bluuebunny/crossref_metadata_2025 huggingface dataset:
Decommissioning Of Subsea Structures In Brazil: Impact Of Invasive Species And Genome Sequence Of The Invasive Azooxanthellate Coral .
Authors: Batista João Humberto Guandalini , Rebelo Mauro , Soares-Souza Giordano
Published: April 2020

Decommissioning of offshore assets in Brazil is subject to high level of uncertainty because of invasive Sun Coral Tubastraea sp. This species has an improved capacity of dispersion and recruitment, and has been associated with the replacement of native species in rocky shores causing severe impact to native biodiversity. Because of that, colonized artificial substrates will require cleaning and actions to avoid dispersion to the surroundings. This paper is proposing to study biology of Tubastraea sp, aiming to identify methods to eliminate and/or decrease its spreading.

A colony of Tubastraea sp. was collected by scuba diving in Angra dos Reis (23o3.229'S / 44o19.058'W), Rio de Janeiro state, Brazil and transferred to a laboratory to proceed with a comprehensive analysis of morphology, cytogenetics, transcriptome, mitochondrial and nuclear genome. Colony morphology was analyzed and the skeleton was deposited in the zoological collection of the National Museum of Brazil (MNRJ 7129). Deoxyribonucleic acid (DNA) extractions were performed in clone polyps for the preparation of sequencing libraries. Bioinformatics was applied to assemble the first draft of the nuclear genome which was subsequently improved for contiguity using molecular and computational scaffolding methods.

Our study showed the genome of Tubastraea sp is organized in 23 chromosome pairs and has 1.4 Gb making it the largest coral and Cnidaria genome sequenced to date. The hybrid assembly using short and long-reads has a N50 of 180,044 pb, 12,320 contigs and high completeness estimated as 91.6% of BUSCO complete genes. Results showed that almost half of the genome consists of repetitive elements, mostly interspersed repeats. Gene content was estimated as about 94,000, a high number that warrants deeper scrutiny.

The Tubastraea sp. genome is a landmark study promising to provide insights not only about the genetic basis for the extreme invasiveness of this coral, but also to understand the adaptation flaws of some reef corals in the face of anthropic-induced environmental disturbances. We expect the data generated in this study will foster the development of efficient technologies corals species management, whether invasive or threatened.

When oil&gas industry has a problem where conventional methods are not efficient enough, a multidisciplinary approach becomes necessary. This study consists in an innovative example of a partnership among high reputation biological entities and one operator was established to bring a broad understanding of an invasive species in Brazilian waters, extremely impactful to Decommissioning activities in country.
Qualification of a Subsea Sulphate Removal System
Authors: Plasencia Jose , Sabedotti Sergio , Andrews Abel , Costa Ana , De Almeida Cristina , Nunes Elizabete , Santos Gabriel , Martins Filipa , Ribeiro Mario , Andreotti Marcelo , Russo Juliano Diego
Published: April 2020

This paper presents the ongoing development and qualification program of a subsea sulphate removal and injection system and provides an overview of the system together with the features that enable its operation subsea. The ongoing development program has completed a dry piloting phase that focused on the design of the system, subsystems, assembly of the pilot and qualification of the process, including the modified operation of the filtration technologies. This development is in cooperation with 5 leading global oil companies. The pilot operation took place over a period of 6 months.

Injection of seawater to provide reservoir pressure support is often the choice to increase oil recovery in a field. Traditionally, large and heavy topside processing systems are deployed to treat and inject seawater. This creates significant operational challenges, especially in brownfields, where topside space and weight capacity are constrained. Moving the system to the seabed will greatly reduce the capacity demand imposed on the floating facility and will eliminate the need for an expensive high-pressure riser and flowline system. The subsea system requires a different operational approach in which the conventional chemical cleaning is eliminated. Special design considerations must be made to maintain operational robustness without the chemical cleaning in place unit.

Baker Hughes and its partners are proposing to move the seawater treatment system to the seabed to simplify and debottleneck the topside facilities and reduce the total cost of ownership. Seawater treatment systems for injection are conventionally topside units. Necessary operational modifications have to be implemented to enable its reliable operation in subsea conditions. These modifications are being validated through piloting.
New Generation Fracturing Fluid
Authors: Perez Oswaldo J. , Lin Genyao , Fragachan Francisco E. , Le Hoang , Qu Qi
Published: April 2020

In the past, high-viscosity fluids have been the preferred method for increased proppant suspension and transport. This methodology has been effective using systems such as borate-crosslinked fluid with the downside of considerable damage to the proppant pack, typically resulting in about 85% percent regain conductivity. While this may still be acceptable, the major limitation of these systems is the additional loss of needed fracture length. Often, with low viscosity fluids such as linear gels and friction reducers, fracture length may be established allowing breaks into the secondary fractures and mechanical reactivation of the pre-existing natural fracture network may be enhanced. However, these low viscosity fluids cannot offer efficient suspending characteristics within the fracture under static conditions, which may lead to early settling. As a response to this industry demand, a novel fluid has been developed to optimize the hydraulic fracturing process by enhancing proppant transport with reduced friction losses, less fresh water requirements and smaller footprint of pressure pumping equipment.

