The world's oceans are critical to sustaining life, controlling climate, and providing economic wealth. Despite this fact, our understanding of the ocean and its seafloor processes is limited, in part because we lack accurate ocean mapping data. The situation is dramatic in the Arctic, where the physical environment is changing rapidly and where the vast majority of the 15,588,000-square-kilometer Arctic Ocean remains unmapped using modern survey methods. Given current and anticipated increases in vessel traffic, resource exploration and development, and impacts of climate change on coastal areas, the need for bathymetric data in the region is becoming increasingly urgent.
The Nippon Foundation-GEBCO Seabed 2030 Project promises a solution for the Arctic's growing data demand. Launched in 2017, the project aims to produce a definitive and publicly available high-resolution map of the world's ocean floor by 2030. To achieve these goals, the program is advancing three strategies. First, existing data must be identified and the remaining gaps mapped. For the Arctic, apart from the ice covered central basin, an appreciable volume of bathymetric data already exists, but the national governments and private sector companies who hold these data will need to make them available to Seabed 2030, even if at decimated levels. Second, the project looks to crowd sourced bathymetry as an important means of acquiring new datasets. Vessels operating in or passing through Arctic waters can log and contribute bathymetric data from their movements. Finally, even if existing data and crowd sourced bathymetry data contributions are made, there will undoubtedly be a need for a coordinated Arctic Ocean basin mapping campaign by a combination of government, scientific, and private industry survey vessels to fill the remaining gaps in coverage.
This paper will review the need for bathymetric data in the Arctic, the potential for the Seabed 2030 project to deliver these data, and the methods that will be used to ensure its success. It will also discuss the anticipated impacts of Seabed 2030 on Arctic resource development.
Current Well Control Procedures require "Divert Overboard" for the handling of riser gas. This rule is a consequence of the Deepwater Horizon accident, where the PRV of the Mud-Gas Separator was the source of the gas that led to the explosion and the death of 11 crew. This practice will inevitably lead to the spill of potentially thousands of barrels of oil based mud.
Current Mud Gas Separators (MGS) on a drilling rig are utilized to separate liquids from gas that are circulated out after a kick has been taken in a conventional well. The current practices, when the primary well barrier, which is the weight of the drilling mud is breached, is to shut the well on BOP (Blowout Preventers) and circulate out the volume of formation fluids (gas/oil/water) that have entered the wellbore. For the safety of the personnel and rig equipment, this kick is circulated out with closed BOP’s which divert the fluids to the rig choke that is lined up to the MGS. This prevents any formation fluids from entering the rig floor or be exposed to the rig environment. The MGS diverts the flammable gases to a vent line. Since the traditional MGS designs are open to atmosphere, the gas flowrates that enter separator have a potential to breach through the mud leg causing a separator blow through if these gas flowrates are higher than gas handling capacity of the MGS. If flow exceeds the limited MGS capacity and a blow through condition occurs, the flammable gas can disperse onto the rig. Taking the experience of Underbalanced Drilling into account, where tens of thousands of barrels of reservoir content can be produced safely in a 24h time period, the learning for separator design and multiphase medium handling are taken as a basis to design an adequate drilling system for arctic use, however in closed system drilling mode with the underbalanced capabilities the operating limit to handle unintended inflows.
Taking the UBD experience into account, a mud gas separator design and operating procedure for spill-free arctic operations is proposed. This paper focuses on using CFD techniques to understand the relationship between the gas handling capacity of the MGS and the separator diameter, its internal geometry and length. The paper attempts to study separation of gas and liquids inside the separator that is open to atmosphere and the reasons that could cause separator blow-through conditions
For the first time, the vast knowledge on 4-phase separation in the production and UBD world is transferred to conventional drilling operations, with the objective of a closed, safe and spill free drilling system as required for the arctic.
Subsea oil and gas developments in the Grand Banks region, offshore Eastern Canada, require mitigation techniques to protect against iceberg keel interactions. For example, untrenched infield flowlines incorporate weak link systems designed to fail in the event of flowline snag to protect upstream and downstram assets. Even with these systems, the assumption that any iceberg contact equates to flowline failure means that flowline lengths in excess of approximately 10 km require trenching to meet safety target levels. Furthermore, all subsea wells to date have been installed in excavated drill centers to avoid contact with gouging icebergs. Based on current design practices, these mitigation measures are cost prohibitive and limit the potential for the development of marginal fields. This paper addresses conventional practice to protect against iceberg interaction and proposes alternative solutions that maintain safety, while reducing costs significantly.
Ice-structure interaction (ISI) is a complex process, which requires a thorough understanding of the underlying physics to ensure safe operations in the ice-covered regions. Application of discrete element method (DEM) to compute ice loads on structures is a widely accepted approach, where the equations of rigid body motions are solved for all ice pieces in the computational domain. In most ISI simulations, the ice zone is assumed to be resting on a static water foundation omitting the hydrodynamic effects (added mass, water drag, wave damping) of the interacting bodies. This assumption can introduce erroneous results to simulations of the floating ice floes behavior, which in turn will incur uncertainties in planning ice management activities.
