Development of a submersible escape capsule for offshore structures

Abstract

During the past 20 years, many accidents in offshore oil and gas industry have taken away the lives of many workers. A new type of evacuation system is introduced in this research. Whereas, all other evacuation systems developed were purposely designed to remove an entire crew from a structure during emergencies, this research describes the development of a high speed escape capsule that could remove a single person from the structure. Capsules would be placed at strategic locations on the deck of the structure. During an emergency each capsule would be catapulted from the deck to the ocean surface. To avoid the effect of strong wind and waves, after impact with the ocean surface, the capsule would sink into the ocean down to a level where water motions are insignificant and wait until the storm subsides. This research focuses only on the post impact trajectory of the capsule beneath the ocean surface. A physical model of the capsule was designed. Two front thrusters were used to generate surge and yaw motions. Heave and pitch motions were controlled by another thruster located at the back. A pressure transducer was used to measure depth, and a digital compass was used to determine direction. A Peripheral Interface Controller (PIC) was used to control the motion of the capsule using an I²C bus to send PWM signals to 20 Amp drivers. A SIMULINK model was developed to study control strategies and the influence of various vehicle parameters. The model capsule was tested in the Deep Water Tank in Faculty of Engineering and Applied Science at Memorial University of Newfoundland and in the Offshore Engineering Basin at the Institute for Ocean Technology. The simulations and tests showed that the capsule can move smoothly along preset trajectories.