New drilling challenges are manifested with pressureextremes or higher temperatures than ever before

required. Failure consequences are so great that the like-lihood of once-routine risks must be reduced even fur-ther in these new operating environments of extremedepths, temperatures and pressures.

Drilling challenging wells places new demands on exist-ing well control equipment. Systematic technology quali-fication processes for HP/HT discoveries—those rated atmore than 15,000 psi and greater than 121 C (250 F)—mustbe followed since existing codes and standards have noclear requirements for such extreme operating conditions.

As a technical adviser to the offshore industry, ABSrecognizes the need to develop offshore equipment de-sign qualification standards. e company is assisting de-signers and manufacturers with developing designstandards for constructing HP/HT subsea BOP stacksand related systems that may be used safely in 20,000 psiand about 177 C (350 F) load conditions.

Another innovative technology that is significantly im-pacting planned offshore drilling operations is the man-aged-pressure drilling (MPD) system, parts of which havebeen used onshore for about 10 years. MPD techniqueshave proven cost-effective, reliable and safe when drillingdifficult onshore wells as well as when drilling from mobileoffshore drilling units (MODUs) with a surface BOP.

Only recently have operators begun viewing MPD as anenabling method in drilling increasingly complex offshorewells from MODUs with subsea BOPs. MPD techniques arebeing used offshore to drill previously “undrillable” wellsand also to enhance a well’s primary pressure barrier. Hav-ing systematically qualified MPD technologies for variousdesigners and manufacturers, ABS is finalizing require-ments that specify certification for MPD systems. ese in-clude applied surface pressure systems and dual-gradientdrilling (DGD) systems with the associated subsea compo-nents for both types of MPD systems.

Updating requirements to reflect MPDe primary function of any MPD system is to containwellbore pressures in a controlled flow system within thewell’s pressure-design “envelope,” while providing both ameans of adding fluids to the wellbore and allowing con-trolled volumes to be removed from the wellbore. e re-quirements will be applicable to any offshore drillingoperations where the primary barrier maintains a stateof constant overbalance, actively managing pressure inthe well by using one or more of several technologies.

Because the overall MPD system and all of its subsys-tems will be considered a part of the primary well pres-sure barrier system, for any ABS-classed rigs all associatedcomponents used in MPD operations will require ABSdesign approval and an ABS survey for installation.

Classification services will be delivered in accordancewith new ABS requirements currently being developedfor the design, construction and commissioning of MPD systems, subsystems and components. ese new criteria will be published in 2015 as an appendix to the ABS Guide for Classification of Drilling Systems (CDS Guide).

Applying new technology offshoreWhen any new technology is proposed for applicationin any drilling operation, it requires a systematic qualifi-cation process by both validation and verification. Qualification is the process of validation and verificationthat the technology will function safely within speci-fied limits.

Applying MPD systems offshore requires careful con-sideration with regard to both equipment and system de-

signs as well as any operational, maintenance and safetyissues. Specifically, this will include the inherent risks as-sociated with offshore drilling practices, ultradeepwaterdrilling rig configuration and systems integration withany new technology being evaluated.

In some cases, no specific requirements may exist forthe proposed application of a new technology, which wasthe case when installing the world’s first fully integratedDGD system on the Pacific Santa Ana ultradeepwaterdrillship now working for Chevron in the Gulf of Mexico.As certified verification agent for this industry-first project, ABS performed the safety reviews and workedclosely with the U.S. Coast Guard and Bureau of Safety and Environmental Enforcement to certify theMPD technology.

Validation and verification of proposed innovativetechnology by an independent third party, such as a clas-sification society, facilitates compliance with applicablerules’ intent and requirements for drilling on the U.S.

Outer Continental Shelf and other environmentally sen-sitive offshore areas.

e objective for design verification is to confirm thatthe HP/HT equipment design is in compliance with itsfunctional specification and the equipment has adequateprotection against failure modes identified for HP/HTequipment. e design validation process is required todemonstrate that the equipment maintains the mechan-ical integrity and functionality/operability to its func-tional specifications.

As operators seek ways to increase safety and reliabilityin the offshore drilling process while continuing to eco-nomically develop previously unreachable offshore reser-voirs, class societies can assist the industry withunderstanding the safety aspects and the core stepsneeded to apply new or adapted technologies in challeng-ing operating environments.

For more information, visit ABS at booth 2816 in Hall D. n

Evaluating Safety Considerations for DeepwaterDrilling Technology n As the industry pushes the HP/HT threshold, a systematic technology qualification process for deepwaterdrilling systems is needed.

BY HArISH PATEl, ABS

TUESDAY | MAY 5, 2015 | OTC SHOW DAIlY

A typical equipment schematic for offshore MPD with a subsea BOP is shown. (Images courtesy of Weatherford)

Based on actual offshore experiences and knowledge gained in recent years working with MPD designers and de-

velopers, ABS has developed sets of requirements for offshore MPD that are now being incorporated into the ABS

CDS Guide.

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