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Drilling Process

General

To drill a well, a specialized piece of equipment known as a drilling rig bores a hole through many layers of dirt and rock until it reaches the oil and gas reservoir where the oil is held. The size of the borehole differs from well to well, but is generally around 12.5 to 90 centimeters wide. To cut through this rock, the drill is pushed down by the weight of the piping above it. This piping is used to pump a thick fluid known as mud into the well. This mud assists in the drilling process by maintaining the pressure below ground in the well as well as by collecting debris created from the drilling and bringing it up to the surface. As the drill digs deeper sections of piping are attached to lengthen the well.

cement

Part of the process of preparing a well for further drilling, production or abandonment, cementing a well is the procedure of developing and pumping cement into place in a wellbore. Used for a number of different reasons, cementing protects and seals the wellbore. Most commonly, cementing is used to permanently shut off water penetration into the well. Part of the completion process of a prospective production well, cementing can be used to seal the annulus after a casing string has been run in a wellbore. Additionally, cementing is used to seal a lost circulation zone, or an area where there is a reduction or absence of flow within the well. In directional drilling, cementing is used to plug an existing well, in order to run a directional well from that point. Also, cementing is used to plug a well to abandon it.

casing

Once a well has been drilled, if it is to become a production well, the well must undergo completion. While drilling a well cuts through the rock formations and allows drilling engineers to reach the reservoir below, the raw sides of the well cannot support themselves. Similar to the bones of your spine protecting the spinal cord, casing is tubing that is set inside the drilled well to protect and support the wellstream. In addition to providing stabilization and keeping the sides of the well from caving in on themselves, casing protects the wellstream from outside contaminants, as well as any fresh water reservoirs from the oil or gas that is being produced.Also known as setting pipe, casing a well involves running steel pipe down the inside of a recently drilled well. The small space between the casing and the untreated sides of the well is filled with cement to permanently set the casing in place.

fishing

In technical terms, a fish can be any object which has been lost or stuck in a borehole, and has a serious negative impact on well operations. Fishes can be anything, whether that is a drill string that has come away, a bit cone, or even a hand tool that has been inadvertently dropped into the well. To solve this issue, fishing involves the use of special tools and procedures to recover the fish and allow drilling to continue. While this article will deal solely with regular fishing, there is also an alternative method, which involves using through-tubing processes that make use of tools on a wireline or coiled tubing.