Underwater Crossings Research Articles

Plane sections method in determining characteristic velocities of water flow in construction and operation of underwater crossings

Plane sections method in determining characteristic velocities of water flow in construction and operation of underwater crossings

Incident during construction of an underwater passage by directional drilling

Relevance. This paper considers the issue of construction of underwater passages of trunk pipelines by the directional drilling method using concrete weight coated pipes. This issue is relevant, since at the present moment there is no standards and technical documentation regulating the calculation procedure of the minimum allowable elastic bend radius of a pipeline with concrete coating in a well. There are situations when design institutes made incorrect design decisions as a result, the pipe string got stuck during works. Those incidents led to unnecessary economic expenditures and a delay in the work implementation plan. Aim. To study the issues which related with the sticking of the pipe string during the construction of the underwater passage of the main pipeline by the method of directional drilling; calculate the minimum allowable elastic bend radius of a pipeline with concrete coating and the actual parameters of the pilot drillhole. Objects. An underwater passage of a trunk pipeline constructed by the method of directional drilling. Methods. Study of standards and technical documents on the construction of underwater crossings of main pipelines and an analysis of the incident in which a pipeline with concrete weight coating got stuck. Results. The authors substantiate the calculation of the minimum allowable elastic bend radius of a pipeline with a concrete coating based on the requirements of domestic standards and technical documentation. The authors have calculated this value by an analytical method, based on studies of the bending stiffness of concrete structures by foreign scientists, as well as actual parameters of the pilot drillhole. The obtained results of the studied values were analyzed and a conclusion was given about the causes of the incident associated with the sticking of the pipe string.

INFLUENCE OF OPERATIONAL LOADS ON BALLASTING PARAMETERS OF UNDERWATER CROSSINGS OF TRUNK OIL AND GAS PIPELINES

The trunk oil and gas pipelines are under operational loads affecting the strength and reliability of the structure. The most significant effect of loads is manifested at pipeline crossings across rivers. The stability of underwater pipeline design position and thus its reliability is achieved by ballasting with the required intensity. The current regulatory document SP 36.13330.2012 provides for the required intensity determination, taking into account the water buoyancy force and pipeline crossing along the longitudinal profile of the transition. At the same time, it should be noted that ensuring pipeline bending along the longitudinal profile of the crossing with the use of ballasting of the required intensity also depends on the internal forces acting in the pipeline wall during operation. However, this document does not take into account operational loads when determining the required ballasting intensity. In addition, ballasting with the ensuring pipeline bending along the longitudinal profile of the crossing leads to the occurrence of bending stresses, in some cases quite high, which affect the level of total stresses, strength and reliability of the structure. In many cases, water occupies only part of the concave section of the pipeline at crossings. Taking into account the above conditions and features, studies of the ballasting of underwater crossings of trunk oil and gas pipelines were carried out.
 The aim of the work is to obtain analytical dependences of the ballasting intensity and bending stress in an underwater pipeline at different altitude water levels at the transition from operational loads and geometric characteristics of the crossing.
 The research method is a theoretical study of the stress-strain state of an underwater pipeline under the action of operational loads and weights.
 The dependences of ballasting intensity with weights of the underwater pipeline on the operational loads and the geometric characteristics of the transition at different elevations of the water level at the transition are obtained, and the highest bending stresses in the pipeline wall at the underwater crossing are determined. Recommendations to reduce the total longitudinal stress level in an underwater pipeline are given.

Диагностирование и определение аномальных зон магистральных трубопроводов на подводных переходах с использованием цифровой модели рельефа

The article considers the issues of geodetic support for monitoring the technical condition of main gas pipelines underwater crossings (MGPUC). The purpose of the research is to increase the accuracy of determining the depth of the gas pipeline underwater crossings of main gas pipelines by taking into account the zones of faulty location of the pipeline (anomalous zones) and the bottom surface above MGPUC. The main problem of determining the technical condition of the gas pipeline underwater crossing is the difficulty of determining the depth of the gas pipeline due to the influence of external factors (soil, constructions and communications) on the measuring equipment (underwater trace detectors). The study indicates the accuracy of building digital elevation models (DEM) of the bottom, from which the calculation of the protective roll over the gas pipeline, which affects the determination of the technical state, and the causes of anomalous zones, as well as the ways of their determination. The variants of increasing the accuracy of calculating the depths of the gas pipeline location taking into account the DEM data are studied. The approach to definition of the method of spatial interpolation for construction of the bottom DEM according to the echolocation data depending on the surface curvature changes is offered. The authors note the interrelation of determining the criterion of technical condition of under-water crossing with the accuracy of DEM construction and determination of the spatial position of the pipeline. The proposed approaches are aimed at reducing the influence of the systematic part of the error and increasing the accuracy of the depth of occurrence, which is an urgent task.

