Quantitative analysis of a transpressional system, El Biod Arch, Ghadames Basin, Algeria

Conference · Mon Jan 01 04:00:00 EST 1996 · AAPG Bulletin

OSTI ID:6862101

Moore, S R; Krantz, R W ^[1]; Akkache, K; Messaoudi, M

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1. ARCO International Oil and Gas Co., Plano, TX (United States)

Trap definition within the northern extension of the Hassi Touareg - Rhourde El Baguel fault zone in the western Ghadames Basin of Algeria is difficult due to complex structural geometries. The fault zone consists of a narrow system of discontinuous. locally en echelon faults. Although north-trending to the south, the zone curves to a northeast trend to the north. Reserves associated with the southern portion of the system total 1500 MMBOR and 2 TCFG. Several lines of evidence support a strike-slip component of motion for the northern segment. Horizontal slickensides have been described in cores taken from wells within the fault trend. Fracture patterns measured from logs taken within the NE-SW fault trend show clusters expected for right-lateral Reidel shears. Although complicated by all evaporate sequence at mid-level in the stratigraphic section, we interpret downward converging faults imaged on recent 2D seismic as positive flower profiles. Map patterns are also interpreted as right-lateral, recognizing that the 2D grid cannot resolve all of the structural complexity. To confirm the component of strike-slip fault displacement, we applied a new quantitative method relating map view structural orientations to the shear magnitude, the degree of convergence or divergence, and the magnitudes of horizontal and vertical strains. Strike-slip to convergence ratios ranging from 2:1 to 3:1 were measured in the study area. Higher ratios (10:1) measured above the salt may indicate a detachment. These ratios also fit the regional tectonic pattern: to the south, where the fault zone trends due north, structural geometries support dip-slip inversion indicative of east-west shortening. Applying the same shortening vector to the northeast-trending part of the zone suggests oblique right-lateral motion, with a strike-slip to convergence ratio of 2:1.

• OSTI ID: 6862101
• Report Number(s): CONF-960527--
• Conference Information: Journal Name: AAPG Bulletin Journal Volume: 5
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
AFRICA
ALGERIA
ARAB COUNTRIES
DEVELOPING COUNTRIES
ENERGY SOURCES
EXPLORATION
FOSSIL FUELS
FUELS
GEOLOGIC DEPOSITS
GEOLOGIC STRUCTURES
GEOPHYSICAL SURVEYS
MINERAL RESOURCES
PETROLEUM
PETROLEUM DEPOSITS
RESOURCES
SEDIMENTARY BASINS
SEISMIC SURVEYS