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Of particular note were the 2004 West Engineering Services studies Review
of Shear Ram Capabilities and Evaluation of Shear Ram Capabilities (TAR studies 455
360
and 463). The main goal of these studies was to answer the following question:
can a rig’s BOP equipment shear the pipe to be used in a given drilling program,
at the most demanding condition to be expected, and, if so, at what pressure?
Before answering this question, one of the studies noted that “[s]hear rams may
be a drilling operation’s last line of defense for safety and environmental
protection.” In arriving at several conclusions and recommendations, the report
described a failure rate of 7.5% where the rams tested failed to shear pipe while
working in a maximum closing force pressure of 3,000 pounds per square inch.

In a 2003 West Engineering Services study funded by MMS, the study
acknowledged that shear ram blocks were not designed to close and seal under
high rate conditions if closure rates were slow. The study also noted that API
Specification 16A did not require testing for rams under dynamic flowing
conditions. The MMS regulatory response was to require operators to submit
documentation showing that the shear rams that they used in their BOP were
capable of shearing pipe in the hole under maximum anticipated surface
pressures.

360 This study followed an MMS‐funded research project in 2003 (TAR study number 431) that
evaluated secondary intervention methods in well control. The goal of the research was to
evaluate the capabilities of the secondary BOP intervention systems in place at the time of study,
and identify the best practices in use and not yet in use. The objectives of the study were to
compare and contrast the capabilities of available secondary intervention technologies; review
and contrast existing secondary intervention systems in place on deepwater drilling rigs; discuss
possible enhancements to existing systems, their benefits, and their costs; and recommend the
best practices for operations in less than and greater than 3,500’ water depth. For a rig in the
dynamically positioned (DP) mode operation with a multiplex BOP control system, like the
Deepwater Horizon, the study recommended the following secondary systems: an emergency
disconnect system, a “deadman” system to supplement the EDS system, the addition of an
autoshear circuit to a rig that had an AMF system, and an ROV. The Deepwater Horizon was
equipped with an emergency disconnect system, a “deadman” system, an “autoshear” system,
and ROV intervention capabilities.

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