Observation of Subsea BOP Response From Field Measurements and Reflections on Conductor Design Challenges

2017 ◽  
Author(s):  
Harald Holden ◽  
Heidi Gryteland Holm ◽  
Youhu Zhang ◽  
Victor Smith ◽  
Randi Næss
Keyword(s):  
Barents Sea ◽  
Complex Loading ◽  
Field Measurements ◽  
Soil Reaction ◽  
The North ◽  
Well Design ◽  
Exploration Drilling ◽  
Vessel Motion ◽  
Design Analyses ◽  
Exploration Well

Subsea exploration well systems are subjected to complex loading due to vessel motion and hydrodynamic forces on the riser. In design of the wells, both the ULS/ALS design under extreme loading and fatigue design under operational loading are heavily dependent on the soil support along the uppermost 20 m of the conductor casing. In today’s practice, design of the conductor against extreme loading is typically performed using the soil reaction curves (p-y springs) recommended in API RP 2GEO [1]. In recent years, 4Subsea have been monitoring the BOP and riser responses during exploration drilling campaigns for Lundin Norway. The purpose of these monitoring campaigns is to track the performance of the wells with time, based on integrity parameters such as well stiffness, BOP resonance frequency and BOP motion rotational depth. This paper summarizes the monitoring results from seven well locations in the North Sea and the Barents Sea. The observed well response is compared with up-front design analyses. The discrepancy between up-front design analyses and the observed performances is discussed in light of the uncertainties associated with the geotechnical input parameters and soil reaction models. The purpose of the paper is to reflect on the challenges faced with exploration well design and highlight areas that improvements can be made.

Well Design for Subsea Exploration Drilling in Shallow Formations of Barents Sea

2021 ◽  
Author(s):  
Mikolaj Stanislawek
Keyword(s):  
Design Process ◽  
Barents Sea ◽  
Weather Conditions ◽  
Design Approach ◽  
Drilling Process ◽  
Well Control ◽  
Pilot Hole ◽  
Planning Phase ◽  
Well Design ◽  
Exploration Drilling

Abstract Subsea exploration drilling in relatively new and not yet fully recognized frontiers like Barents Sea continues to be a focus for Oil & Gas Companies. Safety and robust well barriers are important as ever. This paper describes well design process and execution of a challenging subsea exploration well in shallow formations of Barents Sea by Equinor. Case study for planning and well design process is presented, followed by drilling experiences during execution. Several well design concepts and contingency scenarios that were evaluated and risk assessed in the planning phase are presented, which required extra focus on well design and well barriers. Compensating measures along with high focus on well control and well barriers in shallow drilling environment of Barents Sea were developed during planning phase of this well, and reviewed with planning and execution teams. Design approach encompasses casing design in shallow reservoir well with narrow margin between required formation integrity and fracture pressures, low kick tolerance, drilling in unstable formations, low temperature and pressures. Robust well design in shallow and weak formations is feasible with conventional casing design approach, and well challenges can be overcome by proper planning and contingency measures involving additional preparation of drilling crew, and by use of advanced drilling technology and procedures. Safety and well control is the most important factor in well design. Relevant contingency scenarios should be prepared with equipment and procedures in place. Importance of drilling a pilot hole in unrecognized area near main well and its influence on main well design is crucial. This is a good example of planning and drilling process for challenging well in unrecognized area with limited reference well data, challenging logistics, and weather conditions of Barents Sea. It will demonstrate how many contingency scenarios were fully prepared in planning phase and their rationale, versus encountered drilling experiences, to be a more precise reference for future wells in the area.

