a full suite of LWD technologies run in an HT environment. In the planning phase, special consideration was needed to accurately simulate the expected circulating temperature and have proper procedures in place for temperature management and control.

Being the first horizontal well in the field, thus detailed planning was key for successful execution. Ultra-Deep Azimuthal Resistivity Tool (UDAR) Reservoir-Mapping capability was considered to help optimize the landing and navigate within the reservoir section. A feasibility study was conducted, and a 2-receiver Ultra Deep Azimuthal Resistivity Tool BHA configuration was selected and deployed.

During the execution, the Ultra Deep Azimuthal Resistivity Tool real-time inversion mapped the reservoir geometry, revealing resistive layers within the Garn formation, thereby facilitating optimal placement of the well to achieve the set objectives.

The well execution was largely considered flawless, with the real-time Ultra Deep Azimuthal Resistivity Tool data and corresponding interpretations facilitating decisions.
Riser Robotic Inspection - Reducing Safety Risk While Improving Efficiency and Effectiveness
Authors: Mabile Nere’ Joseph , Vagata Alessandro
Published: August 2021

Integrity management is an ongoing lifecycle process for ensuring safe operation and fitness for service of offshore oil and gas production systems, including risers. Risers offer a means of transporting fluids between subsea wells and the host platform crossing the splash zone that is probably the most critical region for corrosion and exposure to external damages. Furthermore, with their proximity to the personnel on the platform and to the topside equipment, risers are considered safety critical, and are therefore, subject to planned inspections followed by an engineering assessment of the findings. This paper discusses the motivation and business driver for developing and implementing a new and cost effective risers’ inspection methodology in the splash zone based on innovative robotic platforms. The technical features and the capabilities of the robot are outlined.

Traditionally, risers’ inspections are carried out by rope access technicians and divers or ROV below the water line using conventional technologies as spot ultrasonic thickness measurements, traditional radiography and visual assessment. This type of inspection is based on a first visual assessment followed by NDE testing only if some finding is spotted. Internal defects or defect under coating, e.g. splashtron, can be easily overlooked, compromising the entire assessment process. Additionally such activities are often limited by accessibility, weather, and Personnel On-Board (POB) accommodations, but primarily they involve risks to inspector's safety.

Backbone of the presented methodology is the use of a robotic crawler that has the key advantage to inspect autonomously the risers, navigating over obstacles like clamps and supports. The robot can carry a variety of payloads for visual inspections, surface profiling, and NDE examinations with the ability to scan large surfaces with or without coating and detect internal and external defects. It can operate in the topside, splash zone and subsea sections of the riser. The inspection data are processed in real time for an immediate assessment of the integrity of the asset.

Examples are presented and comparison is made between traditional inspection methodologies and robotic autonomous methodologies to demonstrate the improvement of inspection effectiveness and efficiency.

The paper also discusses the potential areas of future development, which include Artificial Intelligence (AI) algorithms to further automatize the process and methodologies of risers’ inspection and data analysis.
A New Fundamental Understanding of Gas in the Drilling Riser
Authors: Leach Colin , Zhou Guangzhao , Denduluri Veerabhadra , Wong George , Krishnamoorti Ramanan , Prosperetti Andrea
Published: August 2021

The work described here originated from the tragic and ultimately environmentally catastrophic event at the Macondo well in April 2010. The first part of the paper addresses the causes for the sudden and often destructive ejection of hydrocarbons from a riser when a gas kick escapes timely detection. The approach differs from previous work on the subject and provides a realistic understanding of the sequence of events responsible for the phenomenon. The focus is on the crucial few minutes and seconds prior to the sudden eruption of gas and provides a quantitative illustration of the extreme rapidity of the ejection which leaves no time for a drill crew to adopt mitigation measures. It is shown that, in many cases, a back-pressure applied at the top of the well can be beneficial. The second part of the paper describes a novel method for the detection of gas which relies on the measurement of pressure differences along sections of the riser. These data are sensitive to the mean density of the fluid in the section and can therefore detect the presence of free gas. Laboratory experiments supporting the idea are described. Proper signal processing can be developed which may be able to allow for automatic mitigation measures to be taken in the event of an otherwise undetected gas influx approaching the surface.
Using Metocean Forecast Verification Information to Effectively Enhance Operational Decision-Making
Authors: Steele Edward , Brown Hannah , Bunney Christopher , Gill Philip , Mylne Kenneth , Saulter Andrew , Standen Jessica , Blair Liam , Cruickshank Stewart , Gulbrandsen Morten
Published: August 2021

