Study Of Petrological Characteristics And Thermodynamic Mechanism Of Secondary Pores In Deep Reservoirs, Songliao Basin

With the increase of depth, the porosity and permeability of volcanic is not influenced by depth. Evidently, clastic rock's porosity and permeability become worse with the depth. Sandstone and rhyolite have better character. Yingzheng group and Quantou group are the main reservoir. At the 2500m, 3000m, 3500m, there appears three sections with high porosity and permeability. At the south of Songliao basin, volcanic breccia has better character. At the 2000m, 2500m, there appears two sections with high porosity and permeability. We think these sections are all high secondary pores belt. The character of deep reservoir rock in Songliao Basin: In the north of Songliao Basin, the clastic rock are mainly lithic arkose and lithic sandstone. The volcanic rock mainly located at Yincheng group and Huoshiling group. And the main reservoir is volcanic rock in Yingcheng group. In the south of Songliao Basin, the sandstone mainly covers lithic arkose and lithic sandstone. And the volcanic rock include basalt, andesite and rhyolite. Like north of Songliao Basin, the volcanic rock mainly distributed at Yingcheng group and Huoshiling group. Through studying on detailed oil water data, we found there are difference between north pf Songliao basin and south of Songliao basin. Quan 1 section and Denglouku group and Yingcheng group, as main reservoir, all have high degree of mineralization. And the type of water is NaHCO3. We inferred that it is the reaction between water and rock which form secondary pores. The area of high degree of mineralization value, low ph value is corresponds to high porosity and permeability. Through analyzing the data of oilfield water, and combing thermal means, we calculated the ion activity. And calculated the formula of feldspar, zeolite, carbonate, kaolinite's solution by thermal means, and got the balance line. Drawing the map by spot the LogK of oilfield water. We think: it is mainly the anorthite and potassium feldspar which form the secondary pores. The albite offer little contribution. The solution of zeolite is the main cause of formation of 3000m secondary pores belt in north of Songliao basin. Besides, we calculated the solution of carbonate, kaolinite. The solution of calcite occurred in stratum with low temperature, in another word, belong to the early stage of diagenesis. In the kaolinite, there can also form secondary pores.