Pipeline Information Modeling: A New Tool for Pipeline Engineering

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<big>'''Pipeline Information Modeling: A New Tool for Pipeline Engineering'''</big></div>

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Zheng Liang<sup>1</sup>，Bao Tian<sup>1,</sup>*，Liang Zhang<sup>1</sup></div>

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1.School of Mechatronic Engineering, Southwest Petroleum University</div>

* Corresponding author: Bao Tian

Affiliation: School of Mechatronic Engineering, Southwest Petroleum University

E-mail: [mailto:tbswpu@163.com tbswpu@163.com]

Address: 8 Xindu Avenue, Xindu District, Chengdu City, Sichuan Province, P. R. China（610500）
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==Abstract==

Pipeline Engineering is a comprehensive system project with huge investment, high complexity, strong technical and strict security requirements. The conventional construction and management mode for pipeline project has encountered a variety of bottlenecks in the development, and digital informatization of pipeline is the inevitable trend for the future pipeline industry development. Therefore, combining with the existing technical achievements, this paper puts forward and defines a new concept- “Pipeline Information Modeling (PIM)”, which can use digital model for the whole life-cycle of pipeline management. Its characteristics and architecture are expounded, and the relationship and difference are summarized between PIM and other related theories such as BIM, pipeline integrity management, and digital pipeline. Meanwhile, a case study of several applications in long-distance oil & gas transmission pipeline engineering is analyzed. Finally, the challenges PIM will face in the future development are discussed. PIM is still in its infancy, and theoretical system and technical method still need to be constantly perfected. But its emergence has important significance for improving pipeline engineering scientific and technological level and accelerating transformation of industry informatization, which will have great application foreground.

'''Key words:''' Pipeline engineering; Life-cycle; Digital model; Long-distance pipeline;

==Introduction==

Pipeline engineering is developing in the direction of digitization and informatization at present, but it still follows design, construction and management methods of architectural engineering. With more and more maximization and complicated networked of pipeline engineering, worse and worse conditions of construction environment, and more and more strict requirements of safety and environmental protection, it exposed many problems in traditional construction process of pipeline (especially oil and gas pipeline), such as lower construction management level and work efficiency, great potential safety hazard, unsustainability of pipeline network construction, lack of comprehensive overall planning, etc.[1, 2]. Aiming at these issues, pipeline industry puts forward technical means like 3D GIS and advanced ideas like pipeline integrity management [3, 4], but most of them only focus on solving a local problem, the problem of project information flowing, exchanging and sharing cause some limitations of their application. Focusing on the above shortcomings, this paper puts forward a new concept-Pipeline Information Modeling (hereinafter referred to as PIM). The concept uses the successful application experience of BIM in the global construction industry for reference, while combining with the characteristics of pipeline construction project. Its appearance makes up imperfections of digital pipeline in theory, and gives full play to the role of various advanced technologies. It is more consistent with pipeline engineering practice, and will be a powerful tool and production mode.

==1 Definition of PIM==

===1.1 Concept and nature of PIM===

Pipeline Information Modeling (PIM) is defined as: The object-oriented management process and method by creating digital models of pipeline engineering, which can provide decision-making and service for project’s life-cycle. The life-cycle include the processes from feasibility research, survey and design, construction to operation and maintenance stage. Its core is the circulation and sharing of information during the project. Using digital models, all concerned parties can analyze and evaluate engineering information on the basis of standardization and collaborative work, and then make reasonable decisions. At the same time, models are updated by receiving the feedback, and provide a visual platform for design evaluation, construction decision and pipeline integrity management. The application objects not only include pipelines route project, but also pipe station construction, and other appurtenant works.

PIM should have the following properties and characteristics:

(1) Digital modeling: digital models of pipeline are not equivalent of the PIM, but the important achievements of PIM, which are digital expression of environmental, physical and functional characteristics of pipeline engineering. They are information carriers and operation objects for all the parties involved.

(2) Standardization: it should be under a common standards framework from creation to application of models, including the standardization of data structure, interface, etc.

(3) Cooperativity: all related parties can work collaboratively on standardized models for multi-specialty pipeline projects on the standardized model. Exchange and sharing of information should be achieved.