Metocean forecast verification statistics (or ‘skill scores’), for variables such as significant wave height, are typically computed as a means of assessing the (past) weather model performance over the particular area of interest. For developers, this information is important for the measurement of model improvement, while for consumers this is commonly applied for the comparison/evaluation of potential service providers. However, an opportunity missed by many is also its considerable benefit to users in enhancing operational decision-making on a real-time (future) basis, when combined with an awareness of the context of the specific decision being made. Here, we present two categorical verification techniques and demonstrate their application in simplifying the interpretation of ensemble (probabilistic) wave forecasts out to 15 days ahead, as pioneered – in operation – in Summer 2020 to support the recent weather sensitive installation of the first phase of a 36 km subsea pipeline in the Fenja field in the North Sea. Categorical verification information (based on whether forecast and observations exceed the user-defined operational weather limits) was constructed from 1460 archive wave forecasts, issued for the two-year period 2017 to 2018, and used to characterise the past performance of the European Centre for Medium-Range Weather Forecasts (ECMWF) ensemble prediction system (EPS) in the form of Receiver Operating Characteristic (ROC) and Relative Economic Value (REV) analysis. These data were then combined with a bespoke parameterization of the impact of adverse weather on the planned operation, allowing the relevant go/no-go ensemble probability threshold (i.e. the number of individual/constituent forecast members that must predict favourable/unfavourable conditions) for the interpretation of future forecasts to be determined. Following the computation of the probability thresholds for the Fenja location, trials on an unseen nine-month period of data from the site (Spring to Autumn 2019) confirm these approaches facilitate a simple technique for processing/interpreting the ensemble forecast, able to be readily tailored to the particular decision being made. The use of these methods achieves a considerably greater value (benefit) than equivalent deterministic (single) forecasts or traditional climate-based options at all lead times up to 15 days ahead, promising a more robust basis for effective planning than typically considered by the offshore industry. This is particularly important for tasks requiring early identification of long weather windows (e.g. for the Fenja tie-ins), but similarly relevant for maximising the exploitation of any ensemble forecast, providing a practical approach for how such data are handled and used to promote safe, efficient and successful operations.
Experience with Interface Shear Box Testing for Pipe-Soil Interaction Assessment on Sand
Authors: Westgate Zack , Argiolas Ricardo , Wallerand Regis , Ballard Jean-Christophe
Published: August 2021

This paper is a companion paper to OTC 28671, titled "Experience with Interface Shear Box Testing for Axial Pipe-Soil Interaction Assessment on Soft Clay", and presents a similar range of experience and best practice recommendations for geotechnical laboratory testing to determine soil properties relevant to pipeline-seabed friction on sandy seabeds. The paper is underpinned by a new database that demonstrates the driving parameters that influence interface friction in granular materials. By accurately quantifying shear resistance along the pipe-soil interface under low normal stresses imposed by subsea pipelines, design ranges in friction can be narrowed and/or tailored to specific pipeline conditions. These improved geotechnical inputs to pipe-soil interaction can alleviate unnecessary axial expansion mitigation and lateral stabilization measures, unlocking cost savings otherwise unavailable through conventional testing.

A large database is presented, compiled from both previously published research and unpublished recent industry experience with low normal stress interface shear testing using various modified direct shear box devices. The test database comprises several coarse-grained soil types of both silica and carbonate minerology tested against pipeline coatings of various material, hardness and roughness.

The database populates a framework for assessing frictional pipe-soil interaction response, illuminating key trends from normal stress, interface roughness and hardness, and particle angularity, which otherwise remain elusive when examined through individual test datasets. This database and the populated framework provides guidance to pipeline and geotechnical engineers in the form of a basis for initial estimates of axial and lateral friction of pipelines on sand and an approach for improving these estimates via focused site-specific testing.

The test database includes previously unreleased project data collected over the past few years for offshore oil and gas projects. Similar to its predecessor paper on soft clays (OTC 28671), this paper shares the authors’ collective experience providing guidance on the planning, execution and interpretation of low stress interface shear tests in sands. The combined databases across both papers provide a significant improvement in early stage guidance for characterization of geotechnical soil properties for subsea pipeline design.
Bringing Flexibility and Automation to Well Testing Operations Through Wireless Telemetry - Case Study
Authors: Temer Elias , Subramaniam Deiveindran , Kaipov Yermek , Merino Carlos , Latvin Vladimirovich , Barylnik Alexanderovich
Published: August 2021

Dynamic reservoir data are a key driver for operators to meet the forecasted production investments of their fields. However, many challenges during well testing, such as reduced exploration and capex budgets, complex geologic structures, and inclement weather conditions that reduce the well testing time window can prevent them from gathering critical reservoir characterization data needed to make more informed field development planning decisions. To overcome these challenges, a live, downhole reservoir testing platform enabled the most representative reservoir information in real time and connected more zones of interest in a single run for appraisal wells in the Sea of Okhotsk, Russia.

