| Author's Name: GAO Zhaolong 1 , PENG Hanlin 1 , ZHANG Xihua 1 , CHEN Cong 1 , LI Tianjun 1 ,
LI Guorong 2 , HE Zhao 3 , LI Xiaoxiao 4 ,TIAN Jiaqi 3 |
| Dolomitization and dolomite distribution are the key factors that restrict the development and distribution of
reservoir of the 2nd member of Maokou Formation in central Sichuan Basin. Based on the previous research results of
dolomite and the understanding of regional geological background, through the observation of core and thin sections, and
the introduction of cathode luminescence, X-ray diffraction, inclusion, C and O stable isotope, Sr isotope and REE analysis,
the further study of dolomitization of the 2nd member of Maokou Formation in central Sichuan Basin has been carried out.
The results show that: (1) There are three types of dolomite in the study area: very fine-fine crystalline anhedral dolomite,
very fine-medium crystalline euhedral dolomite, and saddle dolomite. Very fine-fine crystalline anhedral dolomite is
formed by syngenetic evaporative seawater dolomitization. This dolomitization does not produce reservoir space itself, but
plays a fundamental role in the formation of dolomite reservoirs. Very fine-medium euhedral dolomite is formed by burial
dolomitization in the early diagenetic period, and the intergranular pores and intergranular dissolution pores are developed
at the site of dolomitization, which can form dolomite dissolution pore type reservoir. Saddle dolomite is formed by
hydrothermal dolomitization in early diagenetic period (Dongwu period). This dolomitization is accompanied by
hydrothermal fracture and hydrothermal dissolution, which can lead to the development of dissolution fractures and the
formation of dolomite dissolution fracture and cavernous reservoirs. (2) Marginal platform, coupling with the platform
margin fault，is the best place to develop syngenetic seawater dolomitization, burial dolomitization and hydrothermal
dolomitization in the early diagenetic period, and is also the advantageous development zone of dolomite reservoir. In the
intra-platform highland area, syngenetic evaporative seawater dolomitization and burial dolomitization in the early
diagenetic period are mainly developed, making it a relatively favorable zone for dolomite reservoir development. However,
intra-platform depressions lack favorable conditions for dolomitization, resulting in poor dolomite development. |
