Abstract:

The andesite in north Alsen was formed by at least 12 magmatic eruptionsand 3 volcanic explosions. The lava beds of each eruption can be dividedinto 2-3 belts, and the reservoirs are mainly distributed in 1-2 belts of theupper part. Pores are developed at the main flow line of eruptive subfacies,the eruptive minor facies zone near the crater and structural topes, composedfour kinds of reservoir rocks: lava-flow autoclastic rocks, andesite conglome-rate, vesicular-amygdaloidal andesite and compact massive andesite, andconstituted seven kinds of pores and three pore assemblages. These reservoirsare characterized by low porosity-permeability, poor porous texture, highanisotropy. Original aqueous satuation is up to 89% and aqueous exploitaionstarted at the very beginning.