Analysis of pore type and diagenesis of shallow grain limestone in Nanyishan Oilfield

The shallow grain limestone reservoir in Nanyishan Oilfield of Qaidam Basin is low porosity and low permeability.This paper studies the rock and pore types based on common rock slice,casting lamella and scan- ning electron microscope data,and further studies the diagenesis which mainly includes compaction,early ce- mentation,denudation and late cementation.The impact of various diagenesis on pore development and preserva- tion is also analyzed.Therefore,proper reservoir stimulation measures can be implemented according to the cau- ses of low porosity and low permeability to effectively develop the shallow grain limestone reservoir in Nanyishan Oilfield.