基于叠前偏移成像的高密度观测系统分析评价方法——以准南山前带区块为例

Analysis and evaluation method for high-density geometry based on prestack migration imaging-A case study in the piedmont zone of southern Junggar basin

准南山前带地区具有典型“三复杂”的特点,即“近地表、地下构造、储层”十分复杂,该区的油气勘探为世界级的难题。地震勘探采集的关键在于观测系统设计的优劣,常规单一炮检距属性的观测系统评价方法仅适用于相对复杂的区域,无法满足复杂山前带的高密度观测系统成像质量评价的需求。针对以上现状,探索形成了一套适应山前带的基于叠前偏移成像的高密度观测系统评价方法,利用综合质量因子、逆时聚焦、逆时偏移成像和数据驱动等4种评价手段,能较好地实现复杂山前带地震采集参数论证与优选,将理论模拟与数据驱动处理相结合,得到影响成像精度的观测系统敏感参数排序,炮线距的改变较炮点距的改变对偏移效果影响显著,形成的对“三复杂”山前带观测系统评价优选的方法,有助于提高复杂山前带地震数据的成像精度。将该方法应用于准南山前带地区,获得了较好的成像效果和地质效果,该方法可推广应用至其它山前带或复杂探区。

The piedmont zone on the southern margin of the Junggar basin has the typical“three complexities,”i.e.,complex near-surface characteristics,underground structures,and reservoir,which is a world-renown oil and gas exploration problem.The key to seismic acquisition lies in the quality of the geometric design.The conventional evaluation method that considers geometry with a single offset attribute is only applicable for relatively complex regions and does not meet the needs for the imaging quality evaluation of the high-density geometry in complex piedmont zones.Considering the abovementioned situation,a set of high-density geometry evaluation methods suitable for the piedmont zone based on prestack migration imaging is explored and summarized.By comprehensively utilizing four evaluation methods,such as the comprehensive quality factor,reverse time focusing and reverse time migration imaging,and data driving,the parameter selection and optimization for the complex piedmont zone can be achieved.Through the combination of theoretical simulation and data-driven processing,the sensitive parameters of the geometry that affect imaging accuracy are obtained.Changing the source line distance has a more significant impact on the migration effect than changing the source distance.A method for evaluating and optimizing the geometry of the complex piedmont zone is suggested,which provides significant guidance for improving the imaging accuracy of complex piedmont seismic data.Through application in this work area,quality imaging and geological effects can be obtained,offering potential for applications in other piedmont zones or complex exploration areas.