Effects of Provenance on Porosity Development of Chang 6 Sandstone of the Yanchang Formation in the Center of Ordos Basin

Key words: 
• Ordos basin /
• provenances /
• Chang6 oilbed of Yangchang Formation /
• porosity

Abstract: Chang6 reservoir is the leading pay formation of the Yanchang Formation in the center of Ordos basin, but reservoir quality of genetic sandbodies shows a big difference in horizontal. By studying the light and heavy mineral combination characteristics of chang6 reservoir sandstone and typical outcrops, it is believed that there exist five main source directions of the west, northeast, northwest, north and southeast in the depositional period of chang6 oilbed of Yangchang Formation in the center of Ordos basin. The characteristics of the light and heavy mineral combination, interstitial matrix and diagenetic mineral of chang6 reservoir sandstone controlled by different source directions were different. In addition, there exist some mixed sources areas which were converged by the west, northeast, northwest, north and southeast sources. The characteristics of light and heavy mineral combination, interstitial matrix, diagenetic mineral and porosity of its reservoir were affected by the main source. The controlling factors of the sandstone reservoir porosity development of Chang 6 include the sandstone maturity, grain size, detritus composition, interstitial matrix and diagenesis. The reservoir porosity is closely related to the various provenances. As a result, porosity distribution is predictable.