In the international regulation framework, the energy-efficient operation of ships is becoming standard. In this respect, restrictions on new construction appear to encourage improvement to existing vessels often equipped with outdated technologies. One of the relevant aspects of propulsion plant design and fleet management is the propulsion need to accomplish the design requirements in a wide set of sea states or in conflicting operative conditions (e.g., laden/ballast, sailing/trawling), requiring very different performances. A preliminary assessment of the energy efficiency of the ship system is then crucial for optimizing both the operating costs and the impact on the sea environment. A new efficiency assessment method that includes engine fuel consumption evaluated by ad hoc statistic regressions and ship resistance in calm water and in waves computed by a 3-D boundary element method is proposed. An application to a hard-chine 18 m trawler is proposed as part of a wider decision support system or weather routing algorithm.
Ships are a significant source of air pollutants, such as sulfur oxides (SOx), carbon oxides (COx), and nitrogen oxides (NOx), that have a relevant impact on both some sea ecosystems and populated coastal areas, especially those close to harbors. Although the International Maritime Organization (IMO) introduced the greenhouse gas (GHG) emissions reduction in its agenda in 1995, only in recent years has this seemed to generate constraints on the design of new units (see, for instance, Coraddu et al., 2014). In addition, considering that most pollutants are strongly related to a vessel’s total fuel consumption, optimizing the propulsive efficiency directly reflects as a reduction of exhaust gas emissions. From a designer’s point of view, the need to improve the available methods for efficiency prediction and optimization to achieve better solutions at very preliminary design phases is clear. For example the IMO (2009a, 2009b) introduces technical and economical indexes for emissions regulation, namely, the Energy Efficiency Design Index (EEDI) and the Energy Efficiency Operational Indicator (EEOI). The former is used to assess the design of a vessel, the latter to evaluate the operational profile of a vessel. Despite the relevance of these indexes, some types of ships, such as cruise ships and working boats, are not included in the baseline values provided in the International Convention for the Prevention of Pollution from Ships (IMO, 2011). Moreover, the proposed baseline values do not take into account the environmental conditions in which ships navigate.
Subsea operations—from the need for multidisciplinary teams to delivering equipment and services in a harsh offshore environment—are inherently expensive. These costs are typically recovered through the reservoir production over a number of years. When production ceases, the cost of abandonment is absorbed as a liability, which leads to a stringent focus on cost efficiency. It is, however, an area where the opportunity to achieve significant cost savings through new technologies and an alternative approach to service vessel and campaign structure.
This paper describes a facilitating technology—the subsea wellhead connector, or SWC—that enables operators to undertake monohull and even rig-based subsea abandonment campaigns. Deviating from a semi-submersible rig to a monohull-based campaign has reduced vessel day rates and personnel costs by a substantial margin. To maximize the saving potential for rigless abandonment technologies and equipment, however, require collaboration between the operator and service provider.
The SWC latches and recovers all common 18.75-in. bore wellhead suspension systems. The system offers mechanical, abrasive, or explosive severance tools for plug-and-abandonment (P&A) campaigns and a small re-entry mandrel seal assembly for intervention. Deployment can range from vertically or horizontally rigged orienttions, and operations are limited by the remotely operated vehicle (ROV) limitations.
This paper presents four Phase III campaigns in the North Sea continental shelf as case studies. Each has unique challenges. Monohull vessels were used in the first 3 wells and the final campaign was run from a mobile offshore drilling unit (MODU)—this final approach brough rigless technology to a rig to further enhance operational capability.
ULSTEIN and SeaOwls have launched a pioneering heavy-lift jack-up vessel design. The cruciform structural lay-out makes the solution more than 10% lighter than conventional designs. The concept aims to install the next generation 10-12 MW wind turbines in the same time frame as used today for installing 6-8 MW units, the Group said in a press release.
SeaOwls and ULSTEIN launched SOUL at the Offshore Wind Journal Conference on 7 February 2017. In combination with a high capacity crane, SOUL enables operators to take the next step in developing offshore wind farms.
"The development of this novel jack-up vessel is the logical next step in our strategy to widen our portfolio and become a leading company in supporting the offshore wind industry with more efficient assets", says Tore Ulstein, deputy CEO at Ulstein Group.
"Combining the vast track record in heavy lift vessel designs from our Dutch Ulstein branch with SeaOwls’ experience in jack-up technology, resulted in an innovative jack-up vessel concept based on proven technologies."
Scaling-up conventional heavy lift jack-up vessel designs proves challenging due to the disproportional weight increase compared to gain in Variable Deck Load (VDL).
