--> Sed-Volcanic Clastic Rock Reservoir Characterization and its Significance in Oil and Gas

2018 AAPG International Conference and Exhibition

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Sed-Volcanic Clastic Rock Reservoir Characterization and its Significance in Oil and Gas

Abstract

The paper introduced the comprehensive application of conventional logging curve, core, thin section, image logging and elemental capture spectroscopy logging data in reservoir characterization and depositional environment analysis of the second member of Yingcheng Formation, Wukeshu structure, Yingtai fault depression, Songliao Basin. The lithology and deposition enviroment identification is the biggest challenge for this area. The log response of this lithology is very different with the clastic rock which was previously recognized for this area. Meanwhile, the rock texture is also very different from the volcanic rock as the adjacent blocks. The thin section analysis result revealed that: the reservoir lithology is sed-volcanic clastic which is mainly composed of volcanic components, and also has certain features of the sedimentary structures. This lithology is a transition type formed by the eruption of volcano under the lacustrine environment background. A detail analysis has been done and a very strong relationship has been observed between the core data, image log and lithology. In the current study area, there are many high resolution borehole image log has been acquired but core data is available only for short interval. So, one Borehole Image based workflow has been developed to characterize the sed-volcanic reservoir. Results: The image log character was summarized for different lithology type. Also, three types of deposition environment is predicted: onshore volcano eruption subaerial deposition, onshore volcano eruption subaqueous sedimentary and underwater eruption subaqueous sedimentary. Sed-volcanic clastic of onshore volcano eruption subaerial deposition is characterized with coarse particle, poor bedding, and sub-rounded. Sed-volcanic clastic of onshore volcano eruption subaqueous sedimentary is characterized with a relatively fine grain size, good bedding and cross bedding. Besides, it is close to source rocks and has favorable storage configuration vertically, so it is the major rock type in the study area. Sed-volcanic clastic of underwater eruption subaqueous sedimentary is characterized massive structure, good petrophysics property, and close to the source rock. Although the development scale is limited, it can also be used as a target for further exploration. The integrated methodology of characterizing sed-volcanic clastic reservoir is significant for the exploration of this kind of reservoir developed in other oilfields of China.