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Dr. S. K. Singh

VP & Head-Technical-Unconventional

Unconventional Gas Asia Summit (UGAS 2013)New Delhi, 18-19 April 2013

Examining the Technology of CBM Multiple-lateralHorizontal Well


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• Essar CBM Portfolio

• Key CBM Success Factors

• Well completion types, Traditional approach & its limitation

• Horizontal Well types & its Criteria

• Horizontal vs. Vertical Well

• Horizontal Well Design

• Key Challenges in CBM Multi-lateral

• Economics

• Application of horizontal well technology in India• Conclusion

Agenda


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M:

CBM Resources c. 13 TCF

Essar Portfolio


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Essar – Leading in the Unconventional Energy Space

• Pioneering CBM E&P

work in India

• Among the largest CBM

acreage & resources

• Successful CBM venture

at Raniganj

• Technical manpower &

reservoir understanding


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Field overview

Location : Raniganj Coalfield

State : West Bengal

Reserves/ Resources 113 BCF of (Proved+2P reserves,) 2C resources of

445 BCF, Un-risked Prospective is 297 BCF .

Peak Prod. Estimate of about 3.0 mmscmd

Current status

Phase I & II successfully completed and block is

currently in Phase III (since May, 2012).

Presently block producing c. 55,000 scmd One GGS is Completed and operational ,revamp

under Progress. 2nd is being commissioned and 3rd

is under progress.

Key milestones

About 350 more development wells in comingyears for achieving full production

Surface facilities like GGS, MCS and Gas pipeline

being laid down under a BOO model

Provisional Gas sales approval received from DGH,

India. Final approval expected soon.

Gas sales tied-up in both small and bulk scale.

The Raniganj CBM Success so far…


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Drilling Rig For CBM PC Pumps running

at test wells

Separators installed

at test wells

CSR: Plantation at test well

site

Essar Gas sales customer

end-point

Hydrofrac Unit

Completed GGS at site

The Raniganj CBM Success So Far…

Model Well site


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1. Coal Thickness

• Number, thickness and extent of coal seams

• Typically need > 3m in aggregate

2. Gas Content and Gas saturation

• Biogenic and Thermogenic sourcing

• Coal Rank and Type: bituminous/sub-bituminous

• Gas content and composition: > 2 m3/t, 92+% CH4• Sorption properties of coal: >60% saturation

3. Permeability

• Governed by presence of cleats and natural

fractures

• Coal Rank: 0.4 < Rvmax > 1.6 to promote cleating

• Stress Setting: to promote cleat/fracture opening

4. Dewatering capability

• Isolation from pervasive aquifers

Key CBM Success Factors


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Basin Raniganj East

India

Black Warrior

Basin US

North

Appalachian

Basin US

Powder River

Basin US

San Juan

Basin US

Quinshui

Basin

China

Bowen

Basin

Australia

Depth (ft) 1300 - 4500 800 - 3500 1030 - 6570 400 - 1800 500 - 5000

Thickness of coal formation (ft) 20 - 160 1 - 10 2 - 20 70 - 150 - 20 - 40 50 - 100

Coal Rank HV Bit HV – LV Bit HV – LV Bit Lignite - Sub Bit Sub Bit - LV Anthracite Bit

Gas Content (scf/tn) 88 - 353 125 - 680 26 - 445 25 - 75 100 - 600 300 - 900 200 - 400

Permeability (md) 0.5 - 40 0.01 - 40 0.01 - 40 1 - 1000 1 - 60 1 - 5 100

Reservoir Fluid Saturation (%) 70 - 100 80 - 100 50 - 100 100 - 100 100 - 100 - -

Reservoir Pressure (psi)/(psi/ft) 0.433 - 0.5 0.0875 - 0.12 0.3 - 0.4 - -

No of coal seams 6 3 6 6 2 - -

Reserves (Bscf/well) 1 - 2 0.5 – 1.5 - 0.2 – 0.5 3 - 15 0.4 – 0.8 2.5 – 3.5

Source: SPE 103514

Global CBM Plays – Reservoir Characteristics


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5 1/2”

