Presentation on theme: "Petroleum Geology and the Permian Basin Andrew McCarthy Concho Resources."— Presentation transcript:
Petroleum Geology and the Permian Basin Andrew McCarthy Concho Resources
Petroleum System 2 Source: organic-rich mudrock Heat (burial) and time Reservoir: porous rock Seal: low-permeability rock Trap
Source Sol (our sun) Fusion (of hydrogen and helium) Earth 3,850,000 exajoules per year – Solar radiation 3,000 exajoules per year – captured by plant life 500 exajoules per year – total human use (fossil, nuclear, etc.) 3,850,000 EJ 3,000 EJ burial
Source Heat and pressure Kerogen Kerogen: geo-plastic or geo-chocolate. Lipids, proteins, carbohydrates Gas (methane, ethane, propane) Texas tea (light, sweet crude) CO2 N2 H2S + Shale: high organic material
How much heat? Low temps yield nothing: <60 C High temps yield oil: 60C-120+C Higher temps yield gas: 120+C
100% natural and organic Oil is 100% natural and organic 95%++ of all oil ever generated has been naturally leaked to the surface Millions of natural oil seeps exist around the planet, many under the oceans Yummy! Natural Oil seeps (BP not Involved) Not Iced tea
An oil reservoir at the surface Oil reservoirs are exposed and eroded away. The light oil is biodegraded, tar remains.
OK. So far we have: Source Heat and time Now we need a reservoir, a seal, and maybe a trap
Reservoir The first key to a reservoir rock is porosity intergranularfracture
Reservoir The second key to a reservoir rock is permeability
Seal Imagine if this were clay… We need something to slow the upward migration of oil and gas. A seal will do: it’s a layer of very low permeability. Microscopic view of clay layers
Traps Required for conventional reservoirs…
A very conventional petroleum system: Concho sand organic shale sealing shale oil
Organic mudstone, silty shale, with varying carbonate and silica content 1 source 2 reservoir 3 seal Tight carbonate (seal/frac barrier) Today: Unconventional plays
“Shale” plays What is shale? Silt vs. clay Mudrocks (silt, clay, organics, carbonate) Needs help: must be fracture-stimulated (poor natural permeability) Shale rocks can serve as – Source – Reservoir – Seal
The Permian Basin
Today Active petroleum systems
Basins Low areas; tend to fill with sediment Typically covered with water (ocean, sea or lake) Nature’s landfill shelf slope deep basin
Before the Permian Basin Shales: Devonian Mississippian Barnett Before 370 Ma (Devonian) Ron Blakey, Colorado Plateau Geosystems, Inc.
Early Permian Basin 315 Ma Late Miss/Early Penn time Shale deposition Ron Blakey, Colorado Plateau Geosystems, Inc.
Late Permian 255 Ma Carbonates (shallow marine carb factory) Later, evaporites Ron Blakey, Colorado Plateau Geosystems, Inc.
Sources Organic-rich shales
Reservoirs *Just about everything! sands Shale/silt carbonates
What does a geologist do? Exploration very little data! – Seismic, basin geochem, remote sensing – Everything changes with the first well Development increasing amounts of data! – Well logs, core, production data Operations – Day-to-day drilling When do we have “the answer”?