Technological features of the ducker device for transportation of petroleum products

The efficient operation of main oil pipelines - one of the most important and urgent problems of Russia. Ducker - one of the most technologically advanced stages of construction of the road trunk pipeline. It is important to make the right choice of the method for installing the pipeline, since the speed of construction, economic costs of work, the reliability of the underwater crossing section, and, as a consequence, the uninterrupted operation of the entire main oil pipeline, environmental friendliness of both the installation and further operation will depend on this. underwater passage. Thus, the purpose of this work is to perform a comparative analysis of the methods for the construction of siphons, highlighting the advantages and disadvantages of each method. The results of the work can be applied in the construction of a new route, as well as in the overhaul of underwater crossings that have worked out their time.

Безопасность морских газопроводов

Due to the nature of the development of gas transmission network, the problem of ensuring reliability and safety of the underwater gas pipelines was practically exhausted by the calculation of underwater crossings through the rivers, lakes, and other water barriers. However, in recent years in connection with the development of oil and gas fields on the shelf, and the globalization of the gas transmission network, the question came up related to designing, building, and subsequently ensuring the stable operation of the offshore deep-water pipelines. Individual information about the accident rate of the offshore pipelines is given. They mainly concern the coastal pipelines transporting raw materials from the offshore production platforms to the onshore terminal. The largest number of accidents is typical for the pipelines of small diameters (2–6 inches) — 59 % of their total number. A group of medium-diameter pipelines (8–16 inches) accounts for 32 % of accidents. Pipelines of large diameter (18–36 inches) are the least susceptible to damage — about 3 % of accidents. In recent decades, the offshore main gas pipelines were widely used and are considered as the most promising way of transporting gas due to higher reliability, safety, and environmental friendliness, as well as the advantages of direct Analysis is presented in the article concerning the accident rate and features of failures of the offshore gas pipelines. The criteria of limit states and the algorithm for calculating the stress-strain state of the offshore pipeline, which are the main part of the safety assessment, are given. Methodology for the safety of the offshore gas pipelines was developed, based on which the example of the safety assessment of the Blue Stream gas pipeline is given. The materials of the article were used in the development of the projects for the offshore gas pipelines and are also included in the industry regulatory document.

Concerning the Stream Turbidity During the Laying of the Underwater Crossing of the Main Pipeline Across the River Lena

The stream turbidity significantly changes during the river bed evolution. It depends on the sediment storage, which is affected by the bottom dredging works, the construction of underwater crossings of main pipelines, bridge crossings, and others.In the present paper, we consider the change in the stream turbidity during the laying of the underwater crossings of the main pipelines (ML) across the river Lena. A significant increase in the water turbidity and the discharge of suspended sediment has been detected during the construction of linear structures intended for transporting the energy resources. The river bed erosion in the trench area is one of the factors of the decrease in the service life of the underwater crossing of ML when the siphon is trench laid across a water channel. When the bottom is scoured, and the siphon of the underwater pipeline is denuded, significant hydrodynamic loads not specified by the project are added to the operational loads. Torsional, bending, and overturning moments, as well as the phenomena of hydro-abrasive erosive wear, develop [1]. They lead to fatigue failure of individual sections of the underwater pipeline on the base metal and welded joints. It is crucial to conduct further studies to assess the deterioration degree of the ecological state of the river Lena.

Особенности проектирования подводных переходов магистральных трубопроводов в условиях русловой и пойменной многорукавности

