源外斜坡区油气成藏要素研究——以松辽盆地北部西部斜坡区为例

Hydrocarbon Accumulation Factors of the Slope Area Outside of Source Area:a Case Study of West Slope Area in Northern Songliao Basin

勘探证实,松辽盆地北部西部斜坡区已发现的富拉尔基油田、江桥油田、二站-阿拉新油气田、白音诺勒油气田和平洋油气田超出有效烃源岩的展布范围,距离生油凹陷30～100km,成藏要素一直是制约该区油气勘探的核心问题。本文以构造地质学、沉积地质学和石油地质学等理论为指导,开展了松辽盆地北部西部斜坡区构造特征、沉积特征、典型油气藏解剖研究。深入剖析了研究区油气成藏的主控因素,表明已发现的油气主要富集在四个鼻状构造带和超覆带上,储集砂体为三角洲前缘的分流河道砂体、河口坝、远砂坝和席状砂,指出该区油气成藏和富集程度受构造和沉积砂体类型双重控制。典型油气藏解剖表明,该区油气藏类型丰富,主要发育微幅度构造油藏、岩性-构造油藏、构造-岩性及岩性上倾尖灭等油气藏类型。结合构造、断裂、沉积及油气运移等因素,建立了研究区油气成藏模式,指出不整合面、断层和砂体是油气输导通道,为今后该区油气勘探指明了方向。

Exploration and production has confirmed that a large number of oilfields such as Fulaerji oilfield,Jiangqiao oilfield,Erzhan-Alaxin oil-gas field,Baiyinnuole oil-gas field and Pingyang oil-gas field have been found in west slope area,north Songliao Basin.They are located outside of source area,about 30 to 100 km far from the source sag.Therefore,hydrocarbon accumulation has long been the key issue of oil and gas exploration in the west slope area.In combination with structural geology,sedimentary geology and petroleum geology theory,structural characteristics,sedimentary characteristics and typical reservoir anatomy were studied in detail.The main controlling factors of hydrocarbon accumulation show that discovered oil and gas is mainly enriched in four nose structural belts and overlap belt,distributary channel sand body,mouth bar,far sand dam and sheet sand are oil and gas reservoir,and the hydrocarbon accumulation and enrichment degree are controlled by structural and sedimentary sand body type.Typical reservoir analysis shows that this area have various reservoir types,including micro-amplitude structural reservoir,lithological-structural reservoir,structural-lithological reservoir and lithological updip pinchout reservoir type,etc.Combining with many controlling factors such as structure,fracture,sediment and hydrocarbon migration,we have established a model of oil and gas accumulation for west slope area,and point out that unconformity surface,fault and sand body are hydrocarbon migration channel.This gives a direction for oil and gas exploration in the west slope area.