Abstract:
The southern part of Guizhou Province is the concentration of Upper Paleozoic Carboniferous shales in southern China, where has undergone complex tectonic evolution and petrographic paleogeographic changes. Therefore, the inhomogeneous shale system of the Dawuba Formation is developed. As a typical representative of Ziyun area in southern Guizhou Province, the development of shales in Dawuba Formation varies from region to region. In this paper, the authors studied distribution and reservoir formation conditions of the Dawuba Formation from perspectives of regional tectonic development, formation lithology combination, formation thickness and burial depth, organic geochemical characteristics, shale reservoir physical properties and gas-bearing properties through well CY1, well DY1, and the surrounding outcrops in Luogang Manchang, Sidazhai, and Getuhe area. The results show that Ziyun area was deposited in the slope-pelagic phase at the edge of Early Carboniferous, and the water body gradually becomes deeper from north to south. And the organic-rich shales are concentrated in the I and III section of Dawuba Formation with favorable static indicators of each section, while the drilling wells in this area show good gas content. Through comprehensive comparison and evaluation, two favorable shale gas zones of Zongdi and Shangyuan in Ziyun area were selected, providing next direction for shale gas exploration in this area.