Horizontal Drilling Potential Horizontal Drilling Potential of the Middle Member of the Middle Member

Bakken Formation, North Bakken Formation, North DakotaDakota

Julie A. LeFeverJulie A. LeFever

North Dakota Geological North Dakota Geological SurveySurvey

MT

WY

SD

ND

MBSKAB

North DakotaNorth Dakota

Williston BasinWilliston Basin

Study AreaStudy Area

StratigraphyStratigraphy

Three Forks FormationThree Forks Formation

Bakken FormationBakken Formation

Lodgepole FormationLodgepole Formation

lowerlower

middlemiddle

upperupper

Pelmatozoan limestonePelmatozoan limestone

““False Bakken”False Bakken”

Devonia

nD

evonia

nM

issi

ssip

pia

nM

issi

ssip

pia

n

““Sanish”Sanish”

0

5

1 0

1 5

2 0

2 5

3 0

3 5

4 0

4 5

5 0

5 5

6 0

6 5

7 0

7 5

Isopach Map of the Isopach Map of the Middle Bakken MemberMiddle Bakken Member

Contour Interval: 5 ft

0

5

1 0

1 5

2 0

2 5

3 0

3 5

4 0

4 5

5 0

5 5

6 0

6 5

7 0

Prairie Salt Prairie Salt

Bakken Middle MemberBakken Middle MemberPrairie SaltPrairie Salt

MontanaMontana NorthNorth DakotaDakota

Con

tou

r In

terv

al

Con

tou

r In

terv

al

ft

Lithofacies 5 - SiltstoneLithofacies 5 - Siltstone

Lithofacies 4 – Interbedded Dark Grey ShaleLithofacies 4 – Interbedded Dark Grey Shale and Buff Silty Sandstone and Buff Silty Sandstone

Lithofacies 3 - SandstoneLithofacies 3 - Sandstone

Lithofacies 2 – Interbedded Dark Grey ShaleLithofacies 2 – Interbedded Dark Grey Shale and Buff Silty Sandstoneand Buff Silty Sandstone

Lithofacies 1 - SiltstoneLithofacies 1 - Siltstone

(From LeFever and others, 1991)Lower Shale

Upper Shale

Lithofacies of the Middle Lithofacies of the Middle MemberMember

ProductiveProductive

ProductiveProductive

StratigraphyStratigraphyBakken Limit in North DakotaBakken Limit in North Dakota

NorthNorthSouthSouth

DevonianDevonianThree ForksThree Forks

Mississippian Lodgepole FormationMississippian Lodgepole Formation

Mis

siss

ipp

ian

M

issi

s sip

pia

n

Bak

ken

For

mat

ion

Bak

ke n

For

mat

ionUpper Shale MemberUpper Shale Member

Lower Shale MemberLower Shale Member

Transitional Facies – L5Transitional Facies – L5

Transitional Facies - L1Transitional Facies - L1

Lithofacies 2

Lithofacies 2

Upper (Productive)Upper (Productive)

LowerLower

StratigraphyStratigraphyCentral Bakken Basin in North DakotaCentral Bakken Basin in North Dakota

Devonian Three Devonian Three ForksForks

Mississippian Lodgepole Mississippian Lodgepole FormationFormation

Mis

sis

sip

pia

n

Mis

sis

sip

pia

n

Bakken

Form

ati

on

Bakken

For m

ati

onUpper Shale MemberUpper Shale Member

Lower Shale MemberLower Shale Member

Transitional Facies – L5Transitional Facies – L5

Transitional Facies - L1Transitional Facies - L1

Lithofacies Lithofacies 22

Lithofacies Lithofacies 33

Lithofacies Lithofacies 44

Central Basin Central Basin FaciesFacies

NorthNorthSouthSouth

Bottom & Top SealsBottom & Top Seals

SESW Sec. 13, SESW Sec. 13, T.23N.,R.56E.T.23N.,R.56E.

10564 ft.10564 ft.

10562 ft.10562 ft.10608 ft.10608 ft.

