Controls on fracture distribution in the Giddings Austin Chalk

Conference · Sat Sep 01 04:00:00 EDT 1990 · AAPG Bulletin (American Association of Petroleum Geologists); (USA)

OSTI ID:5968525

Wagner, D T ^[1]

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1. Texas A and M Univ., College Station (USA)

Fracture distribution in the Giddings Austin Chalk is controlled by both structure and the stratigraphy of the Austin Group. Parameters that most affect reservoir performance include fracture width, height, and spacing, as well as the number of fracture sets and their orientations. Lateral variance of these parameters is a function of structural position, while vertical change is related to stratigraphy. The Austin Chalk productive trend is thought to coincide with the hingeline of the Gulf Coast basin, where extension has been concentrated during subsidence of the basin. Fracturing is attributed to a number of mechanisms including normal faulting, bending over buried structures, gravity creep, differential compaction, and aquathermal pressuring. A change in structural style from faulting to flexure takes place from west to east across the Giddings field, accompanied by a change in fracture distribution. In the west, fractures develop only in close proximity to faults whereas in the east they are more widely distributed over broad warps. Stratigraphic controls include lithology, porosity, bed thickness, and ductility contrast between adjacent beds. The Austin Chalk consists of sparse biomicrite interbedded with marls, shales, and clay seams. In general, thin beds are more highly fractured than thick beds, and clean limestone is more highly fractured than marl or shale. Where the more ductile marls and clays exceed a critical thickness, fractures tend to terminate within individual chalk beds, resulting in barriers to vertical flow within the reservoir.

• OSTI ID: 5968525
• Report Number(s): CONF-9010204--
• Conference Information: Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (USA) Journal Volume: 74:9
• 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
58 GEOSCIENCES
580000 -- Geosciences
CARBONATE ROCKS
CLAYS
DISTRIBUTION
FEDERAL REGION VI
GEOLOGIC DEPOSITS
GEOLOGIC FAULTS
GEOLOGIC FORMATIONS
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GEOLOGY
GROUND SUBSIDENCE
GULF COAST
LIMESTONE
LITHOLOGY
MARLSTONE
MINERAL RESOURCES
NORTH AMERICA
PETROLEUM DEPOSITS
POROSITY
RESERVOIR ROCK
RESOURCES
ROCKS
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
SHALES
STRATIGRAPHY
TEXAS
USA