UnconventionalResources and Basin Evolution

Discuss some regional scale controls (plate to basin) on unconventional resources.

Illustrate with five examples (source rock, tight sand and CBM reservoirs).

Objective

Types of Unconventional Resources – Review

Global Screening Analysis of a Few Regional Factors

Selected Examples

Reservoir Deposition and Characteristics

Burial – Maturation and Diagenesis

Uplift and Exhumation

Closing Remarks

Outline

Unconventional Resources –

Categories

~ G a s

~ O i l

~ Heavy Oil

~ Extra Heavy Oil

~ Bitumen/Tar

~ C

on

ven

tio

na

l Res

ervo

irs

~ Ti

gh

t R

eser

voir

s

Reservoir Permeability (k, md)

Flu

id V

isco

sity

(μ

, cp

)

Fracture Stimulation

Therm

al/So

lvent M

etho

ds

Improving Flow:Potential Approaches

Mobility = Permeability / Viscosity

Reservoir Permeability (k, md)

Flu

id V

isco

sity

(μ

, cp

)

Tar SandMining

Steam / Solvents

(e.g. SAGD, CSS, Fireflood,

etc.)

Shale Oil

Sh Gas

Tight Oil

CBM/Tight Gas

Conventional Oil

Conventional Gas

Enhanced Cold Flow (CHOPS)

Note –In reality, there is much overlap between resource types / depletion strategies.

HC Resource Types: Permeability vs. Viscosity

HEAVY OIL

TIGHT OIL & GAS

Unconventional Types:Heavy OilTight Sandstone/CarbonateSource Rock (“Shale”)Coal Bed Methane

Global Screening Analysis of Basin Factors

30

8

4

3

22

2 1 1

Unconventional Plays: Country

USA

Canada

China

Australia

Argentina

Russia

Algeria

Venezuela

Germany

Regional/Basin Controls on Unconventional Resources - Database

• 87 unconventional plays screened. 54 further analyzed based on materiality and maturity.

• Of these 54, 45 plays are significantly commercialized (e.g., Permian Wolfcamp); 9 are emerging with commercial promise (e.g., Nequen Vaca Muerta).

• Representative, but not necessarily comprehensive.

• Dominated by US/Canada because of commercial/infrastructure/regulatory considerations (and favorable geology).

US

Canada

China

Aust.19

22

8

5

Unconventional Plays: Types Evaluated

Tight Sand

SourceRock

CBM

Heavy Oil

N=54

Regional/Basin Controls on Unconventional Resources - Depositional BasinUnconventional plays occur in all kinds of basins – many pathways to success.

Forelands are the most important.

The prominence of forelands, in part, probably includes a bias related to commercial considerations –unconventional developments generally require an onshore setting.

But also, rapid flexural subsidence in foreland basins is often associated with thick source rocks (“shale reservoirs”) and tight reservoir sandstones – discussed later.

Lastly, volcanic arc association may be an additional source of nutrients.

12

16

5

6

11

2 1 1

Unconventional Plays: Depos. Basin

Foreland

Complex Foreland

Cratonic Sag

Extensional

Passive Margin

Back-Arc

Fore-Arc

Transpressional

0

5

10

15

20

25

Unconventional Plays: Reservoir Age

Heavy Oil

Tight Sand

CBM

Source Rk.

Regional/Basin Controls on Unconventional Resources - Reservoir Age

Oceanic Anoxic EventsJenkyns (2010)Brennecka (2011)Algeo et al. (1994)

1 1 1123

1

2

3

Source Rock and CBM Plays – Age

Global HC Source Rocks vs. Age

0

1

2

3

4

5

6

7

8

9

Source Rock and CBM Plays: Reservoir Age

CBM

Source Rk.

Source Rock Reservoir Plays Only

Deposition:Reservoir Presence / MineralogyOrganic Richness

Burial:Reservoir Compaction/DiagenesisSource MaturationPressure Development

Exhumation & Deformation:Folding/FaultingNatural FracturesOil BiodegradationPressure ModificationDrilling Depth

Basin Evolution and Unconventional Play Elements

Sand reservoir

Marine source rock

Reservoir Deposition / Characteristics

Reservoir Presence / MineralogyOrganic Richness

Cross Section from Ettensohn (2019)

UTICA

MARCELLUS

OHIO

Taco

nic

Source Rock (“Shale”) Reservoirs: Appalachian Basin Example

CATSKILL DELTA

Acadian Unc. (Hutton)

