This paper describes a development initiative intended to reduce significantly design cost and duration using digitalization. Subsea pipeline design, and in-place studies in particular, is a complex process that is broken down into a systematic sequence of calculations, all connected to a normalized and serialized meta model. The pipeline digital data model is interpreted by a framework that distributes and collects design data to various algorithms and software, thus automating the entire pipeline design workflow down to production of standardized design reports. The implementation of such an objective requires: Developing a systematic design methodology, covering industry standards as well as the client's special requirements, under a "one-size-fits-most" process; Standardizing a data model serving as a meta-model to necessary models and solvers; Standardizing data format and exchange protocol so that all models are served with required inputs and instructions; Coding design procedures as unitary applications collecting inputs from and relaying relevant results to the data model; Integrating applications into a framework that serves inputs and collects outputs from models and calculations to produce final standardized reports. Design reports with input data, results and methodology are automatically created or updated under various file formats or templates. Engineering productivity is improved drastically and the impact of rework is minimized. The productivity gain is multiplied when the design is still in the early stage and when multiple multi-disciplinary design cycles, including the stakeholder's review, are necessary.
In the "lower for longer" barrel price environment, new projects and field developments need cost effective improved approaches; amongst them, the concept of "Progressive Subsea Field Construction". In this alternative concept, construction of elements that are not critical to first oil but only here to support the assets integrity - typically subsea pipelines foundations and consolidating structures - is deferred to the operational life of the facilities, thus benefiting the cash-flow and net present value of a project. This principle is well known to field architects that strive at ensuring that the cash generated from early production is used to finance the rest of the development - "Production while drilling" is a typical example of such approach. In the vision conveyed in this paper, part of the structural construction can be delivered as a continuous (staged) service rather than an initial investment. The paper analyzes two real cases of pipelines in deep-water West Africa, representing the evolution of the state of the art over the past 15 years. It then benchmarks these real cases against a novel approach, to demonstrate the benefits of continuous service in staged construction and integrity management. Results provided in this paper demonstrate that there is benefit to the economics of a project, a minimal increase of 2% of a pipeline system Net Present Value, in setting a monitoring procedure, a monitoring device (like a resident subsea inspection vehicle) and data management system to allow for continuous construction. The paper also demonstrates that economic benefit is furthermore amplified when time comes to extend the life of the asset, in such case the Net Present Value of the same system increases by 5%. Since the case study focuses on pipeline anchoring, the paper also attempts at showing this concept could be used more extensively in full field developments. Indeed, the novel approach proposed in this paper opens the door to a completely novel collaboration model between contractors and operators, establishing continuity of construction during the full life cycle of a field. It aims at generating discussions and new ways of thinking to help the industry evolve towards lower costs of development and more sustainable contracting models.
Traditionally, the monitoring of the pipeline structural response to dynamic loads during offshore installation is performed indirectly by comparing the observed sea-states to a matrix of pre-run dynamic analysis cases. Offshore work is planned within a weather window such that the vessel’s station keeping and equipment capacities are not exceeded and pipeline integrity remains within code limits. Assessment of actual seastate offshore is subject to interpretation, possibly introducing undue conservatism with respect to pipe lay operations in some circumstances. This paper describes a proprietary pipeline integrity monitoring method for managing pipe-lay operations. Technip has developed and tested this approach to optimise installation weather windows for the company’s reel-lay vessel, Apache. The method integrates both office-based analysis and offshore real-time motion monitoring. Limiting equations, which represent pipeline stresses and tensions during pipe-lay as a function of the motion of the pipeline top connection, are defined during pre-campaign finite element analysis. Considerable time savings are achieved over conventional approaches by utilising multi-parametric optimisation techniques. Once offshore, the actual motions are measured in real-time using a motion reference unit mounted on the lay ramp. Recorded data can then be compared against pre-defined multi-variate response surface. The system provides a real-time indication of the stress and tension levels in the pipeline. It is believed this method could introduce greater accuracy to pipeline integrity management in some circumstances, which in turn could provide more accurate information for making operational decisions. This novel approach is presented together with a description of current dynamic analysis philosophy and an alternative approach made possible by recent improvements in analytical software and computer processing capabilities.
Installation of subsea pipelines using reeling process is an attractive method. The pipeline is welded in long segments, typically several kilometers in length, and reeled onto a large diameter drum. The pipeline is then transported onto such reel to the offshore site where it is unreeled and lowered on the seabed. The deformation imposed on the pipeline while spooled onto the drum needs to be controlled so that local buckling is avoided. Mitigation of such failure is generally provided by proper pipeline design & reeling operation parameters. Buckling stems from excessive strain concentration near the circumferential weld area resulting from strength discontinuity at pipeline joints, mainly depending on steel wall thickness and yield strength. This requires the characterization of critical mismatches obtained by trial and error. Such method is a long process since each “trial” requires a complete Finite Element Analysis run. Such simulations are complex and lengthy. Occasionally, this can drive the selection of the pipeline minimum wall thickness, which is a key parameter for progressing the project. The timeframe of such method is therefore not compatible with such a key decision. The paper discusses the use of approximation models to capitalize on the data and alleviate the design cost. To do so, design of experiments and automation of the computational tool chain are implemented. It is demonstrated that initial complex chain of FEA computational process can be replaced using design space description and exploration techniques such as design of experiments combined with advanced statistical regression techniques in order to provide an approximation model. This paper presents the implementation of such methodology and the results are discussed.
The data necessary for the design, construction and operation of a subsea pipeline system involves many applications and software covering design, construction specifications, fabrication and installation records, inspection database and more. So far, most of the data is exchanged under the format of manually produced reports between clients and contractors, but also to and from manufacturers and subcontractors or other project stakeholders. This was identified as a significant improvement opportunity in terms of cost, time, and quality. As the industry goes through digital transformation, data structuring is a need faced by all. However, diverging data structure creates the need to re-process the data to a mutually acceptable format at each interface point and many times, with a significant cost, quality, and schedule impact. The PDEF project was started with the aim to agree on an industry-wide common interchange format for all the data that is issued in the design, construction, and operation of a subsea pipeline. The primary objective is to exchange data more efficiently between the different parties involved in a subsea field development project. PDEF initially covers subsea pipelines and will be extended to encompass the entire pipeline system, including risers, spools and jumpers, in-line structures and more. PDEF covers the entire product life-cycle, from conceptual studies to operation. PDEF is multi-disciplinary, including business domains such as operating data, linepipe, routing, metocean, geotechnical, fabrication, installation, etc. PDEF is not a common database solution but simply the specification and documentation describing the data format to be respected for data exchange. PDEF is not intended to replace human readable documents or serve the purpose of applications using such data. It is an interchange format to enable smooth and reliable transfer of data between information between systems or project stakeholders. The companies who partnered into the PDEF project include oil & gas operators, EPCI contractors, manufacturers, design consultancy firms as well as other industry partners players from all regions of the world. The project Phase I started in November 2019 and finished in December 2020. The goals and functional requirements were clarified, and the JSON-schema technology was selected as the means for implementation. Thousands of variables were gathered from all partners, classified and structured. Preliminary series of business context objects were developed. A first test of the engineering schema was performed by the partners on real project data, bringing the project to reach the milestone of proof-of-concept. Phase II started in March 2021 and ran till December 2021. The PDEF specification was written and formally peer reviewed by the partners. An improved version of the schema and associated documentation was produced and published. Further tests were conducted by the partners to have PDEF reaching a status of minimum-viable-product.
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