Top-Hole Technology Overcomes Challenging Sand-Based Seabed Conditions and Enables Record Drilling Performance in an Offshore Exploration Well

2021 ◽  
Author(s):  
Camilo Cardenas ◽  
Hans Erik Hansen ◽  
Sigvald Hanssen ◽  
Harald Blikra ◽  
Wolfgang Mathis ◽  
...  
Keyword(s):  
Positive Impact ◽  
Health And Safety ◽  
High Strength ◽  
Cost Comparison ◽  
Environmental Footprint ◽  
Dense Sand ◽  
The North ◽  
Drilling Performance ◽  
Well Design ◽  
Exploration Well

Abstract Top hole construction is a critical part of any well design, especially for subsea wells. It is considered to be the foundation for the well, and it is crucial for ensuring well integrity. Uncertainties and conditions of the seabed and top layers could compromise the stability of the chosen solution. This paper describes the first implementation of the conductor anchor node (CAN®) technology in sand-based conditions and demonstrates its positive impact on the drilling performance for an offshore exploration well in the North Sea. The main challenges identified in the top-hole design for this well were the presence of boulders down to 65 m below the seabed, and hard soil that consisted mainly of very dense sand and high strength sandy-clay layers. Different solutions were evaluated using a risk-based approach, looking to optimize operational performance and decrease the environmental footprint. A technology which consists of a pre-installed short conductor within a CAN was chosen. This solution enabled the operator to establish a competent well foundation above the boulder interval and increase operational efficiency by reducing the critical rig time. However, the CAN technology had not been deployed in this type of soil previously. Thus, the feasibility of its installation became one of the main milestones of the project. This was made possible due to a set of contingencies and modifications that were the result of a strategic collaboration among the parties involved. The CAN was successfully installed by a crane vessel before the rig arrived at location, and the set of contingencies and modifications mentioned in this paper were decisive to ensure it reached the required penetration depth. Furthermore, this paper demonstrates that the CAN technology was crucial for the project to achieve top performance results and become one of the fastest exploration wells drilled in the Norwegian basin. This solution reduced uncertainties related to the conductor cementing, load and fatigue capacities, and deep surface casing cement. Improvement in the drilling performance is determined by estimating the decrease in drilling time, materials and consumables. Those results are then used to perform a cost comparison which demonstrates that the CAN technology reduced the top-hole construction cost significantly on this offshore well. In addition, the reduction in the well environmental footprint is quantified, and its contributions to the projects health and safety goals are highlighted.

Method application of optimal multi-parameter analysis to assess the distribution of water masses as an example of CTD data of the Barents Sea in summer 2017

2019 ◽  
pp. 38-51
Author(s):  
Valeriy G. Yakubenko ◽  
Anna L. Chultsova
Keyword(s):  
Barents Sea ◽  
Field Measurements ◽  
Structural Similarity ◽  
Water Masses ◽  
Parameter Analysis ◽  
Water Dynamics ◽  
Phosphorus Concentration ◽  
Nitrogen And Phosphorus ◽  
The Barents Sea ◽  
Expert Assessments

Identification of water masses in areas with complex water dynamics is a complex task, which is usually solved by the method of expert assessments. In this paper, it is proposed to use a formal procedure based on the application of the method of optimal multiparametric analysis (OMP analysis). The data of field measurements obtained in the 68th cruise of the R/V “Academician Mstislav Keldysh” in the summer of 2017 in the Barents Sea on the distribution of temperature, salinity, oxygen, silicates, nitrogen, and phosphorus concentration are used as a data for research. A comparison of the results with data on the distribution of water masses in literature based on expert assessments (Oziel et al., 2017), allows us to conclude about their close structural similarity. Some differences are related to spatial and temporal shifts of measurements. This indicates the feasibility of using the OMP analysis technique in oceanological studies to obtain quantitative data on the spatial distribution of different water masses.

scholarly journals Estimation of harp seal (Pagophilus groenlandicus) pup production in the North Atlantic completed: results from surveys in the Greenland Sea in 2002

2006 ◽  
Vol 63 (1) ◽  
pp. 95-104 ◽  
Author(s):  
Tore Haug ◽  
Garry B. Stenson ◽  
Peter J. Corkeron ◽  
Kjell T. Nilssen
Keyword(s):  
North Atlantic ◽  
Barents Sea ◽  
Temporal Distribution ◽  
Harp Seal ◽  
Greenland Sea ◽  
The North ◽  
Pagophilus Groenlandicus ◽  
Pack Ice ◽  
Photographic Survey ◽  
Strip Transect

