【摘要】 火山地层是由似层状、层状和块状结构组成的复合体,其地层结构的拟合是火山岩储层地震预测的难点所在,火山地层结构模型的建立是火山岩勘探开发中首先需要解决的关键问题.通过对九台和大屯典型火山岩地层结构的解剖,分析似层状结构和层状结构特征.似层状结构地层内部的岩层倾向和倾角变化大,与地层顶底面表现为斜交.从火山机构喷发中心到远端的同一方向的岩层具有同倾向、倾角逐渐变小的趋势,据此沿其顶面或底面的趋势进行内插可以得到火山机构准确的地层结构模型.以YS2井营城组火山岩为例,在其他条件相同的情况下分别用层状模型和似层状模型拟合地层结构约束波阻抗反演.结果表明二者间的低波阻抗分布范围和厚度均存在较大的差异,其后果是导致储层地震预测的偏差,所以用层状模型不适用于似层状结构火山岩储层刻画、同样反推也不妥.解决的方法是在火山机构的限定下进行储层反演,即在明确各个火山机构的地层结构的基础上,通过对内部结构的插值得到地层结构模型,才能使储层反演结果更加逼近真实情况.该研究可为火山岩油气藏高效勘探开发提供理论依据.更多还原

【Abstract】 Volcanic strata have pseudostratified,stratified and massive textures which are more complex than sedimentary rocks.Thus,it should not simply be simulated with stratified models, and it results in a difficulty in volcanic reservoir prediction with seismic data.A primary key point for volcanic reservoir exploration and development is to build up proper volcanostratigraphic models.Both pseudostratified and stratified models are built up based on typical volcanostratigraphic textures of outcrops of Jiutai and Datun area in the southeastern Songliao Basin.The internal beds of pseudostratified strata show great changes in dipping direction and angles,and contact obliquely with the top and bottom strata.The dip angle of volcanic rock bed decreases from central to distal parts along a given edifice s limb,and the exact stratigraphic textural model is built up by interpolation following the top and/or bottom surface trends.A borehole named as Well YS2 is selected to perform impedance inversion constrained by stratified and pseudostratified models respectively.As a result,both the dimension and thickness of low-impedance show significant differences between the stratified model and the pseudostratified model.Therefore, the stratigraphic texture of volcanic edifice should be precisely characterized before impedance inversion,and then the stratigraphic textural model is built up with internal interpolation to ensure the inversion reliability.This study offers a theoretical basis for effective exploration of volcanic petroleum reservoirs.更多还原