Friday, September 18, 2009

The Cementing Process of an Energy Company

Cement bonds the casing to the hole and prevents fluids in one formation from migrating to another. Cement also prevents corrosive formation fluids from damaging the casing. The operator usually hires an oilwell cementing company to perform the job. Cementing companies stock many kinds of cement and have special equipment to transport it into the well. At the well, Heartland Energy Colorado mixes the dry cement with water to form a slurry -- a thin, watery mixture that is easy to pump. Many kinds of mixers are available to blend the water and cement into a uniform mixture as the cement pumps move it down the casing.

Heartland Energy Colorado then uses a special high-pressure pumps move the slurry through very strong pipes, or lines to a cementing head, or plug container. Previous to this, the cementing crew mounted the cementing head on the topmost joins of casing hanging in the mast or derrick. Just before the slurry arrives at the head, a crew member of Heartland Energy Colorado releases a rubber plug, a bottom plug, from he cementing head. The bottom plug separates the cement slurry from any drulling fluid inside the casing and prevents the mud from contaminating the cement. The slurry moves the bottom plug down the casing. The plug stops, or seats in the float collar. Continued pumping breaks a membrane on the bottom plug and opens a pasage. Slurry then goes through the bottom plug and continues down the last few joints on casing. It flows through an opening in the guide shoe and up the annular space betweent he casing and the hole. Pumping continues until the slurry fills the annualr space.

As the last of cement slurry enters the cassing a crew member of Heartland Energy Colorado releases a top plug from the cementing head. A top plus is like a bottom plus except that it has no membrane or passage. The top plug searates the last of cement to go into the casing the displacement fluid. Displacement fluid, which is usally salt water or a specially formulated drilling mud, moves or displaces the cement from the casing as the cmeent pump applies pressure to move the cement and fluid downt he casing.

Continued pumping by Heartland Energy Colorado will move the the cement, the top plug and displacement fluid down the casing. Most of the cement slyrry flows out of th ecasing and into the annular space. Soon, the top plug seats on or bumps, the bottom plug in the float collar... When it bumbs, the pump operator shuts down the pumps. Cement is only the casing below the float collar and the annular space. Most of the casing is full the displacement fluid.

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