**Peer Reviewed**

**Source**

**Conference**

- The 28th International Ocean and Polar Engineering Conference (2)
- The Eleventh International Offshore and Polar Engineering Conference (2)
- The Eleventh ISOPE Pacific/Asia Offshore Mechanics Symposium (3)
- The Fifteenth International Offshore and Polar Engineering Conference (1)
- The Fourteenth International Offshore and Polar Engineering Conference (1)
- The Seventh ISOPE Pacific/Asia Offshore Mechanics Symposium (1)
- The Sixteenth International Offshore and Polar Engineering Conference (1)
- The Sixth International Offshore and Polar Engineering Conference (1)
- The Thirteenth International Offshore and Polar Engineering Conference (2)
- The Thirteenth ISOPE Pacific/Asia Offshore Mechanics Symposium (2)
- The Twelfth International Offshore and Polar Engineering Conference (1)
- The Twentieth International Offshore and Polar Engineering Conference (2)

**Theme**

**Author**

- Cao, Shujun (1)
- Chen, Geng (1)
- Chi, Kun (1)
- Chu, Xinjie (1)
- Cui, Junnan (1)
**Dong, Sheng (19)**- Duan, Chenglin (1)
- Fu, Xinyu (1)
- Hao, Xiaoli (1)
- Ji, Qiaoling (1)
- Jiang, Fengyuan (2)
- Li, Feng (1)
- Li, Hua Jun (2)
- Li, Jingjing (1)
- Li, Xue (1)
- Liu, Defu (3)
- Liu, Yakun (2)
- Ning, Meng (1)
- Sang, Song (1)
- Takayama, Tomotsuka (3)
- Tao, Shanshan (3)
- Wang, Chao (1)
- Wang, Zhifeng (3)
- Wei, Yong (4)
- Wu, Yanan (1)
- Xu, Bin (1)
- Yin, Qilin (1)
- Zhai, Jinjin (1)
- Zhang, Ri (2)
- Zhao, Yuliang (2)

**Concept Tag**

- ADCIRC model (1)
- adjacent bohai bay (1)
- amplitude (1)
- analysis (2)
- Anchor (1)
- annual maximum wave height (1)
- anomaly (1)
- Artificial Intelligence (8)
- ballast (1)
- ballast tank (1)
- Barent Sea (1)
- Base Shear (1)
- Behavior (1)
- Bohai (1)
- Bohai Bay (2)
- calculation (6)
- case (1)
- characteristic (1)
- China (3)
- coefficient (3)
- coincidence risk (1)
- combination (1)
- compound distribution (1)
- concentric ring (1)
- condition (1)
- construction (1)
- container (2)
- continuity equation (1)
- Copula (1)
- Copula function (1)
- correlation (2)
- correlation coefficient (1)
- corresponding wind speed (1)
- criteria (1)
- cumulative distribution (1)
- data Gumbel Pearson III (1)
- deck displacement (1)
- deformation (1)
- design (2)
- distribution (5)
- Effectiveness (2)
- Engineering (5)
- estimation (2)
- excitation (2)
- excitation wave (2)
- experiment (2)
- failure probability (2)
- frequency (5)
- Gumbel (2)
- Gumbel distribution (2)
- impact energy (2)
- joint probability (5)
- Laizhou bay (1)
- liquid damper (2)
- machine learning (3)
- management and information (5)
- method (4)
- Midstream Oil & Gas (2)
- NLSM (1)
- numerical simulation (2)
- Offshore (3)
- offshore pipeline (2)
- Pareto (1)
- Pbguml (1)
- PBGUML model (1)
- PBLD (1)
- Pearson (2)
- pipeline (2)
- platform (3)
- Poisson (1)
- Poisson distribution (3)
- probability (5)
- Qingdao (1)
- reduction (2)
- reservoir description and dynamics (3)
- reservoir simulation (3)
- return (2)
- return value (2)
- Shandong (1)
- Shandong Peninsula (1)
- Shandong Province (1)
- South China Sea (1)
- storm surge (2)
- structural response (2)
- structure (3)
- submarine pipeline (2)
- Tab (1)
- TLD (2)
- traditional method (3)
- Typhoon (2)
- Uniform Slope (1)
- Upstream Oil & Gas (12)
- variation (2)
- water (2)
- Wave (6)
- wave height (3)
- Weibull (2)
- Weibull distribution (2)
- wind (2)
- wind speed (2)

