bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrically Trace Heated Pipe in Pipe: Technology Upgrade for Extended Application Range
Authors: Gooris François , Ansart Bruno , Rageot Olivier , Kaye David
Published: April 2016

The benefits of active heating of subsea pipelines in terms of operability and flow assurance have been demonstrated, in particular for deepwater and/or remote fields with complex production conditions (hydrate formation risk, wax deposit, gelling issues, short production plateau…).

Electrical Trace Heating was developed to reduce significantly field developments CAPEX by simplifying subsea architectures and topside equipment, and OPEX through a low power consumption, and a drastic reduction in the use of chemicals.

After the first deployment of Electrically Trace Heated Pipe in Pipe (ETH-PiP) in reel-lay on Islay Field (North Sea, 2012), a development programme was launched in 2012, supported by major Operators to upgrade and qualify ETH-PiP technology for long tie-backs and higher power for production or export lines. This paper presents the maturity of all components of the ETH-PiP system. In a second part, the paper emphasizes on tracing cables design, production and validation testing phases as a critical aspect of the overall qualification process.
Drilling for the Next Generation of Multilateral Completion Systems
Authors: Abuahmad Yousif , Saleh Rami , Bouldin Brett , Turner Robert , Ali Bin Al-Sheikh
Published: April 2016

The objective of drilling a well is to accommodate the completion string designed to optimize reservoir production. Streamlining a completion design for a mature field maximizes the chances of achieving the well objective with minimal drilling challenges. Therefore, introducing a new completion technology requires reevaluating the drilling procedures and practices to accommodate for the modified completion, and this is more true when running new completion designs into the open hole as opposed to cased hole completions. The Saudi Aramco drilling team were faced with the challenge of executing a multi-lateral well plan that will allow for running three open hole completions that will segment the open hole laterals and provide active control and monitoring capabilities for each segment. Such a completion requires a complex power and telemetry system that can energize all the segmented lateral completions including the ones that are deployed through the windows. The open hole laterals must be conditioned properly to successfully run the completion components in the open hole without restriction, and land the completions at the pre-planned target depths.

The main power supply and telemetry conduit between the upper completion and the open hole completions is a cable cemented behind the 7 in. liner. This presented several challenges such as running and cementing the liner and milling the windows without intersecting the cable, which would jeopardize the success of the entire completion. The team addressed the challenges by developing procedures to properly execute the mentioned operations while maintaining the integrity of the power system and land the completions at depth. This was confirmed by conducting tests at various stages throughout the implementation process.

An integrated project such as this requires focused collaboration between the drilling and completion teams because the traditional practice is to drill to total depth then complete the well, although this unique completion design requires a drill-complete-drill-complete sequence as the well progresses.

In addition to highlighting the key factors in managing and implementing such a well construction project where various disciplines are interdependent and require continuous coordination, the paper will summarize the modifications applied to the drilling procedures to achieve the objective of the subject well. The emphasis will mainly be on three operations: Under-reaming while drilling the 8-1/2 x 9 in. hole section, hole preparation prior to running the open hole completion, and the implementation of a unique cable avoidance procedure during conventional window milling operations.
Innovative Methods for Methane Leakage Monitoring Near Oil and Gas Installations
Authors: Waarum I-K. , Sparrevik P. , Kvistedal Y. , Hayes S. , Hale S. , Cornelissen G. , Eek E.
Published: April 2016

In recent years, there has been an increased focus on environmental issues near oil and gas production sites and pipelines. The trend is likely to continue as future oil and gas production is commencing in environmentally vulnerable areas, and farther north near the polar ice cap. The exploration in more remote areas implies that online in situ monitoring has great advantages over expedition based monitoring.

The Norwegian Geotechnical Institute (NGI) is an independent research and consultancy foundation having over 40 years of worldwide offshore instrumentation experience. NGI has recently launched a research initiative to develop new methods for in situ and on line environmental monitoring offshore. In 2012, NGI designed and installed an integrated environmental monitoring system for subsea leakage detection. It was installed on the seabed beneath an operating oil and gas platform in the North Sea. We give here an overview of the instrumentation system and the motivation for the different design choices. The system is an example of an integrated monitoring system, where different types of sensors complement each other and gives a more thorough understanding of methane transport at the site of interest. After installation, NGI has analyzed monitoring data and provided decision support to operator personnel. Nearly two years of production site data collection represents a unique data set that enables a comprehensive analysis of methane transport.

