砾岩油藏水驱采油机理研究

【作者】 胡志明； 祝志敏； 高树生； 郭和坤； 熊伟； 单文文；

【机构】 石油勘探开发研究院廊坊分院； 中石油冀东油田公司陆上油田作业区地质研究所；

【摘要】 新疆克拉玛依油田六中区克下组砾岩油藏,至今已注水开发30多年,综合含水68%左右。多年矿场开发实践表明:砾岩油藏在无水和低含水时期采出程度低,而中高含水阶段采出程度高,在含水达到70%后,仍可以采出可采储量的50%,砾岩油藏这种开发特征的机理不明确。在应用恒速压汞、铸体薄片等技术深入研究砾岩储层特征的基础上,应用核磁共振技术、结合水驱油、渗吸驱油物理模拟实验,研究砾岩油藏水驱采油机理。结果表明:六中区克下组砾岩孔喉发育,存在大量的粒缘缝,粒缘缝也是重要的储集空间,储层微观非均质性强,水驱过程中喉道动用的次序差别较大,较大喉道迅速突破导致无水采出程度低;随着含水上升,不同级别的孔喉逐次动用,采出程度不断上升,渗吸作用主要动用中小孔喉内的原油,同时含水率越高,油水接触面越大,渗吸作用越强,这也是中高含水期采出程度较高的原因。更多还原

【Abstract】 The water content ratio of crude oil of the Kexia conglomerate formation in the sixth middle area of the karamay oil fields in Xinjiang is about 68%,which have been developed by water injection over 30 years.Years of development practice reveals that the recovery percent of conglomerate reservoir is low during no water and low water-cut stage, while it’s high during high water-cut stage.50%of recoverable reserves still can be produced after water content reached 70%.The mechanism of this development characteristic of conglomerate reservoir is not clear.To study this mechanism,nuclear magnetic resonance,combined with water flooding and imbibition physical simulation is used based on the application of constant-speed mercury intrusion and casting thin sections to study on the reservoir characteristics of conglomerate reservoir.Results show that the conglomerate reservoir develops pores and throats well,a lot of grain boundary fractures are developed,and these grain boundary fractures are also important oil storage space.The heterogeneity of conglomerate reservoir is very strong.Bigger pores are broken through very soon during early water flooding stage,this leads to the water-free oil recovery very low.As the water content rose,different levels of pore-throat is broken through successively,this leads to recovery rising.The imbibition mainly affects the flow of crude oil within the pores and throats with middle and small radius.The higher water content(greater the oil-water contact surface),the stronger the effect of imbibition.This is another reason why the recovery percent during high water-cut stage is high.更多还原