"We noticed this created uncertainty with turbine manufacturers, wind farm operators and installation contractors on how to install the future generation wind turbines, as floating vessels are not a viable alternative", comments Erik Snijders, founder and managing director at Rotterdam based SeaOwls, and continues:
"So we went back to the optimal jack-up design, a square platform with the legs spaced out as much as possible. Rotating the platform by 45o provided a natural bow shape with two legs and the crane on vessel centre line."
"This seemingly simple twist in the design allowed to make a huge improvement in operational aspects as well," adds Bram Lambregts, deputy managing director at Ulstein Design & Solutions BV.
"With the main crane around the stern leg, optimal main deck reach and over-the-side lifting capabilities is created. And as the hull now houses much larger leg footings, bearing pressures on the seabed are reduced, while the wake of the spud cans does not interfere with the inflow to the propulsion thrusters."
The SOUL series will come in various sizes, allowing the transport of 3 up to 6 of the 10-12MW wind turbines. Still, all loading and installation operations can be performed without the need of ballast water.
A preview of the SOUL concept has been presented to a select group of industry players, which resulted in valuable and very positive feedback from prospective clients, such as:
"One of the most viable new solutions to meet the installation challenges the offshore wind industry is facing."
Ulstein Group ASA is the parent company of a group of maritime companies, specialising in ship design and maritime solutions, shipbuilding, power and control and shipping. The family-owned company was founded in 1917. Ulstein Group ASA started operations on 4 May 1999, and originates from Ulstein Mek. Verksted, established in 1917. Ulstein Group has some 700 employees in seven countries and is headquartered in Ulsteinvik, Norway.
Gas scrubbers are designed to protect process equipment, such as compressors, dehydration towers, pipelines and molecular sieves from liquids. The efficiency of gas scrubbers for separating natural gas liquids (NGLs) is critical to the recovery of most of the entrained NGL before the gas is routed downstream to pipelines.
We present a specific case study in Southeast Asia where offshore production was delivering 300 MMscf/d of gas to an onshore gas processing facility. The gas was chilled in a mechanical refrigeration unit, and liquids were separated in a vertical scrubber equipped with a simple inlet device and mesh pad assembly. The scrubber was designed to handle 450 MMSCFD. Due to an inefficient scrubber design, the facility was experiencing NGL liquid carryover from the scrubber into the pipelines with the original design basis. The scrubber thereby showed significant amount of liquid carryover of 1,550 BPD of natural gas liquids into the gas pipelines.
Computational fluid dynamics modeling of the scenario clearly showed loss in separation efficiency and NGL carryover from the scrubber to the downstream pipeline, documenting that the existing scrubber was not suitable for such high gas loading and increased gas volume.
Customer approached Schlumberger to retrofit scrubber with a new design and resolve the existing liquid carryover issues which led to revenue loss. We have experience in desiging novel internals such as axial cyclonic inlet (ACI) in these kind of scrubber vessels. These have been tested and optimized in the laboratory using model fluids and further tested in a high-pressure real fluid testing loop. Test results show that ACI provides the required gas/liquid separation efficiency under the higher gas loading and thereby increases the overall separation efficiency to 99.9+%.
The retrofit scrubber was designed to process 450 -500 Mmscfd of gas and increase the NGL production by 8540 BPD showing high ROI for the customer. The scrubber with the ACI shows consistently higher separation efficiency even under turndown or lower inlet gas flow conditions.
We present details of the retrofit scrubber design, importance of using high efficiency separation internals, CFD anlaysis and present test results verifying the liquid carryover before and after implementation of the new inlet section.
ADGAS is a leading LNG producer. It is the pioneer LNG supplier in the region. LNG trains are operated since 1977. Through those years of experience, ADGAS has been following a stringent Asset Integrity Management System for all its plants. Among these plants are the flare and relief systems. Flare systems are considered safety critical. Maintaining the integrity of these systems is a challenge. This paper shares ADGAS best practices in maintaining the asset integrity of these plants. The paper also highlights the latest development in the area of flare systems inspection and shares same case histories.
The world of Asset Integrity Management has advanced over the few decades to a great deal. Inspection has progressed from being time based to condition based then to being Risk Based. ADGAS Asset Integrity Management has passed through all these developments. For instance inspection of flare systems and plants was first time based. Then based on the performance of some of its plant systems it became condition based. Afterwards more optimization was added and it became Risk based. Technology has also advanced across the years, for instance, flare tips replacement was a strictly time based program. Then became condition based, then now we can inspect the flare tips systems online using special Unmanned Aerial vehicles (UAV's). This enabled ADGAS to truly optimize on maintenance and replacements of the flare tips. These examples will be shared in the paper. Furthermore at few instances failure of some flare systems provided great experience to avoid recurrence, flashback case, flare piping systems ageing and repair are all cases that are to be shared in the presentation.
