WELL Control PDF

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Summary

Introduction ( including well control equipment)
The Anatomy of a KICK
Kicks - Definition
 Kick Detection
 Kick Control
 (a) Dynamic Kick Control
 (b) Other Kick Control Methods
* Driller’s Method
* Engineer’s Method...

Description

INTRODUCTION TO WELL CONTROL 7.7 Well Control Equipment A kick is an influx of formation fluids into the well bore. This happ pressure in the formation (pore pressure) is higher than the mud densit is an uncontrolled kick. A blowout is very undesirable because: • It endangers the lives of the crew. • It destroys the rig. • It may damage the environment. 7.7.1 Blowout Preventers Blowout preventers or BOP’s, is a device attached to the casing conjunction with other equipment and techniques, are used to close th allow the crew to control a kick before it becomes a blowout. There ar types of blowout preventers on a drilling rig: • Annular Preventers • Ram Preventers • Rotating Head Usually several blowout preventers are installed on top of the well in a stack, c stack. The annular preventer is always on top of the ram preventers. Several p installed so that a kick, or impending blowout, can be controlled even if one of t fails.

BOP stack (from Phil Gavinda).

7.7.1.1 Annular Preventer An annular preventer has a rubber sealing element that, when activated, closes ti the kelly, drill pipe or drill collars or the open hole (if there is no pipe in the hole) effected by compression of a reinforced elastomer packing element.

An annular preventer (from Hydril).

7.7.1.2 Ram Preventer Ram preventers consist of rams (large steel valves) that have seali There are generally three types of ram preventers: • Pipe ram • Blind ram • Shear ram Pipe rams close on the drill pipe and are not able to effect a seal on an open hole. Blind rams are used to close an open hole effectively. Shear rams are blind rams that have a cutting edge to cut the drill pipe completely sealing the hole. They are used mainly in subsea systems.

Ram preventers (from Hydril).

7.7.1.3 Rotating Blowout Preventer The rotating blowout preventer (RBOP) is also called a rotating head or a st They are continuously closed around the drill stem by means of a heavy-duty st that rotates with the drill string. Packing provides a seal between the rotating a elements. Rotating heads are especially useful in drilling with air, gas, foam or any other dri whose hydrostatic pressure is less than the formation pressure.

Rotating blow out preventer.

7.7.1.4 Drilling Spool Choke and kill lines may be connected to side outlets of blowout preventers. Usin on BOP’s reduces the number of stack connections by eliminating the drilling spoo But many drilling contractors prefer these lines to be connected to a drilling spool below at least one preventer capable of closing on pipe. By using a drilling spool the possible erosion to the less expensive piece of equipment is localized additional space between rams to facilitate stripping operations. 7.7.2 Accumulator The blowout preventers are opened and closed by hydraulic fluid, which is pressure in an accumulator. Several bottle- or ball-shaped containers are lo operating unit, and the hydraulic fluid is stored in these containers. High-pressure the accumulator to the BOP stack. The accumulator is located at least 100 feet fr stack.

Accumulators.

A master control panel is used to operate the preventers. A master control panel s located at a safe distance from the wellbore. Another master control panel should b the rig floor or another place that is convenient for the driller to operate.

BOP master control panel on rig floor.

7.7.3 Choke Manifold When a kick occurs, closing in the well using one or more of the blowout prevente first step that must be taken to kill the well (bring the well under control). In ord well, the kick must be circulated out and mud with the proper weight must be circulated. The choke manifold is a series of valves, chokes, gauges and lines that is connecte controls the rate of flow from the well when the blowout preventers are closed. Wh is shut in, the kick is circulated out through the choke line and manifold.

Choke manifold.

A choke is a valve. There are two types of chokes: • Adjustable chokes • Fixed chokes An adjustable choke is operated hydraulically and has an opening that is cap restricted. The choke may vary infinitely in opening from fully closed to fully op controlled from a remote panel on the rig floor. A fixed choke has a flow restriction of permanent size. 7.7.4 Mud-Gas Separator The mud-gas separator is essential for handling a gas kick. It separates the fl from the mud so that the gas can be burned off (flared off) at a safe distance from t Most mud-gas separators are made of a vertical length of large diameter pipe. In are used to slow the mud-gas stream. A gooseneck arrangement at the bottom relatively gas-free mud to flow back to the shakers. The gas vent pipe at the top pe to be flared without too much backpressure on the mud. During a kick the well is shut-in and mud circulated through the choke manifold. T diverted from the flow line or choke manifold to the mud-gas separator. The separa the gas that is then carried by the vent line at the top to a remote flare.

Mud-gas separator....