覆盖密度对准东致密油藏成像响应的影响

THE INFLUENCE OF COVERAGE DENSITY ON IMAGING RESPONSE OF TIGHT OIL RESERVOIRS IN THE EASTERN AREA OF JUNGGAR BASIN

准噶尔盆地致密油勘探起步较晚,相关的采集方法研究还是空白,根据以往地质分析,盆地主要发育以二叠系咸化湖盆沉积的白云岩及白云石化岩类为主的碳酸盐岩致密油藏,埋深大于3000米,主要"甜点"区为溶蚀孔发育型和裂缝-孔隙型两类[1][2]。以往以构造勘探为目标的大面元、低覆盖地震资料采集方法已经难以满足致密油气藏对振幅、相位及裂缝、小断块的分辨能力要求,本文以盆地东部吉木萨尔凹陷地区开展的高密度采集试验实际资料为基础,从叠前偏移角度分析覆盖密度与成像响应之间关系认为,面元一定情况下,增加覆盖密度有利于提高成像精度,且存在覆盖密度变化拐点,该拐点是采集设计确定覆盖密度的底限。

Tight oil exploration is started relatively late in junggar basin,research for its acquisition method is still blank,according to the previous geological analysis,It's mainly developed dolomite and dolomitization of dense carbonate reservoir deposited in Permian Salt Lake basin sedimentary stage in Junggar basin,and buried depth is more than 3000 meters,including two kinds of ' dessert' area with dissolved pore and fracture pore.Previous seismic data acquisition methods to aiming at structure exploration has been difficult to meet tight reservoirs of amplitude,phase and crack,small fault block resolution requirements.This article is based on the actual high density acquisition test data of Ji Mu Sa Er sag areas in the east of Junggar basin,analyses the relationship between coverage density and imaging response from the perspectives of prestack migration.we thought that increasing the coverage density is beneficial to improving the imaging accuracy in the situation of a certain bin,and the change of coverage density has a turning point,the point is to determine the coverage density limit of acquisition design.