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A conducting pipe, also known as a drive pipe, is a short, large diameter pipe used to support the initial sedimentary portion of a well and prevent collapse. It also serves to protect from water carrying sands and drilling debris, and can be installed using drilling or pile driving techniques. The pipe also seals off freshwater areas and supports the surface casing. It is commonly used in onshore wells and can be used as a foundation for the wellhead in subsea wells.
A conducting pipe is a relatively short, large diameter pipe driven into the ground prior to drilling boreholes or oil wells. Also known as a drive pipe, this section of pipe serves to support the initial sedimentary portion of the well, preventing the looser surface layer from sagging and clogging the well. The pipe also serves several other purposes, such as protection from the water carrying the sands and the return of cuttings from the drill head. A leadpipe is most commonly used in this role in onshore wells, although it is often employed for similar reasons when sinking offshore wells. Conductor pipes are typically installed using drilling, pile driving, or a combination of these techniques.
The surface section of any well or borehole is particularly prone to collapse settlements, since the initial layers traversed by the well are typically unconsolidated sedimentary material. The collapse of the upper shaft section not only results in long periods of downtime, but also poses a significant safety risk. To prevent this unstable layer from collapsing, a short, large diameter conductor pipe is driven through the sedimentary layer to support the well during drilling. These pipes are used in both onshore and offshore wells, with onshore projects being the most common application. In the case of subsea wells, the conducting pipe can also be used as a foundation for the wellhead.
Installing a conduit pipe also serves several other secondary purposes in addition to supporting the well. It serves to seal off freshwater areas from the ingress of drilling and well fluids. Drilling debris suspended in the drilling mud is also removed via the lead pipe, while the pipe offers protection and support for the surface casing, which is the next set of outer pipes in the well structure. In addition to these benefits, the pipe also prevents the washout of bulk material below the rig during scuttling operations.
In most cases, the lead pipe is installed in one of three ways. The pipe can either be drilled into a hole made by an auger drill and then cemented in place, or the second method is pile driving, which sees the pipe driven into the ground by repetitive blows of a heavy jackhammer or diesel engine known as a pile driver . The third method is a combination of the previous two procedures and is used when pile driving fails to drive the conducting pipe to the correct depth. In this case the tube is driven to the point where it refuses to continue, the hole is then extended a short distance by drilling and the tube is inserted again until it rejects. This process is repeated until the pipe reaches the correct depth.
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