Characteristics Of High-quality Reservoir Of The Paleozoic Carbonate Buried Hills In The Dongying Depression

There are extensive carbonate strata in the Lower Paleozoic of the Dongying depression,around the depression,many buried mountain belts such as Gaoqing-Pingnan,Zhengjia-Wangzhuang,Caoqiao-Wangjiagang are rich in oil and gas resources.In this paper,we chose the core observation and thin section analysis as the main research materials,combined with rich drilling data,logging data,seismic data,oil-testing data,systematically analyzed the reservoir characteristics of the Lower Paleozoic carbonate buried hills in the Dongying depression,the main results of the dissertation are as follows:1?Based on the carbonate rock-structure classification method,we classify seven kinds of limestone types such as cryptocrystalline limestone,granular limestone and so on,as well as five kinds of dolomite types such as cryptocrystalline dolomite,crystalline dolomite and so on,then we analyzed the characteristics of each type of rock.2?The vital important diagenesis in the study area are dissolution and cementation,among them,the dissolution plays an important role in the formation of reservoir space,and the cementation has a serious destructive effect on the reservoir space.In addition,the reservoirs develop compaction,pressure dissolving,metasomatism and recrystallization.3?Reservoirs are highly heterogeneous,the regularity of reservoir property is not obvious,The storage space is mainly composed of caves,pores and cracks,The caves can be divided into matrix caves,fractured caves and intergranular caves,pores can be divided into matrix pores,intergranular pores,vein pores,intergranular pores,cracks are divided into structural cracks and dissolution cracks.Based on the data of drilling and logging materials,we have analyzed the identification characteristics of caves and cracks.On this basis,the types of reservoir space are summarized,namely,the type of pore-cave-crack compound reservoir,the type of caves or cracks,the type of microcracks and the type tight reservoir.4?The development of the Lower Paleozoic carbonate buried hill reservoir in the Dongying depression is affected by many factors,among which,the dissolution plays an very important role in reservoir development,the strong dissolution area such as Caoqiao area,the storage space developed well and the reservoir performance is good;The faults and fracture system not only can be searved as reservoir space,but also provides channels for the fluids to flow,the existence of Gaoqing-Pingnan fault makes buried reservoirs develop irregular cracks and insider dissolution pore storage system in the adjacent areas;The structure of the buried hills controls the formation of the reservoir from the macroscopic point of view,Zhengjia-Wangzhuang area and the Caoqiao area are mainly developed with insider monoclinic residual hill-type buried hills,Gaoqing-Pingnan and Wangjiagang area mainly develop insider monoclinic block mountains and insider fold broken block mountains;Lithology is the foundation of reservoirs,which affects the development of dissolution and fractures.5?we discussed the development of different buried hill reservoirs in the study area,According to the difference of characteristics and main control factors of each buried hill belt reservoir,based on topography,we have established two reservoir development models of residual buried hills and broken-block buried hills.