Table of Contents
- 1 Unconventional Gas Reservoirs
- 2 Coalbed Methane
- 3 Coalbed Methane India (CBM)
- 4 Problems — Exploration, Extraction of CBM
- 5 Shale Gas
- 6 Shale Gas Reserves Across the World
- 7 Shale Gas Reserves in India
- 8 Problems Associated With Shale Gas Exploitation
- 9 Solutions
- 10 Shale Gas: Low Potential, High Risk and a Better Alternative
- 11 Mains 2013 Questions
Unconventional Gas Reservoirs
- Conventional reservoirs of oil and natural gas are found in permeable sandstone.
- Unconventional Gas Reservoirs occur in relatively impermeable sandstones, in joints and fractures or absorbed into the matrix of shales [Shale is a Sedimentary Rock], and in coal.
- Given current economic conditions and state of technology, they are more expensive to exploit.
- Example: Tight gas, shale gas, and coalbed methane.
- Considerable quantities of methane is trapped within coal seams.
- A significant portion of this gas remains as free gas in the joints and fractures of the coal seam.
- Gas are adsorbed on the internal surfaces of the micropores within the coal itself.
- Extraction — pumping large quantities of water that saturate the seam. [water will occupy the gaps and pores and will push out the gas]
- Important source of natural gas.
- It contains — very little heavier hydrocarbons — propane or butane.
- The presence of this gas is well known from its occurrence in underground coal mining, where it presents a serious safety risk.
Fire Accidents in Coal Mines are mainly due to Coalbed Methane, and Lignite deposits which undergo spontaneous combustion.
Coalbed Methane India (CBM)
- India holds significant prospects for commercial recovery of coal-bed methane.
- The country has an estimated 700-950 billion cubic metre of coalbed methane.
Problems — Exploration, Extraction of CBM
- No right for private participation in exploration of CBM or Shale
- Lack of inter-ministerial coordination — Petrol Ministry v/s Coal
- Capital Intensive | not much profitable
- Technological incapabilities | weak org. Setup
- Restrictive laws
- Complicated Gas pricing in India
- Shales are fine-grained sedimentary rocks formed of organic-rich mud at the bottom of ancient seas.
- Action of heat and pressure
- Over time — migration of gases to nearby SS — becomes conventional gas
- Shale Gas — locked in the nonporous shale | formation and storage at the same place
Shale Gas Reserves Across the World
Shale Gas Reserves in India
- Cambay (GJ), Assam-Arakan Basin, KG Basin
- Tech involved — Hydraulic Fracking
- Need lots of water and land and Gaur Gum (expensive shit)
- Environmentalists have objected to fracking because of the damage to forest cover and possible contamination of ground water.
- One estimate by Indian scientists places potential reserves at as high as 527 tcf.
Problems Associated With Shale Gas Exploitation
- Environmental Hazards | GW contamination | Forest damage
- All the water required must be obtained from rain water harvesting.
- Recycling and reusing of water
- Enforcing clear and practical legislation on environmental and water issues.
Shale Gas: Low Potential, High Risk and a Better Alternative
- India’s shale resources at a more modest 65 trillion cubic feet. India’s CBM potential is estimated at 450 tcf. 450 vs 65 !
- So, focus must be on CBM exploration rather than on risky shale business.