粘土胶SMD的注入特性与地层渗透率的关系

Injection Behavior of Clay Mud as Flooding Agent in Relation to Formation Permeability

通过测定不同渗透率均质填砂模型注入粘土胶SMD的压力随注入量的变化 ,将SMD在地层的注入特性概括为 3种情形 ,随渗透率增加 ,SMD的作用逐步由渗滤面调剖向深部调剖再向驱油转化。基于该结果 ,用地层的不均质性导致SMD沿高渗透层突进解释了现场试验中的驱油效果及油井出胶现象。在填砂模型实验中使用添加高锰酸钾的紫色水溶液和添加碳粉的SMD ,证实了如下情况 :SMD对高渗透层的封堵强度弱 ,对中低渗透层产生堵塞 ,窜胶以后地层内形成SMD窜流层 ,导致注入水和SMD的波及系数降低 ,二次窜胶时间缩短。

Through measuring changes in injection pressure of 4% clay mud, SMD, into homogeneous sand packs of different permeability(7.3—40.0 μm 2) with increasing volume injected (0—1.2 PV), the injection behavior and the function of SMD in reservoir formations are classified into 3 types: filter cake creation and blockage on the sandsurface for low permeabilities(LP); entrance, anchorage and blockage in the pores for medium permeabilities(MP); and flow and oil displacement through highly permeable zones(HPZs). On the basis of the experimental results, the enhancement in oil recovery and the production of clay mud from oil wells observed in the field test on clay mud flood at fault block Tuo 7 of Shengtuo Oil Fields, Shengli, are explained in terms of channelling and fingering of the clay mud through HPZs in imhomogeneous reservoirs. By using colored mud and water it is ascertained that clay mud SMD plugs HPZs weakly and MP zones relatively tightly; channellings are rebuilt after mud production from oil wells and result in more fast mud production after the secondary mud injection. This is in agree with the field observations.