Application of Sequence Stratigraphy to Exploration and Development in Eastern Pearl River Mouth Basin, South China Sea
Shaokun Yang, Huang Lifen, and Xu Shice
Some appropriate conditions for applying sequence stratigraphy in PRMB exist: 1. the PRMB is a Cenozoic extension basin with weak tectogenesis after rifting; 2. the late Tertiary successive sediments deposited over the area from coast to deep marine basin are well developed and their seismic reflection is good in quality; and 3. high resolution quantitative biostratigraphy has provided more precise data of eustasy.
Twenty-two third order sequences since 30Ma were identified and are correlative to global cycle chart, but TB2.1 can be further divided into two third-order sequences. The 22 sequences from a "retrograding stacking pattern" which resulted in no large constructive delta or delta-related rollover anticlines. However, widely deposited seal rock possibly sealed the incised-valley, basin floor fan (BFF), and transgressive sandstone to form valid stratigraphic traps. Stratigraphic traps are particularly important in future exploration because of poor anticline trap types in the basin. Some stratigraphic traps can be predicted after studying the distribution of systems tracts in each sequence as a basic exploration unit. The BFF of TB2.1 which is closed to the source kitchen area could form large subtle trap.
Using the parasequence as a basic unit in reservoir scale will provide a new method to discover new reservoirs. For example, new oil reserves within the predicted stratigraphic trap related to K22, which can be divided into several parasequences in C.A. 16/08, were obtained after drilling.
Sequence stratigraphy has become a valid high resolution tool for chronostratigraphic correlation and fine-division and exploration of stratigraphic traps.
AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California