论文详情
地震属性及地震反演结果中页岩油藏中的“甜点”会出现异常特征不明显的现象,这使得“甜点”预测成为一大难点。准噶尔盆地玛湖凹陷二叠系风城组风二段“甜点”层地震振幅较弱且连续性不好,属性分析和地震反演结果与地质评钻井结果不一致,给地震预测及井位选择等带来了的不确定性。为此,采用了基于属性建模的地震正、反演联合的方法对风二段“甜点”层地震响应特征的不确定性进行了分析。首先将反演得到的波阻抗与测井资料及实际地震剖面进行对比分析,重新计算几何和物性参数,建立用于正演模拟的几何和物性模型;然后利用波动方程数值模拟方法进行“甜点”地震响应特征的正演模拟计算;再将正演剖面与实际地震剖面和已钻井资料相结合,综合分析页岩油藏“甜点”地震响应特征及可能的变化规律,对地震预测的不确定性进行分析评估;最后将上述结论作为参考再次进行属性分析,给出重新预测的结果。研究区风二段“甜点”层地震响应特征不确定性分析为MAY1井的井位选择提供了充分的依据。研究结果表明,地震响应特征不确定性分析方法作为页岩油藏“甜点”预测的技术手段,能够较为准确地判断页岩油藏“甜点”地震响应特征,确立识别参数。
The anomalous features characterizing oil sweet spots in shale reservoirs cannot be clearly discerned from seismic attributes and inversion results.Consequently,oil sweet spot prediction in such reservoirs is a major challenge.The sweet spot layer in the second member of the Permian Fengcheng Formation (Mahu Depression,Junggar Basin) exhibits low seismic amplitude and discontinuous seismic reflection.Sweet-spot predictions via attribute analyses and seismic inversion yield results inconsistent with those of core drilling and geological evaluations,thereby adding uncertainty to seismic prediction and well location selection.In this study,the characteristics of the seismic response and the uncertainty associated with sweet spot layer prediction in the second member of the Permian Fengcheng Formation were analyzed by combining forward and inverse seismic methods based on attribute modeling.First,the wave impedance evaluated from the inversion was compared with logging data and the actual seismic profile,such that the physical properties and geometric parameters could be recalculated to establish a model to use for forward modeling.Subsequently,the numerical algorithm of the wave equation was used to simulate the seismic response characteristics of the sweet spot.Then,the forward modeling profile was combined with the actual seismic profile and drilling data to comprehensively analyze the characteristics and possible patterns of the seismic response in the sweet spots,and to analyze and evaluate the uncertainty of the seismic prediction.Finally,the results of the analysis were used as a reference for a new attribute analysis method,which yielded new prediction results.These results provided a sufficient basis for selecting the location of MAY1 well,thereby demonstrating that the proposed method can yield an accurate characterization of the seismic response of sweet spots in shale oil reservoirs and enable identification parameters to be established.
国家油气重大专项(2016ZX05046-006)和中国石油科技重大专项(2017E-0402,2019E-26)共同资助。