Abstract:

In 390 Ma from Sinian to Silurian,there existed a structure with a rise and two depressions in the palaeohigh, thesourthern flank of the Palaeohigh subsided faster than the palaeohigh itself rose by 45.63%, than northern flanksubsided by 23.3% annually, which indicates that the palaeohigh was a inheritive one. High pressure, strongresistance force and the development of faults and fractures on steep fland resulted in connection and development of dissolved pores and vugs. So, exploring for large-middle size reservoirs are simply focusing on high and steepareas, which is decided by the condition of formation of the reservoirs in the palaeohigh; On the other hand,sedimentary and diagenesis environments are the decisive factors for the reservoirs porosity and pearmeability.The target areas with rich pores and vugs, good connection and high industrial gas well success rata are located inintertidal deposition with meteoric diagenesis environment; As for the carbonate in subtidal deposition with marine diagenesis environment ,reservoirs can be formed only under the condition of fractures linking pores and vugs, of cause, the development of fracture needs a certain folding and faulting strenth.

Key words: Caledonian palaeohigh, Intertidal zone, Subtidal zone, Sedimentary environment, Diagenesis, Sedimentary facies, Oil-gas reservoir,