Devonian Three Forks Devonian Three Forks FmFm

Mississippian Lodgepole Mississippian Lodgepole FmFm

Lower Bakken Shale MemberLower Bakken Shale Member

Contour Interval: 5 ftContour Interval: 5 ft NESE Sec. 27, T150N., R97WNESE Sec. 27, T150N., R97W

Upper Bakken Shale MemberUpper Bakken Shale Member

Contour Interval: 5 ftContour Interval: 5 ft NESE Sec. 27, T150N., R97WNESE Sec. 27, T150N., R97W

Matrix porosityMatrix porosity PrimaryPrimary SecondarySecondary

Fracture porosityFracture porosity Related to Related to

TectonicsTectonics RegionalRegional Salt tectonicsSalt tectonics

Related to HC Related to HC GenerationGeneration

Middle Member BakkenMiddle Member Bakken Porosity Porosity

Regional FracturesRegional Fractures

Heart River FaultHeart River Fault?Mon

tan

aM

on

tan

aCanadaCanada

Lower Lower Bakken Bakken ShaleShale

?

?

Antelope StructureAntelope Structure

North DakotaNorth DakotaMontanaMontana

VF/E

HF/E M

SWSW Sec. 5, T43N, SWSW Sec. 5, T43N, R99WR99W

FracturingFracturingUpper Bakken Upper Bakken

ShaleShale

Balcron Oil - #44-24 VairaBalcron Oil - #44-24 VairaSESE Sec. 24, T.24N., R.54E.SESE Sec. 24, T.24N., R.54E.

Neutron Porosity

Density Porosity

GR

Lodgepole Fm.

Three Forks Fm.

Bakken

Fm

. upper

middle

10

00

0

GRGRGRGR

Shell Oil Company - #32-4 Young Bear BIAShell Oil Company - #32-4 Young Bear BIASWNE Sec. 4, T148N, R92WSWNE Sec. 4, T148N, R92W

Bakken

Form

ati

on

Bakken

Form

ati

on

L2L2LL33

GRGR DenDen

Lithofacies 3Lithofacies 3

Conoco, Inc. - #17 Watterud Conoco, Inc. - #17 Watterud “A”“A”

SENW Sec. 11, T160N, R95WSENW Sec. 11, T160N, R95W

Upper L2 FaciesUpper L2 Facies

GRGR ResRes

Central Basin FaciesCentral Basin Facies

Bakken FormationBakken Formation

• Highly overpressured – 5500 to 5800 Highly overpressured – 5500 to 5800 psi psi • MigrationMigration• Bakken Source SystemBakken Source System

• Hydrocarbon GenerationHydrocarbon Generation• High volumes – 200 to 413 billion bbls (ND + MT)High volumes – 200 to 413 billion bbls (ND + MT)• Bulk volume change in the rockBulk volume change in the rock• Formation of micro- and macro- fracturesFormation of micro- and macro- fractures• Common in zones with higher organic contentCommon in zones with higher organic content

• ProducersProducers• High Gravity Oil – 39 to 46High Gravity Oil – 39 to 46oo API API• No waterNo water

ND bottom hole temperature is higherND bottom hole temperature is higher ND is clastic versus carbonateND is clastic versus carbonate ND bottom hole pressure is higher (.50-.58 ND bottom hole pressure is higher (.50-.58

psi/ft)psi/ft) Bakken shale open hole is not stableBakken shale open hole is not stable Rock propertiesRock properties

Naturally fracturedNaturally fractured Oil wetOil wet Swelling and migrating claysSwelling and migrating clays

Differences – MT to NDDifferences – MT to ND

Non-confidential Non-confidential Drilling Results to DateDrilling Results to Date

Ten (10) wells totalTen (10) wells total Single lateral - Open hole re-entry (1)Single lateral - Open hole re-entry (1) Re-Entry – Open hole – Lodgepole liner Re-Entry – Open hole – Lodgepole liner

uncemented (1)uncemented (1) Dual lateral – Open hole or perforated liners – Dual lateral – Open hole or perforated liners –

Lodgepole liner uncemented (4)Lodgepole liner uncemented (4) Proppant fractured (3), Unstimulated (1)Proppant fractured (3), Unstimulated (1)

Single lateral - Perforated liner (4)Single lateral - Perforated liner (4) Dual lateral - Co-planar – Perforated liners (0)Dual lateral - Co-planar – Perforated liners (0)

ResultsResults

Single lateral - Open hole re-entry (1)Single lateral - Open hole re-entry (1) IP 332 BO / 34 BW / 95 MCFD (Cum BO – IP 332 BO / 34 BW / 95 MCFD (Cum BO –

25,000)25,000) Marginally successfulMarginally successful

11stst Attempt Attempt Hole stability problems in the upper Hole stability problems in the upper

shale? shale? Proppant fracture growth into Proppant fracture growth into

Lodgepole?Lodgepole?

