Preliminary assessment of the Lago Mercedes discovery, Magallanes Basin, Chile

Conference · Mon Feb 01 00:00:00 EST 1993 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:5936994

Dean, J S ^[1]; Wilson, J T; Mainzer, G F ^[2]; Escobar, F; Aguirre, G ^[3]

---

1. Advantage Resources, Denver, CO (United States)
2. Anderman-Smith, Denver, CO (United States)
3. ENAP, Punta Arenas (Chile)

The Lago Mercedes No. 1 well, spudded January 17, 1991, was positioned to test a seismically defined structural culmination located along a blind thrust near the deep foreland axis of the western magallanes Basin. This fault, which defines the leading edge of Andean-related thrust detachment in the region, is responsible for a trap geometry that is genetically related to, but fundamentally different from the numerous unrooted Tertiary folds in the area. Although the Lower Cretaceous Springhill Formation comprised the primary target, it was anticipated that the geometry of the fold allowed for the possibility of several fractured intervals in the hanging wall, including volcaniclastic rocks of the underlying Jurassic Tobifera [open quotes]basement[close quotes] sequence, recently found to be productive elsewhere on the eastern platform of the basin. During drilling of the well, gas and condensate shows were encountered in numerous horizons. The most surprising of these later proved to be a Permo-Triassic granodiorite underlying the Tobifera. Although relatively widespread on outcrop, this represents the first time a pre-rift intrusive body has been penetrated in the subsurface. All of the hydrocarbon-bearing intervals exhibit minimal matrix porosity but varying degrees of fracturing. Subsequent testing of the well yielded combined flow rates of in excess of 12 MMCFD of rich gas and 1140 BPD of 52 A.P.I. condensate. The most prolific zone corresponds to an intensely fractured and partially weathered interval in the uppermost portion of the intrusive. Additional testing is planned prior to any estimate of recoverable reserves. Nevertheless, this unique accumulation underscored the possibility for nonconventional reservoirs throughout the lightly explored Sub-Andean basin trend, particularly fold-thrust belts which have the potential to [open quotes]create[close quotes] reservoirs and trap geometry simultaneously.

• OSTI ID: 5936994
• Report Number(s): CONF-930306-; CODEN: AABUD2
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (United States), Vol. 77:2; Conference: International congress of the American Association of Petroleum Geologists (AAPG), Caracas (Venezuela), 14-17 Mar 1993; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
CHILE
NATURAL GAS DEPOSITS
EXPLOITATION
GEOLOGY
ANDES
BUILDUP
CONFIGURATION
CRETACEOUS PERIOD
FORECASTING
GAS CONDENSATES
GAS YIELDS
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GEOLOGIC TRAPS
HYDROCARBONS
JURASSIC PERIOD
MATURATION
NATURAL GAS
ORIGIN
POROSITY
SITE CHARACTERIZATION
CONDENSATES
DEVELOPING COUNTRIES
ENERGY SOURCES
FLUIDS
FOSSIL FUELS
FUEL GAS
FUELS
GAS FUELS
GASES
GEOLOGIC AGES
GEOLOGIC DEPOSITS
LATIN AMERICA
LIQUIDS
MESOZOIC ERA
MINERAL RESOURCES
MOUNTAINS
NATURAL GAS LIQUIDS
ORGANIC COMPOUNDS
RESOURCES
SOUTH AMERICA
YIELDS
030200* - Natural Gas- Reserves
Geology
& Exploration
030300 - Natural Gas- Drilling
Production
& Processing