Challengeable Engineering Design of a Deck for Coiled Tubing Well Abandonment on a Dynamic Positioning Barge

Abstract

Ship collision with offshore platform is one of the rare events in oil and gas industry and generally associates with huge physical and financial damage. An oil tanker collided with a jacket in the South Pars gas field and caused tough conditions for the operator to restore the jacket and wells to their original state. The crucial stages after the accident were killing a perforated well, wreck removal and cutting the wells below the section they had been bent or distorted and finally the wells abandonment by cementing coiled tubing operation on a dynamic positioning barge. This paper focus on engineering design of a platform for coiled tubing injector head and pressure control equipment on the barge as well as finding a way that coiled tubing string pass through the gap between the platform and the underwater cut point of wells. For this purpose, a deck was proposed to build on the barge having a heavy duty flexible steel pipe extended from the deck to inside the wells cut point. Various measures should be implemented to design this structure in order to have an operational safe method. The structure had to have sufficient strength to resist the forces applied on it especially during the operation in the predominant weather condition of Persian Gulf in the monsoon season. Therefore, a comprehensive study was conducted to determine stresses applied on the structure subjected to different types of wave velocities using finite element method. The engineering design and simulation led to construct the proposed deck extending over the port side of the barge and elevating between the main deck and mezzanine deck with a long 4" flexible steel pipe at its bottom. In order to verify the engineering design and simulation before the operation, the structure load tested up to 40 metric tons. This paper will peer over the challengeable engineering design of the deck for coiled tubing well abandonment under the condition of insufficient offshore facility.