Study On The Macro-heterogeneity Of The Main Small Layer In The Lower Part Of The Minghuazhen Formation Of The Bozhong 34-1 Oilfield

Bozhong34-1 oilfield is located in the southern part of the Bohai sea on the central techonic ridge of the Huanghekou Sag.The reservoir is delta-deposited in shallow water with high porosity and high permeability characteristics.A seires of problems come out as the oilfield gradually enters into high water development stage.For exemple,single well production is reduced,moisture content is increasing during harvesting and so on.The causes of these problems are related to the macroscopic heterogeneity of the reservoir.Therefore,to figure out the macroscopic heterogeneity of the reservoir is important to improve oil recovery.By the application of sedimentology,petroleum geology and reservoir development and other discipline theory methods,based on the well logging and exploring data,combined with previous reserch results to study the heterogeneity of the sandbody in the small layer,Then,Nm ?-7?Nm?-1?Nm?-1?Nm?-2?Nm?-5?Nm?-1,six main layers were selected from the two oil groups to study the macroscopic heterogeneity and the following research results were achieved:?Under the impact from the northeast and southwest source,Bozhong oilfield mainly developed delta front subfacies,delta plain subfacies,microfacies is distributary channel,underwater distributary channel and interdistributary bay,underwater interdistributary bay.,lake basin mud?There are three main types of single-sand-stack relationships in the study area:lateral accretion,vertical accretion,and lateral retrogradation?There are 4 types of permeability rhythm models in the study area:Positive rhythm,reverse rhythm,homogeneous rhythm and compound rhythm,The interior of the small layer is dominated by compound rhythm and positive rhythm,while the inner layer is dominated by positive rhythm and homogeneous rhythm.?There are two types interlayer in this study area,the muddy and the calcareous interlayer.?The interlayer heterogeneity of the main layers is medium to strong ? By calculating the parameters of porosity,permeability,permeability variation,range,we find porosity and permeability are generally larger in the center of the channel,smaller in the edge,and the distribution of permeability variation coefficient and existing two kinds of circumstances,The first is permeability variation is smaller in the center of the channel and larger at the edge of the channel.The second circumstance is quite the contrary.?The sedimention are the main controlling factors that affect the heterogeneity.Such as channel migration and erosion strengthen intralayer heterogeneity,interlayer heterogeneity is generally weakbetweensingle layer of the underwater distributary channelthat accretevertically,small differences between wells;lateral accretion,progradation and retrogradation increases interlayer heterogeneity.