北萨哈林盆地油气成藏主控因素及有利区带分析

北萨哈林盆地属于中新生代弧后盆地，发育中、上中新统奥科贝凯组页岩、上中新统努托瓦组下段页岩、下中新统威宁组和中、下中新统达吉组含煤层系3套烃源岩。主力产层为中、下中新统的达吉组砂岩和上中新统努托瓦组下段砂岩。圈闭类型为背斜、复杂断背斜和断块。统计分析表明，平面上油气主要聚集在盆地东北萨哈林次盆，并且海上油气储量、油气田规模均大于陆上；垂向上油气主要分布在中新统达吉组和上中新统努托瓦组。油气成藏条件综合评价分析认为，盆地油气分布主要受构造和储层两方面因素的控制：上新世晚期形成的构造圈闭是油气聚集的主要场所，上新世晚期—全新世萨哈林褶皱幕对早期形成的圈闭起调整或破坏作用；中、下中新统达吉组和上中新统努托瓦组下段砂岩的展布控制了油气藏的纵横向分布。油气勘探结果表明，东北萨哈林次盆陆上部分勘探程度较高，海上是近几年的储量增长区，也是今后最具勘探潜力的地区，其勘探目的层主要为努托瓦组和达吉组，勘探目标主要为构造—地层型圈闭和地层型圈闭。

Controlling factors of hydrocarbon accumulation and play fairway in North Sakhalin Basin

Locating in the circum-Pacific fold belts of far-east in Russia, the North Sakhalin Basin is a back-arc basin developed from Mesozoic to Cenozoic. There are three sets of source rocks including shale in the Okobykay Formation of the Upper Miocene, shale in the lower Nutovo Formation of the Upper Miocene, and coal-bearing strata in the Weining Formation of the Lower Miocene and the Dagi Formation of the Lower Miocene. Its main oil production derived from the sandstones in the Dagi Formation of the Middle and Lower Miocene and the lower Nutovo Formation of the Upper Miocene. The major trap types are anticlines, complex faulted anticlines and fault blocks. Oil and gas mainly accumulated in the Sakhalin sub-basin in the northeast, with larger reserves offshore than onshore. Vertically, they were mainly found in the Dagi Formation of the Middle Miocene and the Nutovo Formation of the Upper Miocene. The comprehensive evaluation of reservoir conditions showed that the distribution of oil and gas were mainly controlled by structure and reservoir development. The structural traps formed during the late Pliocene provided spaces for hydrocarbon accumulation, and the folding event which took place from the late Pliocene to Holocene functioned as adjustment and even destruction to traps. The distribution of sandstones in the Dagi Formation of the Middle and Lower Miocene and the Nutovo Formation of the Upper Miocene controlled the plane and vertical distributions of hydrocarbon. Compared to the highly explored onshore area, the offshore area has a great potential, and the exploration targets should be focused on the structural-stratigraphic and stratigraphic traps in the Nutovo and Dagi Formations.