Многолетняя практика применения регламентных норм учета русловых процессов и механизма транспорта донных руслоформирующих наносов подтверждает надежность принятых расчетов для проектирования и строительства подводных переходов магистральных трубопроводов (ППМТ) через большинство средних и крупных рек России. Но для рек, «перегруженных» донными наносами, традиционные расчетные методики параметров подводной траншеи трубопровода с учетом заносимости оказываются недостаточными и требуют дополнительных решений. Данная проблема была выявлена при строительстве основной и резервной ниток ППМТ ВСТО-2 через реку Амур и обусловлена гидроморфологическими особенностями, спецификой водного режима и значительным расходом донных наносов, характерными для этого водного объекта. В настоящей статье представлена усовершенствованная технология разработки траншеи ППМТ путем создания так называемых ложных траншей на участках с максимальными удельными расходами донных наносов. На примере строительства ППМТ ВСТО-2 (резервная нитка через реку Амур) рассмотрены сложности проектирования и строительства трубопровода при значительных объемах транспорта донных наносов, проанализированы риски строительства в данных условиях, описаны планирование и реализация технического решения по созданию ложных траншей для перехвата донных наносов. The long-term practice of regulatory standards for recoding of river bed evolutions and the transport mechanism of bottom riverbed-building sediments proves reliability of the adopted calculations for design and construction of underwater crossings of main pipelines through majority of medium and large rivers of Russia. However, in respect of the rivers which are «overloaded» with bottom sediments, the conventional calculation methods of parameters of the underwater pipeline trench, considering sediment accumulation, are insufficient and require additional solutions. This problem was identified during construction of the underwater crossing of the ESPO-II pipeline system across the Amur River and is associated with hydromorphological features, specifics of the water regime and significant flow rate of bottom sediments typical for this water body. This article presents an improved technology for developing an underwater trench by establishment of so-called false trenches in the areas with maximum specific flowrate of bottom sediment. Based on the example of construction of the underwater crossing of the reserve pipeline leg, the difficulties related to design and construction of a pipeline with significant amount of bottom sediment transport are considered, risks of construction under these conditions are analyzed, planning and implementation of a technical solution for establishment of false trenches for intercepting bottom sediment are described.

The modern methods and means of diagnostics and repair of underwater crossings of the pipelines

Introduction. The subject of the study is the process of diagnostics and repair of underwater crossings of the pipelines that transport natural and waste water, gas, oil and petroleum products. Comprehensive diagnostics helps to maintain the reliability of the pipeline system, reduces the cost of repair and restoration work, and also has a high environmental value. Optimization of the diagnostic procedure includes the selection of the most appropriate technical means and methods of inspection and the sequence of work for the location. No less important for organizations that maintain and operate underwater crossings are the issues of current and major repairs of such facilities: the choice of the most optimal engineering and technical solutions has a significant resource-saving effect. The purpose of this work is to present and describe the most effective methods and tools for diagnostics and repair of underwater pipelines to date. Materials and methods. In order to fully study the processes of diagnostics and repair of underwater crossings of the pipelines, a review of the relevant regulatory and technical documentation was conducted, scientific works of domestic and foreign scientists were analyzed, methodological developments and patents of organizations operating and servicing underwater crossings were considered. The review of the market of modern devices, devices and materials used for complex diagnostics and repair of underwater crossings of the pipelines was carried out. The main method of research is documentary. Results. Based on the survey, systematization and analysis of information on modern methods and advanced means of diagnostics and repair of underwater crossings of the pipelines were carried out. The types, methods and stages of diagnostics, devices and apparatuses for conducting surveys of underwater crossings, methods for detecting leaks, types, methods and stages of repairs, devices, apparatuses and materials used for carrying out repair and restoration work, methods of dismantling underwater crossings are considered. The limits of applicability of the considered methods and means of diagnostics and repair were outlined. Conclusions. The theoretical significance of the research consists in a complete description of the methods and means of diagnostics and repair of underwater crossings of the pipelines. The practical significance is the possibility of using the results of the research by specialists in the field of pipeline transport of natural and waste water, gas, oil and petroleum products.

Concerning the Planned-High-Altitude Position of the Underwater Crossing of Hatassy-Pavlovsk MGL Across the River Lena

One of the determining factors for the efficiency of the main gas lines in Yakutia is their interaction with complex geotechnical and operating conditions. The most complex structures are underwater crossings of pipelines across the water bodies. Underwater crossings are among the high-risk systems; they are the most critical. The terms of accident elimination at underwater crossings are much longer than those of similar damage on the linear section of pipeline. Besides, their repair during operation is comparable in complexity and cost to the construction of a new underwater passage. This article provides data on conducting monitoring studies of the state of the Hatassy-Pavlovsk MGL across the channel part of the river Lena, determination of the planned-high-altitude positions of two pipelines on the floodplain sections of the route, on channel processes that affect SSS of welded joints of the pipes and determine the operational reliability and durability of the MGL.The determination of riverbed deformations in the area of the underwater crossing of the main gas line (MGL) is one of the most important issues of the research. Changes in the characteristics of the river flow, safety and service reliability of the underwater crossing of MGL across the river Lena depend on the riverbed deformations. The quicksand disturbance along the course of the river Lena significantly affects the nature of ice drift and spring floods. Due to the erosion of bottom sediments and soil heaving on the coastal slopes of the Hatassky channel, as well as its shallowing, the underwater crossing of the gas pipeline is completely seized by freezing ice and soil of the coastal slopes and is tightly clamped. Studies have revealed the seasonal loosening of the surface pipeline and scour at its underwater part, wearing away of the riverbanks, as well as anthropogenic impact under changing climatic conditions.

