基于吼道分布特征的致密砂岩渗吸模型研究

自发渗吸作用是致密砂岩油藏重要采油机理,正确理解渗吸机理,充分发挥渗吸作用,对提高致密砂岩油藏的采收率具有重要意义。基于LW模型,根据恒速压汞试验喉道分布特征,建立了渗吸初期,自发渗吸质量与渗吸时间的关系式。选取长庆油田B418和B456两块岩心进行恒速压汞试验和渗吸试验,两块岩心根据解析模型求得的结果与渗吸试验结果吻合度较高,说明该方法正确可靠。试验结果同时表明, 致密砂岩自发渗吸与喉道半径相关,喉道半径越小,毛细管力也就越大,其渗吸时间也就越长,渗吸量也越大。

Study on imbibition model of tight sandstone based on distribution characteristics of roar

Spontaneous imbibition is an important oil recovery mechanism to tight sandstone reservoir. It is important to understand its imbibition mechanism and give full play to imbibition to improve the recovery rate of tight sandstone reservoirs. Based on the LW model, and according to the characteristics of roar distribution obtained by rate-controlled mercury injection test, the relationship between imbibition mass and imbibition time at the imbibition early stage was established. Two cores (B418 and B456) of Changqing Oilfield were selected to do rate-controlled mercury injection test and imbibition test, and the imbibition results obtained according to the analytical model were in good agreement with imbibition test results. It shows that the method is correct and reliable. The test results also show that the spontaneous imbibition of tight sandstones is related to the roar radius. The smaller the roar radius is, the bigger capillary force is, so the imbibition time lasts longer, and the imbibition quality is greater.