--> Abstract: 3-D Seismic Stratigraphic Inversion: a Lithology-Based Approach for Seismic Reservoir Characterization in Deep Water Campos Basin, by C. E. B. S. Abreu, P. R. S. Johann, L. C. S. Freitas, C. H. L. Bruhn, R. Beer, D. J. Sarzenski, and Z. Camoleze; #90933 (1998).
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Abstract: Previous Hit3-DNext Hit Previous HitSeismicNext Hit Stratigraphic Previous HitInversionNext Hit: a Lithology-Based Approach for Previous HitSeismicNext Hit Reservoir Characterization in Deep Water Campos Basin

Abreu, C. E B. S.; P. R. S. Johann; L. C. S. Freitas; C. H. L. Bruhn; R. Beer; D.J Sarzenski; Z. Camoleze - Petrobras/E&P

Most barriers to vertical fluid flow are easily recognized in well logs, such as gamma-ray and neutron-porosity logs. Reservoir heterogeneities (e.g. interbedded mudstones and calcite-cemented horizons) in turbidites Previous HitfromNext Hit deep water Campos Basin usually show subtle responses in conventional Previous HitseismicNext Hit amplitude Previous HitdataNext Hit (Fig. 1); this may be due to their reduced thickness and/or the low acoustic impedance contrast between the non-reservoir layers and the reservoir sandstone. Nevertheless, the mapping of these heterogeneities is very important for defining the reservoir drainage strategy, particularly the positioning and completion of horizontal and deviated wells. Nowadays, a great effort is being undertaken to overcome these obstacles.

The use of Previous Hit3-DNext Hit Previous HitseismicNext Hit stratigraphic post-stack Previous HitinversionNext Hit is proposed to improve reservoir characterization, by using both inverted acoustic impedance and reflectivity images. This technique involves the use of three main types of Previous HitdataNext Hit: (1) a conceptual, regional stratigraphic model, (2) a well-log derived acoustic impedance model, and (3) a stacked and migrated Previous Hit3-DNext Hit Previous HitseismicNext Hit volume. The expected results include a better description of the reservoir internal and external geometry, the assessment of reservoir properties in non-drilled areas, and a Previous HitseismicNext Hit processing quality control tool, by investigating the final residual volume Previous HitfromNext Hit the Previous HitinversionNext Hit procedure. A great advantage of this methodology is the integration of Previous HitseismicNext Hit information and well-log Previous HitdataNext Hit at the oil-field scale.

The study area, a giant oil field Previous HitfromNext Hit deep water Campos Basin, includes 26 wells with sonic and density logs, which provided a reliable spatial variant a priori information, the geostatistically-based acoustic impedance model generated Previous HitfromNext Hit well-log Previous HitdataNext Hit. The Previous HitseismicNext Hit-derived volumes, constrained by well information and conceptual stratigraphic models, enabled a more accurate mapping of the reservoir boundaries (Fig. 2) and the prediction of the reservoir properties (particularly in the inter-well area).

The Previous Hit3-DNext Hit Previous HitseismicNext Hit stratigraphic Previous HitinversionNext Hit procedure consists of five main steps: (1) volumetrically constrained well-Previous HitseismicNext Hit calibration, (2) stratigraphic deconvolution, (3) Previous Hit3-DNext Hit acoustic impedance modeling, considering the well and stratigraphic information, (4) Previous HitseismicNext Hit stratigraphic Previous HitinversionNext Hit, (5) interpretation of the high- resolution, inverted Previous HitseismicNext Hit volumes. The uncertainties associated to well-log acoustic impedance and Previous HitseismicNext Hit Previous HitdataTop values are also taken into account, controlling the freedom degree in which the final solution is obtained.

AAPG Search and Discovery Article #90933©1998 ABGP/AAPG International Conference and Exhibition, Rio de Janeiro, Brazil