Nevada Petroleum & Geothermal Society – September 6

Dinner Meeting: Thursday, September 6, 2012 – RSVP today (Tuesday September 4)!
Ramada Reno Hotel; 6:30 PM
1000 East 6th Street, Reno, NV 89512

Speaker: Jerry Walker, Geologist, Reno, NV 
Title: Oil exploration & production in Nevada: a snapshot 

Abstract: There is no other State in the Union quite like Nevada, particularly so geologically.  Because our State lies almost entirely in the Basin-and-Range, we have been abundantly endowed with mineral resources.  Nevada has led the nation in the production of gold, barite, and gypsum.  Though our State is only a minor oil producer – in fact, Nevada currently ranks only 26th out of the 31 producing states – it is undoubtedly recognized as one-of-a-kind when it comes to the character of its oil fields.

There are currently 17 oil fields in Nevada.  These fields are concentrated in two valleys in eastern Nevada – Railroad Valley in Nye County and Pine Valley in Eureka County.  Oilfields are clustered in eastern Nevada because this is the part of the State where source rocks are found.  Geologists have identified two principal source rocks: 1) the Mississippian Chainman Shale, deposited in a marine trough east of the Antler highlands about 330 to 350 million years ago, and 2) the Tertiary Sheep Pass Formation, deposited in a complex of low salinity, alkaline lakes about 40 to 65 million years ago.

The main reservoir rocks in these fields are massive slide blocks in the Tertiary valley-fill; Tertiary volcanic tuffs in the Garrett Ranch Formation; Tertiary limestones and dolomites of the Sheep Pass Formation; and Paleozoic dolomites, as found in the Guilmette and Simonson formations.  Fracturing and dissolution porosity provide the storage capacity and permeability for these reservoir rocks, some of which are indeed world-class.

Traps in Nevada combine elements of structure and stratigraphy, a result of the geologic complexity in the Basin-and-Range.  The key to a hydrocarbon trap in Nevada is an adequate seal.  The best seal is commonly called “Unconformity A”, which is a low permeability zone at the base of the Tertiary valley-fill.

What Nevada is lacking to be a major oil producing state is an excellent seal, such as a thick layer of salt.  Nevada has good source and excellent reservoir rocks, but a paucity of sealing lithologies.  Thus, a large amount of oil generated in Nevada over the last 5 to 10 million years has escaped to the surface.  However, when an oil accumulation is discovered, the flow rates can be very large.

The remainder of this talk will focus on two of the many stories about the Nevada oil patch.  First, I’ll relate the story of the discovery of oil in our State.  Shell created headlines in 1954 when their Eagle Springs well – the first exploratory hole drilled in Nye County – hit oil.  Then, I’ll talk about our State’s most prolific oil field, and why, since its discovery, almost all prospects are “… just like Grant Canyon.”

Cocktail Reception 6:30, Skyline Bar, 14th Floor
Dinner Served at 7:00 PM
NPS Members $20; Non-Members $23; Students $10

Menu:
Buffet style including chicken & beef entrees with side dishes and salad
**RSVP by Tue Sep 4 to Judy Kareck (775) 827-6111 or jkareck@lumosengineering.com

 

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