松辽盆地北部齐家地区青山口组二段互层型泥页岩油富集主控因素

Main controlling factors of the accumulation and enrichment of the interlayered mud shale oil in Qingshankou-Formation Member-2 of Qijia area in North Songliao Basin

松辽盆地北部齐家地区青山口组二段沉积环境为三角洲前缘—半深湖,其岩性主要为厚层泥页岩夹薄层粉砂岩。泥页岩R o>0.75%,处于成熟阶段,形成成熟泥页岩层夹粉砂岩储层互层分布的储集模式,为典型的互层型泥页岩油。通过岩心宏观描述、微观实验分析,结合油藏精细解剖,明确了互层型泥页岩油分布特征和泥页岩油富集主控因素。研究表明:齐家地区青山口组二段互层型泥页岩油横向上呈层状连续分布、连续性好,纵向上多层发育,单层厚度为1~4 m,累计厚度为10~50 m;优质烃源岩发育是泥页岩油富集前提,为泥页岩油富集提供丰富的物质基础;源储一体的组合模式是泥页岩油富集关键,为泥页岩油持续聚集提供充足动力;沉积微相控制不同成因砂体储集性能和含油程度,河口坝、远砂坝、叠置席状砂发育,单层厚度大,储层物性好、孔喉连通性好,纵向上错叠连片分布,油气富集程度高,单井产量高。研究成果为落实甜点层系和甜点区分布指明了方向。

Member Qing-2 in Qijia area of North Songliao Basin belongs to delta front-semi-deep lacustrine sedimentary environment,which lithology is mainly thick mud shale with thin siltstone.The maturity of the mud shale is more than 0.75%.It is in the mature stage,forming the reservoir model of interlayered distribution of the mature mud shale with the siltstone reservoirs,which is the typical interlayered mud shale.Through the comprehensive study was studied on the macroscopic description,microscopic experimental analyses of the cores in combination with the fine reservoir anatomy,the distribution characteristics and main controlling factors of the accumulation and enrichment of the interlayered mud shale oil in Member Qing-2 in Qijia area.The results show that the interlayered mud shale oil in Member Qing-2 in Qijia area distributes horizontally in the continuous layers with much better horizontal continuity,and vertically in multiple layers,the thickness of the single layer is generally 1-4 meters,the cumulative thickness is generally 10-50 meters;the development of high-quality source rocks is the precondition of the mud shale oil enrichment and provides the rich material basis for the accumulation of the mud shale oil;the combination model between the sources and reservoirs is the key factor for the mud shale oil enrichment,which provides the sufficient power for the continuous accumulation of the mud shale oil;the enriching capacity and oil-bearing degree for different-origin sandbodies are controlled by the sedimentary microfacies,the river mouth bar,distal bar and sand sheet sand are well-developed,the thickness of the individual layer is large,the physical properties are much better,the connectivity between the pores and throats is much better as well,characterized by overlapped continuous distribution in horizon,pretty higher hydrocarbon enriched degree and high-production of the single well.The study results have enlightened the exploration directions of ensuring the sweet-spot series and region.