采用直井信息进行砂体定量研究时,往往由于井间对比的不确定性,导致对砂体规模的认识存在较大的不确定性.水平井对储层砂体横向预测具有重要参考价值,这是常规直井难以达到的.因为水平井可以揭示砂体横向变化,从而为我们在砂体定量表征、岩相单元划分等定量化地质研究方面提供帮助.针对研究区辫状河储层特点,结合直井岩心、直井与水平井的测井信息,首先确定出4类岩相单元,进行直井与水平井岩相单元划分;然后结合直井与水平井信息,进行砂体定量研究,确定了心滩和辫状河道砂体的形态及发育规模,进而建立了心滩长宽比、心滩与河道宽度比、夹层与心滩宽度比等定量关系;随后以水平井钻遇砂体信息为约束,进行储层地震波阻抗反演;最后结合砂体定量表征与波阻抗反演结果,进行岩相单元的预测.研究结果表明:基于水平井信息可以精细刻画储层内部岩相分布特征,提高储层砂体定量研究与内部非均质性描述的精度;水平井段信息增加了参与地震储层反演的样点数量,从而减小了井间储层预测的不确定性,可以明显提高储层内部地震反演精度和可靠性,并可以提供更为可靠的储层岩相模型.%When quantifying sandbody with vertical well data,the volume of sandbody often cannot be defined accurately due to the uncertainty of the interwell correlation.Horizontal well data are of significant referential value for lateral prediction of reservoir sandbody,which is difficult to be achieved by conventional vertical well data.Horizontal wells can reveal lateral variation of sandbodies,so as to assist us in quantitative characterization of sandbodies and quantitative classification of lithofacies units.This study is composed of 4 steps.Firstly,it indentified 4 types of lithofacies units according to the braided-river characteristics in the study area,coring data in vertical wells and well logging data in vertical and horizontal wells,with a view to classify lithofacies units in vertical and horizontal wells.Secondly,a quantitative research on the sandbodies was carried out with horizontal and vertical well data,and thus confirmed the configuration and scale of channel bars and braided channel sandbodies.Besides,the length-width ratio of channel bars,the width ratio of channel bar to channel and that of interbed to channel bar were well established.Subsequently,the seismic wave impedance inversion on braided-river reservoirs was carried out under the constraint of information from sandbodies encountered by horizontal well.Finally,prediction of lithofacies units was done based on the quantitative characterization of sandbodies and the results of wave impedance inversion.Results show that:(1)the horizontal well data can be used to finely characterize lithofacies distribution within reservoirs and improve the accuracy of sandbody quantification and description of internal reservoir heterogeneity;(2)the information from the laterals can increase the number of sample points in seismic inversion,thereby lower the uncertainty of interwell reservoir prediction,greatly improve the accuracy and reliability of internal reservoir seismic inversion,and increase the reliability of the reservoir lithofacies model.
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