The most key link is to evaluate reservoir by porosity of reservoir-accumulation stage in the reservoir research. As long as we grasp this key link

we can make appropriate evaluation and estimation. Porosity types of reservoir-accumulation stage may be divided into fivetypes: 1. Primary porosity of burial stage; 2. Secondary porosity of burialstage: 3. Nearsurface secondary porosity of early diagenesis; 4. Nearsurface secondary porosity of late diagenesis; 5. Dolomitization porosity. To estimate the porosity of reservoir-accumulation stage

we must recoverthe history of porosity evolution through the medium of diagenesis re-search

and determine the stages of decarboxylation and reservoir-accumulation based on maturity of organic matter. Through the agency of the relations be-tween the evolution of porosity and organic matter

we may be able to find the space distribution of hydrocarbon reservoirs and the commercial potential.