(4) Completeness: digital model not only describes the geometric topology of the pipelines, but contains closely associated information of geological environment, materials, risk, etc.

(5) Sustainability: models are not only available and updated in full life-cycle of a pipeline project, but could be called and updated when contacting with other projects.

===1.2 Contrast to BIM===

Indeed, there are some resemblances in theory between PIM and Building Information Modeling (BIM). But distinctions of application target and work stages particular focusing on make that PIM is not the application of BIM in the pipeline project. The main differences are as follows.

(1) Difference of application target: BIM is proposed for building construction projects. Although United States National BIM Standard specifies that linear structure, including roads, bridges, channels, pipelines, is one of BIM application scopes, all current research content, methods, development direction of BIM treat pipeline project as subsidiary of building construction project. Research is positioned in the design of pipelines in buildings, such as lines collision detection, etc. While PIM is proposed for large-scale pipeline engineering such as municipal pipe network engineering, long-distance oil and gas pipeline, and so on. The construction projects like station project are appurtenant works of pipeline engineering which general requirements should be satisfied by them.

(2) Difference of emphasis point: For traditional building engineering, the input of manpower, material and funds are large at construction stage, and less maintenance work is needed during using stage. BIM attaches more importance to its application of design and construction, only space, assets, energy consumption and other small aspects are concerned during its operation and maintenance [5]. For pipeline engineering, public security requires that it should be in a safe and controllable working state from construction to usage stage. Continuous investment during commissioning and service period is enormous for pipeline engineering [6]. It is improper to use traditional thinking and methods of architecture project to manage pipeline engineering during operation and maintenance stage.

Although PIM and BIM both are the production tools facing the life-cycle of project, different positioning leads to the differences of emphasis and research means. Thus, PIM, which serves for the construction and management of pipeline engineering, should be generalized and applied as an independent concept and method.

==2 Content of PIM==

In terms of pipeline engineering category, PIM applies to building comprehensive pipeline, municipal pipeline, submarine pipeline, long-distance oil & gas pipeline project, etc. The more complex pipeline project is, the more value of PIM could be reflected. Its basic idea is: visual operation object is provided for all project participants by establishing digital models and corresponding database. Models and database can ensure integrity and transmission of all project information, and provide reliable decision basis for deciders at all stages. Digital model is evolved and updated along with the progress of pipeline engineering. Each stakeholder can also generate its own sub model for a certain application. Finally, complete pipeline information model will be formed. Basic framework of PIM includes perception layer, data layer, model layer, application layer, and decision layer (Fig. 1). Among it, perception layer is a direct platform to obtain measured data and the source of PIM database data. Pipeline information model is established based on the PIM database. The model can be used for a variety of engineering applications, and provide technical support for management decision-making. It is an integrated running system from perception layer to decision layer, including obtain measured data-establish database-build digital models-field application-management decision.

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'''Fig. 1 Framework of PIM'''</div>

In the framework of PIM, the ability of information acquisition of perception layer is more mature. However, digital modeling, as the core content of PIM, is still at the exploratory stage. Establishment of database based on monitoring data also need further improvement. The following discussion focuses on digital modeling in the aspects of model organization, database, and software.

===2.1 Modeling===

Digital modeling includes two aspects: visualization digital models and modeling information database. Visual models can reflect and simulate problems probably appearing during the engineering process. Basing on these models, technicians can conduct simulation and optimal design, as well as all kinds of conventional or advanced pipeline techniques could be researched, emulated and innovated. Visual digital model is the carrier of pipeline information. The model should be multidimensional-parameterized, at least a visual 4D (3D+Time) model integrating spatial and temporal information. Work based on model can provide the sustainable design with low energy consumption, create a highly-efficient collaborative environment in intuitionistic form, afford reliable operation management by comprehensive information synthesis, break old pattern of data exchange and management in file format, has unique advantage in solving problems like budget management, optimization of pipe network, 3D collision detection, deformation monitoring, etc.

In the choice of model architecture, PIM logically is a model that contains all the information of pipeline engineering. But it is a synthesis of multiple models in actual application. Because of its essence is the pipeline engineering management tools, what and how many tools should be used depend on the practical problems. Although Single “Grand unified” model really can bring great convenience, it is extremely difficult and unrealistic to build and apply such a model. We consider that the ideal model architecture should be composed of some master models throughout the different stages and a quantity of application sub-models.

