Methods of Dipmeter Processing and Interpretation
in
California's Productive Facies
Mike Mulhern, Harold Sugden, Jim Vohs
Dipmeters from the major petroleum-producing facies of California have been
computed using INCLINE, a commercially available program. Computational quality
control and conformity of results from logs from different areas and logging
companies are required to complete multiwell fracture analysis and stratigraphic
studies. The flexible program allows the geologist to test processing parameters
to obtain optimal results for the objectives of the analysis.
High-angle dips, for example, common in deformed Monterey Formation strata
and in fault-induced drag zones, require proper search angles and step distances
and can be masked by conventional filtering routines. These rocks are best
studied with oriented microconductivity and eccentricity anomaly plots to
analyze fracture zones. The strike of dominant and subordinate fracture trends
and strike and dip of faults can be used to construct a structural
model. Also
visible are soft-sediment deformation and slump features, corroborated by
microscanner images. Shale drape over fractured metamorphics indicates direction
of structurally higher basement in another example. Dip statistical data have
proven a valuable Monterey producibility index input, with excellent correlation
to production.
In Sacramento Valley turbidites, stratigraphic
computations reveal sediment
transport and channel thickening directions for step-outs. Larger patterns on
structural
computations locate and orient submarine canyon or "gorge" fill
unconformities, indicating truncation or subcrop traps as well as gorge
thickening direction.
In nonmarine (Chanac) and shallow marine (Etchegoin and Temblor Formations) sediments of the San Joaquin Valley, example wells demonstrate directional permeability related to cross-bedding and suggest injection pattern designs to avoid premature steam breakthrough.
AAPG Search and Discovery Article #91038©1987 AAPG Annual Convention, Los Angeles, California, June 7-10, 1987.