Abstract:

The sandstone in Xuer section was mainly dominated by micropores. There were fewer feldspar and detritus solution pores and rare or no carbonate solution pores. This phenomenon has been explained by the steady carbon isotope of calcite and thermodynamics theory. The samples, the porosity of which is over 5%, must contain chlorite coatings and display high water saturation as well as low electric resistvity, which leads to mismisjudging gas an water layer. Detailed petrology researches show that clay minerals play a particular role in the process of diagenesis.The storage cap-acity of samples with clay is better than that with carbonate，.A new concept of“pore life-span”is proposed and its significance in petroleum exploration is discussed in this paper.

Key words: Sichuan basin, Xuer section, Tight sandstone, Porc lifespan