Mobile offshore drilling units

EC60092-505 Part 505 Special features-mobile offshore drilling units. 

API RP 75 was written in response to the need for a SEMP. The API also produced a companion document, RP 14J, for identifying safety hazards on offshore production facilities. In 1994, the MMS published a Notice in the Federal Register that recognized implementation of RP 75 as meeting the spirit and intent of SEMP. RP 75 was updated in July 1998 to focus more on contract operations, including operations on mobile offshore drilling units. 

Deepwater Horizon was a Mobile Offshore Drilling Unit (MODU) working the Macondo field off the coast of Louisiana. The water depth was approximately 1 mile. From a technical point of view the background to the incident was quite similar to the Blackbeard situation that has already been described, although the depth of the well was less but the water depth was greater. 

For this subpart, facilities include all types of offshore structures permanently or temporarily attached to the seabed (i.e., mobile offshore drilling units floating production systems floating production, storage and offloading facilities tension-leg platforms and spars) used for exploration, development, production, and transportation activities for oil, gas, or sulphur from areas leased in the OCS [Outer Continental Shelf], Facilities also include DOI regulated pipelines. 

MODU Operations Manual developed in conformance with flag state requirements and/or the IMO MODU Code for information on routine operations and operating limits on mobile offshore drilling units. 

The lADC structure is directed toward MODUs (Mobile Offshore Drilling Units, including jackups, semisubmersibles, and submersibles). However, this document can be used to help develop a Safety Case for a much wider range of technologies. The lADC structure is summarized in Figure 8.1, which is derived... 

International Association of Drilling Contractors (lADC), 2006. Health, Safety and Environmental Case Guideline for Mobile Offshore Drilling Units. Issue 3.2, October. 

Exploratory Drilling Structures A Mobile Offshore Drilling Unit [MODU] configuration is largely determined by the variable deck payload and transit speed requirements. 

In harsh operational conditions environmental factors can affect the performance of DP which can lead to loss of the position control abiUty. For a Mobile Offshore Drilling Unit (MODU), loss of position without safe disconnection could result in critical damage not only to the well, but also to the subsea equipment. For an Offshore Support Vessel (OSV), loss of position could lead to colhsion with the nearby installation during operation or to damage to the subsea fadhties. In order to increase the safety and reliabiUty of a DP system, it is important to identify and quantify all influence factors and the way that they can affect the DP performance. For example bad weather condition is an effective factor on the position reference sensor or the local position reference system. Such operational conditions can vary from place to place and may have a dynamic nature in a specific location. Moreover, it is important to investigate safe recovery back to position, safe disconnection and reconnection when the loss of position is outside the safe operational range. 

Chen, H., Moan, T. Verhoeven, H. 2008. Safety of dynamic positioning operations on mobile offshore drilling units. Reliability Engineering System Safety, 93, 1072-1090. 

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