Aca

dia

n

0

1000

2000

3000

4000

5000

6000

250270290310330350370390410430450470490510

Dep

th (

m)

Age (Ma)

Fold BeltTaconic Acadian

Uti

ca S

hal

e

Mar

cellu

s Sh

ale

Rh

ine

stre

etSh

ale

Oh

io S

hal

e

Appalachian Basin: Subsidence History, Shale Reservoirs and Orogenies

OROGENYEarly Collision

Alleghany

Acadian Unconformity

Bruner and Smosner, 2011 (DOE)

Devonian Source Rocks and Migration of Acadian Foredeep

Colpron and Nelson, 2009

1

2

3

4

5

5

7

8

Modified from Blakey

Late Devonian Orogenie

s and Organic Rich Mudstones

Black Shale Formations1 Ohio-Marcellus2 Chattanooga3 Antrim4 New Albany5 Woodford6 Sweetland Creek7 Bakken8 Exshaw, Duvernay, Muskwa

8

6

5

2

2

1

Eustasy

• Globally synchronous, spatially consistent.

• Rates high for durations < 0.1 m.y.

• Detailed internal reservoir architecture usually articulated at

this scale.

Accommodation Controls – Eustasy vs. Tectonics

Tectonics

• Temporally heterogeneous, but often correlative within a

basin.

• Magnitude spatially variable and often reversed (uplift and

adjacent subsidence) in same basin.

• Rates much higher than eustasy for durations > 0.5 m.y.

• General models more elusive – many “motifs”.

• Source rock and most tight sandstone reservoir intervals at

this scale.

Eustasy

Accommodation Change Rate vs. Time Duration (Log-Log)

Tectonics (Subsidence /

Uplift)

UpliftSubsidenceSea Level FallsSea Level Rises

MSL

1. Increase in subsidence-related accommodation.

2. Steepening of depositional profile.

3. Differentiation / partitioning of basin.

4. Arc volcanism for retroarc foreland basins.

5. At basin-scale, 2nd order unconformities in updip may be ~equivalent to MFS in downdip areas.

Tectonics and Source Rock Deposition

2

1

3

5

4

Tectonics and Source Rock Deposition: Possible Elements

MSL

1. Condensed section driven by subsidence (concentration of organic matter).

2. Steepened profile, enhancing upwelling (organic productivity)

3. Constructional coastal plain, enhanced terrestrial productivity. Nutrient transport (land plants, volcanic ash).

4. Differentiation of basin, potential silling of water column (dysoxia/preservation)

2

1

4

3

SOURCE TO SINK LAGAir Fall Ash

Terr. Plant Material

Arc-derived zircons (<250 Ma)

Recycled zircons (>250 Ma)

Volcanic Ash Deposition: Inferred Distribution

Adapted from Jacobs et al. (2019)

`

Relative Abund. of Volcanic Ash

Detrital Zircons: Frontier Fm., U. Cenomanian to L. Coniacian

WY

UT

Christianson et al. (1994)

high abund. of ash

Mowry-Niobrara time:• High arc flux• More ash distal

Frontier

Niobrara

MowryDakota

Permian Basin Paleogeography

Midland

Basin Eastern

Shelf

Palo Duro Basin

Matador Arch

Ozona Arch

Amarillo Uplift

Marathon

Orogenic Belt

Pedernal

Uplift

Orogrande

Basin

100 mi.

NMTX

OK

TX

Delaware

Basin

Val Verde

Basin100 km

EP

Guadalupe

Mtns

Delaware

Mtns

Sacramento

Mtns

San

Andres

Mtns

Hueco

Mtns

Sierra

Diablo

Apache

/Davis

Mtns

Sandia

Mtns

Glass

Mtns

Chinati

Mtns

CB

MD

LB

AB

AM

RW

AL

Basin

Platform

Platform Interior

Evaporitic Platform Interior

Alluvial Plain

Highland

Mountains

City/Town

Political

Boundary

Ancestral Rockies and Marathon/Ouachita

Orogenies 300 Ma (Late Pennsylvanian)

Permian Basin

PALEOGEOGRAPHY PRESENT DAY

Marfa

Basin

Hueco Canyon Fm. (Upper Wolfcamp)

Pow Wow Conglomerate (Middle Wolfcamp)

Hueco Mountains, Diablo Platform

Lower Wolfcamp Unconformity

• Culmination of Ancestral Rocky Mountain Orogeny.• Erodes to basement (in places) on Diablo Platform, Central Basin

Platform and Pedernal Uplift.• Transformation of basin architecture from simple ramp to partitioned

uplifts and deep basins (Pennsylvanian to Lower Wolfcamp).

