Through the detailed research of fracture style

strata feature

sedimentary facies (microfacies)

diagenisis process and reservoir characteristics of two exploratory wells in carbonate rocks of Maigaiti slope

the following conclusions can be obtained. The Yingshan Formation consists of a set of intra-platform beaches-inter-beach seas of open platform

and the Penglaiba Formation consists of dolomite flat

dolomite-limestone flat and granule shoal. The diagentic processes in Lower and Middle Ordovician mainly include submarine cementation

early atmospheric fresh water dissolution and cementation

compaction and pressure solution

two periods of atmospheric water karstification

burial and hydrothermal modification. Due to the influence of multiphase tectonic movements

open and relative closed diagenetic facies could coexist in the same limestone. The open diagenetic facies feature in small thickness and multiple intervals. In contrast

the closed diagenetic facies is characterized by large thickness and less intervals. The quality of reservoir was controlled by muti-phases unconformities

faults

fractures and water-rock interaction

so the effective reservoir diagenetic sequences were submarine cementation

compaction and pressure solution-two periods atmospheric water karstification

buried dissolution and hydrothermal reformation. Karst reservoir facies zones were mainly distributed in the superimposed tectonic belt between fault fold top

folding wing or fracture with high frequency sequence boundary

and show a karstification model featuring in superimposition of vadose zone and water hole under the control of multiphase tectonic movements.