COAL BED METHANE ANDCO2 SEQUESTRATION CHANDAN CHAMAN
In the next few minutes…CBM – An IntroductionCBM Reservoir CharacteristicsProduction of CBM – Its Technical AspectsEnhanced CBM & CO2 SequestrationCBM Potential in IndiaPolicy framework for CBM in India
COAL BED METHANE• Standard natural gas: CH4• Methane forms along with coal and is held in the cleats with the coal.• Coal is both source and reservoir rock.• Methane represent more than 90-95% of the gas volume.• Coal is microporous solid with enormous surface area..• Capable of sorbing large quantity of gas:> 600 cft / ton
COAL BED METHANE• Burial digenesis produces-Biogenic gas : 194º FThermogenic gas : 194ºF to 511ºF• Vitrinite reflectance (Ro) 0.4 to 5.0Optimum (Ro)0.4-1.6• Without cleats, coal Without cleats,is porous but NOT permeable!
CBM reservoirs characteristicsCoalbed Reservoir Gas Content Gas Storage Mechanisms - Free gas within natural fractures - Dissolved gas in water within natural fractures - Adsorbed gas within the coal matrix Total gas Free Dissolved Adsorbed = + Gas Volume Volume Gas + Gas Volume Volume Typically > 95%
CBM reservoirs characteristicsCoalbed Reservoir Porosity Primary porosity: micro pores Secondary porosity: macro pores ( fractures) The coalbed porosity and permeability changes as reservoir pressure is lowered and gas production occurs. The permeability of coal vary in two basic ways: 1- Phase-relative permeability effects 2- Change in the effective stress within the seams Coalbeds can hold 2-3 times as much gas as conventional reservoirs.
CBM reservoirs characteristicsGas recovery conventional vs. coalbeds
Stages of Developing CBM• Drilling: Exploration Phase Drilling Pilot Phase Drilling Development Phase Drilling• Casing & Cementation• Cavity Completion• Horizontal Multilateral Well• Establishing a network ofsuch wells
Critical factors with CBM production• Net coal thickness• Coal rank: low coal rank suggests biogenic gas; very high coal rank indicates little CBM potential• Gas content• Permeability: low and very high are detrimental• Hydrodynamics: must have water production• Depth of target bed(s)
Process of developing CBM• On completion of well, dewatering is commenced• Pumping out water reduces the pressure level• Due to pressure depletion, methane desorbs from matrix and diffuses to cleat system• Methane and water flow to well bore• Methane and water is separated; methane is piped to gas stations.• Water after treatment is either used for agricultural purpose or again recharged underground.
CBM Vs Water ProductionVarious stages of a coalbed methane well
Schematic representation of CBM WellA typical vertical well bore for CBM production
Schematic representation of CBM WellA typical horizontal well bore for CBM production
CBM Establishment at Sohagpur CBM gas/ water separtor - SohagpurCBM Flow Computers - Sohagpur
Enhanced Coalbed MethaneThe injection of CO2 in coalbeds is the most attractiveoption; the CO2 is stored and at the same time therecovery of coalbed methane is enhanced.• Coals have the ability to physically adsorb large volume of CO2in a highly concentrated state• Coals are frequently located near large point sources of CO2emissions• The injection of CO2 into coal seams enhances the commercialmethane recovery process
Benefits of ECBM Sequestration of CO2 in coal is a promising market-basedenvironmental solution that can reduce greenhouse gas emissionswhile increasing CBM recovery Increase in total reserves Recovered methane can be used as fuel for electricity andhydrogen generation Reduction of emitted CO2, a contributor to global warming andlong-term climate instabilityThe greatest impact of CBM may be in countries such asAustralia, China and India where coal is the primary energy sourceand conventional natural gas are small
CDM in INDIA : Major MilestonesAccording to research carried out by CIMFRCategory Coal type CoalfieldsCategory-I Gondwana coals ranking Jharia, East and West Bokaro, high volatile bituminous A Raniganj and North Karanpura and above. CoalfieldsCategory-II Gondwana coals ranking South high volatile bituminous A Karanpura, Raniganj, Pench- and below. Kanhan and Sohagpur Coalfields.Category-III Low rank Gondwana coals Talchir, Ib, Pranhita-Godavari Valley, Wardha Valley Coalfields.Category-IV Tertiary Coals/Lignite Assam-Arakan, Himalayan Foothills, Cambay, Barmer- Sanchor, Bikaner- Nagaur and Cauvery basins.
Scope of CBM in Bokaro Coalfield CBM BLOCK : 1 (AREA – 95 SQ.KM) COAL SEAMS : 22 Nos. SEAM THICKNESS : 2 – 36 m DEPTH : 300 – 1500 m GAS CONTENT : 6 – 12 m3/t HYDROGEOLOGY : SUB ARTESIAN AT PLACES PERMEABILITY : GOOD PERMEABILITY CBM RESOURCES : 45.03 BCM ANTICIPATED PRODUCTION : 2 MMSCMD
CBM Policy in IndiaSalient features of the CBM Policy adopted by the Government of India inJuly 1997 are: No participating interest from the Government of India. Allotment of CBM Blocks through open international competitive bidding. Exploration and Development of CBM under confessional type of agreement through Model Contract. Seven years tax holiday from the date of commencement of commercial production. Nominal commercial bonus of US $ 0.3 million on declaration of commercial assessment. Freedom to sell gas at market driven price in the domestic market. 35% income tax for Indian companies and 48% for foreign companies. Provision of 100% cost recovery. Exemption on customs duty on imported equipment.
Policy framework (CBM) in IndiaThe main laws governing CBM exploration and production in Indiaare listed below : Oilfields (Regulation and Development) Act, 1948 Petroleum and Natural Gas Rules, 1959 Environment Protection Act, 1986 Arbitration and Conciliation Act, 1996 Income Tax Act, 1961 Customs Act, 1962
Conclusion Reduction of green house gas emission and improved environmentalprotection Pre-mining de-gassification of coal seam to make subsequent coalmining safer. Development of downstream gas based industries. Prospect of CBM based power generation have distinct advantage overcoal based power generation. Water produced from CBM wells can be utilized for irrigation or industrialconsumption.