The Evaluation On Development Reservoir And The Prediction On Dynamic Effect Of Chang 4+5 Reservoir In YW Area Of Zhidan Oilfied

The Yanchang formation of Triassic system in Ordos basin is an important oil-bearing series for exploration and development.The YW area in ZhiDan oilfield is located in the middle of Yishan slope of Ordos basin,Chang 4+5 oil-bearing series is the mainly position for development.In order to carry out the comprehensive evaluation of reservoir and the prediction of dynamic geological effect,it has a great significance to comprehensive treatment?adjustment and dig up the potential?maintain long-term stable development?improve the oil recovery.In this paper,applied with well logging data,core logging,experimental analysis and dynamic monitoring data,to study the reservoir characteristics and the dynamic geological effect of Chang 4+5 reservoir,the results show that the Chang 4+5 reservoir is further subdivided into Chang 4+52-2?Chang 4+52-1?Chang 4+51-2?Chang 4+51-1four layers,the reservoir sedimentary types of the reservoirs are mainly of complex depositional of underwater diversion channel and mouth bar;The rock type is mainly fine-grained feldspar sandstone.,the main mineral composition is feldspar,time for quartz.the grain mainly subangular,the granularity is good;Average porosity of the reservoir is 9.4%,average permeability is 0.45×10-3?m2.It is considered as a special low porosity and ultra low permeability reservoir.Intergranular pore and feldspar dissolved pore are the dominating pore types,it belongs to micro-fine throat and fine throat.It has been found that the study area is strong in diagenism,mainly including: compaction,pressure solution,cementation,dissolution and authigenic clay minerals,etc.The reservoir heterogeneity of study area is strong.the wettability of the reservoir prefer to hydrophilic,it belongs to the weak velocity sensitive,weak water sensitivity?medium-weak alkali sensitivity?without-weak acid sensitivity and without salt sensitive reservoir.The characteristics of seepage flow are the narrow of common seepage area of oil-water two phase,the higher irreducible water saturation,the average residual oil saturation,and the higher isotonic point.According to the various parameters of the reservoir characteristics research,and combined with the actual situation of the study area,the reservoir of the Chang 4+5 reservoir are classified as four types:I?II?III?IV.Type-II and type-III reservoir can be seen through the study area,Type-I and type-IV reservoirs are less distribute in the area.The study found that,in the process of water injection development,the reservoir permeability is decreased,the porosity increases,the hydrophilic property is enhanced,the micro fracture opens and absorb the water,the reservoir pressure drops,the connectivity and the injection and production correspondence becomes better,studying and predicting the change of these dynamic geological effects will provide the basis for the adjustment and development of oil field.