This paper describes the test requirements, the prejob planning, and automated execution of wirelessly enabled operations that led to the successful completion of the well test campaign in very hostile conditions, a remote area, and restricted period. The use of a telemetry system to well testing in seven zones enabled real-time control of critical downhole equipment and acquired data at surface, which in turn was transmitted to the operator's office in town in real time. Various operation examples will be discussed to demonstrate how automated data acquisition and downhole operations control has been used to optimize operations by both the service company and the operator.
Hydrophobic Dielectric Sealing Material Enabled Highly Reliable Electrical Connectors for Downhole Data and Power Transmission Application
Authors: Xia Hua , Settles Nelson , DeWire David
Published: August 2021

A high-strength dielectric sealing material has been developed for sealing electrical connectors, feedthroughs, bulkheads, and interconnectors. X-ray diffraction analyses have identified that the microstructures of the sealing material could be of amorphous and α-phase mixed morphology, α+β mixed phase, and β-phase dominated tetrahedral microstructure, which primarily depend upon the material processing temperature. The electrical insulation resistance of the β-phase dominated sealing material have nearly two times higher than that of α+β mixed phase sealing material. Both β-phase dominated and α+β mixed phase sealing materials have shown water repelling properties, while amorphous glass phase has shown hydrophilic properties. If a 5,000MΩ insulation resistance is also regarded as baseline for a downhole electrical connector, the maximum operation temperature of α+β mixed phase sealing materials is around 240°C while that of the β-phase dominated sealing material can be up to 300°C. Furthermore, a thermo-mechanical modeling has been developed to quantify if a designed electrical connector has sufficient reliability in the hostile wellbore or downhole environments. The temperature- and pressure-dependent seal compression have suggested that the temperature-related safety factor should be chosen in the range from 2.0 to 5.0 while the pressure-related safety factor should be chosen in the range from 1.5 to 2.0 to ensure 10-20 years electrical connector downhole operating reliability. The qualification tests from prototyped electrical connectors, under 260°C/32,000PSI simulated water-fluid based conditions, have demonstrated that such high-strength sealing material sealed electrical connector could be integrated with logging while drilling (LWD) or/and measurement while drilling (MWD) tools for providing long-term reliable signal, data, and electrical power transmission services, regardless of a water-based or moisture-rich wellbore or/and downhole environment.
Scale Removal In A Deepwater Oil Production Well Using Fresh Water
Authors: Martins Paulo Henrique de Amorim , Freiman Bruno Marins
Published: August 2021

The aim of this paper is to present the results obtained by the use of fresh water in order to remove inorganic scale deposited inside production tubing from carbonate reservoir deepwater production wells with high salinity and low BS&W. The paper covers the entire process from the identification of production loss, the investigation of its main causes, treatment propositions and discussion of obtained results.

One of the hypotheses regarding the scale deposition mechanism in the studied wells is that the precipitation of salts is due to the evaporation of produced water. This phenomenon occurs through the contact of water with dry gas applied in the artificial elevation method (gas lift). The proposed and tested scale removal procedure consists of a soaking of the production tubing with fresh water in order to dissolve the deposition or at least part of it that is soluble in water. Preventive care actions in relation to flow assurance were taken, since the suggested method uses a high volume of fresh water, increasing the hydrate risks.

Scaling in wells with those characteristics was systematically removed through remote acidification (with specialized vessel assistance). That approach has shown to be always effective. On the other hand, remote acidification was always costly and dependent on the availability of critical resources. The technique depicted in this paper requires neither a vessel nor acid and, therefore, incurs significantly lower costs. The results obtained in the first tests were substantially positive since the wells’ productivity was fully restored. In this sense, the hypothesis of water solubility of the scale deposition was confirmed, and the method validated.

Since its validation, the method has been applied a number of times, confirming its repeatability, and extending its use to other wells with similar scaling occurrences, reducing costs and restoring the production in a short time. Nevertheless, new challenges arise in relation to the full comprehension of the deposited material and the prevention of its deposition.