Casing

20”

Casing

9 5/8”

Casing Cement

behind

9 5/8”

Casing,up to

surface

PCP & NTT

PCP &

NTT

Schematic of CBM Well


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Different Completion Types

Open Hole Completion• Simple, cheap & Fracturing not

required

• Generally in high permeability and

high thickness areas

• No Casing is left to obstruct mining

activities

• Cementing does not damage the coals

• Gives unobstructed access to the coal

face from the wellbore


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Open Hole Cavitation• Increases well radius

• Thick seams.

• Good permeability.

• Extensive cleating.

• Ranks of coal beyond the coalification

break.

• Low ash content.

• Over pressured zones

• High in-situ stress



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Cased Hole Completion• Multiple seams per well.

• Thin seams of inches to a few feet thick.

• Marginal economics for producing.

• Large volumes of water produced early in

the life.

• Normally pressured (some under

pressured).

• Depth (1,000 –4,500 ft).

• Coal fines.

• Optimum coal rank, hvAb-lvb.

• Good permeability.



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Open-hole (Barefoot)e.g. Powder River (USA)

Under-reamede.g. Powder River (USA)

Surat Basin (Australia)

Cavitatione.g. San Juan (USA)

Fracture Stimulatione.g. San Juan ,Powder River

Quinshui Basin (China)

Successful Well Completion Types


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Different Technologies; Pad Drilling, Directional well


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• Low gas rate• High well density: 16 wells per

section on 40 acre spacing

• Partial reserve recovery: 10 to 20 ft

coal exposure per well

• Complex gathering system

• Individual well pumps

•Large expensive locations

• Large scale logistic rig movement

Challenges of Vertical wells in CBM


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Lateral in Single zone / Multi zone Multilateralse.g. Qinshui Basin (China)

In –seam & production from vertical

e.g. Bowen basin (Australia)

Multilateral – pinnate pattern

e.g. Bowen basin (Australia)

Horizontal Wells – Different Completion Types


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Well Type Common Scenarios

Vertical/Directional

Cased hole, hydraulic

fracture

•Low-medium permeability (1-30 md)

•Multiple coals / low net/gross ratio

Horizontal or Multi-lateral

•Low-medium permeability (


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• Increased exposure inside reservoir coal

seam per well

• Better connectivity of cleats and fractures

exposure, increased permeability.

• Increased production, better recovery of

coal seam gas, 50-75% in 1.5 to 4.5 mD

• Dewatering time reduction thereby faster

production

• Fewer wells results reduction in surface

facility and land requirement

• Lower CAPEX / OPEX improved returns

Advantages of CBM multiple lateral Horizontal wells


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• Design selection for placement of horizontal drain hole in reservoir – Multi-Seam lateral

– Single seam Multi-lateral, duel, triple, quadi, pinnet

– Horizontal Length of laterals

– Spacing between laterals

Horizontal Well Types


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Multilateral drain hole placement Design options based on

– TVD of coal seams, Number of seams and thickness

– Vertical separation between Coal seam

– Areal extent of coal seam, and structural dip

– Proximity to adjacent formations, like aquifer sand, fractures barrier

–In-situ -stress orientation, directly affect permeability

– Stability of roof and floor formation of coal seam

Completions design based on

– Suitable for placement of drain hole design as per reservoir characteristics

– Dewatering and gas production requirement

– Future work over requirement

– Cased hole completions tubing and casing sizes design based on maximizing

required flow rate.

Process : CBM Multilateral design


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Directional trajectory design:

• Long Radius

– angle build rates : 2 to 6 deg/30 m.

– (long horizontal intervals): 1500 to

2000 m.

• Medium Radius

–angle build rates : 8 to 20 deg/30 m.

– (horizontal intervals): 1200 to 1300 m.

