松辽盆地双城断陷深层原油成藏模式

Main Controlling Factors and Accumulation Mode of Deep Oil in Shuangcheng Fault Depression of Songliao Basin

针对松辽盆地双城断陷深层原油认识程度低、成藏主控因素和深层原油成藏模式不明确的问题,本文利用岩石热解、氯仿沥青“A”和包裹体均一温度等测试资料,结合埋藏史-热史模拟、平衡剖面恢复等手段,通过对烃源岩厚度、排烃强度、圈闭形成、断-砂配置、超压与充注阻力耦合关系等成藏主控因素进行了系统分析。结果表明:1)双城断陷深层可分为登三段背斜、断背斜、断层-岩性油藏和营四段致密油等4种类型。2)登三段构造油藏受烃源岩、断裂和有效圈闭联合控制,高丰度的湖相泥岩是其物质基础;主成藏期前各类圈闭即已形成,断层是油气运移的重要目标;断-砂配置关系决定圈闭有效性。3)营四段致密油受岩性圈闭、排烃强度和超压影响,其中,排烃强度影响致密油宏观分布,生烃增压形成的超压是致密油充注主要动力。综合致密油成藏条件和成藏主控因素,建立西部构造带“源储分离、断层长距离输导、高点富集”、东部断阶“源储紧邻、断砂匹配短距离运移、有效圈闭聚集”和中央洼槽“源储共生、超压驱动裂缝运移、甜点富集”3种成藏模式。

For the problem of low awareness of deep oil,the main control factor of different kinds of reservoirs and deep crude oil accumulation model in Shuangcheng fault depression of Songliao basin,we make sure the main controlling factors such as the thickness of source rock,the hydrocarbon expulsion intensity,the formation of entrapment and its relationship with the main accumulation period,the sand-source configuration,the overpressure and filling resistance,on the base of rock-eval,chloroform asphalt“A”and homogenization temperature of inclusion.The result is that:1)There are four kinds of reservoirs,such as fault-anticline,anticline and fault-lithologic reservoir in the 3 rd Member of Denglouku Formation in the west structure and the east fault bench,tight reservoir in the 4^(th)Member of Yingcheng Formation within the central sub-sag.2)The structure reservoir in the 3^(rd)Member of Denglouku Formation is controlled by the union of mudstone,oil-source fault and effective trap.The abundant source rock is the material base for oil reservoir,and the structure trap in the 3^(rd)Member of Denglouku Formation is almost complete before the hydrocarbon expulsion,fault is the main target for oil migration,the configuration relationship of sandstone and source determine the effective of structure trap.3)The tight oil in the 4^(th)Member of Yingcheng Formation is under the control of lithologic trap,source and overpressure.The tight oil is controlled by the hydrocarbon expulsion intensity,while overpressure is the main power for tight oil charging.We set up three kinds of accumulation models in different regions based on forming condition and main controlling factors of tight oil,such as“reservoir and source separate,migration along the fault in long distance and enrichment in the high point”in west structure,“reservoir and source nearby,long distance transmission of faults and connected sandstone in short distance,accumulate in effective trap”in east fault bench,and“reservoir superpose on source,overpressure drive and migrate along the fissure,enrichment in sweet points”in the central sub-sag.