Simulated Experimental Study On Warming Acid Dissolution Of Volcanic Materials In Junggar Basin

Organic acids are formed in the evolution of organic matter in sedimentary basins,and the products will have a certain influence on volcanic materials.Based on the analysis of the research of different types of volcanic material in zhungaer basin,this paper aims to explore dissolution of volcanic material by organic acid from the maturation of organic matter in the process of basin evolution.Numerous simulation experiments of organic acid dissolution were designed,in order to get the change rule of volcanic material in the process of dissolution.The results hope to provide references for oil and gas exploration in the oil and gas reservoirs in volcanic rocks.The results show that the organic acids affect feldspar,quartz,zeolite,calcite and clay minerals,mainly in the dissolution of related minerals and the formation of new minerals.Among zeolite minerals,turbiditic zeolite is the most easily dissolved.Quartz is less easily dissolved than calcite and feldspar,and quartz is formed throughout the diagenesis stage.Calcite and feldspar are the two most important minerals in volcanic rocks.The PH value of the environment where calcite is located can determine whether calcite is dissolved or deposited.Feldspar,as the most important silicoaluminate mineral,will be dissolved to a certain extent in the case of H⁺and H₂O.Clay minerals can be dissolved as primary minerals or as new minerals produced by alteration.In the temperature-rising acid solution simulation experiment,with the increase of temperature,the contents of different elements in volcanic rocks show different trends,mainly including rising type,falling type,combined type and stable type.Andesite and breccia lava reacted with organic acids in the range of 20℃-80℃,and the relative content of silicate minerals in the rocks decreased.The relative content of Si O₂in the sedimentary tuff has been increasing with the rise of temperature.The large change in the content of Ca O in the sedimentary tuff can be inferred that calcite was first acid dissolued,and minerals with less content later undergo dissolution.Because the Si O₂ content of clay minerals containing Mg and Fe and iron dolomite increased at 20-80℃,the content of most oxides decreased with the increase of temperature afterwards.The increase in Ca O may be due to the increase in PH,which regenerates calcite.The basalt contains Ti element,and the experimental results show that the iron ore containing Ti is not easy to be dissolved,while the iron ore without Ti is more easily dissolved.On the basis of the dissolution of volcanic minerals,it is found that the pore structure changes of different types of rocks are also different.The pore form of basalt,tuff glutenite and sedimentary tuff is H2 type.The hysteresis loop of breccia lava is H3 type.The hysteretic loop types of tuff glutenite and andesite gradually change from H2 type to H2-H3 in shape as the temperature increases.Before and after the simulation experiment,the fractal dimensions of different types of rocks all decreased with the increase of temperature.With the decrease of fractal dimensions,it was indicated that the number of nanometer pores gradually decreased with different reaction temperatures,isolated pores gradually expanded after dissolution,and the connectivity between pores became better.The roughness of pore surface may be directly related to the selective dissolution of unstable minerals.On the whole,organic acids aggravate the dissolution of volcanic rock materials and increase the reservoir space,which is beneficial to oil and gas accumulation in the volcanic rocks.