From the operator side, the motivation for environmental monitoring usually arises from the need to answer clearly defined questions such as ‘Is there a gas leakage in the production system? Where is it? How large is the leakage?’ The leakage detection system is expected to answer these questions, preferrably in an unambiguous manner. However, natural gas can be released to the water phase from several sources e.g. organic matter on the seabed. If the leakage detection monitoring data shall be interpreted in a control room that operates with alarm states, these sources of background noise must be identified and separated from a real leak situation. We look at which circumstances to be aware of and how to maximize the operational value of a leakage detection system.
Lessons Learnt From Pre-Commissioning of Large Diameter Pipeline Using Coiled Tubing in Ultra-Deep Water Offshore Brazil
Authors: Lirola F. , Perreau E. , Dubois A. , Roubertie C.
Published: April 2016

The installation of flowlines in ever deeper and remote areas requires the usage of specific technologies in order to carry out pre-commissioning operations. As the water depth increases, the weight of the conventional equipment to be deployed to perform the required operations becomes a major issue and alternate solutions are thus required. An option lies in using Coiled Tubing. Coiled Tubing consists of continuous pipe that has been coiled around a reel and can be deployed and recovered according to operational needs.

So far, offshore operation of coiled tubing has been limited to small diameters and to short operational duration. The pre-commissioning operations can require the Coiled Tubing to be deployed several times for durations sometimes exceeding a month, and also requires larger diameters (typically 3.5"). As the duration of operations increases, a suitable way of assessing and mitigating the fatigue of Coiled Tubing is required. To that extent SAIPEM has carried out an extensive testing campaign aiming at better understanding the mechanism underlying plastic and elastic fatigue. Once enough confidence in the models has been gathered, the Coiled Tubing has been deployed offshore for the pre-commissioning operations of several Brazilian projects.

This paper reports the lessons learnt from an innovative pre-commissioning method based on Coiled Tubing that was successfully implemented on four ultra-deep offshore pipelines in 2015. All these projects were located offshore Brazil in water depth around 2200 m. The paper will provide feedback on the engineering and operations associated with the use of large diameter Coiled Tubing for pre-commissioning in deep water. A first section will highlight the specificities of the projects while subsequent sections will provide more details on offshore operations.
Efficient Environmental and Structural Response Analysis by Clustering of Directional Wave Spectra
Authors: Vogel M. , Hanson J. , Fan S. , Forristall G.Z. , Li Y. , Fratantonio R. , Jonathan P.
Published: April 2016

Estimation of environmental and complex structural responses, such as fatigue for risers on deepwater floating production systems, is a critical and generally computationally intensive process. Long term damage estimates require the determination of host vessel motions used for riser stress calculations. In principle, riser stress could be calculated for each of a large number of directional sea states, a considerable computational burden. However, it might be possible to identify a representative subset of directional sea states for vessel motion and subsequent riser stress analysis, such that estimated fatigue characteristics (from the full set of sea states and the subset thereof) were equivalent. This would be advantageous as it would require considerably less computational effort.

In this work we use non hierarchical K-MEANS cluster analysis to partition a large set of directional wave spectra for contiguous sea states at a location offshore Brazil, corresponding to a period of approximately 2 years into a number of clusters. We adopt the set comprised of cluster centroids only as representative sea states for efficient characterization of the environment and structural response.

We demonstrate that the representative sea states provide an efficient basis for estimation of overall sea state bulk, wind sea and swell characteristics. We evaluate the effect of cluster size on the performance of the representative sea states using custom built visualization tools utilizing the Kolmogorov-Smirnov test statistics. The representative sea states are further used as input for a VLCC-class FPSO vessel motion analysis. For heave at the turret, roll motions, and relative vessel heading, distributions of vessel motions from analysis of representative sea states are in excellent agreement with those from analysis of all sea states. Guidelines for the application of the methodology are provided.
Delay P&A Through Improvement in Oil Cut for Mature Offshore Facilities
Authors: Clement B.G. , Karicherla P. , Meling T. , Kozicki K.M. , Veeningen D.
Published: April 2016

Enhanced oil recovery operations are less common offshore in comparison to their mature counterparts onshore. Large inter-well distances, facilities and weight constraints as well as capital expenditure limitations due to declining production greatly restrict choices for tertiary recovery strategies. Moreover, as oil cut continues to fall, maintaining economic production requires processing ever-increasing water volumes eventually requiring plugging and abandonment (P&A), even though typically 45 to 70% of the original oil remains in the formation.

Ideally, the economic life of mature offshore facilities would be extended by incremental oil production at a reduced, per-barrel cost to lower the overall lifting expense. As fluid processing and pumping rates are usually already optimized at maximum rates, an ideal enhanced oil recovery method would, in addition to increasing the oil production, also improve the oil-to-water ratio and reduce the per-barrel operating expenditure, or OPEX.

A biological enhanced oil recovery (EOR) solution initially deployed offshore in the North Sea has been validated with multiple onshore demonstrations and is now available for mature, offshore facilities to promote preferential oil flow in water-flooded sandstone reservoirs. The method makes use of the existing biology in the formation, which is activated from its dormant state by continuous addition of a low-dose (ca. 100 ppm) nutrient solution from a small footprint injection unit. The resulting biological growth reduces interfacial tension (IFT) and mobilizes otherwise trapped oil.

