Discovery and geologic significance of organic-biogenic secondary freshwater calcite in the Upper Triassic of Shaan-Gan-Ning Basin

作     者：Zhang, WZ Huang, YM Song, GC Zan, CL 

作者机构：Research Institute of Petroleum Exploration and Development Changqing Bureau of Petroleum Exploration Changqing China 

出 版 物：《Chinese Science Bulletin》 (中国科学通报)

年 卷 期：1997年第42卷第15期

页      面：1297-1300页

核心收录：

学科分类：070903[理学-古生物学与地层学(含：古人类学)] 0709[理学-地质学] 07[理学] 

主　　题：secondary calcite isotope genesis oil and gas migration. 

摘      要：1 Discovery of secondary freshwater calciteFROM well ZJ-23, around 22 m of condensed limestone has been found in member Chang-3 ofthe Upper Triassic Yanchang Formation. Electric log reflects high resistivity, higher densityof rock and lower values of natural gama, with calcite content of 40%—80%. Observation da-ta of 11 core wafers from 883. 05—887.20 m of the well demonstrate that high-angle struc-tural fracture (2 mm wide) and micro-fracture are relatively developed and fully or half