Novel fluid technology from which the polymer was engineered to form a network of packed structures from polymer associations providing the maximum proppant suspension, breaking with the traditional concept relying on viscosity to enhance proppant transport during treatments, is described with extensive experimental testing. The results show that the fluid exhibits outstanding properties and benefits to transport proppant without settling in addition to a considerable reduction in fresh water requirements and maintenance costs associated with surface equipment footprint, as the current trend is unsustainable.

New physics consisting of a hybrid rheology analytical model and fluid structures to correlate elastic fluids rheology parameters, firstly, n′ and k′ values, and secondly the storage, and loss moduli profile (G′ and G″ accordingly), is presented. The complex fluid behavior deviates from common rheology models and, its elastic properties, such as storage modulus (G′), loss modulus (G″), and angular frequency (rad-sec) are discussed in the context of the unique fluid characteristics of a network of packed structures from polymer associations. Physics-based analytical model results compute the viscosity, and elastic parameters based on shear rate to calculate the pressure losses along the flow path from surface lines, tubular goods, perforations, and fracture, optimizing horse power requirements based on reduced pressure loses, will be presented [16].

The presentation will demonstrate that such physics and unique fluid behavior are achieved via a novel elastic and a network of packed structures from accociative polymer fluid, having proper proppant suspension, effectively placed at low viscosity, less fresh water requirement, low injection pressures, with no settling and 98% retained conductivities.
Safety into Design Phase – A New Approach to Enhance the Operational Safety
Authors: Roberto Marcello Augustus Ramos , Andrade John Kennedy Candeira
Published: April 2020

The offshore O&G production has been increasing considerably in the last five years. Therefore, to guarantee the safety of their operations, the O&G companies are being pushed by regulators agencies to establish a robust and efficient safety management system, particularly in Brazil, where the Petroleum National Agency published, in 2015, the SGSS (Technical Regulation of the Subsea Systems Operational Safety Management System). The new regulation forced Brazilian Operators, such as Petrobras, to promote a couple of initiatives, in order to increase the safety of their offshore operations. One of these initiatives has its focus into eliminate or minimize the risks in operational phase, maximizing the potential to avoid them during engineering design phase, where the ability to influence safety is higher than another project phase. One of the challenges of this approach is related to the fact that, in general, and regarding operational safety, the engineering design works in a passive way, in other words, the safety improvements in the new projects only are applied if a strong operational safety issues feedback process is established. Operators have been noted that this operational feedback to design engineers is not the only way to achieve a high level of safety in their operations and facilities. There is a consensus that the engineering design shall work in an active way, being more predictive than corrective, in order to avoid operational issues. The objective of this paper is present a new approach regarding the operational safety focused on engineering design phase, establishing new process, methodologies, actions and closing the gaps between design and operational teams to enhance operational safety.
Subsea Local Heating, a Versatile Thermal Booster to Optimize Flow Assurance
Authors: Anres Stéphane , Muguerra Philippe , Bacati Fabrice , Hallot Raymond , Capela-Moraes Carlos Alberto , Valdenaire Thomas
Published: April 2020

A new technology called Local Heating offers the possibility of significantly raising the temperature of the multiphase production fluid in order to improve flow assurance and consequently the economics of field developments. Heating the flowlines is a way to overcome the thermal constraints, mitigate hydrate & wax risks and provide operational flexibility. Indeed, in the case of long tiebacks, very deepwater applications or when the fluid temperature at the wellhead is too low, conventional flow assurance solutions might be very expensive or even not applicable.

While other heating technologies such as DEH and Heat Tracing have been designed mainly to operate under transient operations (start-up, shutdown, preservation), this heating technology can be operated continuously during production and also during transient operations as long as there is fluid circulation in the flowline. The device is a very simple and robust system integrated into a compact subsea module, installed in parallel or in-line with the main flowline and which can be retrieved for maintenance or relocated. It is compatible with any type of field architecture and can be implemented either on greenfields or brownfields. In the case of greenfields, the use of Local Heating could also be a way to mitigate uncertainties on production fluid temperature or solve an unexpected poor thermal performance of the design. This solution is based on induction and is therefore able to provide very high-power levels (several MW) with a compact module. The temperature is continuously monitored throughout the heating module by means of fiber optic distributed sensors. The technology is fully compatible with preservation by flushing and allows pigging in the event of deposits.

