白云深水区东部重力流水道岩性圈闭特征分析

Gravity flow channel lithologic traps in the eastern part of the deep-water areas of the Baiyun depression

白云深水区东部在早中新世时期处于两种沉积相带的交汇处:古珠江三角洲物源体系深水重力流水道砂岩沉积和东沙隆起台地生物礁物源体系碳酸盐岩峡谷水道沉积。层序地层学、沉积学、构造学研究表明,在白云深水区东部21.0Ma陆架坡折带下方,早期低位体系域发育的条带状优质重力流水道砂岩可以作为岩性圈闭的主力储层;晚期海进体系域大型碳酸盐岩、泥岩充填的峡谷水道,切割了下部早期低位体系域的重力流水道砂体,起到了有效的侧封作用,从而形成了重力流水道岩性圈闭,实际钻井资料证实该岩性圈闭为工业油气藏。

During the early Miocene, there occurred two types of sedimentary facies zones intersecting each other in the eastern part of the deep-water area of the Baiyun depression： one is the deep-water gravity flow channel sandstone deposits in the ancestral Zhujiang delta source system, and the other is the carbonate rock canyon channel deposits in the Dongsha uplift platform organic reef source system. The integration of sequence stratigraphic, sedimentological and structural analysis has disclosed that beneath the 21.0 Ma shelf break in the eastern part of the deep-water area of the Baiyun depression, the excellent banded gravity flow channel sandstones developed in the early lowstand systems tract may contribute to important oil and gas reservoirs of the lithologic traps. The giant canyon channels filled by carbonate rocks and mustones in the later transgressive systems tract dissected the lower gravity flow channel sandstones developed in the early lowstand systems tract, and constituted the gravity flow channel lithologic traps which appear as commercial oil and gas reservoirs as proved by the well data in the study area.