Re-Entry – Open hole – Lodgepole liner uncementedRe-Entry – Open hole – Lodgepole liner uncemented IP 263 BO / 0 BW / 177 MCFD (Cum BO – 23,000)IP 263 BO / 0 BW / 177 MCFD (Cum BO – 23,000)

Proppant Fractured after 4 months and 19,000 BOProppant Fractured after 4 months and 19,000 BO 304 BO / 0 BW / 172 MCFD304 BO / 0 BW / 172 MCFD

Current 304 BO / 0 BW / 172 MCFDCurrent 304 BO / 0 BW / 172 MCFD Successful!Successful!

Liner maintained hole stability?Liner maintained hole stability? Liner hanger packer kept proppant fracture in Liner hanger packer kept proppant fracture in

zone?zone? Pressure drawdown kept proppant fracture in Pressure drawdown kept proppant fracture in

zone?zone?

ResultsResults

Dual lateral – Open hole or perforated liners – Dual lateral – Open hole or perforated liners – Lodgepole liner uncementedLodgepole liner uncemented IP 51 BO / 171 BW / 44 MCFD (Cum BO – 11,000)IP 51 BO / 171 BW / 44 MCFD (Cum BO – 11,000) Proppant Fractured immediately to after 1 Proppant Fractured immediately to after 1

monthmonth 134 BO / 179 BW / 125 MCFD134 BO / 179 BW / 125 MCFD

Current 32 BO / 37 BW / 72 MCFDCurrent 32 BO / 37 BW / 72 MCFD Not successful!Not successful!

Liner maintains hole stability?Liner maintains hole stability? Proppant fracture growth into Lodgepole or Proppant fracture growth into Lodgepole or

higher zones? More pressure drawdown to higher zones? More pressure drawdown to keep prop fracture in zone?keep prop fracture in zone?

ResultsResults

Dual lateral – Open hole or perforated liners – Lodgepole Dual lateral – Open hole or perforated liners – Lodgepole liner uncementedliner uncemented IP 463 BO / 12 BW / 512 MCFD (Cum BO – 22,000)IP 463 BO / 12 BW / 512 MCFD (Cum BO – 22,000) Not proppant fractured yet Not proppant fractured yet Current 172 BO / 0 BW / 166 MCFDCurrent 172 BO / 0 BW / 166 MCFD Fairly Successful! Fairly Successful!

Liners maintaining hole stability?Liners maintaining hole stability? Complicated mechanically?Complicated mechanically? Pressure drawdown may keep proppant fracture in Pressure drawdown may keep proppant fracture in

zone?zone? Mechanical problems may prevent proppant Mechanical problems may prevent proppant

fracturing?fracturing?

ResultsResults

Single lateral - perforated liner – Lodgepole Single lateral - perforated liner – Lodgepole cementedcemented IP 275 BO / 107 BW / 264 MCFD (Cum 12,000 BO)IP 275 BO / 107 BW / 264 MCFD (Cum 12,000 BO) Proppant Fractured immediately to after 3 Proppant Fractured immediately to after 3

monthsmonths 179 BO / 110 BW / 183 MCFD179 BO / 110 BW / 183 MCFD

Current 83 BO / 20 BW / 126 MCFDCurrent 83 BO / 20 BW / 126 MCFD Fairly Successful!Fairly Successful!

Casing maintains hole and stops fracture Casing maintains hole and stops fracture growth into Lodgepole?growth into Lodgepole?

Mechanically simple?Mechanically simple? More pressure drawdown to improve keep More pressure drawdown to improve keep

proppant fracture in zone?proppant fracture in zone?

ResultsResults

ConclusionsConclusions

The Lithofacies are present basinwide.The Lithofacies are present basinwide. Primary reservoir porosity may be Primary reservoir porosity may be enhanced by diagenesis, tectonic enhanced by diagenesis, tectonic fractures, and/or fractures from HC fractures, and/or fractures from HC generation.generation. Porosity enhancement is not restricted Porosity enhancement is not restricted to a single lithofacies within the Middle to a single lithofacies within the Middle Member.Member. Type of fluid used while drilling may Type of fluid used while drilling may have adverse effects on production.have adverse effects on production. The presence of vertical fractures in The presence of vertical fractures in areas of intense HC generation may affect areas of intense HC generation may affect the outcome of stimulation treatment. the outcome of stimulation treatment.

ConclusionsConclusions

Production prior to fracture stimulation Production prior to fracture stimulation treatment may increase the potential of treatment may increase the potential of staying in zonestaying in zone Additional fracture stimulation Additional fracture stimulation treatments may increase reserves.treatments may increase reserves.