Mineral Sensitivity And Dissolution Characteristics Of The Glutenite Reservoir In Es4 In The North Slop Of The Dongying Depression

The glutenite reservoir in the Es₄ north slop of Dongying depression is rich in oil and gas reserves,and the exploration and development potential is huge,which has become the key target of exploration and development in Dongying sag,and the difficulty of exploration in the later stage is increased because of the low maturity of the reservoir structure,the spatial diversity of the reservoir and the poor heterogeneity of the reservoir.Taking the sand four sections of the gravel reservoir in the northern belt of Dongying Sag as the research object,on the basis of previous studies,this paper analyzes the reservoir sensitivity characteristics of the study area through a large number of rock sheet identification,sensitivity experimental data and scanning electron microscopy,and how to optimize the drilling fluid in the future development of this kind of reservoir.Thus,the sensitivity mineral dissolution experiment was carried out.The glutenite reservoir in the Es₄ north slop of Dongying depression are buried deeply,the compaction cementation is strong,the pore structure is diverse,the reservoir physical property is mainly low porosity and low permeability,the reservoir is high in feldspar,debris and clay minerals,and the main developed clay minerals are kaolinite,illite and Ivan/Mongolian layers,and a small amount of chlorite minerals.The content and production of clay minerals are one of the main factors causing reservoir sensitivity.Through reservoir sensitivity test of core samples in this area,it is shown that the reservoir in this study area is non-fast sensitivity,weak water sensitivity,non-weak acid sensitivity and weak alkali sensitivity.In view of the characteristics of this kind of reservoir,how to develop the water-rock simulation experiment for simulation minerals efficiently.Through the experiment of the dissolution of sensitive minerals,we know that the dissolution degree of potassium feldspar and sodium feldspar increases gradually with the reaction time under acidic conditions,and after 12hours the dissolution gradually enhanced.Among them,in the same condition the degree of sodium Shi erosion was greater than that of potassium feldspar,and dissolved along the direction or crack of cleavage,mainly with dissolved pores,dissolved trench marks and dissolution pits,with honeycomb dissolution holes when the degree of dissolution was severe.Erosion rate arrive maximum with acid conditions after 6hours,increase over time,the erosion decreases and tends to stabilize.While Kaolinite was slow to react under acidic conditions,the degree of dissolution was low,and new minerals were produced.The dissolution effect of chlorite and soil acid reaction is better than that of hydrochloric acid reaction.In alkaline environment,with the increase of solution concentration,the dissolution degree of illite and kaolinite increased gradually,and the time to reach the peak of dissolution was shorter.In the reaction process,Kaolinite was produced by New minerals,which were sodium alumite and gibbsite.In the use of water injection development,it is necessary to adopt appropriate injection and displacement pressure,pay attention to do a good job in the development of water injection and formation water,injection of water and formation compatibility evaluation research,to prevent small particles with the liquid movement to block the smaller roar;in the acid dissolving plugging operation to take care to select the appropriate acidizing liquid and in reasonable time of acidification(3?6hours)concentration for operation,to avoid taking long time the clay minerals full pore of reservoir after dissolution,also,avoid feldspar are dissolved which producing particles plugging the throat when small particles are moving in reservoir.If necessary,acidification can be combined with fracturing in order to achieve efficient operation.