This paper shows the rapid improvements of oil production and oil-water ratios over large injector- producer well distances in as little as 2-4 months following initiation of biological EOR. Recommendations are offered that are relevant for extracting otherwise trapped oil and recovering significantly more of the oil-in-place prior to P&A. Strategies are also offered for field-wide implementation to enhance oil recovery and reduce OPEX with minimal capital investment and equipment installation.
Reservoir Baffling Seen by Disequilibrium of DFA Fluid Gradients and by Wireline Pressure Transients and DSTs
Authors: Pfeiffer Thomas , Achourov Vladislav V. , Kollien Terje , Foyn Sven-Erik , Betancourt Soraya S. , Zuo Julian Y. , Di Primio Rolando , Mullins Oliver C.
Published: April 2016

In this reservoir study, three adjacent structures have been subject to largely the same fluid charge with an original oil charge and a very recent light hydrocarbon charge (all indicated by petreolum systems modeling and organic geochemical analyses). In addition, all wells have an oil-water contact (OWC) and two have a gas-oil contact (GOC), while the GOC in the third well is not far away. Thus, all depth-dependent in-reservoir fluid geodynamic processes are visible within each well; no extrapolation away from the wells is required. Moreover, the ~30 meter oil columns in evidently connected sands are amenable to simple dynamic modeling thereby aiding in understanding. All three structures are found to have very different reservoir realizations, particualry regarding the dispositions of asphaltenes in spite of nominally similar initiation conditions after the secondary charge. That is, different reservoir fluid geodynamic processes took place producing different constraints on production in each of the structures. One well showed a light oil underlain by a tar mat. A second well showed large, disequilibrium gradients of gas-oil ratio (GOR) and asphaltene content without phase separated asphaltenes in core. The third well showed a tar mat on a shale break in the oil column not far form the GOC. There were no asphaltenes in core above the shale break and tar mat. However, below the shale break there was asphaltene throughout the core while retaining permeability, but no tar mat on the OWC. These differences were not ascribed to any paleo-OWC nor are they related to differing biodegradation. In addition, these differences are not consistent with any depressurization expalanation.

To resolve the differences, a variety of data streams were used including downhole fluid analysis coupled with thermodynamic analysis from the Flory-Huggins-Zuo Equation of State (FHZ EoS) and its reliance on the Yen-Mullins model of asphaltenes. In addition, well test results provide key production information and are corroborated by vertical intereference testing on wireline. Petroleum system modeling and organic geochemical analysis of oil and core extract samples have also been very useful. The differences seen in the different wells relate to several important parameters such as the different extent of baffling which impacts both production rates as well as equilibration rates of reservoir fluids. Another key parameter is the extent of density stacking versus a lateral fluid front for the secondary light hydrocarbon charge. Proximity to the charge point enhances the lateral nature of the charge yielding rapid asphaltene instability precluding tar mat formation in sections of the well. This information is very useful when projecting reservoir properties away form wellbore.
Development and Qualification of an Innovative and Cost Efficient Heat Traced Flowline Optimized for J-Laying
Authors: Lirola F. , Pionetti F-R. , Agoumi J. , Sundermann A.
Published: April 2016

As more complex oil reservoirs are discovered, innovative flow assurance solutions are required to make the development of new discoveries both technically and economically feasible. Indeed, depending on the size of the field, a long distance tie-back might be relevant to avoid the economic impact of a dedicated production platform. If the tie-back is too long, the water depth too deep and/or the fluid temperature at the wellhead too low, conventional flow assurance solutions might not be applicable. In addition, the size of the reservoir might not justify the installation of a service line or a second production line to generate a loop to allow preservation by mean of flushing the line with dead oil in order to avoid the formation of wax and or hydrates during shutdown. Active heating of the flowlines efficiently covers this gap. Among the available technologies, Heat Tracing appears as being an interesting technology as it features very high efficiency when compared to other solutions. To this date, this solution was limited to reel lay. This paper will present a design suitable for J-laying installation methods thus enabling the technology for larger diameters and remote locations, removing the need for a spool base.

This new solution is based on a sliding pipe in pipe concept that has been adapted and improved in order to include a heat tracing capability while optimizing laying rates and offering enhanced monitoring capability including both temperature and stress surveillance. As in any other heat traced pipe in pipe concept, the electrical cables are spirally winded around the inner pipe and, covered with insulating material and enclosed in an outer pipe. Optical fibers are added in order to monitor stress and temperature. In the case of this technology, several innovations aiming at improving the concept have been implemented and tested.

The concept mainly relies on a specific connector designed for the simultaneous connection of all electrical wires and fiber optic cables in a single and reliable operation. The concept of sliding pipe in pipe has also been improved, relying on packers and specific pipe end design that simplify the handling of quad joints.