The main principles of the technology will be described in the paper, as well as a preliminary design performed for a specific case provided by an operator.

The paper will also present the qualification work recently performed including heating performance lab tests using a small-scale submerged prototype operated under atmospheric conditions with multiphase fluid. The tests have confirmed the good electrical and thermal behaviour of the system.

The paper finally describes the last qualification phase the objective of which is to install a subsea pilot to be connected to a subsea production system on a field located in Brazil. The intention is to perform this work in the frame of a Joint Industry Project.
A Cloud-based Computational Framework To Perform Oil-field Development & Operation Using A Single Digital Twin Platform
Authors: Chowdhury Khairul , Arif Akhteruzzaman , Nur Md Nuruzzaman , Sharif Omar
Published: April 2020

Building a digital oil-field or digital twin, without involving multiple digital partners, and costly time-consuming digital endeavor is a significant challenge in Oil & Gas industry. In most cases, such systems are capable of data integration and visualization for only a part of an oil-field. Real-time analytics is missing to transform the digitalization into a smart and scalable system. The objective of this paper is to present a digital oil-field creator driven by a computational framework to perform key analytics for oil-field life cycles.

A computational framework, networked with decentralized analytics engines that are equipped with a predictive analytics computation system, and an automated design engineering system has been developed. The predictive analytics computation system performs engineering design using data, pipeline integrity, platform structures, and coupled systems integrity and equipment integrity. The automated design engineering engine performs conceptual and FEED for subsea elements such as pipelines. These computational engines are then integrated into a self-service 3D digital twin creator for the user to operate on the front end and to receive analytical insights.

3D digital twin creator is capable of creating oil-field architecture within a fraction of the time utilizing the traditional model. Additionally, the creator optimizes the subsea architecture based on a selected set of criteria including CAPEX or OPEX costs. The system then performs conceptual or FEED level engineering including finite element analysis (FEA) using automated engineering saving as much as 80% of engineering time. Finally, the digital model is able to conduct asset integrity predictive analytics using machine learning from the monitored data. A Gulf of Mexico (GOM) oil field concept architecture was created by the digital twin creator and the computational framework. The system performed an automated pipeline conceptual optimization, buckling and free span design, and finally conducted riser integrity and equipment integrity. The computational framework is flexible and scalable to incorporate any organization's existing engineering process.

The multidisciplinary complex analytics systems are networked in a way to maximize the integration of multiple oil-field systems from multiple companies and their asset's operational status in a 3D visual without a complex or expensive digital system. This digital system not only integrates multiple phases of the oil-field life cycle but also allows the reuse of all processes across different projects and time.
Pressure Losses Calibration in Managed Pressure Drilling
Authors: Ilin Andrew V. , Brana Jose D. , Ameen Rostami Sayamik N. , Koithan Thomas H.
Published: April 2020

Managed Pressure Drilling (MPD) usage is in increasing demand in both offshore and onshore market – especially for wells with narrow drilling pressure margins. Maintaining desired constant Bottom-Hole Pressure (BHP) within given range during MPD operation requires accurate hydraulic modeling for frictional pressure losses. Surface BackPressure (SBP) and StandPipe Pressure (SPP) data, measured in real-time, allows the calibration of frictional pressure losses and an estimation of BHP more accurately.

An estimation of SPP is calculated based on integration from the measured SBP back to the inlet in the hydraulics model. The pressure loss increment in the hydraulics model is calculated based on a difference between the measured and estimated SPP value. The system parameters are monitored during drilling and could be adjusted based on the hydraulics model corrected for the pressure loss. The frictional pressure loss due to the drilling pipe rotation could be calibrated by analyzing a difference between the measured and estimated SPP for two operations: without rotation and with rotation.

This work underscores the development and usage of advanced hydraulics modeling to accurately calculate BHP during MPD operations. In current hydraulics, mathematical models have been developed to account for various operating parameters, wellbore geometry and fluid properties. This is an enabler to estimate pressure, density, rheology, temperature, and cuttings distributions within the wellbore, drill string and surface equipment more precisely. The frictional pressure loss model includes rotational pressure losses, local pressure losses at special tools and tool joints. This model is based on empirical sub-models which require experimental verification for accuracy. The results of the BHP, calculated with a calibrated hydraulic model, are compared with corresponding results calculated with the uncalibrated model.

