珠江口盆地番禺地区珠江组沉积前古地貌及其对沉积体系的控制

Paleogeomorphology of the Lower Miocene Zhujiang Formation and its control on the depositional system in Panyu area,Pearl River Mouth Basin

利用地震、测录井、分析化验资料,在后期构造影响去除的基础上,综合考虑去压实校正、古水深校正等因素,对珠江口盆地番禺地区珠江组沉积古地貌进行了恢复,并通过沉积正演模拟,分析了古地貌对珠江组沉积的影响。研究表明:采用钻井井深校正后的目标层顶底构造面求取地层真厚度的方法在实际应用中操作更简便,井震结合后恢复的结果更准确;分不同岩性恢复压实能够更准确地恢复目标层的原始地层厚度。研究区珠江组沉积古地貌表现为东北及东部高,西南及南部低,整体上起伏平缓,古地貌的微型起伏特征控制着珠江组浪控辫状河三角洲的微相分布。当古地貌参数与实际恢复结果一致时,沉积过程模拟的岩性类型平面展布能够较好地与沉积地层相匹配。

Based on the data of seismic,logging and analysis,and the removal of the later structural influence,the sedimentary paleogeomorphology of Zhujiang Formation in Panyu Area is restored by considering the factors of decompression correction and paleobathymetry correction,and the influence of paleogeomorphology on the deposition of Zhujiang Formation is analyzed through sedimentary forward simulation.The results show that:(1)The method of using the top and bottom structural surface of the target layer after drilling depth correction to obtain the true thickness of the formation is more convenient and practical,and the restored result after well-seismic combination is more accurate;(2)The original formation thickness of the target layer can be restored more accurately by decompression correction according to different lithology;(3)The sedimentary palaeogeomorphology of Zhujiang Formation in Panyu area is characterized by high in the northeast and east,low in the southwest and south,and gentle in the whole.The micro fluctuation feature of the paleogeomorphology controls the microfacies distribution in the wave-dominated braided river delta;(4)When the paleogeomorphic parameters are consistent with the actual restoration results,the plane distribution of lithologic types of sedimentary process simulation can be well matched with the sedimentary strata.