The performed qualification testing includes:

Full scale fabrication;

Testing of the connection system;

Testing of the fiber optics;

Testing of the packers to validate their holding capacity.

All tests have been performed at full scale and included deformation and temperature testing. They allowed to demonstrate that all components can be easily integrated with a conventional Pipe in Pipe design while significantly facilitating offshore operations. The present paper will provide insight on the main features of the technology in addition to details on the performed qualification campaign.
Better Foam Cement with a Liquid Stabilizer: Offshore Case Histories
Authors: Doan Angela Anh , Ejike Mosunmola Omuwunmi , Li Li
Published: April 2016

Foam cementing has been widely used for offshore applications where the formation has low fracture gradients, and shallow water flow may occur. One challenge of foam cementing is to ensure that the foamed slurry is stable at the desired foam qualities with low permeability. Therefore, stabilizers are commonly applied along with the foaming agent. This paper describes the comparison testing and several offshore applications of a new liquid foam stabilizer that improves logistics and flexibility on the rig, and prevents excessive viscosity and foaming during mixing.

The new liquid foam stabilizer was tested in the laboratory to compare its performance with that of a dry stabilizer used previously in the field. The stabilizer was then used in several offshore wells to assess its performance in real-world operations. In particular, one problem with dry foam stabilizers is that they can promote excessive foaming during mixing, which leads to pump cavitation if not controlled with a defoaming agent. The field operations were arranged to test a new operational procedure for use with the liquid foam stabilizer to avoid cavitation without a defoamer.

The laboratory testing determined that the new solids-free liquid foam stabilizer disperses easily in the cement slurry. The new stabilizer was also found to improve the stability of the foam and the density distribution of the set foam cement compared with no stabilizer. Furthermore, several case histories will demonstrate that the combination of the liquid additive and the new operational procedure improved the slurry mixability without any pump cavitation issues.

The new liquid foam stabilizer has more predictable and reliable response than conventional dry stabilizers, and the case histories will demonstrate how its use improves cementing flexibility and logistics.
Safe Hydrate Plug Dissociation in Active Heating Flowlines and Risers - Full Scale Test
Authors: Tzotzi Christina , Parenteau Thomas , Kaye David , Turner Douglas J. , Bass Ronald , Morgan Julie E. P. , Zakarian Erich , Rolland Julien , Decrin Marie-Kathleen
Published: April 2016

Electrically Traced Heated Pipe in Pipe (ETH-PiP) technology has been developed to overcome some of the challenges associated with deeper and more remote offshore oil and gas production. This active heating technology applies power to achieve a production fluid temperature above the wax or hydrate appearance temperature either continuously, during normal production, or intermittently, during shutdown periods. Concerning hydrate management, the contractor Company in collaboration with Major Operators conducting experimental and modelling studies to investigate hydrate dissociation in heated flowlines through a Joint Industry Project (JIP) kicked-off in 2012. The main objective of these investigations is to demonstrate that a long, non-permeable hydrate plug can be dissociated in a safe and controlled manner with the ETH-PiP technology.

Large hydrate plugs (approximately 200 kg each) are formed in an 18m ETH-PiP 6? OD prototype, using a water and gas system equipped with DTS fiber optics systems for temperature monitoring, pressure and temperature sensors, and high accuracy gas flow meters. Different heating strategies are tested to investigate the best active heating procedure for safe hydrate plug dissociation, using temperature, pressure and released gas flow rate monitoring along the entire length of the prototype. Hydrate plug dissociations are performed in open or closed volumes for various conditions during the 2nd phase of the experimental campaign, which started at the end of 2013. High pressure differentials are applied across the hydrate plugs; non-uniform longitudinal heating profiles are applied to reproduce operating conditions similar to direct electrical heating; and three-phase dissociation experiments are conducted to simulate the influence of oil present in the hydrate pores on the plug dissociation.

The paper gives an overview of the experimental set-up and measuring techniques used. It describes the hydrate plug formation, location, and characterization, as well as the successful dissociation of hydrate plugs. Preliminary simulation results based on a specifically developed "in-house" simulator are presented, as well as extrapolation of the results to real subsea conditions. This test program demonstrated that large non-permeable hydrate blockages in single line field architectures could be dissociated without local pressure build-up or plug run-away using ETH-PiP technology.
FPSO Conversions – Fast Track & Cost Effective? Some Lessons Learnt
Authors: Roosmalen Kees van , Strien Hubert van , Kautz Rigardo
Published: April 2016

In recent years the authors company was involved in engineering for FPSO conversions, both tanker to FPSO and for FPSO redeployment, as well as similar engineering works for the life extension programme of naval surface vessels and submarines. The objective of the paper is to share the primary lessons learned in such projects.

The paper describes the generic difficulties encountered in such "brownfield" projects, with an emphasis on technical and engineering aspects of FPSO projects, and some advice for future projects. Examples are given from the authors experience in practical situations on the issues mentioned above and how these might or might not have been avoided.