**File Type**

ABSTRACT

With the increase of human activities at sea, it is inevitable that anchors drop into the water due to operating errors, which may lead to failure of pipelines and cause economic damage and environmental pollution. Previous methods of related analysis are mostly based on the DNV-RP-F107 recommended method (hereinafter referred as DNV method). DNV method hardly considers the variation of anchor's size and weight. And it is insensitive to the pipeline geometry and material properties. Based on reliability theory, DNV method is improved to calculate failure probability under the consideration of the above relevant factors. The efficiency of the proposed method is verified by a practical case. Besides, analysis of the influence of various factors on pipeline failure probability is completed in this paper, including anchor weight, size, pipeline geometry and material properties, the distance from the anchor drop point. Meanwhile, considering the variability, the sensitivities of variables to the failure probability are discussed. Study results indicate that the failure probability calculated by DNV method is underestimated in some situations, which can probably cause a loss for pipeline projects. Whereas the proposed method is able to consider much more influences and leads to reasonable results consistent with the actual situation.

INTRODUCTION

Submarine pipeline is seen as the ‘lifeline’ for offshore oil and gas industry. Pipeline safety is one of the most important problems for engineering practice. Recently, anchors dropping into the sea becomes more frequent due to the increasing human activities at sea. The dropped anchors are likely to impact on pipelines and lead to pipeline failures, which can cause economic damage and environmental pollution. In order to reduce the risk and provide safe design, considerable research efforts have been devoted to risk assessment and reliability analysis of pipelines. In general, methods of the relevant research mainly consist of two categories: one is qualitative analysis, which can study the main influence factors on pipeline failures. Among them, fault tree analysis (FTA) is the most popular methodology and has been extensively applied to pipeline failure analysis. (Wang et al., 2007; Dong et al., 2005; Lavasani et al., 2011). The other one is quantitative analysis, which can determine pipeline failure probability and provide reliable reference for safe design. Katteland et al. (1995) developed a model for risk calculation, and applied it to evaluate the risk of all the installations in the North Sea. Det Norske Veritas (2010) proposed a ubiquitously used method for pipeline risk assessment and failure probability calculation (DNV method). Based on statistics of crane accidents, Det Norske Veritas (2013) also gave the falling probability for typical loads and various objects, which provided abundant references for pipeline risk assessment. On the basic of the above research, Liu et al. (2005) proposed a model to calculate the probability of pipeline being impacted under various anchorage conditions. Ding et al. (2010) modified DNV method and made a risk assessment of pipelines due to third-party activities. Yan et al. (2014) proposed a procedure to estimate the pipeline failure probability caused by anchoring activities. Up to now, to the best of the author's knowledge, quantitative analysis methods are mainly based on DNV method. In some situations, this method is hardly to consider the effect of anchor size and weight on pipeline failure probability. What's more, it is insensitive to the effect of pipeline geometry and material properties, which is not consistent with practice and may cause errors. In order to give an insight into those effects, a method based on reliability theory to calculate pipeline failure probability is proposed.

SPE Disciplines: Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Offshore pipelines (1.00)

ABSTRACT

The impact of dropped objects and trawl board on submarine pipelines are simulated by a non-explicit finite element method. The new method works in three mechanics. The impact process is simulated by adjusting the material properties. The damage of the pipeline is solved using Cowper-Symonds equation. Drucker-Prager model is used to analyze the elastic-plastic properties of soil under impact. Then the present work can take into account the interactions among the dropped objects, pipelines and soil. Furthermore, the effects of the weight, shape, impact velocity and seabed flexibility are discussed in detail.

