Geological conditions are the single most important factor when an oil company like Weatherby Energy is looking for a potential drilling site. In fact, a full geological analysis will be done on the land prior to any drilling processes being started. Since drilling is a very expensive process, Weatherby Energy will want to ensure that the efforts put forth will yield results in the form of oil or natural gas. In order for any area to contain gas, the conditions must be right. The right types of sedimentary rocks must be present along with the potential for a trap to form that will hold the petroleum product.
Types of Petroleum Traps
Weatherby Energy acknowledges that there are two distinctive categories of petroleum traps that will retain the oil in the reservoir. The way that traps are created is by natural geological occurrences. Such occurrences include:
When these geological occurrences happen, a natural petroleum trap can be formed. There are two types of petroleum traps that oil companies like Weatherby Energy look for when determining a drilling site.
Structural Petroleum Traps
Structural petroleum traps occur when there is a geological deformation in the sedimentary rocks of the Earth’s crust. There are three prominent types of structural traps that oil companies like Weatherby Energy are aware of.
• Anticlinal and Dome – These types of traps occur when the rock formations that once lay horizontally shift upwards into the shape of an arch or a dome.
• Salt Dome or Plug Trap – A salt dome, also known as, a salt plug trap is a trap that occurs when salt that lies further down becomes intrusive, pushing rock layers upwards in a dome form.
• Fault Trap – A fault trap is one that occurs when rock layers are stressed both vertically and horizontally. A fault trap is one where the broken layers are pushed vertically and rest against one another. This allows the hydrocarbons to naturally accumulate when a porous rock layer is below a non-porous layer.
Stratigraphic Petroleum Traps
Another type of petroleum trap that companies such as Weatherby Energy look for, are stratigraphic traps; stratigraphic traps do not occur with movement of rocks like structural traps do. Instead, stratigraphic traps are formed when variations occur between stratified rock layers. Although the traps are different in nature, they are still significant to petroleum and make viable traps. Like structural traps, there are three significant kinds of stratigraphic petroleum traps:
• Lenticular Trap – A lenticular trap is one that is formed by potential buried sand layers such as those from buried beaches or river bars.
• Pinch Out / Lateral Graded Trap – This is a trap that is formed by a type of lateral deposition. The environmental deposition must be in an up-tip manner for this type of trap to develop.
• Angular Unconformity Trap – Older rocks that dip under the forces of newer rocks form what is known as the angular unconformity traps.