Master models are updated at the different stages of engineering. They are converted from design models to construction models and further to operation models, accompanying with models’ reconstruction and information transmission. Various sub-models for application relying on their master model are directly manipulated objects. Each participant can set up the corresponding sub-model to solve special problems according to the different PIM targets at different stages. In PIM, sub-models are not isolated. They are unified in a certain master model, or directly contacted with other sub-models. The content defined in any sub-models should be consistent with that defined in its upper master model so as to ensure the accuracy of information and avoid conflict. An example of model architecture for pipeline project is shown in Fig. 2.

Thereinto, master models can be line model, station model, pipe network model and so on. In station model, combination station, compression station, heating station sub-models could be built. In combination station sub-model, in-station process system, power system, monitoring system sub-models are built. According to actual needs, secondary sub-model could be built under its superior model, forming a tree structure. The model type and level of structure are determined by the actual pipeline engineering demand.

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'''Fig. 2 Model Architecture'''</div>

Data support of PIM is provided by model information database which is complementary to digital model. Data represents information. The pipeline information modeling is actually the process of accumulation, expansion, integration and application of the data during the life-cycle of pipeline engineering. An aggregation of all engineering information is finally formed which can completely descript the pipeline.

The availability of model lies in accuracy and dimension of information contained in it. The contents of database are requested in the process of its establishment and use. The factors that restrict the database include the huge amount of data, wide varieties of data formats, data fragmentation from different stages and departments, highly difficult data acquisition. All of these have caused difficulties in collection, collation, storage and use of data. Hence information database should be built on a unified standard and open-source platform. Structured data, semi-structured data and unstructured data all should be associated to PIM database to ensure integrity and real-time of pipeline information.

Huge data cubes would be processed for modeling and management of large-scale and complicated pipe network. Application scenarios face the problem of geographical dispersion. Cloud computing technology will be the most promising way to solve these problems.

===2.2 Software===

Software is the realization means of realization of PIM, which concretize pipeline information. The software of PIM should comprise modeling software, database software, analysis software, management software. It will be a software suite composed of a series of software and functional modules. According to the PIM framework mentioned above, different layers have different requirements on types and functions of software. Software of PIM is model-object oriented, which must have a strong information integration ability to meet the various needs.

Nevertheless, the standalone development of kit PIM software requires significant input of manpower, material resources and time. Software company and pipeline company will shrink back at the sight of uncertain revenue. It is unfavorable for the promotion of PIM. Only PIM will have achieved considerable results in practice, it is possible to form a virtuous circle of software development-software promote the application-application incent development. Using existing software on the market and carrying on secondary development of them is a better choice of most institutions at initial stage. The research and development of software should be based on the unified standard and universal data, and its application should ensure the smooth exchange and circulation of information. Also they are preconditions of bright development of PIM.

==3 Relationship and Difference==

As a new concept in pipeline engineering, PIM has some similarities with the existing concepts like pipeline integrity management and digital pipeline technique but has quite differences from them too. They are elucidated in the paper below.

===3.1 PIM and Pipeline Integrity Management===

The definition of “Pipeline Integrity Management” is a comprehensive and integrated management of all factors affecting the pipeline integrity. Its concrete content is to continuously identify and evaluate all kinds of risk factors, take the appropriate measures to reduce risks, and control the risk level within a reasonable and acceptable range to prevent from pipeline accidents at the different stages of pipeline engineering[7, 8]. Its essence is to evaluate risk factors of dynamic pipeline system, then adjust and optimize corresponding management and maintenance work. It can achieve accidents’ beforehand control based on risk level.

PIM should be a powerful tool for pipeline integrity management which is one of the important functions of PIM to achieve. By definition, pipeline integrity management is a new management concept and pattern instead of a technique. In fact, there are many techniques used to achieve integrity management. The requirement of integrity management is to identify and evaluate the risk factors in the process of pipeline operation, make risk-controlling strategy, and implement risk-mitigation measures and efficiency appraisal. Management technique based on PIM can provide a visual platform for integrity management. Digital models offer multi-objective decision-making and render the effectiveness of various management strategies. And complete databases provide information resources and detailed basic data. Centralized management and analysis of information, including pipeline geological disaster, internal and external corrosion, third-party interference, detection and evaluation, could be achieved. Therefore, the problem of “information isolated island” faced by integrity management all the time will be solved by using PIM. Also, the characteristic of life-cycle of PIM can expand and cover integrity management to all stages of the projects, and then broaden and deepen the fields of application of integrity management.

