Report Part 3

8/11/2019 Report Part 3

1/17

Envireau I4/ater

6

DISPOSAL

METHOD

The

proposal

at

the Ebberston

Moor

Field is

to

inject

produced

waters

to

the

Triassic

Shenuood

Sandstone

formation

rather

than injection

to the Permian

Kirkham Abbey

Formation.

6.1

EngineeringMethod

Water

injection

to

the

Shenvood Sandstone

will

be through

a well completed

through

the

injection

zone

either

with

a

perforated

cemented

liner

or

into

open

hole.

The injection

zone

may

target the full

thickness

of

the

sandstone,

depending

on the

exact nature

ofthe

sandstone

formation

encountered.

6.2

IniectionPressures

lnjection

will

be achieved

by

low

pressure

injection

from surface;

the hydrostatic

pressure

of the water

column

will

assist

the water

injection

with

only limited

additional

pressure

added from

pumping.

No

high

pressure

injection

is

foreseen

since

the

injectivity of

the

injection well should

be

sufficient

to

provide

the

required

rates

of

injection.

During

the life

of

the injection well,

accumulation

of fines

may lead

to

a higher

driving

pressure

being

required

to maintain

injection

rates however,

injection

pressure

will

be designed

to

be

below

fracturing

pressure.

6.3

Injection

Rates

and Volumes

The

proposed

rates

and

volumes

of injection

for

the

initial development

phase

of the

Ebberston

Moor Field

are

presented

in

Table

8 below.

Table

8 Proposed

lnjection

Rates

&

Volumes

Assuming

that

the

totalvolumes

(for

both

phases)

are

injected

into

sandstone with

a

porosity

of L0 ;

and the

water

forms

a

spherical

bubble,

the

radius

of the

bubble for the

total volume

would

be in

the order of

240m

(480m

diameter).

lf

it

is

assumed

that

the

porosity

is L ,

then the

radius

increases

to 520m

(1040m

diameter).

The

act of

injection

will result

in displacement

of

the

formation

water,

with

a

theoretical

zone

of influence in

the

region

of

1km.

The effects

of the

displacement will

be

controlled

by

the elastic

storage

of the formation.

Assuming

this

to

be

1

x

LO-s m3/m3

then head

effects would

be

expected

to

propagate

up

to 5200m

from

the injection

point.

Given

the fact

that the

injection

well

at

EB-A

is 40

km from

the outcrop

where the

Sherwood Sandstone

contains

usefulgroundwater,

then

no

effect will

be

seen

in

the outcrop

area.

6.4

Iniection Water

Composition

and

Iniection

Additives

The

disposal

water

at

Ebberston

Moor

may

contain

small

quantities

of

the chemical

additives detailed

in Section

5.3 and

will

have a

resultant

composition

similar

to

that

presented

in Section

5.4.

Ref:

P:\Third Energt

Ebberston

Moor

(1484)\Reporting\Report

v7.6

Rev:

I0/02/2014 2:45

PM

Up

to

1900

.BB

million

.25

hase

1 &

2

1900

.47 million

.00

hase

2

1600 increasing

to

1900

during

the final

year

.41million

.25

hase

1

Average

Daily Injection

(m3/day)

otal Injection

Volume

(m3)

uration

(years)

evelopment

Phase

Page 25

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Envireau

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7 CONCEPTUAL MODEL

The conceptual

model

presented

below

relates

to this

risk

assessment, as opposed

to

the

full hydrogeological

situation

from

surface

to

depth. lt

has

therefore,

by

necessity been simplified when compared

to

the

geology.

The

conceptual

model is

illustrated on Figure 13

a,b,c)

and

the

principalcomponents

of the conceptual

modelare:

o

The

vertical hydrostratigraphic units

-

namely:

o The

geology

above the Oxford Clay

Layer

1)

o

The

geology

from

the

base

of

the

Mercia Mudstone to the Oxford

Clay

Layer

2)

o

The Sherwood Sandstone

Layer

3)

o The

Zechstein

Permian)

/

Carboniferous

Layer

4)

The lateralvariation

in

geology,

controlled

by

dip and east

west faulting.

a

Recharge

to the

Sherwood Sandstone

formation

is

limited to the outcrop

and

subcrop areas in Vale of

York

/

Mowbray.

Recharge

to the

geology

above the Oxford Clay

is limited

to

the outcrop

on

the

North

Yorkshire

Moors.

