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渤海浅层油气田以上第三系明化镇组下段河流相地层为主，沉积环境横向变化剧烈，储层横向预测难度大，文章针对这一问题进行了研究。对两个有代表性的渤海浅层油气田的40多口钻井的测井和地震资料进行了综合研究，建立了研究区河流相的沉积体系，划分了沉积微相的类型，确立了主要沉积微相的地质相、测井相及地震相特征和识别标志；在精细划分沉积相的基础上，研究了主要河流沉积微相类型与地层速度密度和波阻抗的关系。研究发现，本区沉积微相对某些地球物理参数有明显控制作用，统计拟合的主要沉积微相和速度密度及波阻抗随深度的变化曲线符合二次曲线的变化规律，文章给出了相应的数学表达式；本区85%的油气储层为边滩砂体，在明化镇组下段的不同深度上边滩的波阻抗和密度与其他微相有明显差别，故利用这一规律对地震反演的波阻抗或密度资料做进一步处理，可将边滩砂体单一提取出来，进而实现在沉积规律控制下横向外推预测含油气储层和单个砂体。

RELATIONS BETWEEN SEDIMENTARY MICROFACIES AND GEOPHYSICAL PARAMETERS OF SHALLOW RESERVOIRS IN BOHAI GULF

In Bohai Gulf,the shallow oil and gas reservoirs are mainly composed of the strata of fluvial facies,the lower member of Minghuazhen Formation of Neogene,and the lateral reservoir prediction is greatly difficult because of an acutely horizontal change in sedimentary environments.A research on such a question was carried out by the authors.Through comprehensively studying the log and seismic data collected form more than forty wells in two representative shallow oil and gas fields in Bohai Gulf,the sedimentary systems of fluvial facies in research area were set up;the types of sedimentary microfacies were divided;and the characteristics and identification markers of the geological facies,log facies and seismic facies of major sedimentary microfacies were determined.In addition,the relations between the types of main fluvial sedimentary microfacies and the geophysical parameters as velocity,density and wave impedance were also studied on the basis of finely dividing sedimentary facies.Through investigation it was found out that some geophysical parameters are obviously controlled by the sedimentary microfacies in this area;the fitted curves indicating the changes of these parameters as velocity,density and wave impedance of various sedimentary microfacies at different depths are in keeping with the change law of quadratic curve;and relevant expressions are given out in the paper.Because 85 percent of the oil and gas reservoirs in this area are point-bar sand bodies and the wave impedance and density of the point-bar are obviously different from those of the other microfacies in the lower member of Minghuazhen Formation at different depths,the messages of point-bar sand bodies may be extracted by further processing the seismic inversion wave impedance or density data,thus realizing the lateral extrapolation and prediction of the hydrocarbon reservoirs and single sand body under the control of sedimentary law.