TITLE:
Mechanism and Distribution of Calcareous Interbeds in Songtao Uplift and Its Periphery of Qiongdongnan Basin
AUTHORS:
Peiyuan Zhu, Li You, Qingtao Yuan, Jia Zhong, Aiqun Liu
KEYWORDS:
Calcareous Interbeds, Material Sources, Genetic Mechanism, Distribution Rules, Pore Space, The Songtao Uplift and Its Periphery
JOURNAL NAME:
Open Journal of Marine Science,
Vol.8 No.3,
July
4,
2018
ABSTRACT: Based on core and casting slice observation, well drilling and logging data, the
source of carbonate materials, lithology together with electric properties,
types, genesis mechanism and distribution of calcareous interbeds in Songtao
uplift and its periphery of Qiongdongnan Basin have been thoroughly analyzed.
Results show that typical features have been appeared from well logging
curves, containing low gamma-ray, low acoustic travel time, low neutron value,
high density, as well as bright white calcium nodules or bands in electrical
imaging well-logging curves. Drilling results reveal that calcareous interbeds
developed mostly in high position of paleostructures and their distribution
was controlled by the combined effects of macroscopic and microscopic factors.
Macroscopically, calcareous interbeds relate to paleogeomorphology together
with the combination of sandstone and mudstone. They are also controlled
microscopically by the source of carbonate cements and pore space.
Under normal circumstances, with regard to the same sand, the closer to the
mudstone and the thicker of mudstone, the more conducive to the formation
of calcareous interlayer. Low compaction strength, high content of rigid particles,
coarse grain size, well-sorted sandstone and large pore space during
carbonate cementation are favorable for the development of calcareous interbeds.