【摘要】 随着勘探和开发的需要,岩性油气藏成为柴达木盆地西南区石油勘探的一个重要领域,然而由于受多期的构造叠加改造,致使柴达木盆地西南区岩性油气藏分布规律不清,勘探接替领域不明确。笔者通过研究发现,由于受盆缘及其北西向二级断裂的影响,盆地西南区地震活动强烈,深、浅层均发现一系列与地震有关的震积岩,可见阶梯状小断层、液化砂岩脉、振动液化卷曲变形构造、砂火山、火焰状构造、假结核、震积砂枕、震积砂球构造、串珠状构造及震褶层等原地震积岩的软沉积物变形特征,另外可见地震引起的重力滑塌或泥石流形成的滑塌构造和角砾岩化变形特征,诸如震裂岩、震塌岩、自碎屑角砾岩、液化角砾岩、内碎屑副角砾岩等异地震积岩。事实上这些震积岩能够极大地改善储集层渗透性,使渗透率大幅度增加,为油气勘探和开发提供了新的视角和领域。更为重要的启迪是形成震积岩的古地震具有重要的触发机制,很容易引起三角洲前缘相的岩性发生滑塌,进而形成滑塌扇、浊积等一系列沉积现象,这种储集体将成为油田储量增长的新亮点,本着这种思想,笔者通过叠前地震多属性的预测及先进的叠前AVO反演预测,在柴达木盆地西南区跃东斜坡带发现这种滑塌体的存在,并建立了相应的沉积模式图。这样将可能突破以往该区"环凹找油"的勘探思路,明确提出了古凹陷区仍然是柴达木盆地西南区寻找岩性油气藏的一个主要领域。更多还原

【Abstract】 With the increasing need for exploration and development,lithologic reservoir has become an important domain for oil and gas exploration in the southwestern Qaidam Basin.However,due to multiphase tectonic overprinting activities,the distribution of lithologic reservoir in the southwestern Qaidam Basin is indistinct and the next exploration area is indefinite.Our study found that seismic activities were very intensive in this area due to the influence of basin edge and northwestern second order faults.Seismites related to earthquake were found in deep and shallow beds.Lots of deformation structures were found,such as small step faults,liquid sandstone dikes,vibrating liquid curling structures,sand volcanos,flame structures,pseudoconcretions,seismite sand pillows,seismite sand ball structures,pinch and swell structures,etc.Some rock types were also observed,such as folding seismites,cracked seismites,autoclastic breccias,intraclastic subbreccias.In fact,these smites can greatly increase and improve the permeability of reservoir,and provide a new perspective for oil and gas exploration and development.More importantly,the paleoearthquake responsible for the formation of seismites is an important triggering mechanism easily initiates landslide at the delta front,causing a series of sediment phenomena,such as slump fans and turbidities.This kind of reservoir will become a new growth point of reserves.With this thought,by seismic pre-stack multi-attribute prediction and advanced pre-stack AVO inversion prediction,slip blocks were found in the Yuedong ramp region in the southwestern Qaidam Basin and deposition model was built correspondingly.This might make a breakthrough at previous exploration ideas of "search for oil around sags" in this area.This study suggests that paleosag is still an important exploration domain for lithologic reservoirs in this region.更多还原