In this paper, a smooth particle hydrodynamics (SPH) based computational fluid dynamics (CFD) code is coupled with a three-dimensional DEM model to take the hydrodynamic effects of the interacting bodies including the ice pieces into account. The ice zone is modeled as discrete elements, which allows computing interaction forces by considering contact laws. The water foundation is modeled using smooth particles, which are modelled with the Naiver-Stokes equations.
Several applications of ship and offshore structures interacting with level ice and pack ice are simulated. A scenario of an offshore supply vessel operating in the marginal ice zone (MIZ) that is subject to wave forces is also simulated to show how this approach can be used for modelling complex real-world problems. This scenario is unique in a sense that it yields a multi-physics solution, where ice-structure-wave are all included in a single CFD simulation as a fully coupled analysis. The cost of the simulation is significantly reduced by running the computations on a Graphics Processing Unit (GPU) instead of a typical CPU workstation. Some of the initial results of ice-structure interactions are presented in this paper and a reasonable agreement with reduced scale model test results are found.
Jo, Y. (Daewoo Shipbuilding and Marine Engineering) | Choi, J. (Daewoo Shipbuilding and Marine Engineering) | Park, S. (Daewoo Shipbuilding and Marine Engineering) | Lee, J. (Daewoo Shipbuilding and Marine Engineering) | Ki, H. (Daewoo Shipbuilding and Marine Engineering) | Han, S. (Daewoo Shipbuilding and Marine Engineering)
The activities related to exploitation for oil and gas in the Arctic areas increase significantly. In order to transport increased resources in the Arctic areas, large Arctic commercial vessels such as gas carriers, oil tankers, bulk carriers, etc. are needed for mass transportation. In Arctic area, the ice load is the main factor of environmental load acting on Arctic vessel. The ice load is increased with the enlargement of vessel.
The largest Arctic commercial vessel was built by DSME in 2016. The vessel was delivered after completion of ice trial in March 2017. The size of Arctic LNG carrier is larger than any other Arctic vessels have been constructed so far. The ice load monitoring system was installed for ice load measurement and structural safety of ice navigation of this large LNG carrier.
This paper is concerned with comparison between estimated ice load for structural design and measured ice load for vessel navigation in Arctic area. Design ice load was calculated according to prescriptive rules of the Classification societies. Actual ice load during ice navigation was measured from ice load monitoring system. The arrangement of sensors in the monitoring system was determined for the precise measurement of ice induced loads acting on the hull. FE analyses were also carried out to compare between estimated ice load and measured ice load considering complex structural details in the Arctic LNG carrier.
As the oil and gas industry and international shipping companies push their assets into high latitude marine environments, it is important to thoroughly understand the performance of construction materials exposed to extremely low temperature and / or subjected to high ice loads. In the past, the design considerations have addressed the uncertainty in these areas by adopting conservative approaches. While proven effective, there exists a need for additional testing to gain insight into the safety margin levels that have been implicitly included. The work presented has the potential to lead to a better understanding of how steel materials behave in long-term Arctic conditions.
This paper presents the results of mechanical property tests of aged steel samples from the Kulluk, an ice-class rated drilling barge. This barge was exposed to the Arctic environment for almost 30 years. The Kulluk was built in Japan in 1983, specifically for exploration drilling operations in the Arctic environment. When the barge was scrapped in 2014, hull steel was selectively harvested. The intent was to conduct tests to better understand the behavior of shipbuilding steels that have endured long-term exposure to Arctic environments.
As an initial project phase, four sample groups of hull plate, from four different locations of the barge (one below the waterline, one in the ice belt region and two above the ice belt), were chosen for testing. The laboratory tests included tensile tests, Charpy impact tests and hardness tests. The test results indicate that the yield strengths, ultimate strengths, toughness and hardness of the aged steels continue to satisfy the ABS Rules requirements. A degradation assessment of these samples was also performed using these testing results and the limited data available as tracked from the barge's construction stage.
It is observed that the yield strengths and ultimate strengths remain consistent within the scatter of original or time period data. With respect to Charpy toughness values no conclusions concerning degradation can be made conclusively as the scatter in the data is substantial, especially at low temperatures. The steel in this study that has aged in the Arctic environment appears to maintain its original mechanical properties.
Based on the study presented in this paper, further studies could be performed such as additional sample tests to increase the reliability of results, material properties test for steel samples with butt/fillet welds to understand the variation of the heat affected zone (HAZ) and Crack Tip Opening Displacement (CTOD) tests to get a better understanding of the material toughness.
A new real-time model was developed, based on a deep recurrent neural network (DRNN), to predict response variables, such as surface pressure response, during the hydraulic fracturing process. During the stimulation process stage, fluids are inserted at the top of the wellhead, and the flow is driven by the difference between the hydrostatic pressure and reservoir pressure. The major physics and engineering aspects in this process are very complex; quite often, the measured data includes a large amount of uncertainty related to the accuracy of the measured data, as well as intrinsic noise. Consequently, the best approach uses a machine learning-based technique that can resolve both temporal and spatial non-linear variations.
