致密砂岩油藏高温高压动态渗吸特征及影响因素

为解决致密砂岩油藏水驱过程中基质动用程度低的问题,开展了4种典型表面活性剂作用下的注水吞吐动态渗吸岩心实验,研究了表面活性剂质量分数、驱替速度、注入量、闷井时间、渗透率、裂缝对动态渗吸效果的影响。研究结果表明:动态渗吸驱油效率随驱替速度的加快先提高后降低,随表面活性剂质量分数、注入量和闷井时间的增加而提高,但驱油效率的增幅不断降低;采用AEO-2型阴离子表面活性剂的渗吸效率最高,其最佳注入方式为0.3%质量分数、0.1 mL/min驱替速度、1.2倍孔隙体积注入量和18 h闷井时间;渗透率、裂缝与动态渗吸效率呈正相关性,开展大规模体积压裂和酸化改造是提高动态渗吸效果的重要因素。矿场试验结果显示,油井经过注水吞吐动态渗吸后,平均产油量提高幅度达166%,平均含水率下降幅度达25.8%,增油降水效果显著,具有较大的应用和推广前景。

Characteristics and Influencing Factors of Dynamic Imbibition at High Temperature and High Pressure in Tight Sandstone Reservoir

In order to solve the problem of low matrix producing degree in the water flooding process of tight sandstone reservoir, waterflood huff-puff and dynamic imbibition core experiments under the action of four typical surfactants were conducted to study the influence of mass fraction of surfactant, displacement speed, injection amount, well shut-in time, permeability and fracture on the dynamic imbibition effect. The results showed that the dynamic imbibition displacement efficiency first increased and then decreased with the acceleration of the displacement speed, and increased with the increase of surfactant mass fraction, injection amount and shut-in time, but the increase of displacement efficiency decreased continuously; the imbibition efficiency under the action of AEO-2 anionic surfactant was the highest and the best injection conditions were 0.3% mass fraction, 0.1 mL/min displacement speed, injection volume of 1.2 times pore volume and 18 h well shut-in; permeability and fracture were positively correlated with dynamic imbibition efficiency; large-scale fracturing by stimulated reservoir volume and acidification stimulation were important factors to improve the dynamic imbibition efficiency. The field test results showed that the average oil production of oil wells was increased by 166% and the average water cut decreased by 25.8% after waterflood huff-puff and dynamic imbibition in oil wells. The effect of increasing oil production and decreasing water cut was remarkable, so the dynamic imbibition has a greater prospect of application and promotion.