Abstract:

The pore types and structures of volcanic rocks in Cenozoic of Qikou Sag, Huanghua depression in Bohai Bay Basin  were researched using a large amount of data from core observation, ordinary slices, cast slices and the hydrargyrum injection experiments, and the pore structures were classified and evaluated. The results indicate that the pores of volcanic rocks include primary and secondary pores. The primary pores include stomatas, residual stomatas, inter-gravel pores and primary fractures, and the secondary pores include dissolved pores (holes, fractures), structural fractures and weathering fractures. The diabase has larger pore and throat, worse sorting and better connectivity; the basalt has middle pore and throat, moderate sorting and worse connectivity; the tuff has smaller pore and throat, better sorting and moderate connectivity. Pore structures of reservoirs are divided into five types: types of Ⅰ and Ⅱ are better reservoirs, which are dominated by diabase and tuff; type Ⅲ stands moderate, which is mainly diabase and secondly basalt; type Ⅳ is the worst one, which is mainly diabase; type Ⅴ is nonreservoir, which is mainly tuff. Type Ⅲ has the highest proportion with a rate up to 52%, followed by type Ⅱ, and types ofⅠ, Ⅳ and Ⅴ have smaller proportion.

Key words: pore type, pore structure, volcanic rock, Cenozoic, Qikou sag