What is a Reservoir?
Oil companies like Weatherby Energy spend many years studying lands that they wish to develop drilling sites on. There are many factors that these oil companies have to look for in terms of viable land. There must be significant evidence shown by a geologist that the possibility of the existence of oil is strong.
When a geologist does an analysis on the land for companies such as Weatherby Energy, they are in search of a petroleum trap that houses a reservoir. A reservoir is a permeable source of rocks underneath the surface of the land that allows for both the flow of fluids as well as having storage capabilities. Weatherby Energy will not drill if there is no evidence of a reservoir existing below the surface, as it will prove to be a waste of time, money and efforts. There are two types of reservoirs that are worth noting:
• Sandstone Reservoir – Sandstone reservoirs mainly consist of clastic sedimentary rocks that have accumulated from sources such as beaches, river channels, deltas and lakes.
• Carbonate Reservoir – Carbonate reservoirs do not typically include any clastic sedimentary rocks and if they do the clastic rocks are at a minimum amount. These reservoirs are typically created in marine environments.
It is not enough for a reservoir to exist; further studies must be done for companies like Weatherby Energy to make the decision to drill. There are many characteristics of a reservoir that are measured before a decision is made.
• Depth – There are two depths that are measured in reservoirs: shallow and deep. Slight shifting of the rock formation under the surface of the land normally causes a shallow reservoir. Major faulting in the formations, on the other hand causes deep reservoirs.
• Thickness and Area – This is a major consideration when companies like Weatherby Energy are making the determination as to whether the reservoir is commercial in nature. The greater the thickness and area of the reservoir, the more likely the potential for vast accumulations of gas and oil. It should be noted, however, that there are smaller reservoirs that do produce a large amount of gas and oil.
• Porosity – The porosity of a reservoir is determined by a formula where the volume of the void space is divided by the total volume of the rock. Porosity measures how much storage the reservoir can hold in terms of gas and oil.
• Permeability – Permeability is the calculation of how easily the sedimentary rocks will allow fluid to flow through them. The ability to estimate permeability will allow companies like Weatherby Energy to determine how much of the hydrocarbons will be able to be produced from a reservoir.
Determining all of the factors of a reservoir that has been discovered is necessary for an educated decision to be made on the drilling process. If a reservoir is found to be desirable, the drilling process is likely to commence after a plan has been mapped out.