The use of the pressure calibration for the hydraulics model allows estimating BHP with less error. Recommendations are presented for the accurate mathematical modeling and their applicability and limitations for successful MPD operations.
Acceleration of 4IR Driven Digital Transformation Through Open Source: Methods and Parallel Industries Knowledge Reapplication in the Field
Authors: Haroon Sammy Sarblund , Viswanathan Aruna , Alyamkin Sergey , Shenoy Ramachandra
Published: April 2020

In the age of open source, oil and gas companies that invest in licensing proprietary platforms to build artificial intelligence (AI) solutions will have to closely guard against obsolescence. While the mathematics behind AI has existed for decades, its rapid adoption in virtually all sectors has been powered by open source, where a global community of academicians and data scientists are continuously developing and improving the mathematics behind the predictive and prescriptive solutions of the future.

We posit that the existence of AI software development, which we describe as data driven analytical solutions providing predictive and prescriptive answers to questions, is solely due to the academia's focus on research and its pedagogical goals driving the dissemination of the research to the open source community to move the research to development. Indeed, all data science coursework is steeped in training on open source platforms and tools. When models do not depend on platforms, organizations can deploy flexible and agile software that has the ability to leverage better methods that come out in the future. Borrowing ideas from other industries we can see that just as Wordpress and its open source community of designers and developers revolutionized how websites are created, software that can quickly deploy the best available technology (and be mobile) while maintaining the security of the data is poised for user adoption and success where legacy systems and traditional dashboards fail.

While the mathematics of physics does not change our confidence in its accuracy, in comparison, the mathematics of an AI algorithm is an approximation. This mathematics is being continuously improved though rarely achieving 100% accuracy. Algorithms are built upon open source AI libraries that are continuously improving. Similarly, the methods and techniques for developing the AI algorithms in oil and gas are continuously improving through two main sources, academia and adjacent industries reapplication of AI methods. We provide examples of open source technologies already part and parcel of all data scientists' repertoire of development, who are currently working in oil and gas. We further showcase reapplication of solutions from other industries, such as, medical image data analysis to seismic data processing and subsurface characterization.
Integrating Electrofacies and Well Logging Data Into Regression and Machine Learning Approaches for Improved Permeability Estimation in a Carbonate Reservoir In a Giant Southern Iraqi Oil Field
Authors: Al-Mudhafar Watheq J
Published: April 2020

Integrating discrete facies classification into the estimation of formation permeability is a crucial step to improve reservoir characterization and to preserve heterogeneity quantification. Therefore, it is essential to obtain the most accurate estimation of permeability in non-cored intervals in order to attain realistic reservoir characterization and modeling. In our most recent paper [OTC-30906-MS], the electrofacies classifications have been conduced for a well from a carbonate reservoir in a Giant Southern Iraqi oil field. The same predicted discrete electrofacies distribution was included in this paper along with well logging interpretations to model and predict the reservoir core permeability for all wells. The well logging interpretations that were included in permeability modelling are neutron porosity, shale volume, and water saturation as a function of depth. The regression and machine learning approaches adopted for permeability modelling are multiple linear regression (MLR), smooth generalized additive Modeling (SGAM) and Random Forest (RF) Algorithm. The classified electrofacies were considered as a discrete independent variable in the core permeability modelling to provide different model fits given each electrofacies type in order to capture the different permeability variances.

The matching visualization between the observed and predicted core permeability, the computed root mean square prediction error and adjusted squared R were considered as validation and accuracy tools to compare between the three modelling approaches. Since there are too many intervals with missing core permeability measurements, the modelling was first adopted on the intervals that have permeability readings (known subset). The prediction was then conducted given the same known permeability intervals in addition to the entire dataset (full dataset). The root mean square prediction error and adjusted squared R for the Random Forest were significantly better than in both MLR and SGAM for the known subset and full dataset. It can be concluded that combining the electrofacies in one permeability model has accurate, fast and an automation procedure of prediction for other wells. The two machine learning algorithms were implemented by R software, the most powerful statistical programming language.
Hydrate Management Controls In Saudi Aramco’s Largest Offshore Nonassociated Gas Fields
Authors: Soliman Sahweity Mohamed Ahmed
Published: April 2020

Hydrate management is a major challenge for offshore oil and gas fields, and in subsea pipelines transporting gas from offshore platforms to the onshore processing facilities. This paper is intended to discuss the various hydrate control methods and strategies that have been evaluated and implemented during the project's design, startup, and operation stages to come up with the most efficient and economical solution for hydrate mitigation.

Methanol, MonoEthylene Glycol (MEG) and kinetic hydrate inhibitors (KHIs), as well as Twister Technology, were evaluated to act as hydrate prevention mechanisms. Based on the CAPEX, OPEX and unmanned operation philosophy, KHI was used for hydrate inhibition in the gas Field-A. This paper will discuss different innovative strategies to eliminate hydrates during steady-state and transient operations. It will also consider cold startup, maximum flow and minimum temperature, planned and unplanned shutdowns, depressurization, and purge and pilot gas scenarios.