Hydraulic

properties

of

the

layers have

been

defined by

literature search, but broadly Layer 1 can be

taken

as

having

useful

hydraulic

conductivity and storage;

Layer

2 is

poorly

permeable very

low hydraulic

conductivity) and has

limited

useful storage;

Layer

3

has

useful

hydraulic conductivity and storage; and

Layer

4 has limited hydraulic conductivity and

storage,

and

poorly

permeable

clay and

mudstone

horizons effectively hydraulically

separate

the

Permian

Layer

4)

from

the overlying

Triassic

water

bearing

formation.

Differences

in water

quality

between the water

bearing

formations have been defined by

literature

search and confirmed

in

the

case

of

Layer 4,

from

sampling and

analysis at Knapton.

The change

in

salinity of the

formation

water in

the Sherwood

Sandstone

is

illustrated by

an

arbitrary line

on

Figure 13c.

This

line

denotes a

change from what we

describe

as

groundwater

to

formation water.

The line

has

been located

based on

the

literature

search

and can be conceptualised

as

an isochlor

a

line

of equal

salinity

[or

more

accurately chloride concentrationl).

When combined,

the

various

aspects

of the

conceptual model produce

a

system

with

no

transfer

of

water

vertically between

the

permeable

Layers

1

and 3, either upward

or

downward.

This

is

achieved

by

the

low

permeability

and thickness of Layer 2 and low vertical hydraulic conductivity of

Layer

4. The effectiveness of the

hydraulic separation is

demonstrated

by

the

marked difference in

water

quality

between

Layers 1

and

3, where

the sandstone

is

at depth.

The

quality

of the

sandstone water at depth demonstrates

that

circulation of recharge

into the

Sherwood

Sandstone

is limited

to near the

outcrop/subcrop

areas,

with

very little deep

circulation occurring.

Evidence

published

in

the

literature

from

isotope and ionic ratio

analysis

Section

3.4.3.2 and 5.5) indicates

that the

NaCl

in

the sandstone

water

is

mineral rather

than sea water based.

The significant

down dip

distance

of the

EB-A site

effectively

isolates

it

volumetrically

from

the aquifer

zone.

Ref P:\Third Energ

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Moor

l

484)\Reporting\Report v7.6

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Envireou Water

8 RISKASSESSMENT

This assessment

considers

the dispsal of

produced

waters

only and does not consider

the

risks

associated

with

the

physicalconstruction

phase

of an

injection

well into the

Shenrood

Sandstone

formation.

8.1

AssessmentMethodologr

DEFRI(s

GL

lll

contains

generic guidelines

for

the assessment and

management

of

environmental risks.

GL

lll

outlines a staged approach

to risk assessment

and

the

document

is

intended

to

guide

regulatory

staff in

Government

and

its

agencies,

as

well

as

those

carrying

out assessments, to reach

a

decision on

managing

environmental risk.

A

hydrogeological

risk

assessment for the

proposed

disposal

of

produced

waters

to the Shenrood

Sandstone

formation

at

Ebberston

Moor

has been

carried

out

in

accordance

with

GL

lll

using

the

Source-Pathway-Receptor

(S-P-R)

methodology

described

in the

Environment Agenqy s

Hl Environmental

Risk

Assessment

framework

-

Annex

J

(Groundwater).

Where

S-P-R

linkages

have been identified,

the

sensitivity of

the

receptor,

magnitude

of

impact

and significance

of

effect has

been

considered

in

order to

assess

potential

risks.

8.1.1

ReceptorSensitivity

The

sensitivity of

water resource

receptors

is

based on their status and considered resource value,

as

described in

Table

9 below.

Table 9

Receptor Sensitivity

A

water resource

desated

or directly linked

to a

SSSI.

hincipal aquifer

providing

potable

water to a

small

population

A

river

desated as being of Good

status

or

with a target

of

Good

status

orpotential underthe

WFD

A

water

body

used

for

national

sporting

events

such as regatts or

sailing events

EC designated

Cyprinid fishery

a

a

a

aater

resource

with a high

quality

and rarity

at

a

national

or

regional

level and limited

potential

for

substitution.

High

A

water resource

making up a vital

component of

an SAC

or

SPA

underthe EC Habitats Directive

A

water

body achieving

a status

of

High

status

or

potential

under the

WFD

Princal

aquifer

providing

potable

water to a large

population

EC

designated Satrnonid fishery

a

a

a

ater

resource

with an

importance

and

rarity

at an

intemational

level

with

limited

potential

for

substitution.

