--> ABSTRACT: Reservoir Characterization in Bao and Ma Oil Fields, Kailu Basin, by Feng Shen, Jinliang Zing, Zhiyun Lai; #91020 (1995).

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Reservoir Characterization in Bao and Ma Oil Fields, Kailu Basin

Feng Shen, Jinliang Zing, Zhiyun Lai

Geological and geophysical techniques are integrated to characterize reservoirs in the Bao and Ma oil fields, Kailu Basin, China. Geological studies show that the main reservoirs in Bao are slope-type fan delta systems in the Jurassic Joufutang Formation while the main reservoirs in Ma are Gilbert-type fan delta and delta systems in the Jurassic Joufutang Formation and Shahai Formation. The facies associations and sandstone distribution are related to basin fill architectures. Based on analyses of geological structure and reservoir microfacies, we propose three diagenetic models to explain the formation of secondary porosity: (1) meteoric burial diagenesis, (2) dehydration and transformation of clay minerals, and (3) advective pore water flow.

In order to develop oil fields effeciently, we need to know how reservoir properties change between wells and how oil is distributed in reservoirs. We use forward and inversion geophysical techniques to invert lithological parameters from seismic and log data. Inverted velocity sections suggest that the internal structure and external configurations of reservoirs in Bao are products of sedimentary processes and structural deformation while in Ma they are mainly controlled by sedimentary processes. Using relationships between porosity and velocity estimated from the results of supersonic rock experiments, we obtain porosities from inverted velocities. Two-dimensional porosity sections indicate reservoir heterogeneity is greater in Ma than in Bao, which matches the action of our diagene ic models. Oil distribution in reservoirs is predicted using pattern recognition and the back-propagation model of artificial neural networks, incorporating derived geophysical and reservoir dynamic productivity parameters.

We conclude: (1) The oil pools in Ma are mainly lithology controlled and have varied oil-water contacts. The trap type is a stratigraphic pinch-out. (2) The oil pool in Bao is in a fractured anticline with a consistent oil-water contact. A mudstone lens divides the oil pool near the top of the anticline pool, but the pool is contected at the edges of the anticline.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995