The paper concludes with a review of some lessons learnt and an overview of practical constraints on the extent to which the ideal approach might be achieved in reality.
Wave Energy Converter Arrays for Power Absorption from Ocean Waves with Time Domain Predictions
Authors: Kara Fuat
Published: April 2016

A three-dimensional in-house transient computational code ITU-WAVE based on panel method, potential theory and Neumann-Kelvin linearization is extended to take into account wave interaction in an array system using two and four truncated vertical cylinder arrays. ITU-WAVE transient fluid-structure interaction panel code is validated against analytical array results before applied to power absorption from ocean waves for different array configurations. The effects of the separation distances between array system and heading angles on energy absorption in both sway and heave modes are studied by the support of numerical simulations which show sway mode has wider bandwidth than heave mode for energy absorption. It is also shown wave interactions are stronger when the array systems are close and these wave interactions are reduced significantly and shifted to larger times when the separation distance is increased. The wave interaction is much stronger at the same separation distance and heading angle in heave mode than in sway mode. Numerical experience also shows that more power is absorbed in sway mode than heave mode in both two and four array systems at any separation distances and heading angles when the bodies in array system have the same displacement in both sway and heave modes.
Major Advancement in Pipeline Integrity Management Through an Integrated Quantitative Risk Assessment Approach
Authors: Azouz A. , Hakim M. Abdel , Soliman Y. , Awda H.
Published: April 2016

The requirement to establish, implement and maintain an Integrity Management System (IMS) is crucial for safe guarding the pipeline assets of any Operator. Risk assessment represents a key element of such a system and requires evaluating the risk for all potential threats jeopardizing the integrity of the pipeline system. A key challenge which typically faces the Operator is how to combine the risk assessment of different threats in order to quantify the overall risk level for the entire pipeline system.

This paper presents a new approach that was developed for risk assessment and risk ranking of subsea pipeline systems. It describes the methodology used to evaluate the risk for each threat quantitatively and to integrate the individual risk assessments to arrive at an overall risk level for the entire pipeline system.

The new approach is used to carry out an integrated risk assessment for all threats jeopardizing the integrity of a pipeline system. The approach is valid for subsea pipeline systems and the calculations were calibrated based on in-house experience from historical inspection data. However, the approach can also be applied to other assets with due consideration of the nature of the relevant threats and re-calibration of the calculations based on the in-house experience of the Operator.

The standardization of the risk assessment methodology for the different threats allows for seamless integration of the individual risk assessments into an overall risk level for the entire pipeline system. The approach is therefore capable of risk ranking a fleet of subsea pipeline assets based on the calculated overall risk level for each pipeline. It also offsets the inherent uncertainty in the quantitative risk assessment to a large extent since the calculated overall risk level for a pipeline is relative to other lines in the network.

The presented approach represents a novel method for quantitative risk assessment of all threats jeopardizing the integrity of a pipeline system in a standardized way. The risk ranking of the Operator's pipeline network based on this approach provides a consistent and technically sound basis for prioritizing the pipelines inspection and mitigation plans.
Disconnectable Turret Mooring System for Arctic Drilling
Authors: Efraimsson Fredrik , Ahlstrand Martin , Clegg Rosemary
Published: April 2016

When drilling in shallow waters a pure Dynamic Positioning (DP) station keeping solution may not be sufficient for the small offset requirements, hence to increase the station keeping capacity a mooring system is required. In ice infested waters, with extreme ice conditions, the ability to quickly disconnect the mooring system and leave the location, as well as a short reconnection time, is of great importance for safety and productivity.

To meet the industry need for exploration drilling in shallow water in the Arctic, an attachable turret mooring system for drillships, ATMOS (attachable mooring system), has been developed. Combining the ATMOS with a drillship´s DP system creates a thruster assisted mooring system and significantly increases the station keeping capacity of the drillship.

This paper presents a drillship mooring system that has been designed specifically to meet the challenges of drilling in Arctic regions but also for operation in open water and/or harsh environment in both deep and shallow waters. Stena has spent a number of years developing and refining the ATMOS concept for use with an Arctic 6th Generation drillship. The development process has included engineering, concept approval by Class, and both open water and ice model testing.
Comprehensive Modeling of Scale Deposition Using a Coupled Geochemical and Compositional Wellbore Simulator
Authors: Abouie Ali , Kazemi Nia Korrani Aboulghasem , Shirdel Mahdy , Sepehrnoori Kamy
Published: April 2016

Scale deposition in surface and subsurface production equipment is one of the common problems during oil production resulting in equipment corrosion, wellbore plugging, decrease in production rate, and frequent remediations. In this work, we present a detailed procedure through which a compositional wellbore simulator is developed with the capability of modeling comprehensive geochemical reactions.

