GEL 1 Lecture Notes - Lecture 27: Shale Gas, Monterey Formation, Directional Drilling
Shale gas
●oil and natural gas are generated within organic-rich black shales
●mudstones, siltstones, claystones
○very un-porous material
○may have some pores but still very low permeability -- good host for natural gas but
it doesn't go anywhere
■different from oil deposits, that have good porosity and permeability (pores
are connected)
●deposits have been cooked (increase the temperature of oil → natural gas)
●how do they accumulate?
○some source rock
■trapped by sealing rock (impermeable, like salt or shale)
Who has the Shale Gas?
●China
●Argentina
●Algeria
●U.S.
Fracking
●allows us to access natural gas contained in shale by making rock more permeable
●combines 'directional' drilling with the forcible fracturing of rock using pressurized water
(mixed w/ chemicals and sand)
●several thousand meters down in a place you know you have source rock
○water injected into the end of the drill bit seeps out and creates fractures in the rock
■natural gas can then flow out up the pipe and into the well
A new California oil boom?
●drilling in the Monterey formation
○varies from being incredibly permeable to incredibly not
○contains 3x as much recoverable oil as the next largest shale oil
○avg 11,000 depth
■oil at the surface, natural gas very deep
○less diatoms and more shale that has trapped a lot of natural gas
○could create up to 2.8 million new jobs
○generate $24.6 billion per year
●more fracking regulations
○cut estimate of recoverable shale oil by 96%
Pros and Cons of Fracking
Risks of Fracking
●groundwater aquifer contamination
Document Summary
Oil and natural gas are generated within organic-rich black shales. May have some pores but still very low permeability -- good host for natural gas but it doesn"t go anywhere. Different from oil deposits, that have good porosity and permeability (pores are connected) Deposits have been cooked (increase the temperature of oil natural gas) Trapped by sealing rock (impermeable, like salt or shale) Allows us to access natural gas contained in shale by making rock more permeable. Combines "directional" drilling with the forcible fracturing of rock using pressurized water (mixed w/ chemicals and sand) Several thousand meters down in a place you know you have source rock. Water injected into the end of the drill bit seeps out and creates fractures in the rock. Natural gas can then flow out up the pipe and into the well. Varies from being incredibly permeable to incredibly not. Contains 3x as much recoverable oil as the next largest shale oil.
