安塞特低渗透油田见水后的水驱油机理及开发效果分析

ANALYSIS ON THE WATER-DRIVE MECHANISM AND DEVELOPMENT RESULTS OF ANSAI SUPERTIGHT OIL FIELD FTER WATER-OCCURRENCE

孙卫 曲志浩 李劲峰

SUN Wei QU Zhi-hao LI Jing-feng

西北大学地质系, 陕西西安710069

Department of Geology, Northwest University, Xi'an, Shaanxi 710069, China

应用真实砂岩微观模型水驱油实验对安塞长6特低渗透油层见水后的水驱油机理及特征观察分析认为:贾敏效应对见水后的水驱油效率影响突出,表现形式为注水阻力增大、注入压力升高。随注入压力的增加,注入水形成新的渗流通道后使原已形成的水流通道“锁死”;残留于孔隙喉道处的油滴受毛细管附加阻力影响只发生变形而难以运移。在储层孔隙结构非均质影响下,长6油层中流体的渗流仅作用在部分连通较好的大孔隙内,当注入0.5～0.8倍于孔隙体积的注入水后,油井均已见水。残留于水洗通道中的油滴在水动力作用下不断发生卡断-聚并-再卡断的过程为见水后驱油效率增加的方式之一。在裂缝发育带水驱油的形式主要取决于孔隙渗透率、裂缝渗透率以及驱替压力的大小。

On the basis of water-drive experiments with the micromodel of true sandstone,the water-drive mechanism and characteristics of the Ansai Chang-6 supertight reservoir after water-occurrence is observed and analyzed.It is considered that the Jiamin Effect exert a notable influence on the water-drive efficiency after water-occurrence,and is characterized by the increase of injection resistance and pressure.With the rising of injection pressure,the water-flow pathway formed before is "deadlocked" after injected water forms new seepage pathways,the oil drops left in pore throats only deform and are difficult to migrate under the impact of additional capillary resistance.Affected by the anisotropy of reservoir pore structure,the seepages of fluid in the Chang-6 reservoir only have effects on part well-interconnected macro-pores.When injected water is 0.5-0.8 times of pore volume,water occurs in all oil wells.the continuous jaming-colesing-rejaming process of the oil drops left in water-flushing pathways under hydrodynamic action is one of the ways to raise the oil-expulsive efficiency after water-occurrence.The water-drive patterns in fissure-developing zones mainly depend on whether pore permeability,fissure permeability and displacement pressure are high or low.

https://doi.org/10.11781/sysydz199903256