准噶尔盆地乌尔禾油田三叠系百口泉组储层敏感性评价

针对准噶尔盆地乌尔禾油田三叠系百口泉组低孔低渗的冲积扇储层,储层天然能量较差,未经储层改造难以获得工业油流的问题,采用水基压裂液改造后试油未能获得成功,而在W36井采用油基压裂液压裂后试油获得成功。依据储层分析技术和实验分析技术,参照碎屑岩储层评价标准,分析大量岩心流动实验测试数据,针对百口泉组冲积扇砂砾岩储层敏感性深入研究,指出分析储层敏感性和改善压裂工艺将对油层保护及开发起到关键作用。通过研究发现,伊/蒙混层和高岭石等粘土矿物含量高是造成储层具有较强敏感性的主要原因;百口泉组储层水敏感性、盐敏感性和体积流量敏感性中等偏强,速度敏感性较弱。通过研究结果和生产试验,建议采取脱水油基压裂液、压裂液盐度控制在6 000 mg/L以上、控制流速和体积流量等措施,有效地降低不同敏感性造成的储层伤害,提高油气产量。

Reservoir sensitivity evaluation of the Triassic Baikouquan Formation in Wuerhe oilfield ,Junggar Basin

Triassic Baikouquan Formation reservoirs in Wuerhe oilfield in Junggar Basin are of alluvial fan facies with low-porosity and low-permeability.No industrial oil flow can be tested without stimulation due to the low initial energy.Previous stimulation with water-based fracturing fluid failed,but stimulation with oil-based fracturing fluid in W36 well was successful.By using reservoir evaluation technique and experimental analysis techno-logy and referring to the standards of clastic reservoir evaluation,this paper thoroughly studied the sensitivity of sandy conglomerate reservoirs sensitivity within alluvial fan of Baikouquan Formation based on analysis of large amount of core flow test data.It is pointed out that understanding reservoir sensitivity and improving fracturing technique are quite important for prevention of formation damage and oil recovery.The study indicates that high content of clay minerals such as mixed illite/smectite and kaolinite is the main cause of strong sensitivity of the reservoir.Water sensitivity,salt sensitivity and volume flow rate sensitivity of the reservoir in Baikouquan Formation are moderate to strong(above average).Velocity sensitivity is a relatively weak.According to the results and production experiments,following measures,such as using dewatered oil-based fracturing fluid,controlling salinity of fracturing fluid(above 6 000 mg/L)and controlling flow velocity/volume flow rate,are proposed for preventing reservoir damage from sensitivity and increasing oil-gas production.