Depositional environments and reservoir properties, Lonetree field, southern Denver basin, Colorado

Conference · Mon Aug 01 04:00:00 EDT 1983 · Am. Assoc. Pet. Geol., Bull.; (United States)

OSTI ID:6433146

Dolson, J

Significant accumulations of oil and gas are stratigraphically trapped in the Lower Cretaceous J sandstone in the southern Denver-Julesburg basin of Colorado. Lonetree Field (T3S, R59W) provides a typical example of trapping mechanisms and reservoir properties. The deltaic J sandstone at Lonetree can be divided into three genetic units; a lower delta front (J-3), a middle delta plain sequence (J-2), and overlying destructional marine (J-1). Production at Lonetree is primarily from channel and crevasse splay sandstones of the J-2 interval. Traps are formed by the updip pinch-out of quality sandstone. Channel sandstones are characterized by a coarse to very fine-grained upward-fining sequence. Trough cross-beds predominate at the base, and ripples and rootlets at the top. Carbonized wood is ubiquitous throughout. Crevasse splay deposits show extreme lateral and vertical variation. Both coarsening and fining upward deposits are possible. Rooted zones and ripple cross-stratification are common. Porosity in both channels and splays is secondary in nature, resulting from the dissolution of feldspars and calcite cement. This overprinting of secondary porosity on a complex depositional system has created numerous separate reservoirs within the field. Porosity in producing zones is commonly 13 to 20%, with permeabilities in excess of 75 md. Little petrographic or petrophysical differences appear to exist between productive splay and channel sandstones. Typical cumulatives to date are 100,000 bbl of oil per well from splay sandstones, while channels contribute 125,000 bbl of oil per well. The 17 producing wells are expected to yield 2.4 million bbl of oil and 4 bcf of gas.

• Research Organization: Amoco Production Co., Englewood, CO
• OSTI ID: 6433146
• Report Number(s): CONF-8309274-
• Conference Information: Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Journal Volume: 67:8
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
03 NATURAL GAS
030200 -- Natural Gas-- Reserves
Geology
& Exploration
COLORADO
FEDERAL REGION VIII
GEOLOGIC DEPOSITS
GEOLOGIC TRAPS
GEOLOGY
MINERAL RESOURCES
NATURAL GAS DEPOSITS
NORTH AMERICA
OIL FIELDS
PERMEABILITY
PETROLEUM DEPOSITS
POROSITY
PRODUCTION
RESERVOIR ROCK
RESOURCES
STRATIGRAPHY
USA