INTRODUCTION

Submarine pipelines are the “lifeline” of offshore oil and gas production system and are used as one of the primary ways to transport oil and gas for offshore development. The risk of pipeline leakage is increasing with the rapid expansion of submarine pipeline networks. Statistically, more than 50 percent of submarine rupture accidents are caused by third-party damage such as ship anchoring and trawl fishing (Famiyesin et al., 2002; Cao et al., 2010; Ivanovic et al., 2011). In order to reduce the damnification to submarine pipelines caused by third-party damage, the pipelines need to be buried into sea floor reasonably. It is necessary to investigate the deformation of the submarine pipelines for designers. DNV-RP-F107 (Det Norske Veritas, 2002) gives an empirical formula for the dent depth of the pipelines impacted by dropped objects (Alexander, 2007). However, this specification does not consider the absorption of the impact energy by seabed and soil covered on the pipelines, resulting in a conservative assessment. Some scholars have explored the response of submarine pipelines to the impact of dropped objects. The interaction between pipe and soil is a complex process which contains complex mechanism and thus evaluating the damage on submarine pipelines caused by dropped objects is quite complicated. Alsos et al. (2012) discussed the importance of impact velocity and mass during impact, and found that global deformations would be triggered, which implied that the dissipated energy going into local denting is reduced to a fractional value. Yu et al.used a three-dimensional numerical method to study pipeline deformations due to transverse impacts of dropped anchors and the dent depth of the pipe was estimated by the local Galerkin discretization method. The results showed good consistency with experiment. Zeinoddini et al. (2013) carried out a parametric study to examine the effect of bed flexibility and the results showed that the flexibility of seabed plays an important role in impact energy dissipation. Ryu et al. (2015) investigated pipe-soil interaction using finite element technology in which the soil was simulated using the Mohr-Coulomb failure criterion. Robert (2017) used a modified Mohr- Coulomb model to simulate the behavior of pipelines in unsaturated soil. The model was developed considering microscopic and macroscopic suction hardening mechanisms and was implemented into a commercial finite program.

SPE Disciplines: Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Offshore pipelines (1.00)

ABSTRACT

In this paper numerical simulations are utilized to study the transformation of internal solitary waves (ISWs) of depression type propagation on an underwater slope in a two-layer fluid system. Gravity collapse method is used to generate the depression type of internal solitary waves. The flow evolution of a depression ISW in different physical conditions (i.e. lock length *x*_{0}, step depth *η _{0}* and upper/lower layer depth ratio

INTRODUCTION

Over the past four decades, the combination of in situ and remote sensing observations has demonstrated that long nonlinear internal solitary-like waves are ubiquitous features of coastal oceans. In a continuously stratified fluid, the interface between warm and cold fluid or between fresh and salt water can oscillate forming an internal solitary wave. Ocean internal waves typically have wavelengths ranging from hundreds of meters to tens of kilometers and periods from several minutes to several hours (Massel, 2016). Internal waves in the ocean are primarily important as they affect mixing through the transport of energy. ISWs may also affect nutrients transport towards the surface, in particular when mixing occurs (Lai, 2010), and also may cause lateral transport of nutrients (Lamb, 1997).

SPE Disciplines:

Duan, Chenglin (Ocean University of China) | Dong, Sheng (Ocean University of China, Shandong Provincial Key Laboratory of Ocean Engineering) | Wang, Zhifeng (Ocean University of China, Shandong Provincial Key Laboratory of Ocean Engineering) | Tao, Shanshan (Ocean University of China, Shandong Provincial Key Laboratory of Ocean Engineering)

Variability of winter sea ice in the Barents Sea and its correlations with external atmospheric forcing have been investigated in a statistical approach based on NSIDC sea ice concentration (SIC) and ECWWF surface air temperature (SAT), wind velocity datasets for the period 1979-2016. The relative SIC, defined as the ratio between sea ice area and extent, indicates that the ice regime is towards lower-concentration conditions. The SIC regression results reveal that the most remarkable ice loss occurs in the northeastern Barents Sea, particularly between 74 -78 N and 42 -67 E. The empirical orthogonal decomposition of SIC has distinguished two principal modes of SIC anomaly. The first principal mode describes 57.7% of the total variance and represents SIC multi-year decreasing trends. The SAT and wind field play a fundamental role in sea ice loss. Additionally, the second principal mode (11.3%) behaves as southeast/central anomaly seesaw, revealing sea ice anomalies are in anti-phase in both corresponding zones. Besides, the wavelet variances of the time coefficient of the two principal components for SIC, SAT and wind velocity anomaly have been analyzed. The most significant peaks for three parameters are with similar variation periods. Accurately, the sea ice is experiencing a decreasing process with uncertain oscillations in some periods due to unsteady synoptic process.

