The Thermodynamic Study Of Mineral Corrosion And Deposition In Volcanic Reservoirs In Xujiaweizi Area

Studies on petrography show that feldspar and carbonatite corrosion is rich in the volcanic reservoir rocks of Xujiaweizi area. And feldspar and carbonatite corrosion is are important pores here. Feldspar corrosion results in a lot of secondary pores and it will enlarge the reservoir pore space. For example, in Xujiaweizi area, pores as a result of feldspar corrosion in rhyolitic ignimbrite and rhyolitic tuff make up of 18.61% and 13.71% respectively of the all the porosity.So studies on the influence factors of feldspar and carbonatite dissolution and sedimentation would conclude the evolutionary process of them.In this dissertation, the feldspar (include potassium feldspar, anorthite and albite ) and carbonate corrosion were ratiocinated in detail, and the dissolution and sedimentation phase maps of feldspar calcite and siderite were made. And in these phase maps, the area up the equilibrium line is deposited area and below it is dissolved area.The data of underground water in 32 driven wells were collected. The equilibrium constant constants of potassium feldspar, anorthite albite, calcite and siderite were calculated after the data was were analyzed, cleaned up and filtrated. Then the final data points on the maps were got. Based on the relative relationship between the points and the equilibrium curve, the points in deposited area or dissolved area was were exhibited clearly.The relationship relationships between the pore and the corrosion potassium feldspar, anorthite albite, calcite and siderite were dissertated and the characteristic distribution maps were drew. All these are evidential thermodynamic materials for predicating the favorable gas exploration target of this area.