渤海湾盆地垦利6-1亿吨级岩性油田成藏条件及勘探关键技

垦利6-1油田位于渤海海域南部的莱北低凸起，是一个新近系探明储量超过亿吨的整装、优质大型岩性油田。垦利6-1油田的重大突破打开了渤海海域浅层高产岩性油藏勘探的新局面。垦利6-1油田的关键成藏条件主要有3个方面：①莱北低凸起处于黄河口富烃凹陷的有利排烃方向，且其深层新生界底部不整合面之下发育两大隐伏汇聚脊，为浅层油气的规模成藏提供了优越的供烃条件；②在中新世晚期的湖盆萎缩期，河、湖沉积交互背景下形成的大型复合河道型岩性圈闭为油气的规模成藏提供了优越的储集条件；③连片复合河道砂体与区域湖侵泥岩形成的优质储-盖组合有利于油气在垂向上集中分布。独特的石油地质条件使得垦利6-1油田的新近系具有以"深层远源汇聚-断裂垂向输导-浅层枝蔓式运移"为特征的高效成藏模式。以新近系大型岩性圈闭精细刻画和大型岩性油藏高效集束评价为核心的勘探关键技术为垦利6-1亿吨级油田的高效评价提供了重要支撑。

Accumulation conditions and key technologies for exploration of Kenli6-1 as the hundred-million-ton-level lithologic oilfield in Bohai Bay Basin

Kenli6-1 oilfield is located in Laibei low uplift in the southern Bohai Sea, which is a large high-quality Neogene lithologic oilfield with the proven reserves of more than hundred million tons. The major breakthrough of Kenli6-1 oilfield has opened up a new prospect for the exploration of shallow high-yield lithologic reservoirs in Bohai Sea. The key accumulation conditions of Kenli6-1 oilfield can mainly be summarized from the following aspects. (1) Laibei low uplift is located in the favorable direction of hydrocarbon expulsion in the Huanghekou hydrocarbon-rich sag, and two large hidden catchment ridges are developed under the bottom unconformity of deep Cenozoic reservoir, providing superior hydrocarbon supply conditions for shallow hydrocarbon accumulation. (2) During the lacustrine shrinkage of the Late Miocene, the large compound channel lithologic trap formed under the interaction of river and lake deposits provides favorable conditions for the large-scale hydrocarbon accumulation. (3) The high-quality reservoir-cap combination formed by the continuous compound channel sand body and the regional lacustrine transgressive mudstone is conducive to the vertical concentrated distribution of oil and gas. Due to the unique petroleum geological conditions, the Neogene in Kenli6-1 oilfield possessed the efficient accumulation mode characterized by "deep far source convergence, vertical transportation by faults, and shallow branching migration". The key technologies of exploration focusing on the fine characterization of the large-scale Neogene lithologic traps and the efficient cluster evaluation of large lithologic reservoirs provide important support for the high efficiency evaluation of Kenli6-1 as the hundred-million-ton-level oilfield.