Sharon Goehring's
Summer 2001 Internship

She gained experience on the geologic workstation, used well logs and 3D seismic data. She also learned about the 'field' side of geology. With her interests in both geology and computer science related studies, this internship was a great way to blend the two disciplines. While at RMOTC, Sharon completed a survey of fractures within oil producing strata, mapped structures to correlate with well logging and seismic data, and studied petroleum geology.

Tools

Sharon and her partner, Casie, needed to learn the oil field and how to use the Global Positioning System (GPS). The oil field is on Teapot Dome³ (remember the 1920s Teapot Dome scandal from US history?) near Casper, Wyoming. To do this, they were sent fence mapping - plotting the fence line around the field. The GPS would accurately place the fence on a map on the computer so RMOTC can check if all fences were in place and within the property limits. Here, Sharon is using the GPS, one of the tools of her trade¹. To get around, one of the neat things she gets to do is use cool ATVs^*. Sharon and Casie are posing for the cameras^* on their transports.

Formations

Their next task was to learn the rock formations that are present in the oil field. Formations are thick units of rock that are defined by their lithology (rock content) and usually fall within a particular age because they were deposited under certain conditions. You might think of them as rock layers or beds, but in official terms, those are much thinner. First, they visited an area around Alcova Lake³. Most of the formations were exposed there. Two prominent units are the Chugwater and Goose Egg formation³. The Goose Egg is made of alternating layers of red shale and white limestone rocks. Above it is the Chugwater - the conspicuous bright brick red sandstone and shale formation - which was formed during the Triassic, the beginning of the dinosaur age.

Typical Work Day

A tough day at work means Sharon is busy climbing mountains. One thing all geologists must learn to do is section mapping. A section is an exposed surface, natural or artificial, of the earth's crust. Mapping involves carefully measuring each formation exposed, noting the way it touches the layers above and below it, and a detailed description of the rock found in it. Here Sharon and Casie are working on their section mapping². Sharon is determining the rock in an evaporite bed the old-fashioned way - she's licking it². As it turns out, it wasn't salt, but Gypsum (CaSO₄ 2H₂O), the most common sulfate mineral associated with halite (salt) and anhydrites. Eventually, they did reach the top of the mountain² for a magnificent view. On the way down², Sharon is standing in front of an upward-coarsening sequence. The grains of the rock are getting larger as you continue upward; it's a sign of a shallowing of the water in the region.

Fractures

After learning rock formations, they began work at Teapot Dome. Their main project was to map fractures, cracks in rocks, found within the Steele shale formation. Fractures provide conduits for hydrocarbon flow and can create reservoirs in shale which normally can't hold oil. These fractures, if drilled perpendicular to their most common orientation, might provide a new source of oil and gas. Sharon and Casie needed to determine the most common fracture direction. In this picture, Sharon is climbing up the cliff side¹ to measure the fractures. Here she is measuring fractures¹ using her Bruton compass and hammer. A Bruton is a pocket instrument with a compass, folding open sights, a mirror, a level and climnometer. It can be used for reading horizontal and vertical angles, leveling, and the magnetic bearing of a line (see #5 'You know if you are a Geologist'). An example of a fracture is seen in this large fracture in the Tensleep formation² at Alcova Lake.

Grabens and Faults

Another important task was the mapping of a graben on the east side of the field. A graben is a section of a mountain which is bordered by faults and has dropped downward in relation to the rest of the mountain. A fault is a crack in rock along which there has been movement (a fracture hasn't any visible movement). Here are Sharon, Casie, and one of their mentors, Judith, on the top of the entire graben⁶. Sharon is the one on the far left sitting down and studying some Jurassic dinosaur fossils⁶ they found. To determine how far the graben dropped, a marker bed is measured on the undropped mountain and on the graben. A marker bed is a stratigraphic feature that is distinctive and easily recognized over long distances. Then they can compare the elevation and position of the marker bed on the graben and see how far it dropped from the marker bed on the higher sides. Sharon and Casie had to measure where the faults are. Here they are standing on one of the fault lines⁶ at the top of the graben.

Fossils

Here's an exciting find Sharon and Judith made. It's a giant ammonite³. In her own words, " We were mapping the graben just east of the field. Judith noticed a very large round rock. As we were looking at it, I said it looked like an ammonite and asked if any got that big. Judith said she saw a picture of one that was much taller than a man. This one's about 6'. Anyway, the way it sort of spirals inward and especially the radiating fractures might mean its an ammonite. But if it is, it's a cast - not a proper replacement fossil. A cast is when the critter is buried and the body decays away, but the exact space is left behind. Then later rocks fill in the hole making a cast. You know like in art. So far paleo people that Judith has spoken to and the paleos at the museum are very excited."

Fun and Exploration

Of course, it isn't all work. Sharon got an opportunity to go the NCAA Rodeo Championships³. And the RMOTC internship also allowed Sharon to visit some of the great geologic formations in this part of the country. Here's a picture of the interns at Freemont Canyon². It's about a 30 minute drive from their apartments. They are all standing funny because it's very very windy. From left to right it's: Cassondra, Casie, Sharon, and Alan. Sharon got to visit Yellowstone National Park. Here they are at the entrance to the park⁴ and another at Travertine Falls⁴. A great scenic shot of the river canyon⁵, Old Faithful³, Travertine Falls in Mammoth Springs⁵ (it's a deposit formed by geysers), another view of the Falls³ (the falls are a deposit from the hot springs. They should usually be much prettier, but this year there is a drought and these guys are basically dry instead of spilling into each other), a paint pot³ (very deep hole and the colors are caused by the growth of different bacteria and algae) and another shot⁵ of a river valley. She saw lots of wildlife³ close up. On this trip, Sharon also got a look at the Grand Tetons³.

Papers

Sharon and Casie presented their presentation and paper on 1 August 2001 to the staff at RMOTC. Click here to view their paper (requires Adobe Reader). Due to size restrictions, the paper's Appendices and their Powerpoint presentation are not included.