Kerr-McGee Oil & Gas Corporation operates a fleet of five spars in the deepwater Gulf of Mexico (GOM) in three designs: the classic, the truss and the cell spar. Integrity Management plays a large role in ensuring the safe operation of these assets and provides a means to measure the continued fitness-for-purpose. This paper overviews the development of the program for integrity/inspection management from the first spar, Neptune, when there were no established regulations for spars, through the most recent cell spar, Red Hawk. It covers issues related to inspection philosophy and the development and execution of the In-Service-Inspection Plan (ISIP) for this fleet of spars. This plan manages a continual assessment for technical integrity of the asset and is inclusive of the regulations presently in place. An overview of the inspection challenges, lessons learned and benefits offered are also illustrated.
The management of integrity and inspection of fixed offshore platforms are today governed by sets of rules and industry standards that are recognized as assisting operators to meet their Integrity Management (IM) needs. Standards such as API RP 2A and those established in the Code of Federal Regulations (CFR) are widely understood and used. These documents provide clear guidance to operators of platforms on what activities and inspections must be performed in order to assure structural integrity and satisfy the regulatory requirements.
Production in the GOM has trended toward deepwater regions. In the early years of these deepwater production developments, there was less definitive information and guidance available that could be referenced. Initially the sources of information used were drawn from both the general marine and drilling industries.
In 1995, Kerr-McGee (the operator) proposed the first use of a spar-style hull for development of Viosca Knoll Block 826, commonly known as the Neptune spar. This concept selection would stretch the applicability of the regulations that were in place at that time. Specific questions regarding inspection requirements were directed at this unique floating structure for which definitive answers were not readily available.
As the Neptune design and fabrication process progressed, all parties involved including Kerr-McGee, the U.S. Minerals Management Service (MMS), U.S. Coast Guard (USCG) and ABS worked to formulate an in-service inspection scheme that would be a workable and acceptable solution. This scheme would embody an understanding of the regulatory requirements and selected elements taken from existing industry standards (Such as API RP 2A) and. adopted a "best fit" approach to enable the development of an inspection plan that would cover both structural and mooring system requirements for the 20-year predicted life of the spar. The inspection plan, termed the In-Service Inspection Plan (ISIP) would act as a mechanism to satisfy both the operator's integrity management philosophy and also address the applicable statutory USCG and ABS requirements. This initial ISIP was recognized by all the participants as providing an appropriate start point, with future changes to the ISIP being expected, specifically as operational knowledge increased. The original ISIP was approved by both ABS and USCG.