Fraccing and Shale Gas - Gloucester

Fraccing and Shale Gas

P.H.Velzeboer, M.Sc, C.Eng

Introduction

• Graduated as a Mining Engineer 1965 from Royal School of Mines, Imperial College

• Joined Shell as a Petroleum Engineer and worked internationally in:-

– Brunei, Nigeria, Sarawak, New Zealand, The Netherlands, Egypt, Syria, Scotland

• Last 10 years worked as a consultant Well Engineer on Coal bed methane, Shale gas and Well Reliability/Integrity

Overview

• Introduction

• Fraccing – What is it?

– Why do we need this?

– How do we Frac?

– Fracturing Issues • Fraccing induced seismicity

• Water table pollution

• Environmental impact

Overview (cont)

• Shale Gas Development – Shale gas development issues

– USA experience

– Europe/Africa potential

– Technical challenges • Wellcosts, drilling and Fraccing

• Environmental/Land access

– UK Development

• Conclusions

http://www.youtube.com/watch?v=VY34PQUiwOQ&feature=player_detailpage




Ultimate frac?? A permanent stable cavity caused by the detonation on an

underground nuclear test in 1961.

Fraccing issues

• Seismicity

• Pollution

• Environmental Impact

Fraccing Issues-Seismicity

Seismicity

Seismic acitivity has been recorded around the fraccing operations, M=~2.0

• At this level natural seismicity is quite common in the UK

Fraccing Issues-Seismicity

Seismic activity in the UK during the last six month.

3- Felt by few 4- Felt mainly indoors, Windows and doors rattle 5- Felt mainly indoors, small objects fall down 6- People run outside in alarm 7- Moderate damage, chimney pots fall, cracks in walls However the frac process does create many microsiesmic events, a characteristic used by the industry to monitor the growth of the fracs

Fraccing Issues - Pollution

• All fluids/chemicals used are benign – KCL

– Guar gums

• In order to reduce cost all fluids are increasingly recycled.

• Low risk of ground water pollution – Fracced zones are well below any potential

aquifers

– Dual barrier (casings) system in place

Fraccing Issues - Pollution

European practices need two independent barriers between the Hydrocarbon layer and atmosphere. These barriers are to be tested at regular intervals

Conclusion. Fracced wells are no more dangerous than Conventional oil/gas wells, probably less so because of the very low risk during drilling vis a vis blowouts

Fraccing Issues – Environmental impact

• Locations land requirement

• During drilling phase, transportation

• During frac operation, noise levels

• Noise levels during drilling and compressor activity can be made negligible

• Installation of pipeline/Power line infra structure

Shale gas development

Increasingly up beat press reports regarding shale gas reserves in the UK.

• Current potential estimate >400tcf

(annual gas consumption in UK 3tcf)

• As more exploration projects get underway this will initially get more up beat.

However

None of the exploration wells have been tested so the above can not be regarded as reserves


What are the unknowns in UK shale gas development.

• Production performance…reserves

– Recovery is typically ~15%

• Availability of well sites (footprint)

• Competition from euro/US gas resources


Shale gas and tight gas wells all experience sharp production declines.


• Development will be from multiple well locations

• All wells are likely to be horizontal

• Each horizontal section will have multiple fracs

• The benefit for this approach is limit the locations required and reuse of fluids.

17


12 1/4" hole 9 5/8” csg

8 1/2" hole 7” csg

2400 ft

10,900 ft AH,

5 7/8" hole 4 ½” Liner

5,000 ft KOP

4000 ft horizontal length stimulated at 500 ft intervals

8 stage frac

6 - 9o/100 turn

• No shallow mine hazard

• 2 7/8” completion tied into 4 ½” liner top

Typical development well

Shale gas development US experience





Frac requirements are considerable. Per well we would typically require:-

• Up to 25 stages

• 8000 – 10,000lbs per stage of proppant

• 70,000 – 100,000glns of water

• Pumping pressure ~9000psi

• 12000HHP required




Shale gas development – will it happen?

A ‘back of the envelope’ calculation Caudrilla claim to require 100 locations for full development:- At 6 wells per location, infers 600 wells At 3 months drilling per well, infers 150 rig years 5 year development would require 20 land rigs Total drilling cost £10x106 per well, £6x109 Pipelines/Compressors etc ??? GIIP 200tcf, rec ~30tcf…0.02p/cf ~ 2p/Therm Current price at the Henry Hub ~$0.3/Therm

Conclusion

Technically possible, But:-

– UK Reserves have not yet been demonstrated

» Will offset North sea gas decline

» Will decrease reliance to imported gas

– Drilling and completion costs are about 3 X more expensive

– Population density is much higher

– Land owners may not benefit directly

Conclusion One last comparizon with the states

Fraccing – Intro

Fraccing requires a good understanding of the formation(rock) strength

Units (British Standard Units)

• Relate to a London Transport double decker (HP, length, weight) and Nelsons column (height)

Height 169ft

Length 30ft Height 14.3ft Volume 429 cuft Weight 7.35Tons Power 115hp

Fraccing – Why do we need it? Reservoir permeabilty dictates the completion type.

For Shale gas reservoirs permeability usually well below 0.1mD

Fraccing – Typical permeabilities

Fraccing – Why?

• Primarily to increase the flow area into the wellbore

Fraccing – How do we frac? Typical Shale gas well

Shale gas development-Leaking Wells

UK Shale gas headlines

Fracking will mean lower energy bills, Cuadrilla vows

Shale could fuel UK for 10 years, say experts

Documents

Fraccing and Shale Gas - Gloucester