Introduction to Geology

The formation of hydrocarbons depends on a variety of geologic processes, and basic knowledge of geology is essential to understanding the process.

Geology

What exactly is geology?

Images of an old, scraggly prospector examining a crystal may come to mind.

But geology is much more than the study of rocks and minerals.

Geology attempts to describe, conceptualize, and predict the behavior of the entire Earth System. This system includes the rocks of the earth’s crust, the oceans, the atmosphere, and the deep interior of the earth.

The aim of geology is to come to an understanding of the interrelated processes that occur within these systems over long spans of time.

Geology isn’t just for prospectors and academics, though. It literally underlies everything we do in the hydrocarbon-based energy environment.

Distributed throughout this course, we will learn from the experience of experts from different parts of the business and regulatory community as they share their thoughts about topics under discussion. In this Perspectives piece, let’s hear from Bill Sydow, Director of the Nebraska Oil and Gas Conservation Commission, as he shares his perspective on why subsurface geology is important for regulators to understand.

Transcript

Subsurface Geology – Bill Sydow – Nebraska Oil and Gas Conservation Commission

I want my people to be pretty familiar with the subsurface geology. Geology, to me, is a core … I don’t even know if I want to call it a science, an art. But when you know about a well and what maybe the company really expects, I think you can feel like you have some ownership of that well, even though you don’t and we can’t, but you have some ownership of that. So the interest level is up a little bit more. As well, just to know about a well, because the general geology in that location, there are many things that come off the geology.

The well design, as far as casing and where the casing needs to be set so we can, in one fashion, protect drinking water from the underground sources in the reservoir, but that well needs to be set, so geology controls that. Geology will control the type of the drilling fluid that you use. Actually, the geology of a specific reservoir maybe will dictate certain parameters of the drilling fluid, like especially the water loss of the filtrate. Perhaps even there are swelling clays or water sensitive clays in the reservoir that you need to protect, so that goes back to geology. When you complete the well, again, it’s geology. Maybe for the stimulation fluid, if it was acid soluble or you need to fracture stimulate it, those fluids, again, will be dictated by the geology. Reservoir pressures, it’s all inclusive. I just found this out when I used to drill our own wells, before I was in this position. I could come in and know pretty much exactly where that well was at, what we were drilling through. It’s just a visual help.

Petroleum Geology

Petroleum geology uses the tools and theories provided by geology to study the formation, migration, and entrapment of oil and gas. A petroleum geologist aims to find new oil and gas reservoirs, estimate the contents of existing reservoirs, and develop models of the subsurface in order to inform oil and gas recovery efforts.

The study of petroleum geology draws upon a wide range of concepts within the field of geology. In this section, we’re going to cover the most important of these concepts.

Images: “Folded Rock” by Matauw via iStock