Bone Springs

Wolfcamp

Wolfcamp

Spraberry

3rd

2nd1st

LowerUpper

Dean

Delaware Basin Central Basin Platform

Midland Basin Eastern ShelfWest East

AB

C

D

Avalon

Permian Basin: East-West Cross Section

Modified from WTGS, 1984

SL

-4

-6

C Ord S Dev Ms PermP Tr CzJur Cret

100 MY

Central Basin Plat.

Diablo Plat.

Eastern Shelf

Midland Basin

Delaware Basin

After Horak, 1985

Subsea D

ep

th (

km

)

Geol. Time

Passive Margin A.R.M.Orogeny

Post-Comp/Subsidence

Mid-Wolfcamp Unc.

-2

Permian Basin: Subsidence History & Tectonic Phases

Other Examples of Source Rock Reservoirs Associated with Tectono-Subsidence

50 km

20

0 m

Pinous et al (2001)

BazhenovVasyugen

Neocomian Clinoforms

Vartov

Pokur

EastWest Well Log Cross Section

MFS

Bazhenov, West Siberia Basin

Niobrara, Denver-Powder River Basins Vaca Muerta, Neuquén Basin

San.

Con.

Tur.

Pal.

Maa.

Cam.

66.0

72.0

84.2

89.7

93.9

86.3

W E

Modified from Rudolph et al (2015)

Depth (m)Geohistories

0 1000

2000

3000

4000

5000

6000

6570

7580

8590

9510

0

Depth (m)

Age

(Ma)

Alb.

Cen.

100.5

Sevier Foreland (BackbulgePosition)

Dynamic Subsidence

(+ Sevier Foreland)

Uplift / Low Subsidence*

Laramide Uplift and Flexural Subsidence Partitioning /

Differentiation

Modified from Rudolph et al (2015)

Niobrara

Leanza et al., 2011

AchimovShale Oil

Tight Oil

Uinta Mountains

Sevier Fold Belt

Deep Basin

WY

COUT

WYUT

ID

~ Middle Maastrichtian Paleogeography: Schematic Perspective View

Active Laramide Uplifts

Flexural Thicks

Sediment Transport

Tight Sandstone Reservoirs: Green River Basin Example

FluvialNext Slide

Southern Wind River BasinWind River MountainsNW Green River Basin

50 km

2.0

sec

49-013-20527

(proj. 4 km)COCORP Seismic LineWSW ENE

Velocity Pullup

49-037-21752

Bsmt

Pz

UCretUCret

Cz

Top Cret

Top Cam.

Bsmt?

LOADFLEXURE

Wind River MountainsSevier

Orogenic Belt

20 km

NW Green River Basin: Surface Geology and Lance (~Maastrichtian) Isopach

Pinedale Field (10 TCF)

Jonah Field (3 TCF)

NorthwestGreen River

Basin

49-013-20527

THIN

THICK

600

SouthernWind River

Basin

49-037-21752 Wind River Basin

Isopach based on Johnson et al (2014)

Gross Sand Map

49-035-2364427-T30N-R107W

49-035-2160811-T29N-R108W

49-035-218581-T28N-R109W

49-035-206088-T27N-R110W

49-023-2041829-T26N-R111W

Top Cretaceous(Datum)

Top Cretaceous(Datum)

NNESSW

~10 km

20

0 m

49-023-2051021-T25N-R112W

WINDRIVER

MOUNTAINS

Northwest Green River Basin:Upper Cretaceous

Stratigraphic Cross Section

Wind River Mountains

Sevier Orogenic

Belt

20 km

Pinedale Field (10 TCF)

Jonah Field (3 TCF)

NorthwestGreen River

Basin

49-013-20527

THIN

THICK

49-013-20063

600

SouthernWind River

Basin

49-037-21752

IP 6

.5 M

MC

FGP

D

Pinedale FieldJonah Field

IP 5

.4 M

MC

FGP

D

Perf’ed/Frac’ed Interval

Flexural Moat

Flexural Bulge

Burial / Maturation

Reservoir Compaction/DiagenesisSource MaturationPressure Development

USGS Assessment Team, 2002 Pranter and Sommer, 2011

Piceance Basin: Tight Sandstone Example (gas)

Basin-Centered Tight gas Play

50 kmC.I. = 0.1 km

-108°

40° 40°

-108°

-109°

39°39°

-109°

COUT

White River Uplift

Douglas Creek Arch

Adapted from Johnson et al (2004). Poor age control, possibly includes some upper Campanian in interval.

