Planning application no. LCC/2014/0096by Cuadrilla Bowland Limited to drill at

Preston New Road, Lancashire:

Objection on grounds of geology and hydrogeology

by

Professor David Smythe

Emeritus Professor of Geophysics, University of Glasgow

Introduction

Shale is a very common kind of rock (UK not special)

Shale basins of the UK very different from USA

Royal Society etc. :- fracking environmentally safe if ‘well regulated’.

Geology sections concentrated on:

• Induced seismicity• Fracture growth by fracking

Hardly a mention of pre-existing faults as conduits

Relied on a US industry (Halliburton) study:

• Ten thousand fracked wells in the USA collated• None of the fracks penetrate upwards anywhere near the local aquifers• So pollution of groundwater by fracking not a problem

- in the USA

Faulting:a crucial problem in Europe

USA and UK at same scale

Oklahoma

England

Pennsylvania

Texas

Details in later slide

Shale basin sizes:UK: 5-50 times thicker than US, but 10-100 times smaller in area

NorthernEngland

Weald

( ) USA

BowlandBasin

Faulting and fracked wells

Marcellus Shale, Bradford County, NE Pennsylvania

Geology shown in colour, dots are wells

Faults in the Fylde and Bowland Fellsat same scale

UK basins have 500 times more faults than US average

Preston New Road

Problem of pre- existing faults as

conduits

Target horizon

Groundwater layer

German study 2012

France: groundwater circulation to over 3 km depth

Faults areproven conduits

Source:University ofMontpellier

Bath-Bristol area: groundwater circulation to over 2 km depth(British Geological Survey)

Faults areproven conduits

The Sherwood Sandstone Group (SSG) at the surface: the the most important groundwater aquifer in the north of England.

West of the Woodsfold Fault and south of the Wyre the SSG is covered by younger rocks, and the aquifer is highly saline.

SSG covered by younger rocks

Sherwood Sandstone Group (SSG) at

surface

Woo

dsfo

ld F

ault

Bilsborrow

Fault

BowlandFells

Coa

stlin

e

R. Wyre

BilsborrowFaultWoodsfold

FaultRecharge

Fresh

Saline

Recharge

Dissolution

Bowland Fells to Fylde:Groundwater movement across faults (Environment Agency)

Faults areproven conduits

Perspective view looking north

Woodsfold Fault

EA cross-section

Bilsborrow FaultBilsborrow and Woodsford Faults diverge southwards from Garstang (G). Since the former fault is transmissive, it is highly unlikely that the latter is a sealing fault, especially in the blue-ringed zone where sandstone is juxtaposed against sandstone.

G

Sherwood Sandstone at surface in West Cumbria:United Utilities drills water wells into geological faults “to give the best access to the yields”.

Preston: Groundwater movement across faults (Environment Agency 2006)

Aquifer

Flow through faults

Faults areproven conduits

Preston New Road

• Cuadrilla - potential upward fluid migration will be “prevented by management” during fracking.

• Well to be drilled through a fault - interpretation is unlikely and unconvincing.

• Seismic data on which this sketch is based have not been released.• All layers above fracked shale, except the thin Manchester Marls,

are very permeable.• Many potential migration pathways exist.

Progressive decrease of 3D quality

Fracked shale

1

4 3

2A

B

Fault-1

Fluid flow paths:

1. Directly upwards from the Upper Bowland Shale into the permeable Millstone Grit Group.2. Up the transmissive fracture zone of Fault-1.3. Along the highly permeable Collyhurst Sandstone, generally up-dip to the east, and only partially confined by the Manchester Marls.4. Directly upwards from all the preceding sources through the Permian and superficial deposits to the surface.

Cuadrilla's Fault-1 is geologically improbable; therefore it is reinterpreted on the right at point A (monoclinal flexure made into a fault) and at B (continuation of the fault up to the sub-Permian unconformity at the base of the Collyhurst Sandstone).

Preston New Road

Preston New RoadNW SE

WoodsfoldFault

Permian and younger rocks

Extension of Cuadrilla cross-section to south-east

11 km

ThistletonFault

Two main varieties of fault:• Pre-Permian - only cut the Carboniferous• Faults which cut all rocks up to the surface

Carboniferous

The 3D seismic survey:

Location of the 2011 tremorsFault identification

Bottom of wellboredeviated to east

Cuadrilla 2011: faults atPreese Hall-1 on2-D seismic image

Faults Wellbore probably deviated to avoid faults

3D survey coverage incompleteand inadequate

100% limit

Quality 0% at outer edge

Preston New Road

Cuadrilla interpretation

Preese Hall-1

Modified fault interpretation

1000 m vertical

Earthquakehypocentre

Oblique view of horizontal plane

Preese Hall-1

Cuadrilla 2014: The ‘tremor’ fault near the bottom of Preese Hall-1

2800

Deformed bore

Stage 2

Stage 1

Cuadrilla faultinterpretation

Better faultinterpretation

500 m

Scaled cross-section through Preese Hall-1 wellbore

Hypocentre

2400

2500

2600

2700

2900

3000

2930 m depth

TVD ss depth (m)

Preese Hall-1 did penetrate the ‘tremor’ fault• matches the 3D seismic image better• explains the well pipe deformation• accounts for why tremors started just after stage 2 fracking

West EastWellbore

Lessons from Preese Hall-1 and the 3D survey

• 3D survey not up to scratch

• Faults very hard to recognise in shale

• PH-1 went through ‘tremor’ fault

• Poor understanding of faults

• US shale experience is no guide to UK• Faulting important in Bowland Basin

- Faults often act as conduits for fluids• Cuadrilla PH-1 drilled a fault in 2011

- (just like Balcombe, Sussex)• 3D seismic survey mediocre quality• Cuadrilla fault interpretation unreliable

- (just like Balcombe, Sussex)• EA self-contradictory, over-optimistic• Rocks above shales poor fluid barrier• More earthquake triggering likely

Applying the precautionary principle to the risk of contamination by fluids and methane -the application should be refused

Conclusions