The optimum hydrate management control for Field-A offshore platforms and subsea pipelines was a combination of different strategies. For the Field-A, KHI and MEG injection were utilized in combination or independently depending on the scenario.

The challenges experienced during the commissioning, startup and operation of the first Saudi Aramco offshore facilities resulted in many potential innovations and patents as follows: Development and installation of the PMS resulted in reducing the operating cost.Development of variable speed pipeline pig technology.

The challenges and lessons learned associated with hydrate management will be discussed in addition to the advantages and disadvantages of the used chemicals.
Multilateral Expandable Metal Anchoring Packer Design, Development, and Application in the North Sea
Authors: Kelsey Matthew , Stautzenberger Arthur , Einervoll Olav , Dietz Wesley , Lajesic Boris , Stokes Matthew
Published: April 2020

Multilateral technology can provide a higher recovery factor of hydrocarbons by achieving a longer field life supported by the cumulative production of the multiple laterals, turning otherwise unviable reservoirs into economically sound targets while keeping construction costs down and minimizing risk.

Application of expandable liner hanger technology to junction creation in multilateral wells can improve completion efficiency and flexibility by offering increased tensile and torque ratings along with larger IDs over previous solutions.

This paper highlights the development, testing, and a successful case study of a new expandable anchor packer designed for a multilateral TAML Level 5 application in the North Sea.

Well construction has changed in recent years with more operators turning to multilateral technology due to slot-constrained pads and a desire to increase reserves by combining targets that are separately uneconomical or improving the efficiency by extending the life of mature fields. The foundation to constructing a multilateral well is a reliable main-bore anchor point, which provides a service tool landing point from which a casing exit window is milled, and a lateral leg drilled and completed.

Using an expandable anchor packer, based on an existing expandable liner hanger design widely accepted in the industry, provides a broader scope to position and orient the packer at the desired depth to begin lateral construction while providing increased completion flexibility through increases in tensile, torque, and ID capabilities. These improvements provide the capability to deploy screens directly below the anchor packer, eliminating the need for a separate trip with a liner deployment system (LDS). The larger packer ID makes the system compatible with a field-proven multibranch inflow control (MIC) junction.

This new approach to an anchor packer for a multilateral TAML Level 5 junction provides not only increased load, torque, and ID capability, but improved sealing reliability as well. Validation testing has confirmed that the high-performance, advanced metal-to-metal sealing technology of this new expandable anchor packer provides a compliant metal-to-metal seal with a fully bonded resilient elastomeric seal, which can compensate for imperfections in the parent casing and provide isolation to a potential gas cap in the main bore below the lateral window.

By employing field-proven expandable liner hanger technology with its superior load, geometry, and sealing capabilities to multilateral TAML Level 5 junction creation for a North Sea application, improved efficiency and flexibility in the completion can be achieved.
The Flow Assurance Criticalities and Challenges Management of Zohr Deepwater Giant Gas Field
Authors: ElSayed Mohamed Salah , Zayed Samir , Tolba Mohamed Ahmed , Omar Muhammad Karam , Hussein Ola Amr , Darwish Hatem Mohamed , Negm Mohamed Nagy
Published: April 2020

Offshore oil and gas fields have gained tremendous importance for the world's energy supply. Our ability to tap into these reserves is one of the main reasons that the predictions of the "Club of Rome" in 1972 about diminishing hydrocarbon reserves and "limits to growth" turned out to be pessimistic.

As the transport of oil and gas products in a multiphase manner is increasingly stretched over greater distances with development in more hostile environments, especially when designing large-scale ultra-deepwater production network, it is mandatory to ensure sustaining reliable and robustness operations as the access to subsea infrastructure becomes increasingly limited and to reduce the influence on the downstream facilities.

An integrated multiphase dynamic model was used to optimize operating procedures for initial well clean-up and ramp-up to production from a sizeable deepwater production system before first gas. This approach was essential to create and test start-up scenarios given several well and reservoir uncertainties.

On the other hand, the transient analysis was performed to optimize the system's time-dependent operations, e.g., 215 KM pipelines start-up and shutdown; production Ramp-up; maximum no-touch time without hydrates; Depressurization of the network to remove hydrates and ensure flaring system adequacy; Optimized well routing; and Hydrodynamic slugging. All the simulations accounted for the uncertainty of the associated controlling parameters.

