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“BOP”

 Definition

BOP is the acronym of Blow Out Preventer or Blowout Preventer.

The Blow Out Preventer (BOP) is a safety equipment to prevent the well to blowout.

Designed and engineered for high oil and gas pressures, it is installed on the top of the well casing to contain anything to pass through and generate sub-sea leakages or surface explosion.

Comments

The BOP is designed as a large valve installed at the top of a well that may be closed in the case of losing the control of drilling or production operations.

By closing this valve (usually operated remotely via hydraulic actuators), the drilling crew usually regains control of the reservoir.

Then the normal procedure is to inject massive quantity of mud to generate a counter pressure until it is possible to open the BOP again and retain pressure control of the formation of fluids in the risers.

Each BOP is selected to match with the requirements of each well.

This selection is critical to optimize emergency operations.

BOPs come in a variety of styles, sizes and pressure ratings.

There are different types of BOP, depending on their technology they are designed to:

 – Seal around tubular components in the well, like a rubber doughnut, the annular BOP.

 – Close over an open well bore, the ram BOP.

– Cut through the drill pipe with hardened steel shearing surfaces.

An annular BOP has a rubber sealing element that, when activated, seals the annulus between the kelly, the drill pipe, or the drill collar.

If no part of the drill stem is in the hole, the annular BOP closes on the open hole.

The ability to seal on a variety of pipe sizes is one advantage the annular BOP has over the ram BOP

While not considered as reliable in sealing over the open hole as around pipes, the elastomeric sealing doughnut is required by API specifications to seal adequately over the open hole as part of its certification process.

Ram BOP are large steel rams, that have sealing elements.

One type of ram BOP is called a pipe ram because it closes on the drill pipe; it cannot seal on open hole.

Blind ram BOP are straight-edged rams used to close an open hole.

A ram BOP consists of two halves of a cover for the well that are split down the middle.

In the ram BOP, large-diameter hydraulic cylinders, normally retracted, force the two halves of the cover together in the middle to seal the wellbore.

The halves of the covers, formally called ram blocks, are available in a variety of configurations.

In some designs, they are flat at the mating surfaces to enable them to seal over an open well bore.

Other designs have a circular cutout in the middle that corresponds to the diameter of the pipe in the hole to seal the well when pipe is in the hole.

These pipe rams effectively seal a limited range of pipe diameters.

Variable-bore rams are designed to seal a wider range of pipe diameters, albeit at a sacrifice of other design criteria, notably element life and hang-off weight.

The various ram blocks can be changed in the ram BOP, enabling the drilling crew to optimize BOP configuration for the particular hole section or operation in progress.

Also, some well control techniques require both the annular BOP and the ram BOP to create a BOP stack.

Most BOP stacks contain at least one annular BOP at the top of the BOP stack, and one or more ram BOP below.

As a critical safety equipment the BOP is inspected, tested and refurbished at regular intervals determined by a combination of risk assessment, local practice, well type and legal requirements.

BOP tests vary from daily function testing on critical wells to monthly or less frequent testing on wells thought to have low risk after performing the risks assessments.

For more information and data about oil and gas and petrochemical projects go to Project Smart Explorer

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