醇诱导盐沉析技术对高温高盐油藏的调剖作用

Profile control effect of high-temperature and high-salinity reservoirs improved by alcohol-induced salt precipitation technology

西部某油田埋深为4 880m,根据其油藏流体高矿化度的特性,采用醇诱导盐沉析技术,对该油田高温高盐油藏水驱油剖面进行了调剖实验,以扩大波及系数,提高原油采收率。依据盐沉析量和单位结晶量两个参数对注入体系进行筛选,同时采用扫描电镜,粒度分析仪和三维物理模拟实验对最优体系的结晶颗粒微观结构、粒度分布、压力分布和提高采收率情况进行了分析。实验结果表明,NaCl和KCl作为主剂时,诱导剂和主剂体积比相同的条件下,按诱导剂的诱导能力其排序为醇-A>醇-C>酸-2>酸-1>胺-X。在诱导剂的作用下,小晶体连续堆积的盐颗粒能在溶液中析出,其平均粒径为63.645μm。对于纵向非均质油藏,醇诱导后的盐结晶颗粒能使油流动阻力增大,压力上升,流动转向。在平面上,后续水从主流线流向两侧的剩余油区,驱替剩余油,提高平面波及系数。在纵向上,后续水从高渗层转向低渗透层,提高纵向波及系数。实验数据显示:注入0.5PV诱导剂后,后续盐水驱替量为1.5PV,采收率提高到62.8%,比水驱采收率提高了27%。

The reservoirs of an oilfield in West China have the characteristics of high temperature（123℃）,deep bury（4880m）,high salinity（18.1×104mg/L） and high pressure.The alcohol-induced salt precipitation technology was adopted to control the profile of the reservoirs for enlarging the sweep efficiency and enhancing oil recovery.The massive experiments were performed to pick up the excellent injection system by means of two parameters,including the salt precipitation quantity and unit crystal quantity.The microscopic structure of crystal grain,distribution of grain size,distribution of pressure and the situation of enhanced oil recovery were analyzed by means of SEM,grain size analysis units and three-dimensional physical simulation.The experimental results indicated that under the same volume ratios of inducing agent and salt solution,the inducing agents arranged according to their induction ability from big to small as follows： alcohol-A,alcohol-B,acid-2,acid-1 and amine-X.The investigation showed that the salt grains with the form of consecutive distribution could be precipitated from solution.The average grain diameter of the salt grains is 63.645μm.In the vertical heterogeneous reservoir,the alcohol-induced salt grain could elevate the fluid flow resistance,increase the injection pressure and change the flow direction.In the lateral direction,follow-up water could flow from the mainstream line to the remaining-oil region to displace the remaining oil and enhance the plane sweep efficiency.In the vertical direction,follow-up water diverted from the high-permeability layer to the low-permeability layer to enhance the vertical sweep efficiency.The experimental data indicated that oil recovery was increased to 62.8% and was elevated by 27% comparing with the first water flooding after injecting 0.5PV inducing agent and 1.5PV follow-up water.