In this paper, we will present how we developed the integrated model. We will show how we used the simulation as a guidance tool to develop appropriate procedures for different transient operations. The framework presented here applies to any similar deepwater field with extra-long tie-back. This model is a handy tool not only for engineering simulation but for operator training and real-time surveillance as well.
How Machine Learning is Improving Production on Offshore Platforms
Authors: Herve Philippe , Prado Gabriel , Rosner Marla
Published: April 2020

The oil and gas industry is known for its volatile boom and bust cycles, and this has a particularly strong effect on offshore platforms, which are substantial investments that do not always succeed in generating profit. To generate value and remain competitive in the offshore sector, operators must ensure that their operations are efficient, optimized, unlikely to be interrupted by unexpected failures, and resilient to fluctuations in oil prices. Artificial intelligence, and more specifically, machine learning, applications allow operators to do all of this. This paper presents two specific case studies demonstrating how machine learning has been proven and scaled in a deployed environment, with tangible increase in offshore production leading to significant business value to the operator.
A Secondary Guide for Fracture Density Incorporating Structural Deformation, Distance from Faults and Fault Displacement
Authors: Valencia Israel
Published: April 2020

The objective of this paper is to show a methodology that generates a secondary guide for propagating fracture densities as input to a DFN (Discrete Fracture Network). Our goal is to provide a new idea for geomodelers who deal with complex fractured fields, and do not have enough information to build robust models for exploration and simulation.

The secondary guide was developed to help geomodelers populate fracture properties on a reservoir model. The seismic data was of low quality, making it difficult to obtain good seismic attributes. Therefore, a guide was created that incorporated on the same attribute, information about the geocellular grid deformation, the distance from the fault planes, and the fault's displacement. All of the information used to generate the secondary guide was created from the structural model (interpolated surfaces -faults and horizons - perfectly sealed) and geocellular grid.

It is also important to know that, depending on the type of deformation defined for the model, deformation results can vary. Once the three properties were calculated and placed in the same domain (the geological grid), they were rescaled. After that, they were merged in a new property according to the geomodeler's criteria.

The quality of the results relied on the seismic interpretation of faults and horizons, so in order to generate a good guide, it was important to obtain the most accurate representation of the structural model. The values of the new output property varied as a function of the distance from the faults, but also as a function of the fault displacements, and the presence of the deformed rock. This allowed its correlation with the fracture density through use of a statistical function. The secondary guide did not include other fracture controllers, such as the probability of fractures, which was also controlled by the geomechanical parameters. That would be another property to be weighted in the process.

The process was designed and applied to a real case. The methodology enabled the geomodeler to distribute fracture densities and their properties without the use of seismic attributes. The workflow is applicable to any kind of fractured reservoir and can be used anywhere, from exploration to production.
Qualification of Corrosion Resistant Steel Catenary Risers using Polymer Lining Technology
Authors: McCord Craig , Jones Colin
Published: April 2020

Corrosion protection of water injection Steel Catenary Risers (SCRs) has been identified as a multi discipline challenge facing the industry. Readily available solutions often lead to excessive riser weight and top tensions, expensive materials, complex welding solutions, and increased fabrication time and risk. Currently, a technology qualification program for an integrated liner system in dynamic riser service is aiming to address this and achieve formal Technology Readiness Level 5 (TRL5 from DNVGL-RP-A203) by Q3 2020.

Individual components of a liner system are often unique and proprietary requiring individual qualification. This multi discipline program utilizes an integrated liner system incorporating carbon steel host pipe (including girth welds), polymer liner (including butt fusion welds), electrofusion welded polymer connectors (EWPC), and mechanical corrosion resistant alloy terminations (MCRAT). Fatigue testing is the primary method of assessment in this case, a series of nine fatigue trials spread over three stress ranges; 200MPa, 150MPa and 100MPa, have been scoped.

Initial positive results have proven the concept of using the integrated liner system components in the dynamic riser application with successful completion of high stress range (200MPa) fatigue tests utilizing the full integrated liner system. To date, the conducted fatigue testing achieves performance equivalent to DNVGL-RP-C203 S-N curve D (in water with cathodic protection) after subjecting the pipe to pre-straining via reeling trials. Upon scope completion, it is expected to extend performance to meet the requirement for S-N curve C/2. Completion of testing with an intact corrosion barrier combined with assessment of vertical orientation on the system enables design of polymer lined pipelines suitable for dynamic riser service.

The integrated liner system offers a potential step change in SCR and SLWR design. The technology application is able to provide key benefits such as an optimized design over the life of the pipeline, improved flow assurance, minimized installation complexity, optimized host and operational needs, thus resulting in an efficient and optimized field life cycle.
Mobile Mudmats for Subsea Field Development Structures
Authors: Bughi Sabrina , Marchionni Lorenzo
Published: April 2020

Mobile mudmats are increasingly adopted as foundation solution for subsea structures in offshore field developments, to allow their horizontal movement under the cyclically imposed expansion/contraction operating loads from the connected lines. The foundation compliance grants the dissipation of the applied loads while the structure slides on the seabed and the required base dimensions are reduced. Foldable solutions can even be installed integrated with the related lines, passing through the pipelay vessel tower.