===3.2 PIM and Digital Pipeline Technique===

Digital Pipeline refers to comprehensive utilization of all sorts of technologies to achieve pipeline informatization. PIM is a concrete technology and the embodiment of digital pipeline. The effect of PIM is that pipeline information can be displayed to the user in a real and visual three-dimensional environment, and users manage the pipeline through the interactive mode. These fully reflect the characteristics of digital pipeline. The concept of Digital Pipeline is extensive, including hardware and software. While, PIM focuses on pipeline digital modeling and software application. Current technologies for digital pipeline, such as GIS, SCADA, etc., can be well combined with PIM and applicated in it. They are the foundation and strong technical support for the future development of PIM.

==4 Application of PIM==

PIM has a wide range of applications (Fig. 3). The whole life-cycle of the pipeline is covered from feasibility research, to operation and maintenance in the longitudinal direction, as well as all the work involved in each stage is covered in the horizontal direction. Different PIM targets at each stage correspond to different PIM applications.

Taking the long-distance oil & gas pipeline engineering as an example, this paper explores several possible application points at its survey and design stage, construction stage, operation and maintenance stage.

Long-distance oil & gas pipeline belongs to highly dangerous structure. It is a strongly comprehensive and higher complex pipeline project with the largest investment and the most stringent security requirements in various countries. It includes not just line project, but the station project and other ancillary works. There is a wider space and stage for PIM playing a significant role.

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'''Fig. 3 Application Range of PIM'''</div>

===4.1 Application at survey and design stage===

Survey and design is the beginning of pipeline engineering, as well as the application of PIM. Providing a visual digital model is an essential function of PIM. But the visualization of PIM is not only to provide a kind of effect diagram, but also realize digital simulation and evaluation on the information model. Design will be analyzed on the basis of visualization, combining with the simulation.

Long-distance pipeline is spread over a vast expanse of geographic area. It is unpractical to use a single model to represent the whole pipeline project. The combination of line models in local geographical region and several signal station models along the pipe is a realistic choice. Local geographical region is divided by key nodes as boundaries. For example, it can be divided according to administrative division, process-changing place, and so on [9].

Geological Hazard is one of the important reasons of pipeline accidents. The main countermeasure to reducing accidents is how to evade high-risk zone or adopt active protection measures at exploration and design stage. Developing pipeline geological-risk analysis module in PIM can solve this problem. Aiming at a certain bilateral range along with the pipeline, pipeline engineering geological database is established in accordance with upfront evaluation and geological investigation firstly, then geographic database, fundamental geological database, hydrological database and meteorological database, etc. are incorporated into it. Secondary, several geological hazards containing landslide, debris flow, collapse, etc. could be assessed by using relevant prediction analysis methods. Investigation and assessment information of possibly developed geological hazards along the pipeline would have been obtained. Finally, the 3D digital model of pipeline environment could be built on basis of such information. Results of geological hazard assessment, such as detail information of hazard type and grade, can be visually positioned inquired. So relevant monitoring methods and protective measures would be designed according to difference of the type and grade, and the database of them is established to be accessed anytime by construction and operation departments. Models and databases provide visual information assistance and data support for active prevention and control of geological risk.

===4.2 Application at construction stage===

The applications of PIM are varied at construction stage, covering the whole process of construction from preparation to pigging and pressure testing. It’s a case study of pipeline crossing project which is controlling work in pipeline engineering. Firstly, according to the survey information and regional geological information database established at the design stage, 3D model of pipeline crossing area is built to confirm the areas need to be avoided like rock excavation, high-filling, and so on. Appropriate crossing route will be determined on the model. And then it's the choice of crossing methods. Modules of numerical simulation and process analysis are developed on the basis of 3D model, and analogue simulations of main structure can be done. The simulation results of the project investment, construction period, difficulty of construction, operation and maintenance, and environmental impact are obtained. Construction side can choose the optimal crossing solution, and arrange the construction site in the model according to equipment will be used. During the construction process, model and database are updated in real-time by monitoring the construction information, such as structures’ stress and strain. So construction procedure, crew, equipment, period, and so on, are continuous optimized to implement visual control of entire construction process. The data and model information accumulated during the design and construction stages are convenient for digital handover in PIM. This contributes to health monitoring of crossing pipeline going into service to achieve life-cycle management of crossing project.