Dynamic thermodynamic calculation data of sea ice thickness since 1947 to 1996 in Chengdao oilfield is applied here to calculate corresponding design ice thickness. The fitting curves for these observations are selected from Gumbel, Weibull, lognormal, Pearson type-3 and maximum entropy distribution. Corresponding return values given by these curves are regarded as the best design sea ice thickness parameters. Based on distribution fitting tests and comprehensive consideration, lognormal distribution is chosen as the best fitting curve of annual extreme data for sea ice thickness conclusively. Then different return values can be deduced under different return periods, and maximum likelihood method is applied to determine interval estimations of these return values. The calculated results can provide a reference for disaster prevention and offshore structures design.

Technology:

**Abstract**

A very flexible bivariate joint probality distribution based on Copula function of wave height and wind speed is applied in this paper for use in joint statistical analysis of winds and waves. Bivariate Normal Copula and four kinds of common-used Archimedean Copulas (Clayton Copula, Frank Copula, Gumbel-Hougaard Copula and Ali-Mikhail-Haq Copula) are presented here to construct joint probability distribution of annual maximum wave height and corresponding wind speed on a jacket platform in Bohai Sea, which are applied to verify the efficiency of these joint distribution models. Besides, considering constraint conditions of offshore platform responses (base shear, capsizing moment and deck displacement), the joint design criteria of wave height and wind speed is built. The joint probability design based on Copula decreases the design criterion of ocean environmental factors.

annual maximum wave height, Artificial Intelligence, Copula, Copula function, corresponding wind speed, deck displacement, estimation, joint design, joint distribution, joint probability, joint probability distribution, marginal distribution, platform, probability, probability density, probability distribution, return period, Upstream Oil & Gas, wave height, wind speed

Technology: Information Technology > Artificial Intelligence > Representation & Reasoning > Uncertainty (0.71)

A refined grid mathematic model is established to simulate astronomic and typhoon storm of Sea area around Shandong Province of China in this paper. Based on the Advanced Circulation Model (ADCIRC), an astronomical model is established by adding four main constituents to open boundary. The typhoon storm model is established based on typhoon wind field model. Three typical typhoon processes, namely No.8509, No.9216 and No.9711, are hindcasted numerically. The spatial and temporal distributions of storm surges are analyzed. After simulating the series of typhoons from 1960 to 2011 by using the verified ADCIRC model, the 100-year return values around Shandong Peninsula are estimated by a Poisson-Gumbel distribution. The return values will be adopted for storm surge disaster mitigation plan in the nearshore area of Shandong Province.

SPE Disciplines:

For the suction penetration of shallow foundation platforms, before formal application it is important to perform an on-site test study. The scheme, method and procedure of suction penetration test in the sea field for one-bucket shallow foundation will be described in this paper firstly. Based on this method, CB20B oil production platform was successfully installed. Results showed that the method proposed in this paper can be used for references in the installation and construction of shallow foundation platforms in the offshore field.

The sea areas of Bohai Sea, the East China Sea and the South China Sea are rich in oil and gas resources. In order to exploit these natural resources, offshore drilling platform and oil production platforms are necessary. Generally, fixed pile jacket platforms are widely used. In 1994, the Norsk Statoil succeeded in using the bucket shallow foundation platforms in the North Sea for the first time. The bucket shallow foundation was utilized instead of pile foundation to bear the external load in order to reduce steel consumption. Meanwhile the method of suction penetration was proposed in offshore installation to save construction time. The platform can be relocated and reused, which improves efficiency and protects marine environment (Andersen, et al, 1989; Andersen, et al, 1993; Bye, et al, 1995; Dyvik, et al, 1989). This bucket foundation platform has been described as "the dawn of a new era of jacket-based engineering" by marine engineering experts (Huang, 1996). The Norsk Statoil conducted a series of theoretical analysis, indoor and on-site test. Field tests were carried out before the successful construction of Europipe 16/11 platform (Tjelta, et al, 1990; Tjelta, 1995a; Tjelta, 1995b). Thus, field tests on the sea are essential to the installation of offshore platforms.

