TRAWL PULLOVER DESIGN AND MODELING USING FINITE ELEMENT METHOD ON SUBSEA PIPELINES IN NATUNA SEA

• Main Author: Muhammad Elan, Farel
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/69690
• Institution: Institut Teknologi Bandung

Oil and gas have an essential role in promoting affluence and prosperity in the aspects of the Indonesian economy. Indonesia has been active in the oil and gas sector for 130 (one hundred and thirty) years after the first oil discovery in North Sumatra in 1885 and based on a review of world energy statistics by BP in 2019, Indonesia has oil reserves of 3,2 billion barrels at the end of 2018 [1]. Subsea pipelines are one of the important components in the oil and gas industry of offshore hydrocarbon sources which include pipelines for transportation from one platform to another and subsea manifolds, injection of water or other chemicals, which are designed according to applicable standards and codes which are then issued on the seabed. Intending to have a good and safe underwater piping system, subsea pipelines need to be designed according to the applicable stages by adjusting several parameters that apply to the environment in which the submarine pipeline operates. Transportation of hydrocarbons using subsea pipelines is quite efficient and economical, with that indirectly the offshore subsea pipeline network has gradually become the main option for oil and gas transportation at sea [2]. Several hazards are associated with the operation of offshore pipelines that result in disruption to the carrier and production of hydrocarbons and can lead to health, environmental, and accident disasters. Half of the total accidents on subsea pipelines are caused by anchoring and impact from an object falling from a ship passing through the subsea pipeline. One object that can have an impact on underwater pipelines is the use of trawls for fishing. In the final project, a trawl pullover modeling on the subsea pipeline with the presence of an expansion spool using the finite element method in the ABAQUS software to show the integrity of the subsea pipeline in the event of an accident due to trawling. Before the pipe is used and the trawler pullover is modeled, a design will be carried out using several applicable standard code criteria. Based on the design process that has been carried out in this Final Project, the wall thickness value of 12,7 mm (0,5 inches) has been adjusted to the standard code DNVGL-ST-F101 and API 5L, the concrete layer thickness value is 40 mm with a depth of trenching is 5,6 millimeters and has been adjusted to the standard code DNVGL-RP-F109 and the allowable free span length value is 22,4 meters which have been adjusted to the standard code DNVGL-RP-F105. In the modeling, a mesh convergence study will be carried out to find the most optimal meshing size and variations in the direction of the angle of incidence of the trawling to the subsea pipeline. Based on the modeling results, it is found that the influence of the direction of incidence of the trawling angle on the pipe by obtaining yield and tensile values at different review points, and there is a dogleg effect on the modeling of the trawler pullover on the subsea pipeline.