===4.3 Application at operation and maintenance stage===

Application of PIM at operation and maintenance stage mainly serves for pipeline operation management and integrity management. The combination of PIM and SCADA can realize remote visual monitoring of long distance pipeline.

Pipelines would be repaired or replaced during service period. Firstly, pipeline defects database is established based on the pipeline internal and external inspection results. Whether need to be repaired or replaced for target pipeline is determined by assessment results such as residual life in accordance with risk assessment methods. Then, in the choice of repair or replacement scheme, construction simulation of various schemes can be conducted on a visual model, including if transportation need stopped or not, location and time for stopping transportation, influences to upstream and downstream, potential safety hazard, and so on. Finally, reliable maintenance strategies could be identified to ensure safe and effective operations, and reduce the impact on the environment and personnel. In daily production, PIM can also provide functions of visual training and virtual emergency exercise for pipeline enterprise.

There are many applications in long-distance oil & gas pipeline, not limited to the above. More applications need to be excavated. Effective approach to promote PIM is utilizing existing technology to realize PIM’s thought.

==Challenge and discussion==

The concept of PIM will affect every stages from feasibility research, survey and design, construction to operation and maintenance deeply, and change the traditional working model thoroughly. While the authentic development of its value need the revolution of employee’ viewpoint and the solution of numerous technical problems achieved.

At present, the perfection of PIM theoretical system and strengthening of its technical foundation is the primary problem. If not, PIM will be a castle in the air. Experiment in practical engineering is the only way to reveal and carry forward the advantage of PIM. Of course, PIM will face many technical challenges in future, such as application software development technique, multi-dimensional modeling technique, visualization technique, database technique, and information standardization technique, etc. Aiming at the huge-scale, mass data and calculated amount of pipeline engineering, the advanced scientific and technical measures, such as cloud computing, big data analytics, augmented reality(AR), and virtual reality(VR), which are proposed to solve problems as high precision, complex texture and large-scale scene’s smooth display, will be the powerful help and even the development tendency of PIM in future.

In the concept of PIM, digital model is the foundation of all parties’ cooperation and various works implementation of pipeline engineering. As an innovative tool, its practical application in pipeline engineering need thoroughly changes of project management method, manpower organization, working model, matching technology, software and hardware facilities. These changes would be achieved by huge funds investment, time and training in early phase. The popularization and application of PIM cannot be the work of a single day. The urgent bottlenecks should be surmounted firstly from beginning of the solution of partial project issues by the existing techniques with the thinking of PIM. Then from part to whole, the perfection of PIM will be achieved and PIM will be a powerful tool to solve pipeline engineering issues gradually. Above all, PIM will undergo an unceasing progress with sustainable development.

==Conclusion==

The concept of PIM proposed in this paper is expected to provide a new production tool for pipeline engineering, especially for oil & gas pipeline engineering. PIM, the integrated result of engineering management and computer science, combines several advanced managerial strategies, technologies and concepts, such as modern project management, BIM, integrity management, digital pipeline, etc. It shows a bright foreground and attractive application value on improving scientific and technological level of programming, design, construction, operation and maintenance of pipeline industry, enhancing the exchange and sharing of pipeline information, rising the speed and accuracy of decision-making, reducing cost, promoting the quality, developing the informatization and digitization of pipeline field, etc. This paper just builds the concept of PIM, which is immature comparing with other developed theories. Its more connotation and future development still need joint discussion and efforts of scientific and technical personnel. Its value and advantage will be revealed in future practice. The modernization and informatization of pipeline engineering has been the inexorable trend. This study hopes to bring some inspiration and references to pipeline industry by our work.

==Acknowledgement==

This work is supported by National Key Research and Development Program of China, Grant No. 2016YFC0802100.

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