VeryHigh

Ref P)Thrd Energt

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Erwreau Water

A

non

'main'

river or steafri or

other water

body without significant

ecological habitat

a

ater

resotrce with

a

low

qual

and

rarity

at

a local

scale.

[w

o

Secondary aquifer

providing

potable

water to a small

population

o

An

aquifer

providing

abstaction

water for

agricultural

and industial

rse

Water

resource with

a

high

qualrty

and

rarity at a

local

scale;

or

Water resource

with

a

medium

qualrty

and

rarity at a

regional

or

national

scale.

Medium

8.1,2

Magnihrdeoflmpact

The

magitude

of a

potential

impact

on a

receptor

depends

on

the

nature

and

eltent of the

proposed

development, and

is

independent

of the sensitivity of the

wter

resource,

as

described

in

Table

10.

Table 10

Magnitude

of lmpact

Physical

impact to

a

water

resource,

but no

sigrificant

reductior/

increase in

quality,

productivity

or

biodivers

No

significant

impact

on the economic value

ofthe

feature

No

increase in floodrisk

a

a

esul in an impact

on attibute

but

of

insignificant magnitude

to

affect

use

and/or integity.

VeryLow

Measurable

changes

in

attibutg but of

limited

size and/orproportion

esulg

in minor

impact to

attibutes.

Iw

Loss /gain in

productivity

of

a

fishery.

Conibution

/

reduction

of

a significant

proportion

of

the effluent in a

receiving river, but insufficient to change its

WFD

classification

Reduction

/

incree in the economic value

ofthe

feature

a

a

esuls in

impact

on

integrity

of

attibute or

loss

.of

part

of

attibute.

Medium

lss

ofEU desated

Salmonid fishery

Change

in

WFD

clsification

ofawaterbody

Compromise employment source

Ioss offlood

storage/increased

flood

risk

Pollution of

potable

source of

abstaction

a

a

a

a

esults in a major change to

atibutes.

Hieh

ffi

MIE

Ref,

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Moor

(l

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8.1.3 Significance

of

Effect

The significance

of the

potential

effect is

derived

by

combining

the

assessments

of

both

the sensitivity of

the

water

resource

and

the

magnitude

of

the

impact in

a simple

matrix,

as

presented

in Table 11

below. Effects which

are assessed

to

be major or moderate

are considered

to

be

significanf

whilst

those

that

are minor

or

negligible

are

not significant.

Table

11

Significance

of Effect

8.2 Hazardldentication

The

conceptual model

presented

in

Section

7

suggests

that

injection

of

produced

water

containing

small

quantities

of

hydrocarbons

and additives

to the

Shenruood

Sandstone

formation

represents

a

potential

hazard, as

summarised

in

Table

12

below.

Table

12

Source-Pathway-Receptor

Linkage

(lnjection

of

Produced

Water

to

Shennood

Sandstone)

Negligible

egligible

inoroderate4inor

Neglible

inor

oderate/I4inor

oderate

Minor

oderate4inoroderateajor4oderate

Moderate/lr4inor

oderate

ajor/lvloderate

ajor

Yes

he Shenvood

Sandstone

aquifer at

outcrop

(wholesome,

lowsalin

groundwater)

Migration

ofproduced

water from

the

point

of

injection

through the

Shenrood

Sandstone

formation

to the

outcrop

area

Yes

roundwater

bearing

formations above the

Li

and any

public

or

private

water

supplies

targeting

them;

surface

waters

Failure

ofwell

casing

and migration

of

produced

water

through

groundwater

Injection well

targeting

Shenpood Sandstone

formation

at

Ebberston

Moor

@B-A

wellsitQ

Produced

water

containing

hydrocarbons and

i4jection additives

Ref,

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Energ

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Moor

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llater

The two

S-P-R

linkages

above

are

also

shown

in

the

risk

assessment

summary

in

Table

13, which

shows that

whilst

there

is

a

potential

pathway

between

the

injection

well

and

groundwater

receptors,

the

likelihood of occurrence

is

low and

negligible respectively

because:

Approximately 750m

of

low

permeability

formations

provide

a

vertical separation between the

point

of

injection and the

nearest

groundwater

supplies.

