The sequence stratigraphy and sandbodies control pattern of the lower-member in Zhujiang Formation of the northern Baiyun Depression in the Pearl River Mouth Basin have been studied in order to reveal the sequence evolution and the sandbodies distribution of the delta which has a low accommodation space with the help of the theory and method of sequence stratigraphy in combination of the comprehensive utilizing of core, logging information, and 3D seismic data. There are six sequence boundary types which have been recognized, they are exposed erosional unconformity which is caused by forced regression and normal regression, conformity surface corresponding to the unconformity, flooding surface, maximum flooding surface, bottom surface of forced regression and maximum regression surface. Based on the sequence boundary, the lower-member of Zhujiang Formation in the research area has been divided into one and a half third-order sequences. Meanwhile, the sedimentary boundaries of the delta with a low accommodation space coincides with or is slightly lower than the base level , the boundary of the parasequence which formed mainly during the semi-cycle of the rising base level is the exposed erosional surface corresponding to the flooding surface, and the formation of the sedimentary boundaries is predominantly controlled by the fall of relative sea level. The sandbodies are distributed in the delta front and lower delta plain horizontally and the lateral continuity of the sandbodies is deeply affected by the formation rate of new accommodation and the prevenient size of residual accommodation. The sandbodies locate longitudinally in both the highstand systems tract of the SQ1 and the lowstand systems tract of the SQ2, further the highstand systems tract formed from when the base level rises slowly to drop and the lowstand systems tract formed from when the base level drops to the lowest point to a slow rise to maximum flooding surface. For the better lateral continuity, the excellent source-reservoir-cap rock association and the favorable migration pathways, those sandbodies might be favorable area for oil-gas reservoir.
Yu Ye Zhang Changmin Li Shaohua Du Jiayuan Huang Yanran Wang Li. Sequence stratigraphy and sandbodies control pattern for the delta with a low accommodation space[J]. Chinese Journal of Geology, 2019, 54(4): 1223-1236.