Regulators say the blowout that killed five workers on a Patterson-UTI rig in Oklahoma was the product of a slow-moving series of missed signals, misleading testing, and miscalculations that failed to control a natural gas influx. A new tool enables variable bore rams and shear rams to be tested in one run, cutting rig time significantly. Developing a well-specific subsea-capping contingency plan involves assessing the feasibility of deploying a capping stack from a floating vessel, determining the weight and stability, and performing dynamic-flow simulations of closing the capping stack outlets. Despite multitier safeguards, blowouts occur. When such accidents happen, rate estimation is an important and daunting task.
Content of PetroWiki is intended for personal use only and to supplement, not replace, engineering judgment. SPE disclaims any and all liability for your use of such content. A conditional surface pressure barrier often consisting of a set of hydraulically operated rams containing equipment designed to grip pipe, seal around pipe, shear off pipe or seal an open hole during drilling or a workover. It may also contain an annular preventer.
Content of PetroWiki is intended for personal use only and to supplement, not replace, engineering judgment. SPE disclaims any and all liability for your use of such content. An elastomer bag or donut type seal, pushed into contact with the pipe or tools in the blow out preventer (BOP). It is designed to seal around pipe or any other irregular surface tool (packers, guns, pumps, etc.) that may be in the BOP, including itself if the wellbore is empty. May also be called a Hydril preventer.
Ultradeepwater drilling units are are the technological forerunners and pioneers in the offshore drilling business. Table 1 gives some characteristics of these units, most of them drillships of extraordinary size, but some are semis as listed in Table 2. All were built in the late 1990s and early 2000s. Most have some degree of dual-rig activity (i.e., they have two drilling units on one hull). The Transocean Enterprise Class drillships (Figure 1), for example, have the capability to run two riser and two blowout preventer (BOP) systems with one system drilling and the other completing a well on a subsea template.
The well-control stack system is a critical part of the coiled tubing (CT) unit pressure containment package and is composed of a stripper assembly and hydraulically operated rams, which perform the functions described next. Figure 1--Typical quad-ram well-control stack configuration (courtesy of SAS Industries Inc.). The blind rams are used to seal the wellbore off at the surface when well control is lost. Sealing of the blind rams occurs when the elastomer elements in the rams are compressed against each other. For the blind rams to work properly, the tubing or other obstructions across the ram bonnets must be removed.