The lateral distance between

the

point

of

injection and the feather edge of

the

Triassic

Sandstone

where

the formation

provides potable

water

is

in

excess

of

40km. Significant

geological

faulting

between the

injection

point

and the outcrop

area will

limit lateral

movement. lnjection

displacement

of formation

water

over

the

lifetime of

the

scheme

is in the region of

lkm, with

pressure

effects

limited to

less

than

5.2km.

Consequently,

the

only

plausible

S-P-R

linkage

would be due to a

failure

of

the injection well

casing

due to

inadequate construction and migration

of

produced

waters

into

groundwater

and surface

water systems local to

the

EB-A

wellsite.

8.3

ReceptorSensitivity

Table

12

shows the

potential

receptors

to

the

produced

water

hazard will

be

local to

the EB-A

wellsite

and

comprise

the

formations

containing

groundwater

above

the

Lias that

might

be targeted

for

public

or

private

water suppliet or

which

may

provide

base flow

to streams

and

rivers.

The sensitivity of the

identified

receptors

is

considered

in the

risk assessment summary

in

Table 13. The most

significant

groundwater

receptor is

the

Principal Corallian

aquifer,

which is assessed as

having a very high

sensitivity. The Secondary aquifers

that

exist between the Corallian

and the

Lias

are

assessed

as having a

medium

sensitivity.

Groundwater

from the

Principal and Secondary

aquifer systems

may be utilised

for

water

supply

and

is

also likely

to

support

base

flow

to a

number

of surface

water features

(streams

and rivers). For the

purpose

of

this

assessment,

the

sensitivity of those

receptors is conservatively

considered

to

be

the

same

as

that of the

aquifer

systems themselves.

8.4

Magnitudeof

Impact

The magnitude of the

impact

on the

identified

receptors

is considered in

the

risk

assessment

summary

in Table

13.

lf

produced

water

entered either

the

Principal Corallian aquifer

or any of the Secondary aquifer

systemg

the

magnitude

of the mpact would be high.

8.5

Signicance

of Effect

The

signifcance of effect

is

also considered

in the risk assessment

summary in Table

13. Based

on the

methodology

presented

in Section 8.1,

it

follows

that

there could

be a major effect if

produced

water entered

the

Principal Corallian aquifer and a

moderate effect if Secondary

aquifer systems

were

affected.

Ref P:\Third

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ll ater

8.5.1

EmbeddedMitigation

Construction

of

the injection

well

will

be controlled

by

The

Offshore

lnstallations

and Wells

(Design

and

Construction,

etc.) Regulations

1996,

which

in

summary

places

obligations on

the welt-operator

to:

Regulation

13:

Ensure

that

a

well

is

designed,

modified,

commissioned,

constructed,

equipped,

operated,

maintained,

suspended

and

abandoned

such

that

there

is no

unplanned escape

offluids

from

the well

and

that the

risks

to the

health

and safety

of

person

from it

or anything in

i or

in strata

to

which

it

is connected,

are

as low

as is

reasonably

practicable.

Regulation

18:

To make

and

put

into

effect

arrangements

in

writing for independent

examination

by a

competent

person

before

the

design of the well

is commenced.

This

independent

examination

is intended

to

provide

the Well-Operator

that the

well is

designed

and

constructed

properly

and is

maintained

adequately.

Specific

emphasis is

given

to

the impartiality

and

independence

of those

responsible

for

carrying

out

independent

examinations.

The

regulations

ensure

the

protection

of

the

environment

and

persons

through

careful

design. Following

a

number

of

internal

reviews,

the

operations

are reviewed

by

an

independent

competent

third

party.

This

process

ensures

that the

well

is

designed and

planned

to the highest

standards.

As

shown in

the

risk

summary

table

in

Table

13,

for

the

purpose

of

this

assessment

it is

assumed that

the injection

well will

be

constructed

in

accordance

with

standard

best

practice

and

these

regulatory

requirements.

Consequently,

the aquifer

systems

above

the

Lias

will

be cased,

grouted

and

sealed before

the well

is

progressed

into the

Shenruood

Sandstone

where

saline

formation water will

be

encountered.

.

8.5.2

AdditionalMitigation

The injection

pressures

required

to

achieve successful

injection

of

produced

water

nto

the Shenood

Sandstone

will be low

and

it

is

envisaged

that

the

hydrostatic

head

of

the

produced

water

column

will

provide

a sufficient

driving force.

lnjection

pressures

will

be controlled

to

ensure

they

do not

exceed

the fracturing

pressure

of the formation,

which

will

provide

additional

mitigation.

