# p 1 - ISGC 2013

Mechanics

Oct 24, 2013 (4 years and 8 months ago)

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From a global perspective,
unconventional gas resources
are vast, but
undefined. No systematic evaluation has
been carried
out on global
emerging resources. The magnitude and distribution of worldwide
gas resources in
unconventional reservoirs
has yet to be understood
.

WORKFLOW

Working with ill
-
posed systems

Converting ill
-
posed systems to well
-
posed systems

Solving well
-
posed systems

2

(

)
=
(

)

q

t

M

Y

F

Y
=
=
=
,

where:

: production & pressure characteristics at

a future time
t

: mathematical fluid flow model

: domain characteristics

(

)
=
q

t

Y

(

)
=
M

F
=
Y
=
,

F

Y

: recovery process

Basic Approaches:

Deterministic Modeling:

M,
F
,

and

are
all fully known

Stochastic Modeling:

M,
F
,

and

are
partially known

THE BASIC RELATION FOR RESERVOIR EVALUATION

Flow

mechanisms in

tight reservoirs

Understanding

geo
-
mechanics

???

C
apillary

pressure

characteristics

Numerical

representation

of the stimulated

zone

Designing

architectures

Relative

permeability

characteristics

Liquid rich

shale reservoirs

Complexity

and changes

a
re the
issues

facing the

industry

We are
operating

much more
challenging
reservoirs

and living in a

much
more

challenging

world.

There are many

critical key

components

for unlocking these

challenging gas

reservoirs

CHALLENGES

1

3

2

Calculation of Mixed
-

Pure Component Isotherms:

CO
2

C
2
H
6

CH
4

N
2

PRESSURE

PRESSURE

PURE COMPONENT
ISOTHERM
S

MULTI
-
COMPONENT
ISOTHERM

TOTH

ALGORITHMS

UNILAN

Thermodynamics of Mixed
-

Vapor
-
Liquid
Equilibria
:

VAPOR

LIQUID

FREE GAS

GAS

(1)

Real Gas

Solution Theory

(2)

Extended Langmuir Isotherms

POTENTIAL FIELD

MACROSCOPIC
-

DARCIAN FLOW

CONCENTRATION FIELD

RANDOM MOLECULAR
-

FICKIAN FLOW

p
1
<

p
2

r
1
=

r
2

p
1

r
1

p
2

r
2

p
1
<

p
2

r
1
<

r
2

p
2

r
2

p
1

r
1

IN TIGHT FORMATIONS TWO FLOW FIELDS
CONTROL THE GAS FLOW DYNAMICS

p
1

< p
2

r
1

= r
2

p
1

r
1

p
2

r
2

p
2

r
2

p
1

r
1

p
1

< p
2

r
1

< r
2

(a) Incompressible fluid

(b) Compressible fluid

MULTI
-
MECHANISTIC FLOW
CONCEPT

Single
-
Phase

Gas Flow :

where

Multi
-
Phase

Gas Flow :

where

k=0.0001 md k=0.001 md k=0.01 md k=0.1 md k=1 md

FICKIAN

DARCIAN

MULTI
-
MECHANISTIC

MULTI
-
MECHANISTIC FLOW
CONCEPT

Percent
Decrease in
Pressure

Percent
Recovery
Achieved

(2) NUMERICAL REPRESENTATION OF THE

STIMULATED ZONE

Two ANNs have been developed:

Equivalency ANN
-
I

Establishes an equivalency between two different hydraulic fracture
representations

From transverse fracture representation

TO

Crushed zone fracture representation

Two ANNs have been developed:

Equivalency ANN
-
II

Establishes an equivalency between two different hydraulic fracture
representations

From crushed zone fracture representation

TO

Transverse fracture representation

Transverse Hydraulic
Fracture Representation

Crushed Zone Hydraulic
Fracture Representation

Sw

Krw

Pcow

0

0

0

1

0

0

Sg

Krg

Pcog

0

0

0

1

1

0

Model

Gri d System

25
x 25

Gri d size on X di rection (ft)

222.22

Gri d size on Y direction (
ft
)

222.22

Area (acres)

707

Depth (ft)

6300

Thi ckness (ft)

300

Matri x Porosity (%)

10

Fracture Porosity (%)

0.9

Matri x Permeability (md)

0.0003

Fracture Permeability (md)

0.0012

Fracture Spacing (ft)

2

Res. Temperature (
°
F)

145

Res. Pressure (psi)

4000

S
w

i n Matri x (%)

10

S
w

i n Fracture (%)

10

Langmuir Vol. of CH4 (scf/ton)

70

Langmuir Pres. of CH4 (psi)

700

Langmuir Vol. of CO2 (
scf
/ton)

75

Langmuir Pres. of CO2 (psi)

400

Hor. Wel lbore length (ft)

2000

Hydraulic Fracture Half
-
length (ft)

400

Producti on Constraint
-

P
sf

(psi
)

500

SRV Fracture Porosity (%)

0.5

SRV Fracture Perm (md)

0.011

SRV Fracture Spacing (ft)

1.8

5 YEARS

25 YEARS

50 YEARS

70 YEARS

5 YEARS

25 YEARS

50 YEARS

70 YEARS

-
STEERING TECHNOLOGY

Maximum Reservoir Contact (MRC) Wells

Multiple

Targets

intersect

different

pay

zones

Reduces

surface

footprint

Reduces

pay

back

period

(1) Maximum reservoir contact
w
ells have
one or more branches (laterals) tied back to a
mother wellbore, which conveys fluids to or
from surface.

