Type of Conventional oil wells

Exploration wells are tentative ventures that drill in new areas with the hope of discovering untouched resources. 

These tend to be the highest risk wells in terms of failure versus success.

Exploratory Well (Succeed)

Appraisal wells are used to evaluate the characteristics of existing hydrocarbon accumulation.

An oil and gas company will typically go on to drill an appraisal well once a discovery has been made. The wells, which have a higher chance of success and are more expensive than exploration wells, are used to determine the size of an oil gas field (both physically and in terms of its reserves) and its expected production rate. 

Appraisal wells can offer the best risk/reward ratios when speculating on drill outcomes. 

Appraisal wells

Wildcat wells are projects located outside of already established oil and gas fields.

Wildcat wells are usually drilled to find out if there is any oil or gas present in an unproven location.

However, they can also be used to extend the limits of a known pool.

Wildcat wells

Production wells or development wells are constructed specifically for harvesting oil and gas.

These wells typically have a much higher chance of success than those previously mentioned. However, they are also very expensive, costing anywhere from $1m to $9m each. This is because they are broader and deeper than exploration or appraisal wells and their life cycle and operational period is significantly longer.

Production Well

 

abandoned wells are wells that are permanently sealed.

Sidetrack wells are used when a well has already been drilled or part-drilled but there is a need to drill out of one side of a well to a different target.

Side track Well

Relief wells are used to stem oil or gas flow from a separate, damaged well. Firms will often base these wells at some distance from the damaged well before using directional drilling to intersect the damaged well at a great depth. Specialised liquid like heavy drilling mud or cement is then pumped into the damaged well to stem any unwanted flow.

Relief wells

Infill drilling wells are, wells that are drilled between two oil two oil proved wells to know whether oil is present or not in between.

Infill Drilling

Injection wells are used to place fluid or gas underground into porous geologic formations. Anything from water to carbon dioxide can be injected into anything from deep sandstone to shallow soil layers for purposes such as enhancing oil production, waste disposal, and the prevention of salt water intrusion.

Horizontal wells are becoming an increasingly popular alternative to traditional vertical wells. Rather than terminate drilling once its well has reached its desired depth, a firm operating a horizontal well will rotate its drill bit by 90 degrees and continue to drill along its target horizon horizontally for up to 10,000 feet.

Horizontal Well