Consequentl

as shown in

the risk

assessment

summary

table

in Table

13, the

resultant

significance

of

effect is considered

to

be

negligible.

Ref P

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I

ErnireauWater

Table

13

tnjection of

Pnoduced

Water- RiskAssessmentsummary

Ref: P

:llhird

hergt

Ebberstot Mot

(

484)lReponng@pol

v7.6

Rev: 10/022014

2:45

PM

hoduced

wEr

iecion

well

Mgration

of

produced

vafr

to

the

oJtqtop

afea

Faihne of

well

*iog; migrion

of

produced

wafr

lbrough

groundwer

Sheruood

Sandstone

aquifer

(

outcrop)

Secondary

aquifers

Principal

Corallian

aquifer

Yes

Yes

Yes

Negligible

VeryIow

Verylow

VeryHigh

High

Verl'High

High

Medirm

High

Major

Moderate

l fajor

D

or

ge

an

lo

inj

pa

Be

we

re,

H

H

@

ru

@

@

w

w

r4

fi


9/17

Envireau

lTater

9

ALTERNATIVETECHNOTOGIES

9,1 BestAvailableTechnique

The

water

disposal

technology

described in

this

assessment

is

unique,

in

that it

involves

the

injection

of

produced

water into

a

geological

formation

at a higher stratigraphic level

than the

producing

unit. As

such,

it is

important

that

the technology

is

checked

to

ensure

that

it

is

the

Best

Available Technique

(BAT).

As a unique technology

its

status wth respect

to

BAT has

been

derived using an approach based

on that described by the Nuclear lndustry

Safety Directors Forum

document

titled

'Best

Available Techniques

(BAT)

for the Management

of the Generation

and

Disposal

of

Radioactive

Wastes

-

A

Nuclear

lndustry Code of Practice',

published

in

December 2010.

This

document

provides

a robust overview

of the

definition of

BAT, in

an

industry where risk

management is

paramount.

ldentification

and

implementation

of

BAT implies a balanced

judgement

of

the

benefit derived from a measure

and

the

cost

or

effort of

its

introduction.

There

is

no single

'right

way'

to

identifo

BAT;

although

it

is

accepted

that

all studies

will be based

on

information,

verified where

practicable,

and documented

for transparency. BAT may

be established by reference

to

previous

studies, or

as

an independent

comparison of detriments

and benefits. The

general

rule

is

that the level of

effort

expended

to

identifu

and implement BAT should

be

proportionate

to

the

scale of

the

issue

to be resolved. ln

many cases, studies

will

be

constrained by one

or

more

factors, depending

upon the assessment

context. A number of

assumptions may also be required,

particularly

where long timescales

are considered.

lt is important

that the

process,

and

any

underpinning constraints

or

assumptions, must be

documented and

justified.

Overall,

the following

principles

should also be taken into

account:

o

sustainabledevelopment;

o

waste

hierarchy and waste

form;

o

the

precautionary

principle;

and

the

proximity principle.

This chapter

sets out and documents

the

identification,and

justification

of

the

BAT for the disposal

of

produced

water at Ebberston

Moor.

9.2 TechnologyOptions

The following

technology options have

been considered:

o

lnjection

of

produced

water into

the

hyper

saline Sherwood Sandstone formation;

o

lnstalling

an injection well at Ebberston

Moor to target the Kirkham Abbey

production

formation;

.

o

lnstalling

an

injection well

at Ebberston Moor

to

target

the deeper Carboniferous

strata;

o

lnstalling a

pipeline

to transport

produced

water

back

to

KG from where it would

be transported

out to

the existing injection

well

in

the

Vale

of

Pickering;

and

o

Disposalvia municipal

sewage

treatment

works

and discharge to

surface

water.

Ref:

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llater

The

following

sections describe the

key

components

of the options

wth

respect

to

a

scoring matri

which

is

presented

as

Table

13.

The

scoring

matrx

is discussed

in detail

in

Section

9.3.

9.2.1.

Iniectionto Sherwood Sandstone

Formation

(Base

Case)

The

proposed disposal

route

is

to

the

Sherwood Sandstone

formation. This

route

has

the following

primary

benefits:

o

Engineering

practicality

as

the technique

is

a

proven,

wellestablished

technique offshore;

o

While a

high cost option,

the

less deep

injection level means

that

wellconstructon is

lower;

o

Low

environmental

risk

(see

above);

o

Low sustainability score, based on

low energy

use;

and

o

Low

precautionary

principalscore

based

on

robust

risk analysis.

