松辽盆地北部连续型致密砂岩油藏的认识及其地质意义

Tight sand oil reservoir of continuous type in northern Songliao basin and its geological significance

综合利用钻井数据、地震解释成果、测井解释数据、试油试采等动态测试数据,系统剖析了松辽盆地齐家古龙凹陷葡萄花油藏的聚集特征,认为该油藏可以称为连续型致密砂岩油藏,其聚集特征明显与常规油藏不同:1)油藏在构造低部位埋深大于-1 600m范围内大面积分布;2)含油储集层致密,储集层孔隙度普遍小于10%,渗透率普遍小于1mD;3)具有油下水上的倒置型油水接触关系;4)含油储集层压力异常,压力系数普遍大于1.3;5)超压为主要聚集动力,油藏下部烃源岩层压力系数介于1.4～1.5之间.研究结果表明:连续型致密砂岩油藏是一种自然存在的油藏类型,"连续展布的致密砂岩储集层"和"下部超压强排烃烃源岩"是形成该型油藏的关键,综合分析认为松辽盆地三肇凹陷深部位葡萄花储集层具有致密、大面积连片展布、下部烃源岩超压(压力系数1.3～1.8)的特征,是连续型致密砂岩油藏的有利发育区.

This study used the dynamic testing data, such as drilling-will data, seismic interpre tation data, well logging interpretation data, production test data and so forth, and systemati- cally analyzed the aggregation characteristics of Putaohua in Qijia-gulong Sag, Songliao Basin. Through the analysis above, this study concluded that this reservoir could be called as the tight sand oil reservoir of continuous type and its aggregation characteristics were dramatically different from conventional reservoirs in following aspects： 1） the reservoir largely distributed at the structural bottom, with depth greater than --1600 m; 2） the reservoir is tight, with porosity smaller than 10% and permeability smaller than lmD; 3） the reservoir has a reverse oil-water contact relationship; 4）the pressure in oil-containing layers is abnormal, with pressure coefficient greater than 1.3; 5） overpressure is the main hydrocarbon aggregation dynamics, with pressure coefficient under source rock ranging from 1.4 to 1.5. The research results show that the tight sandstone oil reservoir of continuous type do exist in nature, and the continuously tight sandstone reservoir stratum and hydrocarbon expulsion source rock below the reservoir with overpressure are the key factors for aggregating this type of reservoir. Through comprehensive analysis, this study concluded that Putaohua tight sandstone reservoir had the following characteristics： tight, largely successive distribution, overpressure of the under part of source rock overpressure （the pressure coefficient ranges from 1.3 to 1.8）. This region was the conducive to the development of continuous type tight sand oil reservoir.