The compositional wellbore simulator (UTWELL) is developed by applying different numerical approaches and flow regimes to accurately monitor multiphase flow in the wellbore. In addition, several deposition mechanisms are incorporated and validated against experimental data to study the transportation, entrainment, and deposition of solid particles in the wellbore. Subsequently, a geochemical module (i.e. IPhreeqc) is integrated into the wellbore model to handle homogenous and heterogeneous, reversible and irreversible, and ion-exchange reactions under either local equilibrium or kinetic conditions. This package provides a robust, flexible, and accurate integrated tool for mechanistic modeling of scale deposition in the wellbore.

Through our integrated simulator, deposition profiles of carbonates and sulfates scales in the wellbore are predicted for several realistic case studies. Significant effects of physiochemical properties (i.e. pressure, temperature, salinity, and pH) on the scale deposition in the wellbore are discussed. In addition, comparing simulation results with experimental data reveals that hydrocarbon dissolution has a significant impact on geochemical calculations compared to the temperature/pressure variation effects. Finally, the results indicate that combined effects of solid particle concentration and transportation in the flow stream affect the solid deposition rate.

To the best of our knowledge, there is no comprehensive simulator available in the industry through which scale deposition in the wellbore can be predicted accurately. In this work, by including 1) the interaction of the hydrocarbon phases on the aqueous-scale geochemistry (by using a compositional wellbore simulator) 2) effects of parameters that vary greatly in the wellbore (i.e. pressure, temperature, and pH) and 3) comprehensive geochemical databases (provided through coupling of the wellbore simulator with IPhreeqc), scale deposition profile in the wellbore is estimated. The results of this study will help evaluate scale deposition risk and planning the work-over for scale prevention in the production and injection wells.
Improvements and Capabilities of the CRD100 Subsea Robotic Drilling Platform
Authors: Hampton P. J. , Soylu S. , Crees T. , Jackson E.
Published: April 2016

This paper is focused primarily on the current capabilities of the CRD100 subsea robotic drilling platform. An overview is given of the available hardware and interface approach. Time analysis of our wireline system over conventional drilling is included. Reasoning for several design decisions are provided. Aspects of the interface and its semi-automated hierarchical control system of Ethernet distributed pressure tolerant electronics (PTE) I/O modules are presented.

The discussion includes explanation of several ‘lessons learned’ that have been encountered over several years of off-shore drilling experience. From these we have determined that the method of human control of the remote subsea robotic drill should be performed by two operators simultaneously. A pilot chooses what they want to control, be it the drill, its arms, the thrusters or the legs and their co-pilot chooses a complementary set of controls. Data from factory acceptance tests are used to demonstrate how well two operators expedite the procedure.

Although we strive to automate as many aspects of the drilling operation as practical, we show that at present two competent operators (assisted by automated processes) drive the system more efficiently than one. The wireline system has greatly reduced the time to acquire core samples compared to conventional drilling techniques. Further, we have developed this system so that core barrels may be exchanged for scientific probes, such as the cone penetration test (CPT), without the need for conventional trip out.

Our system was implemented with the first subsea PTE that operates over Ethernet. Using distributed PTE has reduced the costs of controlling subsea robotic equipment, both in cost of the electronics housings and cabling, while improving data collection. The paper discusses the use of several of these PTE in a hierarchical control system. The applications of our drill to the petroleum industry is primarily in the exploration and ground analysis for off-shore construction. The approach of using robotic sea floor drills is a means to avoid the expense of employing drill ships for geotechnical exploration.
Large Module Installation and Intervention System at Aasgard
Authors: Dahle Mikal , Meignan Loic , Rossi Rafael , Ludvigsen Andreas
Published: April 2016

With the vision of a "Subsea Factory" the maintenance and repair work on process equipment is moved from topside to subsea. Operators will still have a high regularity requirement for their process plants, meaning that they need to be prepared to perform such complex subsea operations at any time of the year and with a minimum of time spent waiting on weather (WoW).

This paper will explain the solutions chosen for the world’s first subsea compression system at the Åsgard field in the Haltenbanken area in Norway.

To meet the regularity requirements for the plant the process modules had to be replaceable in weather conditions up to significant wave heights (Hs) of 4.5m. With module dimensions exceeding vessel moonpool sizes and weights well exceeding 300t, the traditional method for overboarding and retrieval would be to use a large capacity crane. However, crane lifts of large, heavy and complex structures will normally have a weather limitation in the order Hs 1.0m – 2.5m.