This route

has

the

following

primary

dis-benefits:

o

Moderateregulatoracceptability.

9,2.2

Iniectionto

Production

Formation

(IGF)

-

Ebberston

Moor

The

current

injection

of

produced

water

in

the Vale

of

Pickering

field

results

in

recirculation

of

fluids from the

injection well,

whereby

the fluid

travels through

the

fracture network

within the KAF to

the

production

well.

This

results

in 'watering-offl

whereby

high liquid rates are

produced

from

the

production

well,

resulting

in further

processing

of

fluids at surface and

lower

overall

gas

recovery

rates,

thus

limiting

the

commercial

viability of the

Ebberston

Moor

Field.

lt is

a

condition

of the licence issued to

Third

Energy

by

the

UK Government

(DECC)

that

recovery of hydrocarbons

must

be maximised.

lf a new injection

well is

installed within the

boundaries of

the

Ebberston

Moor

field,

then it

is

fully

expected

that

the

same

historic

issues

relating

to

recirculation of

fluids will be observed.

This

leads

to a

high Production

lmpact

score.

lf

a

KAF

injection

well

was

constructed

at

Ebberston Moor,

then

it would most

likely be constructed

as

far away

from

the

production

well

as

possible.

Assuming an injection

well was constructed

on the furthest

boundary of

the

gas

field, this

would mean a

produced

water

pipeline

of around

10km

in

length

would

be

required

to transport

produced

water

from the

production

site to the disposal

site.

The deeper

injection

well

(relative

to

the

base case)

increases

the cost

score.

As an

accepted

and

permitted

disposal

route, this

option has a

low regulator

acceptability

icore.

The

produced

water

pipeline

increases the environmental

risk

score

(see

g.2.41.

9.2.3

Iniection

to

sub Permian Strata

-

Ebberston

Moor

lnjection

into

the

sub-Permian

Strata

oses

engineering

challenges,

primarily

due

to the

low

permeability

(injeaivity)

of

these formations.

Below

the

limestones

of

the

Permian,

the

strata become dominated

by clay

rock

(shale)

and indurated sandstone.

lnjection into these

formations is

unlikely

to

be

possible

at

low

pressures

and

is.

Ref

P:\Third

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(1484)Weporting\Report

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Water

likely

to require

pressures

that

signfcantly

increase

the risk

of fracturing.

lf this

were

to

occur, while

it

would

not

be likely

to

increase

the

environmental

risk,

it would

increase

the

production

ris(

via movement

of water

back

to

the

production

horizon.

Costs increase

over the

base

case

due

to the increased

depth

of injection.

As an

accepted

and

permitted

disposal

route,

this option has

a low regulator

acceptability

score.

9.2.4

Injection

to

Production

Formation

(KAF)

-

Vale

of

pickering

lf the

existing

injection

well in

the

Vale

of

Pickering

is used

as a disposal

route for

produced

waters

originating

from

production

wells

at

Ebberston

Moor,

this will further

diminish

the

productivity

of the

existing

wells in

the

Vale

of Pickering,

thus limiting

the

commercial

viability

of the

Vale

of

Pickering

Fields. tt

is

a

condition

of the

licence

issued

to Third

Energy

by

the

UK

Government

(DECC)

that

recovery

of hydrocarbons

must be

maximised.

ln

order to

utilise existing

injection

wells

in the Vale

of Pickering,

a

pipeline

will

need

to

be installed

to

transport

produced water

from

Ebberston Moor

to

KGS.

The

pipeline

would

be

around L0km in length

and

would

follow

a

relatively

direct

route,

subject

to

landowner

agreement.

The

construction

of a

pipeline

for

produced

water would

introduce

a number

or

environmental

risks,

as

presented

in

Table

14

below.

The risks

illustrated

in

Table

i.0

represent

the situation

after

taking

appropriate

mitigation

measures.

lt

is

not

the

intention

of

this

report

to

undertake

a

detailed

risk

analysis

of

pipeline

construction,

but

to

recognise

that

risks

remain

after construction,

and

during

the operation

of

a

pipeline.

Table 14

water

Related

Risks

Associated

with

a

produced

water

pipeline

The most

significant

risk

associated

with

a

produced

water

pipelines

is

the

potential

for

disturbance

and

pollution

of

the

hghly

sensitive Scarborough

SpZ.

