Horizontal Drilling Potential of the Middle Member Bakken

Horizontal Drilling Potential of the Middle Member Bakken Formation, North Dakota Julie A. Le. Fever North Dakota Geological Survey

Williston Basin AB SK MB ND MT WY North Dakota Study Area SD

Devonian Mississippian Stratigraphy Lodgepole Formation “False Bakken” Pelmatozoan limestone upper Bakken Formation middle lower “Sanish” Three Forks Formation

Isopach Map of the Middle Bakken Member Contour Interval: 5 ft

Bakken Middle Member Prairie Salt Contour Interval ft Montana North Dakota

Lithofacies of the Middle Member Upper Shale Lithofacies 5 - Siltstone Lithofacies 4 – Interbedded Dark Grey Shale and Buff Silty Sandstone Lithofacies 3 - Sandstone Productive Lithofacies 2 – Interbedded Dark Grey Shale and Buff Silty Sandstone Productive Lithofacies 1 - Siltstone Lower Shale (From Le. Fever and others, 1991)

Stratigraphy Bakken Limit in North Dakota South North Upper Shale Member Transitional Facies – L 5 Lower 2 Devonian Three Forks ies ac of th Li Upper (Productive) Transitional Facies - L 1 Lower Shale Member Mississippian Bakken Formation Mississippian Lodgepole Formation

Stratigraphy Central Bakken Basin in North Dakota Mississippian Lodgepole Formation North Upper Shale Member Transitional Facies – L 5 Lithofacies 4 Lithofacies 3 Lithofacies 2 Transitional Facies - L 1 Lower Shale Member Devonian Three Forks Central Basin Facies Mississippian Bakken Formation South

Bottom & Top Seals Devonian Three Forks Fm 10608 ft. Mississippian Lodgepole Fm 10562 ft. 10564 ft. SESW Sec. 13, T. 23 N. , R. 56 E.

Lower Bakken Shale Member Contour Interval: 5 ft NESE Sec. 27, T 150 N. , R 97 W

Upper Bakken Shale Member Contour Interval: 5 ft NESE Sec. 27, T 150 N. , R 97 W

Middle Member Bakken Porosity n Matrix porosity n n n Primary Secondary Fracture porosity n Related to Tectonics n n n Regional Salt tectonics Related to HC Generation

Regional Fractures Canada ? Antelope Structure Montana ? ? Lower Bakken Shale Heart River Fault

Fracturing Upper Bakken Shale SWSW Sec. 5, T 43 N, R 99 W HF/E VF/E Montana North Dakota M

Balcron Oil - #44 -24 Vaira SESE Sec. 24, T. 24 N. , R. 54 E. GR Bakken Fm. Lodgepole Fm. upper 10000 Density Porosity middle Three Forks Fm. Neutron Porosity

Shell Oil Company - #32 -4 Young Bear BIA SWNE Sec. 4, T 148 N, R 92 W Bakken Formation GR Den L 3 L 2 GR

Conoco, Inc. - #17 Watterud “A” SENW Sec. 11, T 160 N, R 95 W GR Res Lithofacies 3 Central Basin Facies Upper L 2 Facies

Bakken Formation • Highly overpressured – 5500 to 5800 psi • Migration • Bakken Source System • Hydrocarbon Generation • • High volumes – 200 to 413 billion bbls (ND + MT) Bulk volume change in the rock Formation of micro- and macro- fractures Common in zones with higher organic content • Producers • High Gravity Oil – 39 to 46 o API • No water

Differences – MT to ND § ND bottom hole temperature is higher § ND is clastic versus carbonate § ND bottom hole pressure is higher (. 50 -. 58 psi/ft) § Bakken shale open hole is not stable § Rock properties § Naturally fractured § Oil wet § Swelling and migrating clays

Non-confidential Drilling Results to Date n n n Ten (10) wells total Single lateral - Open hole re-entry (1) Re-Entry – Open hole – Lodgepole liner uncemented (1) Dual lateral – Open hole or perforated liners – Lodgepole liner uncemented (4) n Proppant fractured (3), Unstimulated (1) Single lateral - Perforated liner (4) Dual lateral - Co-planar – Perforated liners (0)

Results n Single lateral - Open hole re-entry (1) n IP 332 BO / 34 BW / 95 MCFD (Cum BO – 25, 000) n Marginally successful n 1 st Attempt n Hole stability problems in the upper shale? n Proppant fracture growth into Lodgepole?

Results n n Re-Entry – Open hole – Lodgepole liner uncemented IP 263 BO / 0 BW / 177 MCFD (Cum BO – 23, 000) n Proppant Fractured after 4 months and 19, 000 BO n 304 BO / 0 BW / 172 MCFD n Current 304 BO / 0 BW / 172 MCFD n Successful! n Liner maintained hole stability? n Liner hanger packer kept proppant fracture in zone? n Pressure drawdown kept proppant fracture in zone?

Results n Dual lateral – Open hole or perforated liners – Lodgepole liner uncemented n IP 51 BO / 171 BW / 44 MCFD (Cum BO – 11, 000) n Proppant Fractured immediately to after 1 month n 134 BO / 179 BW / 125 MCFD n Current 32 BO / 37 BW / 72 MCFD n Not successful! n Liner maintains hole stability? n Proppant fracture growth into Lodgepole or higher zones? More pressure drawdown to keep prop fracture in zone?

Results n Dual lateral – Open hole or perforated liners – Lodgepole liner uncemented n IP 463 BO / 12 BW / 512 MCFD (Cum BO – 22, 000) n Not proppant fractured yet n Current 172 BO / 0 BW / 166 MCFD n Fairly Successful! n Liners maintaining hole stability? n Complicated mechanically? n Pressure drawdown may keep proppant fracture in zone? n Mechanical problems may prevent proppant fracturing?

Results n Single lateral - perforated liner – Lodgepole cemented n IP 275 BO / 107 BW / 264 MCFD (Cum 12, 000 BO) n Proppant Fractured immediately to after 3 months n 179 BO / 110 BW / 183 MCFD n Current 83 BO / 20 BW / 126 MCFD n Fairly Successful! n Casing maintains hole and stops fracture growth into Lodgepole? n Mechanically simple? n More pressure drawdown to improve keep proppant fracture in zone?

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

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