(a) Before the casing is run, a check trip should be made to ensure that there are no tight spots or ledges which may obstruct the casing and prevent it reaching bottom

(b) The drift I.D. of each joint should be checked before it is run.

(c) Joints are picked up from the catwalk and temporarily rested on the ramp. A single joint elevator is used to lift the joint up through the ā€œVā€ door into the derrick (Figure 10).

casing running

(d) A service company (casing crew) is usually hired to provide a stabber and one or two floormen to operate the power tongs. The stabbing board is positioned at the correct height to allow the stabber to centralise the joint directly above the box of the joint suspended in the rotary table. The pin is then carefully stabbed into the box and the power tongs are used to make up the connection slowly to ensure that the threads of the casing are not cross threaded. Care should be taken to use the correct thread compound to give a good seal. The correct torque is also important and can be monitored from a torque gauge on the power tongs. On buttress casing there is a triangle stamped on the pin end as a reference mark. The coupling should be made up to the base of the triangle to indicate the correct make-up.

(e) As more joints are added to the string the increased weight may require the use of heavy duty slips (spider) and elevators (Figure 11).

casing elevator

(f) If the casing is run too quickly into the hole, surge pressures may be generated below the casing in the open hole, increasing the risk of formation fracture. A running speed of 1000 ft per hour is often used in open hole sections. If the casing is run with a float shoe the casing should be filled up regularly as it is run, or the casing will become buoyant and may even collapse, under the pressure from the mud in the hole.

(g) The casing shoe is usually set 10-30 ft off bottom.

Institute of Petroleum Engineering, Heriot-Watt University

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