Figure

1.2

illustrates

the

extent

to which

pipelines

could infringe

on

the

Scarborough

SPZ. Approximately

3km

of

the

pipeline

to

Knapton

would

cross

the

SPZ,

whilst

a

pipeline

to

an injection

well

in

the

Ebberston

Moor

Field

(located

as

far

as

possible

from

production

wells)

would

cross up

to

10km

of

the

SPZ. Conversely,

an injection well

targeting

the

Sherwood

Sandstone

would

be constructed

at

the same

site

as the

production

well

(EB-A)

and

would

therefore

totally

remove

the

need

for

a

produced

water

pipeline

crossing

the

SPZ.

Based

on this,

the

environmental

risk

score

has

been increased

for the

pipeline

options.

Ref P:\Third

Energt Ebberston

Moor

(14]4)Weporting\Report

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2:45 PM

Moderate

oderate

igh

ipeline

leakage

and

pollution

of DTWPAs

and

SPZs

Low

ow

igh

ollution

disturbance

of

DTWPAs

and

SPZs

during

pipeline

construction

Low

ow

igh

isturbance

of wetland

ecosystems

Riskikelihood

onsequence

azard

Page

35 of4l


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9.3 ScoringMatrix

Table 15

presents

a scoring matrix which

evaluates

the

BAT

criteria. The matrix

looks

at

each

of

the

criteria

presented

in

Section

9.1

together with

other

important factors. The only aspect

that

is missing is

"waste hierarchy

&

waste form".

The

waste hierarchy

is

summarised in

the

embedded figure below.

Prefened Environmentl

Opton

Use BATto ensure

wasteis not

generated

unnecessadly

Waslecreatcd:

UseBATto ensure

waste discharges are

minimised

Liquld

Waste

discharged:

UseBATto

minimise impads

Least Prefened

Environmental Opton

Within

the context of the

produced

water,

the

water has

to be

produced.

lt

is

a

part

of the

process

of extracting

gas.

The high

salinity of the water means

that

it

has no

practical

re-use

or options

for

recycling, other than in

th

development of new

gas

wells, which isn't

the intention within the context of this

proposal.

Energy recovery is not

applicable in this case and

therefore disposal is the only option. Size reduction is not applicable.

Table 15

provides

a

relative

scoring system

that

has

been adjusted by a simple

weighting.

Cost has been reduced

in significance, as while it is important

it is not an overriding factor. The most important factors

are environmental

risk and

production

impact.

The

former

because

this

is

what

is being

protected

and

the

latter

because

loss in

production

will result in failure

of the company

and

goes

against the

requirements

of the

DECC

licence conditions.

The matrix has been designed

so

that a low number

gives

the best option.

9.4

Summary

The scoring matrix identifies in a

systematic

way

that the Sherwood Sandstone formation disposal route is BAT

Given that the overall disposal is

low

risk

(Section

8)

Envireau

Water consider that this

qualitative

BAT assessment

is appropriate and meets the requirements

of the BAT

guidelines

referenced above.

Ref P:\Thrd Energt Ebberston Moor

(1484)\ReportingWeport

v7.6

Rev: 10/02/2014 3:37 PM

Reduce lmpact

through Chemical

and Phyrical Form

Gas

Solid

I

;,,

Rgg.t--$9

r--t;

-.

.: .i.': r':,i..

-.:

Re-use

Reduce

Avoid

Page

36

of4l


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ErwireauWater

Tablel5

BATScodngMatrix

VoP

=Vale

of

Pckerng

EM=Ebberston Mr

Ref, P:\Ihrd herg Ebberxtot

Mr

(14&l)lReportinglRept

v7.6

Rar 10/022014 3:37

PM

Discharge

to

xce

watr

Pline to VoP

and

inject o KAF

Injection

into

srb Permian

Str

@M

site)

Injection into I(AF

@M

si)

Discharge

to

uface

uater

fnjection into

Shntrood

Smdstone

Pline

o

VoP

ad

tuect

to

KAF

Injection into srb

Permian Stn

(EM

site)

iectionintoKAF@M)

