There is a lot more to successful oil production than simply finding some ground seepage, drilling a hole, and extracting oil. There are various types of oil wells and stages of drilling, each of them having its relevant purpose, cost, and associated risks. Paul Favret mentions that oil and gas companies first have to complete a range of crucial exploration activities even before thinking about where to drill a well. Typically, geologists are the ones who identify areas that are likely to contain hydrocarbons based on factors like geological conditions and nearby production.
Exploration wells or wildcat wells represent the very first stage of the drilling efforts of a company. They are basically drilled to find out whether or not there is any gas or oil present in unproven locations. At times, they can even be used to extend the limits of a known pool. Rather than production, exploration wells are used to make a discovery and build on existing groundwork areas like fluid and rock properties, reservoir productivity, and initial reservoir pressure. It takes approximately five years or so years for a petroleum discovery made by an exploration well to reach production.
Appraisal wells conversely are drilled once a discovery has been made by oil and gas companies. These wells have a higher chance of success than exploration wells and are commonly used for the purpose of determining the size of an oil gas field and its expected production rate. Appraisal wells are able to provide good risk/reward ratios when speculating on drill outcomes.
Paul Favret says that once a hydrocarbon accumulation has been discovered, analyzed, and deemed economic, a company moves into the next phase, which is to drill a development well. Paul has been a part of the oil and gas industry for years. Through three prior public company purchases, his company, Resource Energy, acquired a stake in more than 384 wells in its first year. His work in the industry has provided him with a wealth of knowledge about diverse aspects of the oil drilling process.
Developmental wells have way more chances of success than both appraisal and explorations wells but are more expensive as well. These wells are deeper and broader than exploration or appraisal wells. Moreover, their life cycle and operational period are also considerably longer. Companies usually try to maximize the economic production of a developmental well by leveraging the data collected from its previous work and drilling to depths it considers likely to be most productive.
Sidetrack wells are commonly used when a well has already been drilled or at least part-drilled, but there is still the need to drill out of one side of a well to a distinctive target. There can be several reasons for doing this. For instance, a part of the original well might have been rendered unusable owing to a collapsed wellbore.