Petroleum Reservoirs for Utter Dummies

petroleum reservoir, trap, and seal

Several of the staffers here at the Antisocial Network have their "go-to topics" for days when the eternal search for internet bogosity is going a little too slowly. One of them spent a couple of decades working in the "oil patch," and he says that the odds that a freelancer will "get it right" about the oil industry run about 15:1 against. He's already proven that point more than 30 times. Well, he's here again to present today's DotD to Esther Ejim of WiseGEEK.com for her attempt to explain, "What Is a Petroleum Reservoir?" (now at AllThingsNature.com).

Let's get the correct definition out of the way already. The iconic Schlumberger OilField Glossary defines a reservoir as "A subsurface body of rock having sufficient porosity and permeability to store and transmit fluids" (by "fluids, they mean crude oil and natural gas). You could go a little farther and mention that a reservoir comprises three parts: the porous "reservoir" rock, a geometry that "traps" or allows the accumulation of fluids, and an impermeable "seal" that keeps the fluids from leaving.

We looked at Ejim's post, and while she repeats the word "reservoir" sixteen times; "rock," "seal," and "trap" all appear exactly zero times. Instead, Esther regales her readers with verbiage such as,

"A petroleum reservoir is a term that is used to describe the accumulation of crude oil in a defined location. Usually, the location where the crude oil may have formed is often [sic] underground or beneath the sea or ocean floor. These formations are the result of the decomposition of organic matter over the course of centuries, which is why the fuel or energy that is derived from such is known as a nonrenewable source of energy."

Let's "unpack" that bushwa and make a few suggestions to improve Ejim's accuracy: A reservoir is where the oil accumulates, not necessarily where it forms. Reservoirs are always subsurface, not "Usually... often underground or beneath the sea or ocean floor" Reservoirs are not caused by decomposition of organic matter; hydrocarbons are the result of that decomposition. Reservoirs are inorganic rocks. It takes hundreds of millennia to convert organic matter to hydrocarbons, not "centuries."¹ Ejim seems to be completely unaware of the processes involved in petroleum exploration, suggesting to her readers that,

"A petroleum reservoir may be discovered by accident, as has happened when the oil seeps to the surface or when the oil seeps into water supply [sic], consequently revealing its presence in that location. Other times, it is often necessary to intentionally explore different regions through the application of scientific and geographic knowledge with the view of discovering other places that may contain petroleum reservoir [sic]."

If oil is so easy to find, then why did Exxon-Mobil budget almost $1.8 billion for exploration in 2017? According to Esther, the stuff is just lying around! And finally, Ejim seems to be rewording a second-grade science book as she explains the exploration process:

"Some of these oil companies have expensive oil rigs located on both onshore and offshore facilities where they are utilized in drilling holes that go down many feet into the ground as part of the process of extracting the crude oil from the reservoir."

Ummm, yeah: that's the ticket.  Ejim's definition of a petroleum reservoir is beyond sophomoric and her understanding of the work of "big oil" is clearly limited to thinking that there must be an oil well under every gas station. When we find someone this ignorant getting paid to "edify" the public, we are more than happy to hand them the Dumbass of the Day award.

¹ When we see numbers like that, we wonder if the author is merely ignorant or perhaps subscribes to the "young earth" idea of Bishop Usher, who estimated the age of the planet at about 8,000 years...

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