Horizontal drilling the Bakken Formation, Williston basin: A new approach

Conference · Tue May 01 00:00:00 EDT 1990 · AAPG Bulletin (American Association of Petroleum Geologists); (USA)

OSTI ID:6985658

Lefever, J A ^[1]

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1. North Dakota Geological Survey, Grand Forks (USA)

Horizontal drilling is an attractive new approach to exploration and development of the Mississippian/Devonian Bakken Formation in the southwestern part of North Dakota. This drilling technique increases the probability of success, the profit potential, the effective drainage area maximizing recoverable reserves, and the productivity by encountering more natural occurring fractures. The target formation, the Mississippian/Devonian Bakken, consists of three members in an overlapping relationship, a lower organic-rich black shale, a middle siltstone/limestone, and an upper organic-rich black shale. It attains a maximum thickness of 145 ft and thins to a feather edge along its depositional limit. Considered to be a major source rock for the Williston basin, the Bakken is usually overpressured where productive. Overpressuring is attributed to intense hydrocarbon generation. Reservoir properties are poor with core fluid porosities being generally 5% or less and permeabilities ranging from 0.1 to 0.2 md. The presence of natural fractures in the shale are necessary for production. Two types of fractures are associated with Bakken reservoirs: large vertical fractures (of tectonic origin) and microfractures (probably related to hydrocarbon generation). An economic comparison between horizontal and vertical wells show that well completion costs are approximately two times higher (average costs; $1,500,000 for a horizontal to $850,000 for a vertical) with average payout for horizontal wells projected to occur in half the time (1.5 yr instead of 3.4 yr). Projected production and reserves are considered to be 2 to 4 times greater from a horizontal well.

• OSTI ID: 6985658
• Report Number(s): CONF-900605-; CODEN: AABUD
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (USA), Vol. 74:5; Conference: Annual convention and exposition of the American Association of Petroleum Geologists, San Francisco, CA (USA), 3-6 Jun 1990; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
58 GEOSCIENCES
DIRECTIONAL DRILLING
PETROLEUM DEPOSITS
EXPLORATION
WILLISTON BASIN
BLACK SHALES
CARBONIFEROUS PERIOD
DEVONIAN PERIOD
GEOLOGIC FORMATIONS
GEOLOGIC FRACTURES
LIMESTONE
NORTH DAKOTA
PERMEABILITY
RESERVOIR ROCK
SILTSTONES
SOURCE ROCKS
BITUMINOUS MATERIALS
CARBONACEOUS MATERIALS
CARBONATE ROCKS
CHATTANOOGA FORMATION
DRILLING
ENERGY SOURCES
FEDERAL REGION VIII
FOSSIL FUELS
FUELS
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC STRUCTURES
MATERIALS
MINERAL RESOURCES
NORTH AMERICA
OIL SHALES
PALEOZOIC ERA
RESOURCES
ROCKS
SEDIMENTARY ROCKS
USA
020200* - Petroleum- Reserves
Geology
& Exploration
020300 - Petroleum- Drilling & Production
580000 - Geosciences