Abstract From 14 March to 6 April 2002 aerial surveys were carried out in the Greenland Sea pack ice (referred to as the “West Ice”), to assess the pup production of the Greenland Sea population of harp seals, Pagophilus groenlandicus. One fixed-wing twin-engined aircraft was used for reconnaissance flights and photographic strip transect surveys of the whelping patches once they had been located and identified. A helicopter assisted in the reconnaissance flights, and was used subsequently to fly visual strip transect surveys over the whelping patches. The helicopter was also used to collect data for estimating the distribution of births over time. Three harp seal breeding patches (A, B, and C) were located and surveyed either visually or photographically. Results from the staging flights suggest that the majority of harp seal females in the Greenland Sea whelped between 16 and 21 March. The calculated temporal distribution of births were used to correct the estimates obtained for Patch B. No correction was considered necessary for Patch A. No staging was performed in Patch C; the estimate obtained for this patch may, therefore, be slightly negatively biased. The total estimate of pup production, including the visual survey of Patch A, both visual and photographic surveys of Patch B, and photographic survey of Patch C, was 98 500 (s.e. = 16 800), giving a coefficient of variation of 17.9% for the survey. Adding the obtained Greenland Sea pup production estimate to recent estimates obtained using similar methods in the Northwest Atlantic (in 1999) and in the Barents Sea/White Sea (in 2002), it appears that the entire North Atlantic harp seal pup production, as determined at the turn of the century, is at least 1.4 million animals per year.

scholarly journals Hydrography in the north–western Barents Sea, July–August 1996

2001 ◽  
Vol 20 (1) ◽  
pp. 1-11
Author(s):  
Terje Brinck Løyning
Keyword(s):  
Barents Sea ◽  
The North ◽  
North Western

scholarly journals NH<sub>3</sub>-promoted hydrolysis of NO<sub>2</sub> induces explosive growth in HONO

2018 ◽  
Author(s):  
Wanyun Xu ◽  
Ye Kuang ◽  
Chunsheng Zhao ◽  
Jiangchuan Tao ◽  
Gang Zhao ◽  
...  
Keyword(s):  
North China Plain ◽  
North China ◽  
Ph Value ◽  
Primary Source ◽  
Field Measurements ◽  
Oh Radicals ◽  
The North ◽  
The North China Plain ◽  
First Time ◽  
Hydrolysis Of

Abstract. The study of atmospheric nitrous acid (HONO), which is the primary source of OH radicals, is crucial to atmospheric photochemistry and heterogeneous chemical processes. The heterogeneous NO2 chemistry under haze conditions was pointed out to be one of the missing sources of HONO on the North China Plain, producing sulfate and nitrate in the process. However, controversy exists between various proposed mechanisms, mainly debating on whether SO2 directly takes part in the HONO production process and what roles NH3 and the pH value play in it. In this paper, never before seen explosive HONO production (maximum rate: 16 ppb/hour) was reported and evidence was found for the first time in field measurements during fog episodes (usually with pH > 5) and haze episodes under high relative humidity (usually with pH 

scholarly journals Experimentally determined temperature thresholds for Arctic plankton community metabolism

2013 ◽  
Vol 10 (1) ◽  
pp. 357-370 ◽  
Author(s):  
J. M. Holding ◽  
C. M. Duarte ◽  
J. M. Arrieta ◽  
R. Vaquer-Sunyer ◽  
A. Coello-Camba ◽  
...  
Keyword(s):  
Barents Sea ◽  
Average Rate ◽  
Seawater Temperature ◽  
Field Measurements ◽  
The Arctic ◽  
Temperature Threshold ◽  
Metabolic Rates ◽  
Metabolic Theory ◽  
Threshold Response ◽  
Plankton Communities

