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珠江口盆地在晚渐新世—早中新世先后经历了2次大的构造运动,多期构造活动诱发的地震导致盆地内发育多种与地震活动有关的震积岩原地系统的软沉积物变形构造,这些构造赋存于海侵沉积序列内,垂向上具有一定的叠置关系,反映了地震作用的不同阶段对原始沉积序列的改造,其垂向震积序列自下而上可分为7段:A段为具有原生层理的滨岸砂岩,作为震积序列中的底部层段沉积于地震发生前的宁静期;B段为未固结砂质碎屑在后期强烈地震活动中发生液化形成的蛇曲状液化砂岩脉;C段为发生一系列液化卷曲变形的砂泥岩互层;D段为在地震活动衰减期快速堆积的沉积物因差异沉降形成的阶梯状微断层;E段为泥岩内的薄砂层在地震活动趋于停止时期发生拉伸或挤压变形形成以断续砂质条带为特征的缩胀构造;F段为在地震活动末期形成的由重力驱动的负载构造;G段为发育于地震活动停止期具显微细水平层理的浅海陆棚相泥质岩层。研究表明,地震活动有利于岩性地层圈闭的形成,地震作用形成的裂缝及液化砂岩脉能极大地提高储层的储集性能,对油气的运移也有积极影响,但同时地震活动对盖层的封堵性会造成一定的破坏。加强对古地震记录的研究必将给珠江口盆地的油气勘探提供新思路。
The Pearl River Mouth Basin experienced two major tectonic movements from Late Oligocene to Early Miocene successively. The earthquakes triggered by multi-phase tectonic activities led to the development of a variety of seismic-related seismites in situ in the basin. Soft sediments These structures occur within the transgressive sedimentary sequence and have a vertical superimposition relationship, which reflects the transformation of the original sedimentary sequence at different stages of seismic action. The vertical seismogenic sequence can be divided into 7 Sections: Section A is a coastal layer of sandstone with primary stratification, as the bottom section of the seismotectonic sequence is deposited in the quiescent period prior to the earthquake; section B is the liquefaction of unconsolidated sandy debris during the later strong seismic activity Formed serpentine liquefaction sandstone veins; section C is a series of sandstone and mudstone interbedded with a series of liquefaction curls; section D is a stepped microtach formed by differential settlement of rapidly accumulating sediments during the decay period of seismic activity; section E is The thin sand in the mudstone stretched or crushed during the period when the seismic activity tended to be stopped to form an expansive structure characterized by intermittent sandy belts. Section F is a gravity-driven load structure formed at the end of seismic activity ; Section G is Developed in the hanging of seismic activity with fine horizontal stratigraphic shallow shelf continental shale. The results show that the seismic activity is favorable to the formation of lithologic trap. The fractures and liquefied sandstone veins formed by seismic action can greatly improve the reservoir performance and have a positive impact on the migration of oil and gas, but at the same time, Sealing layer will cause some damage. Strengthening the study of paleoseismic records will surely provide new ideas for oil and gas exploration in the Pearl River Mouth Basin.