The requirement for reaching Hs 4.5m for these large and heavy modules called for new solutions to overboarding and retrieval of subsea structures from an installation vessel.
Hyperbaric Excavation: New Insights and Simulation Tools
Authors: Boomsma Wiebe , Grima Mario Alvarez , Los Jan
Published: April 2016

This paper addresses the Royal IHC research program concerning the effect of high hyperbaric pressure on rock cutting forces and power requirements. An overview of the rock cutting experiments conducted in a hyperbaric tank in Brest, France is summarized. The results of the experiments along with the hyperbaric cutting model developed so far have been used to create our in-house software ‘Gibraltar’. Examples of simulations results with the software are shown. Current research on numerical methods and lab experiments conducted so far are mentioned as well as possible research directions in the near future. It can be concluded that ‘Gibraltar’ is in fact a generic and flexible framework, a universal world in which additional tools and excavation knowledge may be added and it has already been used to design some of the future excavation tools of Royal IHC, showing his added value.
Simulation Experiment and Mechanism Research on the Change of Lateral Friction Against Surface Conductor in Deepwater Drilling
Authors: Meng Wei , Yang Jin , Tong Gang , Hu Nanding , Zhu Yi , He Li , Deng He , Zhao Yihui , Wang Xiao
Published: April 2016

Lateral friction against surface conductor plays an important role in the stability of subsea wellhead. It changes during jetting process and increases with soaking time. But the change rule and mechanism remain unclear. Therefore, the purpose of this paper is to explore the change mechanism of lateral friction during and after conductor jetting process by field experiment and numerical simulation.

Firstly, a field experiment was conducted to simulate actual surface conductor jetting process. The time- dependent change rule of radial pressure, pore water pressure and effective skeleton pressure were obtained. Then, the stress states of soil bodies during this process were analyzed. Based on experiment and analysis results, the primary reason that causes the change of lateral friction was found. After that, to explore the specific change features of bearing capacity of seabed soil for surface conductor, another field experiment was conducted. Finally, finite element method was adopted to simulate the conductor jetting process and to verify the research conclusions.

The field simulation experiment showed that the sensor at the base of surface conductor suffers conspicuous higher value of radial pressure than other sensors above. Meanwhile, the effective pressure of each layer has a tendency of declining as time increasing and then gradually adds after reaching a certain value. These regularities matches the change rule of radial pressure on piles during driving process. Based on the stress analysis, it is certain that the soil compaction effect does exist in conductor jetting process, caused by which, the formation and dissipation of pore water pressure during jetting process would be highly related to the change of lateral resistance against surface conductor. After jetting into position, soil lateral friction would increase with time non-linearly. The change rate would gradually rise at the first 10 hours. After 72 hours, the added values of friction are small and the change rate turns to flat. According to the numerical modeling results, under the action of jetting force, on one hand, soil bodies that are closed to bit are cut into grains and flow out from wellbore with drilling fluid; on the other, soil bodies that are farther from bit would be squeezed down and then pushed around.

Previous studies mainly considered the soaking time and bearing capacity of surface conductor, focused on specific values. This research designed a system to simulate surface conductor jetting process to explore the change mechanism of lateral friction against surface conductor by combining the method of numerical modeling and field experiment.
Integrity Management: Today and the Way Ahead
Authors: Villano Gregory , Scott Richard , Walters Paul , DeWitt Cris
Published: April 2016

Over recent decades, sophisticated industrial control systems (ICS) have benefited offshore vessels, but the benefits have been at the expense of operational simplicity and transparency. Continuing questions about how system integrity is best managed raises important issues about the nature, measurement, management, and perhaps even basic concepts of system integrity in the maritime industry. Traditional definitions, concepts, and measurement tools do not adequately support the specialized integrity management needs of the maritime industry. The industry needs practical tools that are readily understandable, supported by a meaningful measurement technique, minimally disruptive to the current data and integrity management workflow, and sufficiently useful so as to endure and evolve the industry's knowledge about integrity in complex systems.

This paper explores a structure for a metric supported by a process to systematically evolve the maritime industry's knowledge about integrity in complex systems. The structure introduces a vital concept for system integrity management instantiated as a "corruption vector" that has dimensions useful for gauging the relative impact of integrity-reducing practices and incidents, while supporting the determination and mitigation of the root causes of those incidents. This paper also contemplates the implementation of an analytical method based on, (a) commonly accepted and well-understood software engineering models; (b) commonly collected information for describing the dimensions of a corruption vector; and (c) a transparent and practical decision support tool for quantifying, gauging, trending, and ultimately managing ICS integrity.

New integrity management concepts, tools, and processes are needed to clarify the nature of ICS integrity and provide actionable guidance to system managers. Utilization of a structure that embraces the concept of defining, gauging, and eliminating corruption vectors from complex systems is a leap forward in ICS integrity management.
Calculations Methodology for Dry - Transportation of Large Floating Units
Authors: van Burik R. , de Jonge J. B.
Published: April 2016

Traditionally, floating production systems such as FPSOs are either self-propelled or wet-towed from their new-build or conversion yard to the place of destination. Heavy lift vessels were not considered suitable for these kinds of transportation projects due to their size. Since the inception of the Dockwise Vanguard in 2012 and the successful introduction in the market early 2013, an alternative is now offered to the industry making dry-transportation of FPSOs and other floating production facilities a reality. Early 2015 Dockwise transported the Goliat FPSO, a Sevan type, and the Armada Intrepid FPSO on the Dockwise Vanguard. The FPU for Moho Nord is scheduled for August 2016.

