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珠江口盆地北部坳陷带文昌组分布广泛,是该区主要烃源岩发育层段。对文昌组的划分以及分布规律的认识,是洼陷评价的基础。通过井—震标定,从单井资料入手,结合地震反射特征分析,认为文昌组顶、底界面在洼陷边缘为不整合面,洼陷中央为整合面,具有4种类型;根据井—震标定将文昌组分为2~3段,洼陷陡坡带发育扇三角洲相(楔状、杂乱、弱反射)和冲积扇(楔状、杂乱、强反射),深陷带发育滨浅湖相(中—低频、中等连续性、弱反射)和中深湖相(低频、连续、强反射),缓坡带发育三角洲相(前积结构、中—高频、中等连续、中—弱反射);文昌组沉积物纵向表现为粗—细—粗的特征,洼陷底部为冲积扇—扇三角洲相,中部过渡为滨浅湖—中深湖相,顶部为扇三角洲—滨浅湖相。受物源、水体以及后期剥蚀作用,不同洼陷沉积环境不同。
The Wenchang Formation in the northern depression of the Pearl River Mouth Basin is widely distributed and is the main source rock development zone in this area. The understanding of the division and distribution of Wenchang Formation is the basis for the evaluation of the subsidence. According to the well-seismic calibration, starting from single-well data and combining with the seismic reflection characteristics analysis, it is considered that the top and bottom interfaces of Wenchang Formation are unconformity at the edge of the depression and the center of the depression is an integrated surface. According to well-earthquake The Wenchang Formation is divided into 2 ~ 3 sections, and the fan delta facies (wedge, messy and weak reflection) and alluvial fan (wedge, messy and strong reflection) are developed in the steep slope depression, Low-frequency, medium-continuous, weakly reflections) and mid- and deep-lacustrine facies (low frequency, continuous and strong reflections), gentle slope zone developing deltaic facies The features are coarse-thin-coarse in the longitudinal direction, alluvial-fan delta facies at the bottom of the depression, middle-shallow lake facies-middle lake facies in the middle and fan-delta-shallow lake facies in the top. By the provenance, water bodies and post-denudation, different sag environments are different.