Sedimentology and Paleoenvironmental Characteristics of Fine‐grained Sediments in Coal‐bearing Strata in the Eastern Ordos Basin: A Case Study of the Exploratory Well in the Zizhou Area

Abstract

AbstractThe continuously collected cores from the Permo–Carboniferous coal‐bearing strata of the eastern Ordos Basin are essential for studying the hydrocarbon potential in this region. This study adopted sedimentological and geochemical methods to analyze the sedimentary environment, material composition, and geochemical characteristics of the coal‐bearing strata. The differences in depositional and paleoclimatic conditions were compared; and the factors influencing the organic matter content of fine‐grained sediments were explored. The depositional environment of the Benxi and Jinci formations was lagoon to tidal flat with weakly reduced waters with low salinity and dry‐hot paleoclimatic conditions; while that of the Taiyuan Formation was a carbonate platform and shallow water delta front, where the water was highly reductive. The xerothermic climate alternated with the warm and humid climate. The period of maximum transgression in the Permo–Carboniferous has the highest water salinity. The Shanxi Formation was deposited in a shallow water delta front with a brackish and fresh water environment and alternative weak reductiveness. And the paleoclimate condition is dry‐hot. The TOC content in fine‐grained samples was averaging 1.52%. The main controlling mechanism of organic matter in this area was the input conditions according to the analysis on input and preservation of organic matter.