Abstract: Yingyi-D1 well, an exploratory well, was drilled to reveal the insider of standard section of Yingcheng Formation in 2006. Volcanic lavas, pyroclastic lavas, pyroclastic rocks and sedimentary pyroclastic rocks have been found in this well. The volcanic lavas include rhyolite, pitchstone, perlite and basalt. Pyroclastic lavas are consisted of breccia lava, tuff lava and ignimbrite. Pyroclastic rocks are mainly composed of volcanic breccia and tuff. Sedimentary pyroclastic rocks are mainly sedimentary tuff and sedimentary volcanic breccia. They mainly belong to effusive facies, explosive facies and volcanogenic sedimentary facies. The average porosity is 15.17％ and the average permeability is 1.51×10^-3μm². The porosity is linearly correlated to permeability. Based on the mercury injection capillary pressure data, the pore structures could be classified into six types. Synthetical evaluation of porosity & permeability and pore structure, the reservoirs were classified into four types. Type I is a perfect reservoir with high to super-high porosity and super-high permeability, coarse throat dominating. Type Ⅱ is good reservoir with high porosity & permeability, fine throat dominating. Type Ⅲ is a medium reservoir with medium porosity, medium permeability and fine throat. Type Ⅳ is a poor reservoir with medium to low porosity, low permeability and fine throat.

Key words: Yingcheng Formation, lithology, lithofacies, porosity & permeability, reservoir assessment