Post Mortem Failure Assessment of MODUs During Hurricane Lili
Authors: Sharples B.P. Malcolm , Smith Charles E. , Bea Robert G. 
Published: October 2008

MODUs in the Gulf of Mexico are a critical part of the infrastructure that brings oil and gas prospects to development. Getting the standards that govern safety into perspective has been a critical part of ensuring that the MODUs are both safe, and affordable. Verifying the criteria and methods used is vital to ensuring that there is a balanced view of structural integrity.

Hurricane Lili in October 2002 tracked through a high-density corridor of MODUs in the Gulf of Mexico. One semi-submersible parted moorings and drifted to the beach. Another semi-submersible broke some moorings but stayed on location. All but two jackups survived the event with little or no noticeable change in their situation. The two jackups were total losses and several other jackups had footing settlements.

In the aftermath of a hurricane there is a unique opportunity to reflect on the events that took place, to chronicle them, and give industry an understanding of their impact on the standards that the industry considers appropriate in maintaining an envelope of safety for MODUs.

In the aftermath of Hurricane Andrew - a study was undertaken, sponsored by the MMS to seek recommendations from the lessons learned from the failures. This paper reports on that study and considers information, which was available from Hurricane Andrew in putting Hurricane Lili events in perspective.

INTRODUCTION

MODUs in the Gulf of Mexico are a critical part of the infrastructure that brings oil and gas prospects to development.

Hurricane Lili in October 2002 tracked through a high-density corridor of MODUs in the Gulf of Mexico. A series of studies was commissioned by the Minerals Management Service of the Department of the Interior (MMS) to chronicle the incidents that affected the infrastructure of oil and gas equipment: this paper reports on the study on the Mobile Offshore Drilling Units. The specific task:

To study the failures associated with MODUs during Hurricane Lili, gathering information on loss of station keeping of a semi-submersible MODU, collapse of 2 Jack-up MODUs and 3 other rigs that had settlement and possible related damage which could have resulted in (rig) casualties. Develop any recommended updates on criteria, review the Hurricane Andrew recommendations, and make recommendations for future mitigation action

The study relies upon the work of Oceanweather who carried out the meteorological hindcast (Ref. 1).

MMS had commissioned a study in the aftermath of Hurricane Andrew in 1992 (Ref 2). This study investigated failures associated with mobile offshore drilling units (MODUs) during intense Gulf of Mexico hurricanes. The study addressed jack-up units, drillships, drilling barges, and semi-submersible drilling units. The study also addressed mooring and abandonment procedures for units exposed to hurricane wind, wave, and current forces and provided recommendations for securing procedures for MODUs in advance and during hurricanes. The project used MODU failure and survival experiences from past hurricanes including Andrew, Betsy, Camille, Carmen, Hilda, and Juan to verify the securing procedures. Reference is made to the Hurricane Andrew report in order to compound the learning available from these two major hurricane events.