How to install the oil casing correctly

Oil casing is a steel pipe used to support the walls of oil and gas wells to ensure the normal operation of the entire oil well after the drilling process and completion. Each well uses several layers of steel casing pipe according to different drilling depths and geological conditions. After the steel casing pipe is put into the well, cement is used for cementing. It is different from oil pipes and drill pipes and cannot be reused. It is a one-time consumable material. Therefore, the consumption of casing accounts for more than 70% of all oil well pipes.

Oil casing installation method

The oil casing is composed of a coupling and a pipe body. In order to ensure the function and facilitate transportation, the separate pipe body and the coupling are bolted and then transported to the oil and gas field. They are connected end to end on site and used after meeting the specified length. In order to strengthen the compressive strength and fastening operation of the bolted connection, electric welding is required after the coupling and the pipe body bolts are connected. Therefore, it is particularly important to analyze the electric welding characteristics of thirty-seven Mn5 and formulate a scientific and reasonable welding method.

After each technical oil casing and oil layer oil casing are solidified, if the concrete does not return to the ground, some oil casings will float in the wellbore without support, which is free oil casing. The force of this part of the oil casing is pressed against the sealed oil casing. During production, the pressure and temperature of the free oil casing will cause the expansion of the oil casing to change the internal stress, which will easily damage the oil casing. Therefore, the casing head should be reinstalled after the concrete is waiting to set, so as to seal the annular space between the double-layer casings and suspend the force of the free section of the casing. This force is applied to the surface oil casing.

The casing head is divided into slip type and screw type according to the structure of the suspension oil casing, including three layers of oil layer oil casing, technical oil casing and surface oil casing. A layer of casing head is installed on the top of the surface oil casing, and is connected with the pipe thread of the surface oil casing with threads, and the flange level of the casing head is basically flush with the road surface. After the technical oil casing has concreted, a part of the free section is suspended, and the slips are seated in the cone of the casing head. Make the hanging weight press on the cone and seal the annular space between the double casings, just remove the landing joint.

Mastering the correct installation of oil casing can avoid

1) During the drilling process, as the well depth increases, the required mud density will increase, and the upper bottom layer may be leaked. The function of the casing is to prevent the upper layer from leaking when drilling the lower layer.

2) The last oil pipe and tailpipe are the passages for oil. Of course, it is for the instability of the formation and to prevent collapse. If the formation is hard, the well can be completed in the open hole.

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