(2) Combining
the technologies of
horizontal/multilateral underbalanced
drilling gives operators the means of
improving production rates and increasing
the percentage of hydrocarbons through
greater formation exposure and better
reservoir drainage
.

(3) Overall
costs are reduced due to
increased rates of penetration, elimination of
lost circulation, reduction of stuck pipe, and
increased bit life
.

-
steering technology is in
control.

Saudi Aramco Technology and Innovation

MAXIMUM RESERVOIR CONTACT(MRC) WELLS

Pressure
field after
5 years of production

Pressure field
after
15
years of production

Run 2: Horizontal Single Lateral
with 4 Wings at 45
o

Pressure
field after
5 years of production

Pressure field
after
15
years of production

Run 3a: Horizontal Single Lateral with

4 Wings at 45
°
and

°

Pressure
field after
5 years of production

Pressure field
after
15
years of production

Run 5: Horizontal Single Lateral with

4 Wings at 45
°

16 Wings at 45
°

Pressure
field after
5 years of production

Pressure field
after
15
years of production

Run 7
:

Horizontal Single
Lateralwith

4 Wings at 90
°

and 8 Wings at 90
°

Pressure
field after
5 years of production

Pressure field
after
15
years of production

Frac
-
2:

Fracture Penetration

Length 850
ft

Well Architecture

Description of Wings

Production at

15 Years (BCF)

Hydraulically Fractured

5
-
stage; 400
ft

2.8

Hydraulically Fractured

5
-
stage; 850
ft

3.1

Hydraulically Fractured

5
-
stage; 1,000
ft

3.3

Horizontal (Run 1)

Single
-
Lateral

2.4

Horizontal (Run 2)

4

(at 45
o
)

3.0

Horizontal (Run 3)

4 (at 45
o
) + 8 (at 45
o
)

3.8

Horizontal (Run 3a)

4 (at 45
o
) + 8 (at 30
o
)

3.6

Horizontal (Run 5)

4 (at 45
o
) + 8 (at 45
o
) + 16 (at 90
o
)

3.8

Horizontal (Run 6)

4 (at 45
o
) + 16 (at 45
o
)

3.9

Horizontal (Run 7)

4 (at 90
o
) + 8 (at 45
o
)

3.7

Horizontal (Run 8)

4 (at 90
o
) + 8 (at 90
o
)

2.4

SUMMARY OF NUMERICAL EXPERIMENTS

(1) Increasing the rate of recovery

Multilateral
wells
are capable of increasing
production by

three
to five times
of the
horizontal
wells by increasing
the

contact
area between the well and the
reservoir.

(2) Decreasing
the drilling expenses

Drilling
multilateral well
increases recovery
by three to five

times
and the drilling cost by 1.5 to 2
times on per foot

drilled basis.

(3) Decreasing
the environmental impact

Using a multilateral
well
decreases environmental
impact as

the
multilateral well needs a single surface borehole instead

of
many boreholes, to cover the same reservoir contact area,

if
any other technique
is being used
.

(4) Decreasing the operating costs

Using multilateral
well
effectively accelerates
the
production

and rapidly depletes
the
reservoir. The
operating costs will be

reduced
as the
field
life cycle
is reduced.

THE BENEFITS OF MULTILATERAL WELLS

It is recognized that the principal barriers
to implementing new technologies to
respond to today’s concerns are not the
cost, lack of benefits or technical risk, but
other issues such as the resistance to
change
.

New technologies and innovations may
require changes to established work
routines and procedures
.

Furthermore, we believe that practitioners
are not resisting to specific technologies or
proposed technical solutions but to
creation of a discontinuity in technology
.

However, it is this very same discontinuity
which sets our understanding and thinking
on a new trajectory in technology
confident that the analysis protocols that
will be developed will have immediate
application opportunities
.

Economic
and

commercial

viability

Field project status

and
feasibilit
y

?

opportunity

clarity

Aversion to risk often means large organizations
forego significant opportunities.

late to the
game

THE DILEMMA OF INNOVATION

opportunity

clarity

THE ROLE OF R&D IS TO ACCELERATE CLARITY

Scientific developments and innovative technology will be instrumental
in unlocking the major sources of natural trapped in unconventional gas
reservoirs, dramatically altering the energy landscape.

The missing knowledge
-
base needed for these developments can most
effectively be developed in academic environments working shoulder to
shoulder with the industry.

In the 21
st

Century exploration

research and development environment, a
petroleum engineer/an earth scientists is expected to manage:

Knowledge

Technology

and…

INNOVATION