南海西部原油领域勘探进展与突破方向

Exploration progress and breakthrough direction of crude oil in the western South China Sea

南海西部原油领域历经多年勘探,探明程度高,勘探难度日益增大。近年来,转变思路,大力拓展新领域。攻关岩性圈闭发育机制,建立了流三段“低位转换带控砂,湖侵互层叠置连片”的广覆式砂体沉积模式,阐明了大面积连片岩性圈闭形成机理,创建了“近源广覆式有序富集”成藏模式,发现南海西部首个大中型岩性油田;攻关深层大型储集体和优质储层发育机制,建立构造-层序-地貌耦合控砂分析技术,提出了限制型辫状河三角洲发育模式,明确了相带与溶蚀差异控储机制,涠西南凹陷B洼深层、乌石凹陷反转构造带倾末端、文昌B凹陷双古领域获得了勘探突破。同时明确了大型构造脊大型储集体耦合的深层领域、富烃凹陷周缘地层-岩性圈闭领域、源储对接潜山领域和烃源条件落实边部凹陷是南海西部原油领域下步重点勘探方向。

After several years of exploration,the field of crude oil in the western South China Sea has been in a high degree of exploration and the exploration is becoming more difficult.In recent years,new fields are expanded vigorously by transforming mindest.The development mechanism of lithologic traps was researched.The widely covering sand sedimentary model of“low-stand transfer zone controlling sand,extensively overlapping of lacustrine transgressive interbeds"in the third Member of Liushagang Formation was established.The formation mechanism of extensive and continuously distributed lithological trap was elucidated.The"widely covering sequential accumulation adjacent to source”model of accumulation was created.And the first large and medium-sized lithologic oilfield in the western South China Sea was discovered.The development mechanism of deep large reservoirs and high-quality reservoirs was studied.The analytical technique of controlling sand by the structure-sequence-geomorphology coupling was established.The development model of restricted braided-river deltas was proposed.The mechanism of controlling reservoir by the facies belt and differential dissolution was clarified.And exploration breakthroughs have been made in the deep strata in B sub-sag of Weixinan sag,the pitching end of inversion tectonic belt of Wushi sag,and the field of Paleogene and buried hills in Wenchang B sag.Meanwhile,it is clear that the deep-strata coupled with large tectonic ridges and large reservoirs,the stratigraphic-lithologic traps adjacent to hydrocarbon-rich sags,the buried hills with source-reservoir connection,and the marginal sags with reliable source rock conditions are the next key exploration directions of crude oil in the western South China Sea.