Concerning the Bottom Erosion and Frost Heaving on the Section of the Underwater Crossing Route of MGL Across the River Lena

The uneven nature of the planned-high-altitude positions (PHAP) of the gas pipelines in the floodplain of the river Lena is affected by the hydrological, natural environment, and climatic processes and such permafrost processes as heaving, thawing, and freezing.The effects of hydrodynamic and permafrost processes, heaving phenomena on floodplain areas and shore slopes together increase the non-functional loads on the underwater gas pipeline. Due to these factors, high longitudinal tensile stress arises in the welded joints of siphon pipes and facilitates accidents and incidents at the underwater crossing of MGL. A numerical experiment was performed with the initial data on the river Lena in the area of the underwater crossing of the main gas pipeline (MGL) using hydrometeorological data. The dynamics of erosion over time is presented. A change in the profile of bottom sediments negatively affects the state of the pipeline. Dangerous exogenous processes: seasonal heaving, frost cracking, thermal subsidence, thermokarst, and coastal erosion, intensify when the natural conditions are disturbed (underwater crossings).

Neural Network Approaches to Modeling of Natural. Emergencies. Prediction of Lena River Spring High Waters

Floods play a significant role in terms of damage and safety during construction and operation of crucial objects such as a bridge over the Lena river and underwater crossings of trunk pipelines in the North and the Arctic.A rapid rise of spring high water on the Lena river is due to accelerated melting of snow in a basin and a meridional flow direction of the river.If flood control measures are not taken, then severe economic and social consequences are inevitable, especially in places with complex infrastructure. As, for example, heavily populated cities, the strategically important objects, the underwater crossings of the trunk pipelines, bridges and power lines.This paper presents results of a study of a possibility of use of neural network algorithms to predict danger of the flood from the spring high waters on a section of the Lena river based on statistical archival data obtained over 70 years and an assessment of effectiveness of the neural network approach. The artificial neural networks have proven their effectiveness in solving various prediction problems, especially when using the statistical data. The use of the neural network approach based on the prediction of a time series from previous values gives the good results. Modeling was carried out using methods of a multilayer perceptron (MLP) and radial basis network (RBF). Both selected methods showed sufficient adequacy of selected statistical models.

Design and construction of underwater pipelines crossings

The new territories exploration for housing construction and production facilities within the country and the increase in the export of hydrocarbons require the constant development and improvement of pipeline transport. There are often cases when the need for the pipeline network crossing by various obstacles is recognized as the only possible design solution and economically reasonable, among the most difficult of which there are water bodies. Natural and waste water, oil and petroleum products, and gas are transported by underwater pipelines crossings. Aiming at optimizing the design and construction of underwater pipeline crossings requires constant monitoring of the technologies, equipment, and materials offered by the modern market. The research methods were based on the review of current regulatory and technical documentation, modern scientific and periodicals, and security documents. A special feature of the underwater pipelines crossings design is needed to predict the channel processes for the entire estimated period of their use. Underwater crossings construction is made by the trench and trenchless methods. The latter ones, which are currently the most popular, imply the following main types: horizontal directional drilling, directional drilling, tunneling, microtunneling. The construction technology choice is determined by the topographical features of the water body bottom, its hydrological characteristics, the geology of the construction site, the required length, the diameter of the pipeline network, and the features of the surrounding area as a whole. The results of the review study may be of interest for the specialists in the field of pipeline transport.

Буровые растворы для сооружения подводных переходов методом наклонно-направленного бурения. Часть 1

Буровые растворы для сооружения подводных переходов методом наклонно-направленного бурения. Часть 1

Оценка готовности скважины к протаскиванию трубопровода при строительстве подводного перехода

Directional survey results are used to monitor the condition of the well when pulling through the pipeline. They can be considered as a technical justification for the regulation of design and contracting organizations specialized in the construction of underwater crossings. The objective of this paper is to analyze methods of obtaining and processing directional survey data to assess the suitability of a well for pipeline pulling. It is established that using modern research and development methods it is possible to describe the directional survey results and construct a geometric model of the well to calculate the stress-strain state of the pipeline during pulling. However, in order to build a model as close to the real conditions as possible, it is necessary to provide the results of the directional survey both on the lower generating line and on the arch. This is possible using downhole gyroscopes. It is possible to survey the lower generating line by any methods, and to survey the well arch only through a plastic (polypropylene) or aluminum pipe. The results of the directional survey carried out along the lower generating line and arch of the well will make it possible to describe them in an analytical way, to build an appropriate geometric model of the well bore and use it to assess the readiness of the well for pulling the pipeline during the submerged crossing construction.

