A rotary drilling rig works by rotating a drill string, which applies downward pressure to a drill bit that grinds the earth. Drilling fluid or air is pumped down the drill string to cool the bit, carry cuttings to the surface, and stabilize the borehole.
[pdf] Jackup rigs are so named because they are self-elevating with three, four, six and even eight movable legs that can be extended (“jacked”) above or below the hull. Jackups are towed or moved under self propulsion to the site with the hull lowered to the water level, and the legs extended above the hull. The hull is actually a water-tight barge that floats on the water's surface. When the rig reaches the work site, the crew jacks the legs downward through the water and int.
[pdf] Before any workover, the well must first be . Since workovers are long planned in advance, there would be much time to plan the and so the reverse circulation would be common. The intense nature of this operation often requires no less than the capabilities of a . The workover begins by killing the well then removing the wellhead and possibly the flow line, then installing a B.O.P. commonly known as a , then lifting the fr.
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