A New Image Processing Workflow for the Detection of Quartz Types in Shales: Implications for Shale Gas Reservoir Quality Prediction

Sen Guo, David Misch, Reinhard F. Sachsenhofer, Yanming Zhu, Xin Tang, Weichen Bai

Publikation: Beitrag in FachzeitschriftArtikelForschungBegutachtung


A shale lithofacies scheme is commonly used to characterize source rock reservoirs of the Lower Cambrian Niutitang Formation. However, this classification ignores that individual components such as quartz may have different origins, potentially affecting reservoir quality. The main objective of this article is, therefore, to present a refined scheme for lithofacies and an image processing workflow for the detection of quartz types in the Niutitang Formation shales from the Jiumen outcrop in the Guizhou Province (Upper Yangtze Basin, SW China). In order to do so, a combination of bulk density, optical and scanning electron microscopy and image analysis was used. The shale lithology was macroscopically classified into seven major categories and nineteen subcategories. Subsequently, the shales were investigated at the microscopic level, mainly focusing on quartz types and microstructural variations. Afterwards, the workflow to calculate the weight per unit volume (1 cm3) of the quartz types was presented, i.e., firstly, by calculating the weight of mineral matter by subtraction of the measured weight of organic matter from the bulk shale; secondly, by calculating the weight of total quartz in bulk shale from the weight of mineral matter and its proportion calculated from X-ray diffraction data; thirdly, by calculating the weight of detrital quartz and non-detrital quartz with energy dispersive X-ray mapping, image processing and quartz density; finally, by calculating the weight of clay-sized quartz by subtracting of the weight of detrital and non-detrital quartz from the weight of the total quartz. The bulk quartz content was found to be dominated by clay-sized quartz, which may mainly control the mesopore volume available for gas storage and, hence, the shale gas reservoir development.
PublikationsstatusVeröffentlicht - 16 Aug. 2022

Bibliographische Notiz

Funding Information:
This research was funded by the Science Research Foundation of Coalbed Methane Resources and Reservoir Formation Process Key Laboratory of the Ministry of Education, China University of Mining and Technology (Grant Number 2020-010, by Sen Guo), The National Natural Science Foundation of China (Grant Number 42172156, by Yang Wang), The Fundamental Research Funds for the Central Universities (grant number 2022YCPY0201, by Yang Wang), and scholarship of the China Scholarship Council (grant number 202006420093, by Sen Guo). The APC was funded by David Misch.

Publisher Copyright:
© 2022 by the authors.

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