Publicações

The Class Location concept is adopted by most gas pipeline standards as a way to mitigate risk of third party damage in densely populated areas. These standards define a straightforward process to determine the Class Location, as well as the Maximum Allowable Operating Pressure (MAOP) based on the population living close the pipeline. While this process is well established, there are several challenges faced by pipeline operators when implementing it. These challenges include: (a) locating and classifying buildings close to the pipeline, (b) counting the number of buildings making use of the sliding mile concept and (c) correlating the geographic position of the identified Class Location segments with the pipeline characteristics such as diameter, wall thickness, material and pressure test level. This paper presents a method to perform Class Location Change assessments along pipelines using a computational tool aided by georeferenced map imagery and counting algorithms. The tool also provides a framework where right-of-way inspection teams are able to locate and classify buildings near the pipeline. A building-based sliding mile has been implemented to appropriately count buildings and identify the current Location Class. Post-processing algorithms evaluate possible MAOP restrictions, such as pipe replacement and hydrotest. This methodology has proved to be effective by completing Class Location Assessments in 6500 km of gas pipelines.

The use of drag reduction agents (DRA) can be a decisive factor in determining the technical and economic feasibility of new pipeline projects, meeting demands not foreseen and accommodating seasonality without large investments in infrastructure. Knowing the friction reduction mechanism and its impact on the operating procedure of existing products is essential in order to guarantee the benefit for a given application. Most published works report field experiences obtained from its application, seeking to determine the influence that internal and external factors have on the polymer. However, few authors have sought to identify the best way to operate an existing pipeline with DRA, with either an increase in capacity or an energy reduction. Operationally, the use of drag reducing agents may decrease the currently used arrangement of pumps, or even allow the complete shutdown of a pumping station. This paper presents a case study of the application of drag reducing agents in a Brazilian high-energy pipeline. It features five intermediate pumping stations and three withdrawal points along its nearly one thousand kilometer stretch. With the aid of computer simulation software, a methodology is proposed to evaluate the best application condition, minimizing pump costs and polymer volume while meeting the scheduled demand of the month. A reduction in energy consumption of 49% was noticed, and considering the costs with DRA, the monthly movement had a 35% drop in the total costs of operation.

The Brazilian law number 11909 from 2009, commonly known as the Gas Law, improved the regulatory rules related to free access to the infrastructure of natural gas transportation and imbued the National Oil & Gas Agency (ANP) with the attribution to set standards and criteria to determine the capacity of transport gas pipelines. Despite the legal framework establishing several definitions for transport, booked, available and idle capacity, no technical procedures to calculate those capacities were defined. In the Brazilian case, the legislator's concerns in establishing the several definitions of capacity were focused on optimizing the transport infrastructure and promoting free access to it. With this in mind, ANP developed a two-year project in partnership with PUC-Rio/SIMDUT that raised the main characteristics of all the transport gas pipelines, defined the minimum requirements for a thermal-hydraulic flow simulator, standardized the capacity reports for the transport companies, created and documented models for all national gas pipelines and defined the methodology to calculate capacity. This methodology follows a step-by-step system where initially the maximum transport capacity is calculated for each delivery point, without violating any technical or contractual condition of the pipeline network. The methodology was applied to the national gas network, using historical delivery values, and the results were registered in standardized tables, validating the feasibility of the project.