Долгосрочное прогнозирование стоковых характеристик методом математического моделирования гидрологических процессов

In recent decades, climatic anomalies have been recorded that give rise to long-term changes in the hydrometeorological regime and the system of interaction of the water mass with the underlying surface, in particular, on channel and floodplain sections of rivers that are the site of underwater crossings of main pipelines. Currently, these changes are not taken into account during the course of design & engineering, construction and operation of underwater crossings, although the period of safe operation of the pipeline depends on the conditions that the engineering structure is exposed to. In this article, the influence of long-term changes in the hydro-meteorological situation on the runoff characteristics of the river Ob located near the alignment of the underwater crossing of the Aleksandrovskoe – Anzhero-Sudzhensk main pipeline has been considered. It has been determined that the method developed by the Russian State Hydrometeorological University is optimal for runoff characteristics prediction. Using this mathematical model, changes in the hydrometeorological regime have been assessed in the river Ob – Aleksandrovskoe section, a violation of its stationarity in 1979–1980 was established. The main flow-forming factors – the amount of precipitation and the temperature regime – have been determined. Approbation of the runoff formation model showed that the maximum convergence of the predicted and actual values is observed when using predictions with an additional parameter. To predict the runoff characteristics for 2011–2040, climatic scenarios were used as initial data – representative concentration trajectories according to which the temperature and precipitation amount is expected to increase during the specified period of time. The results obtained indicate a tendency for an increase in water content and a redistribution of runoff vs. time, which, in turn, will catalyze the intensity of the processes of channel and floodplain deformation. It is concluded that it is necessary to consolidate the use of the prediction of runoff characteristics in regulatory documents in order to increase the efficiency of measures to ensure the safe operation of underwater crossings of trunk pipelines, as well as the accuracy of calculations in the design and construction of these facilities.

Application of mathematical programming and modeling methods for monitoring the technical condition of underwater crossings of main gas pipelines

The article deals with the problem of geodetic monitoring of the technical condition of underwater gas pipeline crossings. The theoretical scheme of increasing the accuracy of depth determination is studied in detail. In this paper, the goal is to increase the accuracy of obtaining the depth of the gas pipeline. The accuracy of the planned position for the largest survey scale (1:500) is 0.75 meters and is achieved using satellite equipment, even without the use of a dynamic positioning system, which allows, if necessary, to increase the accuracy of the data obtained by determining the orientation angles of the vessel. Despite the high popularity of this complex, the accuracy of depth measurements does not correspond to regulatory documents, which raises the question of the need to change the method of measurement and data processing, since the performance of work on monitoring the technical condition of gas pipelines is an important and relevant task. In order to control the developed methodology and automate measurement processing, two programs were written in the Python 3.7 programming language in the Spyder environment.

Monitoring of spatial position of the underwater crossing of MGL across the Lena river by instrumental methods

The problems of ensuring the operational reliability of underwater crossings for the main transmission of oil and gas are of great importance since failures and accidents on them far exceed similar incidents on the linear part by their economic and environmental consequences. The article describes the determination of the planned-high-altitude position of the lines-I and -II of the underwater crossing of MGL across the Lena river on floodplain areas from the right and left banks by the method of sounding the pipeline with the RD-8000 line locator. The changes in the stress-strain state of the pipeline are defined by monitoring the spatial position with instrumental inspection methods. Based on the survey results, graphs were constructed according to the Baltic system of heights, where the surface of the earth’s relief and the main gas pipeline are indicated. The results of field examinations of the I and II lines show that the pipe of the underwater crossing goes almost parallel with the surface relief. No pronounced elevation differences, gullies, and channels are observed on the islands from the right bank of the riverbank. However, there is a change in the planned-high-altitude position of the underwater gas pipeline. A significant change in the planned-high-altitude positions of the I-st and II-nd line siphons of the underwater gas pipeline in the area of the Haptagay channel has been revealed compared to the earlier locations. As a result of such deterioration, the lines can completely freeze in the winter period, and the stiffness of their jamming strengthens.

Сохранение устойчивости глинистых отложений при сооружении подводных переходов методом наклонно-направленного бурения

Сохранение устойчивости глинистых отложений при сооружении подводных переходов методом наклонно-направленного бурения

Бестраншейное строительство подводных переходов нефтепроводов

Бестраншейное строительство подводных переходов нефтепроводов