The described experience is based upon design and installation of mobile mudmats for subsea structures in the last twenty years of activity in several deepwater areas all over the world. The design has been improved with time and its robustness has been demonstrated using alternative analytical approaches and Finite Element Model of the system with proper definition of soil-foundation behavior through equivalent springs. The geotechnical engineering effort focused to ensure the foundation adequate bearing capacity and its ability to slide under repeated thermal/pressure expansion loads during design lifetime, without developing excessive settlements and pitch/roll unacceptable rotations that could compromise the system performance.

The purpose of the present work is to raise awareness of the need for reference international criteria for the design of mobile foundations, which represent an important solution for a subsea field development. Available Codes and Standards do not cover the relevant aspects of the mobile foundation engineering: they are based upon fixed foundation concept, which is expected to be stable under all the applied load combinations without developing any significant displacement. The mobile foundation engineering challenge is to accept that a failure mechanism develops in sliding condition while proper design criteria of system stability and reliability are fulfilled.

Valuable and impressive research works have been carried out and published on the subject in the recent years. However, for practical application, specific criteria are required to provide a unique basic reference for design (minimum safety requirements/methodology/guidelines), which might be supported or not by more detailed and complex approaches, as occurs for traditional "fixed" foundations. Subsea structures could be regarded in the future as special components of the pipeline with a proper methodology to investigate their interaction with the seabed for the subsequent structural analyses.
Understanding Sliding Mudmat Behavior using Eulerian-Lagrangian Simulations
Authors: Hossain M. Kabir , Audibert Jean M. , Bryant John T.
Published: April 2020

At deepwater sites, skirted mudmats with a sliding mechanism have been the preferred choice to support pipeline or flowline end terminations (PLET or FLET) on soft clay seafloor to accommodate line expansions and contractions that occur during shutdown and restart cycles. The sliding mechanisms can experience line expansions of up to 4 m, or if it were to lock-up, horizontal forces in excess of 2,000 kN. The design and fabrication of sliding mechanisms for such large movements can often become challenging and costly. As an alternative, the industry is now designing mudmats that do not utilize sliding mechanism but rather slide directly on the seafloor, if necessary. While it is an attractive alternative and is gaining popularity, all aspects of direct sliding mudmat design are not sufficiently understood because of the complexity that arises from the interactions among the various components, i.e., flowline/pipeline, mudmat, jumpers, and the supporting soft seafloor behaving as one system. The design must ensure that the mudmat will not unduly sink, rotate or dig into the seafloor in the course of the back and forth sliding caused by many shutdown and startup cycles during the field's operating life. Therefore, it is essential to sufficiently understand the characteristics of the sliding motions and estimate as accurately as possible the resulting interaction forces in the flowline-mudmat-jumper-seabed system. This will allow the designer to avoid the risk of any system instability from incoherent component motions, or potential overstressing of connections.

This paper investigates the direct sliding behavior of the mudmat motions using realistic simulations of the flowline-mudmat-jumper-seabed system. The simulations rely on coupled Eulerian (soft seabed) and Lagrangian (flowline, mudmat and jumpers) finite element analysis (FEA) method. The simulations yield insight into the complex mudmat sliding behavior interacting with the jumper, the hydrocarbon line and the supporting seafloor. The simulations show that merely modeling the mudmat alone fails to capture the actual behavior of a real-life PLET/FLET's back and forth cycling on the seafloor, because for example, the restraints (and attendant stresses) at the flowline and jumper connections are not accounted for, or that slanting the sides of the mudmat reduces its tendency to self-embed decreasing connection stresses. The paper demonstrates that realistic simulations allow important visualization of mudmat interactions with flowline, jumper, and the seabed during the shutdown-startup cycles, and provide accurate determination of the associated critical responses.
Investigating the use of Geometric Shadowing and Thermal Radiation Mapping to Improve Fire Modeling in Offshore Facilities
Authors: Stahl Mike W. , Staszak Andrew J. , Clutter James K.
Published: April 2020

The offshore segment of the oil & gas industry has led and continues to lead the way in the use of computational fluid dynamics (CFD) in perusing inherently safer designs. Despite this, modeling focus has remained fixed on vapor cloud dispersion and explosion modeling. Typically, during the design process hundreds of various scenarios will be simulated using CFD through the later design stages. These studies will evaluate various sizes and locations of releases and clouds, changes in ignition location, release orientation, and evaluate loads at sensitive receptors throughout a facility. Extensive probabilistic and statistical calculations will be conducted to interpolate and extrapolate these results.

