Cementation Characteristics and Pore-Forming Evolution of Clastic Reservoirs in the Saline Lake Basin

Abstract

The Cenozoic of Qaidam Basin is a terrestrial salinized lake basin, with developed clastic reservoirs, many types of cement, strong cementation and complex pore evolution. In order to clarify the type of salted lake cement, the control of cement in lake salt water, and the pore evolution characteristics of different saline water bodies. Using the experimental test data and core data of trace elements, cast thin sections, whole rock minerals, clay minerals, porosity and permeability, etc., the ancient salinity of water bodies in different periods of the basin was restored, and the relationships of the ancient salinity , cement types , contents and their control over pore evolution were established. Four types of cements, including carbonates, anhydrite, zeolites, and siliceous materials, have been identified in the salty lake basin clastic reservoirs; controlled by the ancient salinity of the water, when the paleo-salinity is less than 8‰, it is mainly cemented with carbonate. When the ancient salinity is 8-15‰, it is cemented with carbonate and anhydrite, and the ancient salinity is greater than 15‰, it is cementation of anhydrite; In the development zone of high-salinity water bodies, the pseudo-contemporaneous-early diagenetic stage A, the calcite of cemented anhydrite and mud crystals has strong cementation, high cement content, large reduction of pore volume, deviation of reservoir properties, and easy evolution of clay minerals to the mudstone and green mud mixed layer, In the development zone of low-salinity water, the cementation is weak, the amount of diminution is small, and the physical properties of the reservoir are preferred. The evolution of clay minerals is easy to form illite, yimonite and kaolinite.Innovatively put forward the control of cementation by ancient salinity and establish two kinds of pore evolution patterns.

AAPG Datapages/Search and Discovery Article #90332 © 2018 AAPG International Conference and Exhibition, Cape Town, South Africa, November 4-11, 2018