Uncompahgre Uplift

50 kmC.I. = 0.2 km

0.2

39°

40°

-108°-110°

39°

40°

-108°-110°

41° 41°

SanRafael Swell

THIN

Uncompahgre Uplift

White River Uplift

Uinta Mountains

Adapted from Johnson et al., 2017

COUT

Douglas Creek Arch

50 kmC.I. = 0.05 km

39°

40°

-108°-110°

39°

40°

41° 41°

SanRafael Swell

THIN

Uncompahgre Uplift

White River Uplift

Uinta Mountains

COUT

Adapted from Johnson et al., 2017

-108°-110°

Douglas Creek Arch

Upper Campanian - Maastrichtian Paleocene – Lower Eocene Upper Eocene

Reservoir Deposition Burial – Source Maturity and Porosity Evolution

Piceance Basin: Isopachs (km)Flexural thick developed west of a major Laramide uplift (White River Mountains).Provides space for deposition of thick non-marine reservoir interval (Upper Cretaceous).Deposition of overburden (Paleoc.-Eoc.) that matures coaly gas sources and develops capillary seal of tight sandstones.

Basin-Centered Tight Gas

Based on Saylor and Rudolph, in prep.

Flexure Models

Nucio and Roberts, 2003

Vitrinite Reflectance (Ro) at base of Mesaverde Gp.

Piceance Basin: Mesaverde Coal Maturity (Gas Source)

Peak Gas Generation

Onset of Generation

Rudolph

Deformation and Exhumation

Oil BiodegradationPressure ModificationNatural FracturesDrilling Depth

Exhumation

Piceance Basin: Burial History

• Approximately 1.2 km of exhumation in Neogene.

• Related to uplift of Colorado Plateau and more widespread epeirogenic uplift of western North America.

• Potential implications of exhumation:

• Shallower drilling targets• End of gas generation• Overpressure• Microfractures via

unloading

Rudolph

Fracture Example: Fruitland Coal Bed Methane, San Juan Basin, NM

Green River

PowderRiver

Denver

WR Wind River

Uinta

San Juan Raton

BHB

UU

FR

SC

G

U

WR

M

P

SJ

L

La

KP

NP

SP

RS

BT

Big Horn

MP

ShHa

Piceance

HU

DC

A

CA

N

FR

OC

200 km

CO

WY

NM

UT

Partly based on Heller and Lui (2016)

Basin

Uplift

Cz Volcanics

Thrust Belt Front

Fruitland CBM

Tremain et al. (1994)

Fruitland Cleat Orientation, Ft. Lewis, CO

Paleo-Stress Direction controls cleat orientation.Horizontal wells need to be oriented to intersect face cleats orthogonally.

Drill Direction

Research Questions of Industry Interest

Understanding the original porosity and permeability in tight unconventional reservoirs:Quantitative and accurate estimates of organo-porosity, inter-particle, intra-particle and adsorbed gas.Role of natural microfractures for permeability.

What is the impact of exhumation, which is common to many unconventional plays?Under what circumstances are hydrocarbons and pressure retained?What geologic histories lead to capillary entrapment (basin-centered gas) and can we reliably predict its occurrence?

What is the correct way to understand and model aggregate properties (“scale-up”) relative to flow. The fine-scale matters, but as it composites over ~50m frac height and 3 km lateral?Appropriate sequence stratigraphy models at the basin-wide, 2nd order scale (i.e., not LST-TST-HST schema)

What is the induced propped fracture network and can we better predict it?Microseismic only gives us a rough picture of the entire fracture network, most of which does not contain proppant.

Is there an environmentally more benign way to extract heavy oil, which makes up a large portion of remaining oil resources, but has a large carbon footprint.

Influence of volcanism on organic productivity.

Closing Comments

Predicting, understanding and developing unconventional petroleum reservoirs has historically relied on empirical indicators, direct analysis/interpretation and field experimentation.

However, the same basin-scale controls that are germane to conventional resources are also relevant to unconventional resources.

While these controls are unlikely to provide important commercial insights in established unconventional plays, they should be understood and utilized in poorly-constrained (“frontier”) settings.

Just as in conventional resources, there is not one (or even a few) success factors – there are many pathways to success (and even more to failure!).

So beware of purported general models, including what you have heard thus far - a consistent, integrated technical approach is more important.