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0 <br />• <br />Oii Exploration and Production Wastes Initiative Key Terms and Conce is <br />Figure 2: Digital Photograph of a Drilling Rig <br />Oil well <br />An oil well can be described as a wellbore that has been completed and prepared <br />for production. Not every new well becomes a producing well. If no oil is found, <br />the well is abandoned through a process called well abandonment. If oil is found <br />in economically feasible amounts, the well is completed, in a process known as <br />well completion. In 1999 in California, 1,752 new wells were drilled, out of which <br />1, 379 wells were completed. Non -producing new wells and wells that have been <br />depleted are plugged and abandoned. 1, 307 wells were abandoned in California <br />in 1999 (CDC, 2000). <br />A first step in well completion is the installation of casing, or hollow tubing that <br />preserves the structural integrity of the wellbore by isolating it from the <br />surrounding strata. Casing is cemented inside the wellbore and houses the <br />production tubing later installed to pump and transport oil from the producing <br />formation to the surface. The above -surface portion of a well is the pumping unit, <br />which may be a mechanical or a more sophisticated hydraulic or electrical <br />device. Figure 3 is a representation of a mechanical pumping unit. <br />Statewide Compliance Division 'MaX 2002 <br />-4- <br />