• Short Radius

– angle build rates : 20 – 70 deg/30 m.

– (horizontal intervals) : 300 to 400 m.

CBM Multilaterals, Medium Radius

Profile are most suitable, with wide range

of DLS 6-20deg/30m, for placing drain

hole within available TVD

Process : Directional Trajectory


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• Horizontal well to be drilled in the direction

of minimum horizontal stress (minimum

permeability), perpendicular to maximum

horizontal stress direction.

Fracture Orientation and Horizontal Well Placement


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• Use of advanced error model survey techniques for proper landing of thewell in the reservoir with minimum deviation from Geological marker

• Use of near bit inclination and Azimuthal Gama and geosteering technique

for placement of drain hole inside coal seam

• Selection of logging tool parameter specific for identification of coal

Key Challenges - Geosteering with LWD


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51%

22%

11%

16%

Vertical Well : 1100 - 1400 m

Drilling

HF

Completion

Surface Facility

53%

20%

13%

14%

Directional Well : 1100 – 1400 m

Drilling

HF

Completion

Surface Facility

Well Cost : Vertical-Deviated-Horizontal

80%

0% 10%

10%

Horizontal Well : 500 m

lateral, 1200 m depth

DrillingHF

Completion

Surface Facility


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Marked difference observed in drilling and completion costs for vertical and horizontal wells

0

500

1000

1500

2000

2500

3000

Australia USA China Australia USA China Australia USA China Australia Australia USA China

Core Hole Vertical - 600 m Vertical - 1000 m Single

Lateral

Dual

Lateral

Tri

Lateral

Tri

Lateral

Comparitive CBM Well Costs US$’000

Surface Facilities

Stimulation

Completion

Drilling

Source: RISC Analysis, Geof Barker, 5th annual CBM & Unconventional Gas June 2012

Worldwide CBM Well Costs


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• Horizontal multilateral wells have

advantages

– 1 horizontal well gas recovery

equivalent to 4 vertical wells gas

recovery

– Smaller surface requirement for

horizontal wells – 1 horizontal well cost equivalent

to 2 vertical wells cost

• Performance of Horizontal wells in

multi-seam reservoirs?

Application of Horizontal Well Technology in India

Lower

CoalSeam

Upper

CoalSeam

Surface

Casing

Carrier String With Up stock on bottom

Up-Stock

Operation

0.00

300.00

18.00

75.00

~ ~

~ ~

~ ~

~ ~

Tertiary

Top Soil

Panchet

EDT - 02

RL-72.00

TD - 700.00

IronstoneShale

625.00

300.00

625.00

Raniganj

RN-4

RN-3

RN-1&2

2.24397.76-400.00

374.54-376.62

432.82-433.54

468.40-470.62

488.40-493.00

504.20-507.20511.30-513.94

563.96-567.78

2.08

0.72

2.22

4.60

3.002.64

3.82

365.58-367.18 1.60 2.24397.76-400.00

374.54-376.62

432.82-433.54

468.40-470.62

488.40-493.00

504.20-507.20511.30-513.94

563.96-567.78

2.08

0.72

2.22

4.60

3.002.64

3.82

365.58-367.18 1.60


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Possibility of Horizontal Wells in Indian CBM Basins

Jharia (2)•

2 horizontal wells – 1000 m depth, 1000 mlateral, Side -lateral/Pinnate Wells – 2000 m

side-laterals

• Seam thickness – 5 m, permeability – 3-5 mD

• Side-lateral collapsed

• ~5 MSCMD production from upper zone after

isolations

Sohagpur (6)• In-seam well - 800 m lateral

• Seam thickness – 8 m, permeability – 200 mD

• Peak production ~4 MSCMD but couldn’t

sustain due to very high water production

Bokaro (3)• 1 horizontal well – 1000 m depth,

1000 m lateral

• Good gas production

Typical

Gondwana

multi-seam

thickness

Tertiary coal

sequence


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