Reservoir Characterisics Of Sandy Conglomerate Body In The 4th Member Of Shahejie Formation, Yan 22 Block Of Yanjia Area

In this paper, reservoir characterisics of sandy conglomerate body in the 4th member of Shahejie formation, Paleogene, Yan 22 block of Yanjia area in Dongying Depression are systematically studied by comprehensive use of core, logging, and analysis of testing data. Rock types of the 4th member of Shahejie formation in this area are divided into five types through detailed observations of cores.Based on the fine core location, quantitative identification standards of rocks are set up according to AC&CNL logging response characteristics, and the rock types developed in every well were identified.Nearshore subaqueous fan developed in research area, the 4th member of Shahejie formation, which includes inner fan, middle fan and outer fan sub-facies.The inner fan is devided into main channel and main channel edge micro-facies. The middle fan is devided into braided channel, frontchannel and interchannel micro-facies. The outer fan is devided into deep-cutting channel, end sand of channel and outer fan mud. Based on kinds of facies marks, single well microfacies were carefully divided. Stratigraphic division and development of micro-facies features are studied, which shows that in the longitudinal direction,sedimentary facies have a positive rhythm of inner-middle -outer fans form below whit thickness thinning. Thickness of sandy conglomerate body is maximum in northern source area, and it's thinning in southern, eastern,and western directions.In the plane, area of nearshore subaqueous fan decreased with the increasing of lake area and depth.The diagenesis types, diagenesis stage and reservoir spaces are studied by means of core observation, thin section analysis, physical property analysis, scanning electron microscopy. Sandy conglomerate reservoir of this area is in middle diagenesis stage A.Solution pore and pore-fracture compound system are the main reservoir spaces. Sandy conglomerate reservoir of this area are mainly medium-porosity low&extra-low- permeability, low-porosity extra-low-permeability and low porosity extra-low& super-low permeability. There are several pore zone in Sandy conglomerate reservoir of Es4 member. Pore structures are divided into 3 types of macro-medium pore with medium-fine throat, medium-small pore with fine throat and small pore with microthroat by using pore structure parameters and mercury injection curve. Reservoir physical property is mainly controlled by sedimentation, diagenesis and pore structure characteristics. The results show that, under the influence of acid dissolution, the physical property of grain-supported conglomerate with macro-middle pore and medium-fine throat developed in braided channel of inner fan is best.The reservoir lower limit is porosity of 5%, and permeability of 0.1×10-3μm2 according to comprehensive analysis of four properties ' relations. Sandy conglomerate reservoirs of Es4 in Yan 22 area are classified into 3 types: medium-porosity low permeability, low-porosity extra-low-permea- bility and low porosity extra-low& super-low permeability reservoirs, and their reservoir properties and oiliness decrease gradually. Favorable reservoirs mainly distribute in braided channel sediments of middle fan subfacies in 3-5 subzone of sand set II.