Injection ino Sherwood

Sdstone

3

5

I

J

3

3

5

8

J

3

5

5

3.5

5

2.5

t0

IE

l0

7

l0

5

l5

7.5

1.5

7.5

1.5

10

5

I

5

I

0

l5

6

15

0

0

t0

4

10

0

8

J

I

I

I

J

I

I

I

I

0

5

I

I

I

l0

5

I

I

I


14/17

Envireau lVater

10

fusTrFrcATIoN

FoR

IN|ECTION

TO THE SHERWOOD

SANDSTONE

Based

on

the

risk assessment

provided

in Section 8 and the

BAT

analysis

in Section 9,

the

alternative

methods

of

water

disposal

involve technologies

which will:

o

Reduce

productivity

and the rates

ofgas

recovery

o

Limit the commercial

viability

of

gas production

from

the Ebberston

Moor

Field

o

lntroduce significant environmental

risk

By

comparison,

the

proposed

method of water disposal by

injection to the

Sherwood Sandstone

will:

o

Maximise

productivity

and

the

rates of

gas

recovery

o

Maximise

the commercialviability

of gas

production from

the

Ebberston

Moor

Field

o

Minimise environmental

risl most significantly

because

there

is no

requirement

for

a

pipeline

to

transport

produced

water

across

the

Scarborough

SPZ

It

is

therefore

considered

that

in this

particular

casd,

the disposal

of

produced

water to the

Sherwood Sandstone

represents

both

the

BAT

and

the BPEO.

Ref P:\Third

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ll'ater

LI

SUMMARY

CONCLUSION

The

technical

analysis

and

risk

assessment

presented

above

demonstrates

that fundamentally

and crucially,

there

is

no

(or

essentially

no)

environmental

risk

associated

with

properly

designed and

managed

disposal.

This

is

based

on

clear hydraulic

and

geochemical

separation

of the

water

bearing formations

of the

Trassic

and

the

aquifers of

the

shallow groundwater

system

of

the

Upper

Jurassic.

The

conceptual hydrogeological model underpinning this

assessment

has

been

discussed

and agreed

in

principle

with

the

local

Environment

Agency

Groundwater

Contaminated

Land

team.

Comparison

of

the North

Sea

salinity

with

the

main

constituents

of the

produced

water

from

the

KAF

and the

Shenvood

Sandstone

formation

water

show

that the

KAF

water

is

approximately

two

times

more

saline than

the

Shenood

Sandstone

formation

water.

However,

this

is

within

the

context

of

both waters

having

total

dissolved

solids

concentration

(TDS)

n

excess of

18Q000mg/1.

Both

waters

show significant

amounts

of

naturally

occurring

hydrocarbons,

with

the

produced

water

showing

more,

as

would

be

expected.

The

produced

water

and

Shenruood

Sandstone

formation

water

are 10 and

5 times more

saline

than

the

North

Sea,

respectively.

On

this

basis,

and

in

line

with

UKIAG guidance

the

Shenvood

Sandstone

formation

water

has

no resource value.

Therefore

the formation

water,

into which

disposalwilltake place

can

be

defined

as:

o

Permanentlyunsuitable

o

Deep

and isolated

o

Of

no resource

value

On this

basis the

WFD,

GWDD

and

UK

regulations

which cascade

from

them,

allow disposal.

The design and management

of the

disposal

well

(borehole)

will

utilise standard oil

and

gas

field

practices

wh

respect

to

casing

setting

and

grouting,

curing and

testing

to

ensure

full

protection

of

the

shallow

aquifers

and

groundwater

system.

Envireau

Water

03

December20LS

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material

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the compilation of this technical

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referto the relevant Regulations, Directives,

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Allen,

D. J.,

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al

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England

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UK

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lndustry

Safety

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December 2010.

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S.H.,

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al

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Combined isotopic and

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H.,

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Effects

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British GeologicalSurvey

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1:50

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E027

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Durham

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Barnard

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Harrogate

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York

E064

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Great

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Leeds

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Beverley

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Hornsea

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the Water Framework

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Downing,

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British

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Ebberston

Moor

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PM

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Envireau lil'ater

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Official

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Gale,

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(1983).

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Carboniferous rocks

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lnvestigation

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the

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Guidelines

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Environmental

Risk

Assessment

and

Management:

Green Leaves lll.

Revised

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Guidance Prepared

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Defra

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Understanding

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Managing

Natural

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Environmental

Risks, Cranfield

University, November 2011.

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OF

THE

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of

12

December 2006

on the

protection

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groundwater

against

pollution

and

deterioration.

Official

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the

European Union.

Groundwater

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Council Directive

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December

1979

on

the

protection

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groundwater

against

pollution

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certain

dangerous substances.

OfficialJournal

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