When it comes to fire modeling, the reliance is still with the use of simple phenomenological modeling. This is not to say that CFD fire modeling is not done, but rather when used, it is in a limited capacity with a focus on specific scenarios. These are usually the large scale, high consequence events. So, why don't we give fires the same treatment as explosions? This questions is particularly important, as facility risks are normally dominated by fire risks.

The simple answer is, that fires, their behavior, and the resulting hazardous effects are more complex and sensitive to variation than compared to vapor cloud releases and explosions. In addition, fire modeling is significantly more computationally intensive, i.e. more cost and time to a project. This makes running hundreds of scenarios and developing probabilistic maps to be used for interpolation and extrapolation much more difficult. A lot of work is being done to investigate improvements to CFD fire modeling, many of which are focused on simplifying the problems we solve and the physics we represent.

The biggest concern of fires, beyond direct impingement is thermal radiation. Thus, if we simplify the problem and focus on how thermal radiation is represented and calculated in fire models, we may be able to apply much more simplified modeling, while significantly increasing the quality of our solutions.

The focus of this paper will be on the use of geometric shadowing calculations to improve thermal radiation representations. This paper will investigate how these techniques can be applied to offshore facilities, identify where and how they could be applied, as well as look at shortfalls in which further research is required. With the goal being to work towards bringing fire modeling to the same standard of explosion modeling without the additional cost and schedule burdens to projects of traditional CFD fire modeling.
Strategic Mergers and Acquisitions: An Enabler of Marginal Oil Field Development in Nigeria.
Authors: Oruwari Humphrey Otombosoba , Oriaku Timi , Itsekor Lucky Ubini
Published: April 2020

The objective of this study was to evaluate the role of strategic mergers and acquisition (M&A) as a panacea for success of marginal oil fields development in Nigeria and to make recommendations for policy decisions. Data for the study were obtained from literature review, document analysis and multiple case studies from operating marginal oil field companies in Nigeria. The cases of Platform Petroleum, Sheba Petroleum, Seplat and others were investigated and analyzed. These case studies identified how marginal field operator's utilized mergers and acquisitions in the form of business restructuring, consolidation, strategic alliances, joint venture formation and partnerships as a development support strategy to remain competitive in the oil and gas industry. Other mergers and acquisitions activities by other companies were also examined. The study findings revealed that strategic mergers and acquisition is one of the survival options for marginal field operators in Nigeria. Mergers and acquisitions enhances the business growth for the marginal oil fields operators by expanding the opportunity for raising capital required for oil and gas operations and provision of larger equity base; including provision of access to technology and manpower. As the oil price in the global oil and gas market remains low, investors in oil and gas business are looking for ways to cope with the fall in revenues. In this dynamic business environment, one fact remains unchanged, marginal oil field operators in Nigeria must re-strategise in order to survive. The marginal oil field operators in Nigeria are encumbered by inadequate funds and other constraints such as lack of capacity, low volume of production and inadequate technology, therefore they have to adopt one of the critical success factors for business survival in a challenging environment. Herein lies the role of strategic mergers and acquisitions. The findings of the study will serves as a decision-making frame work for investors in oil and gas business wishing to participate in the sustainable management of marginal oil field in Nigeria. The study recommendations indicate that policy makers in Nigeria should create a favorable investment climate among which are: stable macro-economic policies, legal system that allows contracts to be enforced and clearly support access to channel of arbitration.
Design Wave Based Verification of Global Strength on an Unconventional FLNG Design
Authors: Bosman Theo
Published: April 2020

One proposal FLNG uses tri-lobe tanks to store the LNG. This tank is supported by two cradles. Between the cradle and the tank loads are only transferred by the parts in contact. The contact area changes due to loading of the LNG tank, motions and deformation of the vessel. This paper gives an overview of the challenges in structural analysis resulting from this non-linear behavior and how to resolve them without loss of fidelity of the solution.

For spectral analysis the contact is to be linearized for the calculation of the stress RAOs and the response conditioned design waves. In performing the final structural analysis where loads from the hydrodynamic analysis are used, the contact problem is to be included. This results in an impractical processing time on one computer when considering all load cases. A superelement solution reduces the size of the model involved in the contact problem which for multiple solutions gives shorter wall times. However, these wall times are still impractical.

The comparison of the linearized model and the model containing the contact shows that the effect of the non-linear contact is localized. This opens the way for a staggered approach. The linearized model is used for a brute force evaluation of the structure taking all possible relevant time instances into account. A local model, one compartment with two tanks including the contact problem, is used to determine the stresses using loads and boundary displacements from the global linearized model.