Characteristics Of Glutenite Reservoir Of The Es4 North Slop Of Dongying Depression And Experimental Study On Dissolution Of Clay Minerals

The reservoir of the Es4 in the north slop of Dongying depression is a typical glutenite reservoir with abundant reserves,great exploration and development potential.It has become a hot spot and focus in the exploration and development of Dongying depression.However,the glutenite reservoir has the characteristics of low maturity,low compositional maturity,high content of miscellaneous and clay,various reservoir space,strong heterogeneity and poor physical property.The reservoir development is difficult and the economic benefit is low.In the process of development,the reservoir damage caused by clay minerals accounted for70%.Therefore,it is of great significance to study the acidizing properties of the reservoir in order to improve the physical properties of the glutenite reservoir to increase the productivity of the oilfield.Firstly,this paper studies the characteristics of glutenite reservoir of the Es4 in the north slop of Dongying depression.The content of feldspar,lithic and clay minerals in the reservoir is high,and the quartz content is low.The diagenesis is complex and the cementation compaction is strong.The pore structure of reservoir is various,and the primary pores,induced porosity and fractures are developed.The reservoir physical properties are mainly medium porosity and low permeability,low porosity and extra-low permeabilit,low porosity and ultra-low permeability.The main clay minerals are illite,kaolinite and smectite mixed layer.Reservoir damage is mainly water sensitivity and velocity sensitivity.According to the study of the sensitive mineral composition and content of the glutenite reservoir in the study area,investigation and analysis of the corrosion solution.According to the"hydrofluoric acid/fluorine boric acid+hydrochloric acid+oxidant/additive"proportioning scheme,the types and concentrations of different chemical reagents were selected.Experimental study on hydrothermal corrosion of clay minerals?illite,kaolinite,montmorillonite,chlorite?.Primary selection and two screening of acidified solution based on mass loss of clay minerals.Continue to carry out clay single mineral hydrothermal experiments on the selected acidified solution.The corrosion solution was optimized by changing the mass loss and concentration of clay minerals.According to the content of clay mineral,the effect of acidizing corrosion and development cost,determination of"15%HCl+8%HBF₄+30%H₂O₂+9%NH₄F"is optimal acidizing scheme.The acid corrosion time is 2-3 hours.Finally,using reservoir core samples and core purification of mixed clay minerals,the application effect analysis of the acidizing scheme with the help of mass loss,SEM,permeability and ion concentration.After the reaction,the dissolution of the mixed clay was above 40%.Dissolution pores and fractures increased significantly,the permeability increased several times of the core samples.It can meet the needs of the development of glutenite reservoirs in the study area.