This paper addresses the technical challenges that had to be overcome to realize these projects and describes the extensive research program executed, and the feedback retrieved from the first FPSO dry transports.

Due to the sheer size, the stiffness of this type of cargo has an influence on the load distribution on the heavy transport vessel. Finite element analysis (FEA) has been executed to determine cribbing pressures as well as to study the structural strength of the construction. Varying the stiffness of the cribbing wood has shown to be of influence on the static as well as the dynamic load distribution. This initiates the discussion whether the traditionally used wood still poses the best technical and operational solution. Early 2015 Dockwise have conducted testing on alternative materials. Also real-time measurements on actual cribbing compression during a voyage have been performed and compared to the calculated values; this validation provides insight and possibilities to further improve the calculation methodology.
Pipeline Bundle Extended Length for Subsea Development
Authors: Animashawun Kolawole , Goodlad Martin
Published: April 2016

The Subsea 7 Pipeline Bundle fabrication facility in Wester, Scotland UK has been utilised for the fabrication, pre-commisioning and launch of Pipeline Bundles in the North Sea and Norweigian Sea regions for over 36 years.

Subsea 7 has installed:

Three Pipeline Bundles in Australia for Esso’s Bream & Tuna Fields

Eight Pipeline Bundles for Elf Exploration Angola Girassol Field

Over seventy five Pipeline Bundles installed in the North Sea and Norwegian Sea regions

Research and Development work has been conducted to extend the length of a single Pipeline Bundle beyond the current site capacity of 7.7km, thereby further enhancing the Pipeline Bundle technology for longer subsea tie-backs.

Pipeline Bundle length extension can be achieved with the use of onshore tie-in methods such as golden welds, mechanical connectors or fabrication at a different site with sufficient length capacity. This paper presents an overview of potential methods that can be used for fabricatation, launch, tow and installation of Pipeline Bundle lengths greater than 7.7km. Case studies for Pipeline Bundle lengths between 8km and 15km inclusive have been analysed as part of the work.

The work confirms the feasibility of Pipeline Bundle length extension and the potential for significant reduction in CAPEX for subsea fields requiring long tie-backs. The use of the different connection methods further confirms that the Pipeline Bundle technology can be applied globally once a site with a suitable length is identified.

The work presented in the present paper highlights the critical elements associated with the application of Pipeline Bundle Extended Length. Emphasis is made on the Pipeline Bundle control during tow operation based on the companies tow expertise developed over the past three decades.
Testing & Simulation of HPHT Pipeline Bundles
Authors: Qadir K. S.
Published: April 2016

Pre-tensioned Pipeline Bundles (towed pipeline production systems) unlock HP/HT fields by making them economically feasible and technologically possible. Analysis shows pre-tensioning allows HP/HT Bundles to be designed to operate at 220°C & 1379 bar without the need for global buckling mitigation, rock dump, buckle initiators, expansion spools, cooling spools, HIPPS, etc. and hence provide a cost-effective fully integrated HP/HT solution. The pipeline Bundle product has matured (over 35 years, with more than 75 installed to date) to the upper pressure and temperature limits of 604 bar and 160 °C respectively, as realised on the Total E&P UK West Franklin Project. This paper presents the results of the FEA and elaborates the testing program planned at the Subsea 7’s Wester Pipeline fabrication facility, North East of Scotland, on a Bundle pipe in pipe section approximately 170m using a jacking system to introduce pretension and then heated to 220 °C with one end fixed.

A fibre optic monitoring system will be used in conjunction with strain gauges to monitor axial, hoop and temperature strains respectively on the production and sleeve pipes. These strains will then be compared with the results of the FEA simulation as part of the verification process. The simulation models the effects of thermal expansion, pre-tension, centraliser friction, impact of compression on subsequent loading cycles and pressure.

At high pressure and temperature operational conditions, the results show that pre-tensioning introduces significantly lower compressive forces in the production pipe as well as lower tensile forces in the sleeve pipe. This allows stress based design within the linear elastic region, thereby allowing associated design advantages and cost reduction for certain HP/HT conditions strain based criteria can be employed while still avoiding ECA. The FEA simulation model and approach is shown to accurately predict the behaviour of the pre-tensioned pipeline Bundle system for future HP/HT projects.

Pre-tensioned Bundles enable fluid transport at 220 °C and pressures up to 1379 bar and reduce cost of design, build, test and operation phases by mitigating the need to use HIPPS, expansion spools and cooling spools for each HP/HT tie back individually.