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- Title
柴北缘下干柴沟组深部碎屑岩储层发育特征 及主控因素.
- Authors
田继先; 纪宝强; 曾 旭; 王晔桐; 李曜良; 孙国强
- Abstract
The northern margin of Qaidam Basin is low in exploration degree and has high resources potential. In order to determine the characteristics and controlling factors of deep sandstone reservoir in the northern margin of Qaidam Basin, a comprehensive study on the reservoir of the Xiaganchaigou Formation in the northern margin of Qaidam Basin was carried out by using the cast thin section, scanning electron microscope, physical property data and logging data. The results showed that the deep reservoir in Qaidam Basin of Xiaganchaigou Formation is mainly composed of feldspathic lithic sandstone and lithic arkose, good separation, grinding medium, with relatively high composition maturity and structural maturity. The primary pores were developed, porosity and permeability are well correlated, with average porosity and permeability up to 10.7% and 25.74×10−3 μm² . The pore throat was medium to slants thin, with good connectivity. Subaqueous distributary channel sand and shore-shallow lake mat sand are the basic conditions for forming excellent reservoirs in braided river delta front. In the early diagenesis stage, the content of carbonate cement is less than 15%. In the early diagenesis stage, it is buried shallowly for a long time, and in the late diagenesis stage, it is buried deep quickly, which was effectively protecting the primary pores. Some feldspar particles and early carbonate cement were dissolved in the later stage of diagenesis, forming a certain amount of dissolution pores in and between grains, and improving the reservoir petrophysical properties to a certain extent. A large set of thick mudstone is developed in the upper and lower part of the reservoir sandstone. In the process of sedimentation-diagenesis and rapid burial, the pore fluid in the reservoir rock is blocked out and stays in the pore space. Abnormal high pressure zone developed by braided river delta of Xiaganchaigou Formation in Paleogene is a favorable zone for natural gas exploration and development in the central area of northern margin of Qaidam Basin.
- Publication
Natural Gas Geoscience, 2022, Vol 33, Issue 5, p720
- ISSN
1672-1926
- Publication type
Article
- DOI
10.11764/j.issn.1672-1926.2021.07.011