--> Abstract: Well and Seismic Correlation of Devonian Reef Sequences: An Example from the Canning Basin, Western Australia, by P. N. Southgate, J. M. Kennard, M. J. Jackson, P. E. O'Brien, and M. J. Sexton; #91015 (1992).
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ABSTRACT: Well and Previous HitSeismicNext Hit Correlation of Devonian Reef Sequences: An Example from the Canning Basin, Western Australia

SOUTHGATE, PETER N., JOHN M. KENNARD, M. JIM JACKSON, PHIL E. O'BRIEN, and MIKE J. SEXTON, Bureau of Mineral Resources, Canberra, Australian Capital Territory, Australia

Integrated sequence interpretation of well logs and Previous HitseismicNext Hit Previous HitdataNext Hit provides a powerful tool for analyzing sedimentary successions in areas where interpretation of Previous HitseismicNext Hit Previous HitdataNext Hit alone is ambiguous, and where well-Previous HitseismicNext Hit ties based on synthetic seismograms are equivocal. The method is based on the recognition of repeated wireline log trends both within and between wells, and is illustrated with an example of reef sequences in three wells (Yarrada, Meda, and Terrace) from the Lennard Shelf, northern Canning basin. Interpretations of these trends are constrained by well cuttings, cores and biostratigraphic Previous HitdataNext Hit. Well interpretations are then extrapolated back to, and mapped, on Previous HitseismicNext Hit Previous HitdataNext Hit.

Sequence boundaries are generally recognized by abrupt shifts or shoulders in wireline log patterns, and in most cases this reflects abrupt lithofacies discontinuities. Depositional systems within a sequence can be identified by more subtle log trends and the stacking patterns of individual log cycles (parasequences). Lowstand deposits are characterized by progradational to aggradational log cycles, and comprise either siliciclastic conglomerate and sandstone (incised braid-stream and deltaic deposits), carbonate conglomerates (slump and debris flow deposits), or bioclastic wackestones and packstones (shallow shelf deposits).

Transgressive deposits usually Previous HitdisplayNext Hit a backstepping progradational pattern on gamma logs, culminating at a maximum gamma value. Progradational cycles comprise glauconitic, calcareous sandstone and sandy oolitic carbonates, and the interval of maximum flooding is represented by marine shales or shaly carbonates. Highstand deposits Previous HitdisplayTop a long term upward-decreasing gamma trend representing either progradational marginal slope ("clean" uniform gamma log, upward-increasing dipmeter), reef ("clean" uniform gamma log, erratic "bag of nails" dipmeter pattern), or platformal carbonates ("dirty" variable gamma log).

 

AAPG Search and Discovery Article #91015©1992 AAPG International Conference, Sydney, N.S.W., Australia, August 2-5, 1992 (2009)