Oilfield Places:

- Asia > China > Shandong Province > Shengli Field (0.99)
- Asia > China > South China Sea > China Basin (0.98)

SPE Disciplines: Facilities Design, Construction and Operation > Offshore Facilities and Subsea Systems (1.00)

Ji, Qiaoling (College of Engineering, Ocean University of China) | Dong, Sheng (College of Engineering, Ocean University of China) | Cao, Shujun (College of Engineering, Ocean University of China) | Tao, Shanshan (College of Engineering, Ocean University of China)

One of the important bases to determine the coastal engineering design criteria for disaster prevention is confirming the return value of the storm surge elevation. To date, the long-term statistical analysis of the storm surge mainly focused on one concrete place. Actually the storm disasters occur in a larger spatial scope. Because of the different properties of the different nearshore areas, the observation data of a single tidal station cannot represent the disaster characteristic of a relatively broader area. Thus, the study of the coincidence probability of the storm surges in different tidal stations is very important for the general planning of the storm-prevention and the disaster-reduction, which will influence the transport of the disaster-prevention material and the establishment of the warning system. The storm-induced disasters in Bohai Bay and Laizhou Bay are the most serious in the Bohai area of China. The maximum surge elevation sequences are sampled from two typical tidal stations, namely Tanggu Tidal Station and Longkou Tidal Station. On the basis of bi-variable Gumbel Logistic distribution, the joint probability of these two long-term sequences is calculated. Return values of storm surge elevations are given for reference when the government departments make a storm-prevention program.

Bohai, a semi-enclosed inland sea, is in northern China where the storm tide occurs frequently. Its nearshore area is broad, the slope is flat and the mean water depth is more than 20 meters. Because the depth of water is shallow, the storm surges encountering the astronomical spring tides frequently generate huge disastrous phenomena, such as the bank breaking, the dam damaging and the seawater overflowing. Usually the occurrence frequency of typhoons is lower in Bohai sea than south sea of China and it takes a long way to arrive Bohai sea so it decays rapidly.

In this paper, thirty years of negative storm surge data measured from Qingdao hydrologic station are selected to set up different statistical samples according to time division, such as year, season or month. Besides the Annual Maxima method and the Peak Over Threshold method, a combined distribution method is presented to estimate the return values of negative storm surge in shallow water area of Qingdao under the consideration of seasonal variation. The statistical results show that the negative storm surges occur in spring, autumn, and winter in Qingdao. This paper shows that, as the most frequently occurred negative storm surges are caused by cold waves, it is feasible to estimate the return values of the negative storm surge by sampling from dominant climate rather than from the climates occurred all the year around.

Storm surge is the uncommon piling up of the seawater along the shoreline induced by intense atmospheric interference such as tropical or temperate cyclones. Coinciding with high astronomical tides, it generates serious coastal flooding and results in severe damages along the coastline. In the coastal area of medium and high latitude, cold waves often produce negative storm surges. For example, northerly winds, which may blow for several days and at considerable speed, produce negative storm surges in the coastal area of Qingdao (35°35''~37°09''N, 119°30''~121°00''E). When the negative surges occur, offshore winds blow the ocean water down from the coastline and a large area of shallow shoal expose to the air. The water level lowering is a potential threat to the navigation of super bulk carrier or giant oil tanker. Previous studies focus on the long-term prediction of extreme water level for structural design (i.e. Gumbel, 1954; Lennon, 1963; Yang et al., 1970; Ackers and Ruxton, 1975; Graff, 1981).

Country:

- Asia (0.48)
- North America > United States (0.47)

Industry:

- Transportation > Marine (0.68)
- Transportation > Freight & Logistics Services > Shipping (0.54)
- Energy > Oil & Gas (0.48)

Thank you!