The approach followed in this paper provides a long short-term memory (LSTM) network-based method to predict surface pressure in a fracturing job, considering all commonly known surface variables. The surface pumping data consists of real-time data captured within each stage, including surface treating pressure, fluid pumping rate, and proppant rate. The prediction of a response variable, such as the surface pressure response, is important because it provides the basis for decisions made in several oil and gas applications to ensure success, including hydraulic fracturing and matrix acidizing.
Currently available modeling methods are limited in that the estimates are not high resolution and cannot address a high level of non-linearity in the treatment pressure time series relationship with other variables, such as flow rate and proppant rate. In addition, these methods cannot predict subsurface variable responses based only on surface variable measurements. The method described in this paper is extended to accommodate the prediction of diverter pressure response.
The model presented in this paper uses a deep learning neural network model to predict the surface pressure based on flow rate and proppant rate. This work represents the first attempt to predict (in real time) a response variable, such as surface pressure, during a pumping stage using a memory-preserving recurrent neural network (RNN) variant (for example, LSTM and gated recurrent unit (GRU)). The results show that the LSTM is capable of modeling the surface pressure in a hydraulic fracturing process well. The surface pressure predictions obtained were within 10% of the actual values. The current effort to model surface pressure can be used to simulate response variables in real time, providing engineers with an accurate representation of the conditions in the wellbore and in the reservoir. The current method can overcome the handling of complex physics to provide a reliable, stable, and accurate numerical solution throughout the pumping stages.
Stewart, Helen (Fugro USA) | Khadjinova, Rada (Fugro USA) | Brumley, Kelley (Fugro USA) | Earl, Shannon (Fugro USA) | Waugh, Alex (Fugro New Zealand) | Thomas, Nick (Fugro New Zealand) | Waugh, Bob (Fugro New Zealand) | Rycroft, David (Fugro New Zealand)
Challenges and complications of hydrographic and marine surveys in the last mile between sea and shore are compounded in the Arctic by remoteness, lack of infrastructure facilities, difficult transport, and environmental hazards. Without safe, cost-effective, and technologically fit-for-purpose survey solutions, these last-mile surveys are often neglected or inadequate for their design purposes. These special challenges pose similar difficulties to littoral marine and freshwater surveys in temperate New Zealand. To meet these challenges, experienced surveyors from the New Zealand branch of a global survey company partnered with a New Zealand-based naval architect to design and build a seaworthy class unmanned surface vehicle (USVs) for work in remote and isolated environments. The new nearshore class USV is easy to transport by any commercial means, inexpensive, safe for a two-person crew to operate, and has a customizable payload with large capacity for its size.
The ability to work safely in harsh, remote environments at a reasonable cost make the new nearshore class USV an attractive and cost-effective option for surveying in the Arctic. This paper presents information on this survey solution and discusses advantages to USVs as a survey platform in Arctic environments.
The United Nations Convention on the Law of the Sea (UNCLOS) dictates under international law how all offshore maritime frontier waters are to be "divided up" in the world today. All Law of the Sea (LOS) applications, begin with coastlines and/or their related coastal frontages. The United Nations (UN) lists 152 countries (conventional coastal states) as being applicable to the rules of procedures for LOS applications. Additionally, and more recently, we include three coastal countries (landlocked "sea/lake" states) in the Caspian Sea, as well as seven additional coastal (landlocked "lake") states, for the Great Lakes of Africa. Therefore, basic LOS mapping principles, that begins with coastlines and/ or coastal frontages will impact 162 countries in the world today. The accuracies of present-day mapped features that are components of all coastal (and landlocked "sea/lake") states' coastlines', will be used to produce various mathematical applications for the LOS. The offshore Arctic maritime spaces (for five relevant littoral countries), is one of the more complex regions of the world, and, from a current LOS standpoint, basic summaries on the status of LOS and how it directly relates to the oil and gas industry will be reviewed.
Icebergs can pose risks to platforms in arctic and subarctic regions. These risks require careful consideration during design, and as well during operations. Platforms must be designed to withstand potential impacts from icebergs, or to disconnect and move offsite to avoid impacts. ISO 19906 allows use of ice management to mitigate iceberg and sea-ice actions. In the case of icebergs, management may include detection, monitoring, towing, disconnection and evacuation. Threat assessment is also a critical input to the iceberg management decision-making process. For example, given one or more detected icebergs and available information on the iceberg and environment characteristics, what is the probability of exceeding platform design ice actions? Based on the threat assessment, better decisions can be made regarding which iceberg to manage, whether more information should be acquired, and whether shut-down or evacuation is needed.
This paper describes a new tool developed to estimate the distribution of iceberg impact actions from an encroaching iceberg given concurrent metocean conditions, conditional on impact. The tool can be used in a number of ways depending on the information available to the user. It can be used to assess the threat from a single iceberg or can be used to compare actions from multiple icebergs in the region, or for the same iceberg but with changing weather conditions. The iceberg load assessment tool is demonstrated for several example cases on the Grand Banks, showing the benefit of improved iceberg characterization obtained through rapid iceberg profiling.