Abstract. Climate warming is especially severe in the Arctic, where the average temperature is increasing 0.4 °C per decade, two to three times higher than the global average rate. Furthermore, the Arctic has lost more than half of its summer ice extent since 1980 and predictions suggest that the Arctic will be ice free in the summer as early as 2050, which could increase the rate of warming. Predictions based on the metabolic theory of ecology assume that temperature increase will enhance metabolic rates and thus both the rate of primary production and respiration will increase. However, these predictions do not consider the specific metabolic balance of the communities. We tested, experimentally, the response of Arctic plankton communities to seawater temperature spanning from 1 °C to 10 °C. Two types of communities were tested, open-ocean Arctic communities from water collected in the Barents Sea and Atlantic influenced fjord communities from water collected in the Svalbard fjord system. Metabolic rates did indeed increase as suggested by metabolic theory, however these results suggest an experimental temperature threshold of 5 °C, beyond which the metabolism of plankton communities shifts from autotrophic to heterotrophic. This threshold is also validated by field measurements across a range of temperatures which suggested a temperature 5.4 °C beyond which Arctic plankton communities switch to heterotrophy. Barents Sea communities showed a much clearer threshold response to temperature manipulations than fjord communities.

scholarly journals Field Measurements of Surface and Near-Surface Turbulence in the Presence of Breaking Waves

2015 ◽  
Vol 45 (4) ◽  
pp. 943-965 ◽  
Author(s):  
Peter Sutherland ◽  
W. Kendall Melville
Keyword(s):  
Field Experiments ◽  
North Pacific Ocean ◽  
Large Fraction ◽  
Field Measurements ◽  
Breaking Waves ◽  
Sea Surface ◽  
Near Surface ◽  
Wave Energy Dissipation ◽  
Eddy Simulation ◽  
The North

AbstractWave breaking removes energy from the surface wave field and injects it into the upper ocean, where it is dissipated by viscosity. This paper presents an investigation of turbulent kinetic energy (TKE) dissipation beneath breaking waves. Wind, wave, and turbulence data were collected in the North Pacific Ocean aboard R/P FLIP, during the ONR-sponsored High Resolution Air-Sea Interaction (HiRes) and Radiance in a Dynamic Ocean (RaDyO) experiments. A new method for measuring TKE dissipation at the sea surface was combined with subsurface measurements to allow estimation of TKE dissipation over the entire wave-affected surface layer. Near the surface, dissipation decayed with depth as z−1, and below approximately one significant wave height, it decayed more quickly, approaching z−2. High levels of TKE dissipation very near the sea surface were consistent with the large fraction of wave energy dissipation attributed to non-air-entraining microbreakers. Comparison of measured profiles with large-eddy simulation results in the literature suggests that dissipation is concentrated closer to the surface than previously expected, largely because the simulations did not resolve microbreaking. Total integrated dissipation in the water column agreed well with dissipation by breaking for young waves, (where cm is the mean wave frequency and is the atmospheric friction velocity), implying that breaking was the dominant source of turbulence in those conditions. The results of these extensive measurements of near-surface dissipation over three field experiments are discussed in the context of observations and ocean boundary layer modeling efforts by other groups.

scholarly journals Traffic calming measures and their effect on the variation of speed

2016 ◽  
Author(s):  
Hernán Gonzalo Orden
Keyword(s):  
Urban Areas ◽  
Field Measurements ◽  
Speed Reduction ◽  
The Road ◽  
The North ◽  
Traffic Calming ◽  
Road Users ◽  
Technical Basis ◽  
Serious Injuries ◽  
North Of Spain

In recent years the number of deaths and serious injuries is decreasing in Spain, but, although the reduction outside the cities has been very strong, inside the urban areas, it has been smaller. This is especially hard if you look at the most vulnerable road users such as pedestrians and cyclists. In many accidents the speed factor appears closely linked not only to the number, but also to the severity of the accidents suffered inside the urban areas. Therefore, a reduction in the speed would improve the road safety. There are different measures known as "traffic calming measures" whose objectives are to reduce both the number and severity of accidents that occur on urban areas, by reducing the traffic flow through the streets, as well as the speed of the vehicles. However, the efficiency in speed reduction of each measure is not entirely known. That's the reason why they are implanted, in many cases, with no technical basis. The aim of this article is to show the effectiveness in reducing speed of some of the traffic calming measures. To this effect, field measurements were done on street sections with different types of traffic calming measures, in different places of a city of Burgos, in the north of Spain. These measurements were compared with other ones sited on other streets sections of similar characteristics but without traffic calming measures. Finally the conclusions are shown and some recommendations for improving their effectiveness are given.DOI: http://dx.doi.org/10.4995/CIT2016.2016.4217

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