COAL BED METHANE

Presented by

Vivek priyadarshi

M.Sc Petroleum Geosciences

Sem-III

What is coal bed methane?

• Standard natural gas: CH4

• Methane forms along with coal

• It is held in the cleats with the coal

• Substantial water pressure needed to keep methane in the coal: 400 to 1000 ft ?

Ref.www.Coalbed_methane.htm

" Decaying Organic matter is: – Buried – Cooked – Pressurized

" Creating – Coal – Methane – Other gases

The (Simplified) Science of CBM

Ref.www.Coalbed_methane.htm

Methane Storage in Coal

Methane in coal is:

• Adsorbed on the surfaces of the coal

• Stored as free gas in the cleats and open pores

Ref:-www.wsgs.uwyo.edu/Coal/CBM_Info.aspx

CBM EXPLORATION

“act of searching thoroughly and/or travel for the sake of discovery” - Chambers

PARAMETERS IN CBM EXPLORATION

• Regional geology of the area • Mapping and surveying• Areal extent of coal seams• Thickness of the coal seams• Permeability in the Coal as measured by tests, logs, etc.• Gas content data

INITIAL STAGES OF CBM EXPLORATION

Stacking of location Planning strategy for cbm - geo technical order. - preparation of master log.

CBM DRILLING

CBM DRILLING

BORE HOLEVERTICAL DRILLING

CONVENTIONAL VERTICAL DRILLING

BORE HOLE DRILLING

• Low Clay Polymer Mud system

• Surface casing only• Continuous coring of

formation• Plotting of litho columns.• Correlation of litho columns

on the basis of borehole data.

• Sub-surface information are revealed and interpretations are done. Ref:- Raniganj bore hole drilling (photograph)

CONVENTIONAL VERTICAL DRILLING

• Mud circulation for the -stability of bore hole and -removal of cuttings. • Mud used:- - bentonite suspension and -PHPA (Partially hydrolyzed

polyacrylic amide) • Casing – 2 Casing Policy (12¼” - 9⅝”, 8 ½”-

5 ½”)• Cementation - Two stage

cementation or light weight cementation- due to large column of cement & low fracture gradient of Coals.

• Casing perforations

Ref:-www.coal bed gas drilling information.htm

CBM PRODUCTION TECHNIQUE

HYDRAUFRACTURING

Ref:-www.prowell-tech.com/impulse hydrofracturing.html

DEWATERING

Ref:-Coalbed_methane.htm

Pressure drawdown profile of a single well

Water Flow Only

DiscontinuousGas Flow

ContinuousGas Flow

For CBM reservoirs, we need to deplete the reservoir pressure down low to get the gas out.

Source : ONGC Task Force Report 2006

SL.NO. COUNTRY COAL RESOURCES CBM RESOURCES( BILLION TONNES) (TCM)

1 RUSSIA 6500 17-1142 CHINA 4000 31.83 USA 3970 124 AUSTRALIA 1700 10.85 CANADA 7000 10.26 INDIA 241 1.07 S. AFRICA 150 3.28 U.K. 190 2.89 POLAND 160 2.8

10 GERMANY 320 2.811 ZIMBABWE 8 0.05

WORLD WIDE CBM RESOURCES

USES OF COAL BED METHANE

• Clean burning fuel for domestic and industrial uses.

• Motor fuel • Cleaning of recovered substances and methane

supply to natural gas pipelines • Electricity generation (diesel generators, gas

turbines, internal-combustion engines ) • Supporting mine operations • Community needs (heat and electricity) of

adjacent territories • Mine boilers – switching from coal to gas