Utilization of latest inspection technology, latest repair technology and monitoring enabled ADGAS to optimise its inspection and maintenance costs. The last savings on flare systems maintenance were estimated at a value of USD MM 3.5. Some old flow control measures were proven to possible create problems, for example restriction orifices to control the flow of purge gas can get blocked if not maintained. Restriction orifices can be changed for other means of control to avoid possible restriction of purge gas flow which is essential for the integrity of flare systems.
Latest UAV inspection technology has added towards the inspection and maintenance of flare systems. Utilization of more advanced monitoring and flow control of flare purge gases is of high importance. Usage of novel techniques in piping repair represented an important aspect in optimizing the maintenance cost of flare systems.
Nowadays more than ever there can be no doubt that world economy and especially global energy markets are driven by technology innovations. As Arctic currently serves as a potential game changer for energy markets, emerged technologies it will bring to the market and its infrastructure development can totally reshape the global landscape of the international energy market.
This paper highlights benefits that development of international projects in the Arctic can bring to the market by making it more innovative and competitive along with potential usage of some of its technologies in other offshore and marine projects.
Sakhanlin Energy Investment Company operates 3 offshore platforms in the Sea of Okhotsk east of Sakhalin Island in the Russian Ferderation. The Piltun Astokhskoye oil field is being developed by the PA-A and PA-B integrated drilling and production platforms. The Lunskoye gas field is being developed from the LUN-A integrated drilling and production platforms. The Lunskoye field is being developed using ERD technology and the sandface completions have transitioned from oriented perforations to open hole gravel packs. Executing these openhole gravel packs in these challenging extended-reach wells is quite challenging. And this is further complicated by the harsh climatic conditions around the island. Sakhalin Energy recently completed two of these wells successfully which are delivering over 400 MMscf/d of sand-free gas to the island's liquefied natural gas plant.
This paper presents the solution developed by Petrobras to support oilfield development in Campos and Santos (pre-salt) Basins. This system solution consists of a ship fitted with specialized topside and improved production string design, which together allow for quick XMT installation avoiding slickline or wireline operations, thus completely dismissing drill rigs after production or injection strings.
A method for determining the ocean current normal to and tangentially to a seismic streamer is introduced. High resolution real time estimation of ocean currents is valuable for optimal lateral steering of seismic streamers. With optimal steering, crossflow noise caused can be reduced. Additionally, improved steering can reduce line-change times. Further, estimated ocean currents can contribute to world current oceanographic models.
A PID controller approach is used in the estimation process. The controller adjusts the ocean current normal to the streamer tangent for minimizing offsets between simulated and measured streamer positions. The streamer model is 3-dimensional and incorporates cable stretch, tension, steering devices and tailbuoy.
The current estimation method has been tested on 50 line-change data from a seismic survey. Especially on line-changes, cable steering, and hence current estimation, contribute to steering efficiency. Line-changes are time consuming, typically 3 or more hours. Efficient lateral steering could reduce this time, resulting in time and cost savings for seismic surveys. Unfortunately, steering wing angles were not available in the study data set; hence the estimation assumes zero wing angles. However, only large currents could account for the magnitude of streamer displacement relative to the zero current model result. This implies that the algorithm is capturing a significant current effect and translating it into current force quite well, as simulations given the estimated currents show good agreement with the actual streamer positions. Computational time of the algorithm is much less than real time. Hence current predictions can be made available to the streamer control system with little delay. Further, streamer prediction can be performed using the simulator with the updated ocean currents. Additionally, the estimated current can be transmitted in near real time to oceanographic research institutes.
To the authors' knowledge the present approach of current estimation has not been attempted previously. Since there exist small scale local variations in current, measuring the current only at the vessel and some stationary positions has limited value. As the current estimation algorithm can be run continuously in real time, it would provide more accurate and higher resolution information to the steering system, facilitating improved steering efficiency.
Venero, Germain (Hugues Corrignan - Wood Group) | Muniz, Leandro (Hugues Corrignan - Wood Group) | Diezel, Alexandre (Hugues Corrignan - Wood Group) | Gomes, Victor (Hugues Corrignan - Wood Group) | Fachini, Rafael (Hugues Corrignan - Wood Group)
This paper presents the procedure for the calibration of a soil model represented by P-Y curves in the global finite element model of a drilling riser system using onboard measured data.
In the case of lack of real data or data uncertainty regarding the soil properties of one specific well location, the soil model can be calibrated using measured data during the drilling campaign.
The calibration procedure improves the accuracy on the prediction of the wellhead bending moment and stresses along the conductor pipe based on global riser analyses performed during the operation to assure the integrity of the well structure and thus, safe operations.