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What Is The Types And Uses Of Oil Casing
2021-11-18 10:44:17

According to the function of petroleum casing, it can be divided into surface casing, technical casing and oil casing.

1. Surface casing of petroleum casing:

(1). Used to seal the unstable and soft, easy to collapse, easy to leak formation and water layer in the upper part;

(2). Install a wellhead device to control the blowout;

(3). Partial weight of support technology casing and reservoir casing.

The depth of the surface casing depends on the specific situation, and is usually tens of meters to hundreds of meters or deeper (30 to 1500 meters). Extracorporeal cement is usually put back on the ground. When drilling high-pressure gas wells, if the upper rock layer is loose and broken, the surface casing needs to be deeper in order to prevent high-pressure gas flow from the surface. If the surface casing needs to be deeper, if the secondary drilling time is longer, the lower layer of the pipeline should be considered before the lower surface casing. Its function is to seal the surface, prevent the wellhead from collapsing, and form a drilling fluid circulation channel, which is convenient for long-term drilling. The depth of the catheter is generally 20-30 meters, and the cement outside the tube returns to the ground. The catheter is usually a spiral tube or a straight tube.

2. Oil casing technology casing:

(1). It is used to seal the complex stratum, severe loss layer and oil, gas and water layer which are difficult to control by drilling fluid, and prevent the diameter from expanding.

(2). In high-inclination directional wells, insert casing under the section to facilitate safe drilling of directional wells.

(3). Provide conditions for the installation, blowout prevention, leakage prevention and suspension of well control equipment stern tube and protect oil casing.

The technical casing does not necessarily need to be lowered. Take measures such as high-quality drilling fluids, speed up the drilling speed, and increase drilling efforts to control complex downhole conditions, so that technical casings cannot be obtained or reduced. The depth of the technical casing is determined by the complex formation to be sealed. The return height of cement should reach more than 100 meters of the sealed layer. For high-pressure gas wells, in order to prevent leakage, cement is often returned to the surface.

3. Oil casing and oil casing:

It is used to separate the target layer from other layers; separate oil, gas and water layers under different pressures, and establish oil and gas channels in the well to ensure long-term production.

The depth of the oil layer casing depends on the depth of the target layer and the completion method. The cement slurry of the oil layer casing generally returns to the oil and gas layer above the upper layer 100 meters. For high-pressure wells, the cement slurry should be transported back to the surface, which is conducive to strengthening the casing and strengthening the oil casing steel wire seal, so that it can withstand larger Well pressure.