油气井固井多棱石英砂冲洗液的研制与现场应用

Research on a Polygonal Quartz Sand Flushing Fluid for Cementing Oil and Gas Wells and Its Field Application

在油气井固井过程中,常规冲洗液存在难以有效清洗井壁上滤饼的问题,尤其是油基钻井液会在井壁形成含油滤饼、在套管壁会附着油膜,严重影响了固井质量。为此,基于加强冲洗液物理冲刷作用的理念,优选了具有尖锐棱角、形状不规则的多棱石英砂颗粒及悬浮剂,配制了多棱石英砂冲洗液。室内试验发现,该冲洗液具有稳定性好,与水泥浆、钻井液相容性好的特点,且冲洗效率比常规冲洗液高10~30百分点。多棱石英砂冲洗液在胜利油田4口井进行了成功应用,固井质量均有明显的提高。研究应用结果表明,多棱石英砂冲洗液能够有效清除井壁滤饼、油膜及岩屑,改善固井二界面胶结环境,从而提高固井质量,满足大型压裂对水泥环胶结质量的要求。

Conventional flushing fluid cannot effectively remove the filter cake from the well walls during oil and gas wells cementing, especially oil-bearing filter cakes formed by oil-base drilling fluid on the well walls and the oil film attached to the casing walls, both of which seriously affect cementing quality. Therefore, it was hypothesized that polygonal quartz sand particles with sharp corners and irregular shapes mixed into an ideal suspending agent would strengthen the physical scouring capabilities of flushing fluid. With that in mind, a polygonal quartz sand flushing fluid was prepared. The laboratory test revealed that the prepared flushing fluid was highly stable and compatible with the cement slurry and drilling fluid, and the flushing efficiency was higher than that of conventional flushing fluid by 10 to30 percentage points. After the successful laboratory results, the prepared flushing fluid was successfully applied in four wells in Shengli Oilfield, and the cementing quality was significantly improved. The research and application indicated that the prepared flushing fluid could effectively remove the filter cake, oil film, and cuttings on the well walls and improve the cementing environment of the cement-formation interface. In this way, the cementing quality was enhanced to meet the requirements of large-scale fracturing for the cementing quality of cement sheaths.