Application of Seismic Sedimentology on the predication of Beach and Bar Sandbodies in Lacustrine: a case study of the Cretaceous in Chepaizi area, Junggar Basin, NW China

Dongna Zhao
China University of Petroleum Beijing, China
[email protected]

Seismic sedimentology is a newly emerged interdisplinary subject, which uses seismic data to gain insight into the rocks and their forming processes. It is a very effective tool for mapping high-frequency sequence and depositional systems, and plays an important role in the exploration and production of thin sandstone reservoirs. In Cretaceous, Chepaizi area mainly deposited shore-shallow lacustrine beach bar microfacies which is characterized by thin single sand layer(usually 2-5m), fast lateral pinchout and strong reservoir heterogeneity. These beach-bar sandbodies are NE-extended, usually 5~10km long and 2~3km wide. Most of them are oil-bearing, and vertical superimposed, constituting the main production reservoirs of Cretaceous.

In this study, under the guidance of seismic sedimentary theory, and by making use of the 90° phase shift technique, frequency spectrum decomposition and stratal slicing, the sliced cuds were made to display the distribution of sedimentary microfacies and reflect the evolutionaly history. With the assistant of comprehensive analysis of core, lithology and well-logging date, the beach-bar sandbodies of the typical slices was interpreted subtly, and the distribution and evolution of bearch-bar microfacies was predicted. The whole workflow will emphasize the integration of seismic and geologic interpretations and balanced use of seismic sedimentology, sequence stratigraphy and seismic stratigraphy.

Overall, this study will provide a reliable approach in exploration of subtle reservoirs in lacustrine and also could be used as a reference for seismic sedimentology study in non-marine basin, especially in an area where more detailed seismic work has been done but a few holes drilled.

AAPG Search and Discovery Article #90157©2012 AAPG Foundation 2012 Grants-in-Aid Projects