180℃液硅防气窜剂粒径优化及性能研究

Study on Particle Size Optimization and Performance of a Silica Water Suspension as Anti Gas Channeling Agent at 180 ℃

为了改善常规液硅防气窜剂在超深井中的防气窜性能,通过在原材料中加入白炭黑和增加砂磨机物理机械研磨等方式,对液硅防气窜剂进行了粒径优化并进行了性能对比评价实验,通过基本性能实验评价了其与水泥浆的配伍性,通过抗压强度、渗透率和胶结强度评价了水泥石的防气窜性能,利用XRD和SEM分析解释了180℃液硅水泥浆体系的防气窜机理。实验结果显示,粒径优化实验制得了平均粒径为300 nm的液硅防气窜剂,与水泥浆配伍性能良好,15%加量以上的液硅使得水泥石抗压强度长期稳定,渗透率小于0.02 mD,胶结强度大于4 MPa,水泥水化产物氢氧化钙极大减少,微观水泥石结构从块状向条状和纤维状转变。研究结果表明,粒径优化后的液硅防气窜剂适用于现有水泥浆体系,能够改善常规液硅防气窜剂在超深井中的应用效果。

To improve the gas-channeling prevention performance of regular silica water suspension in ultra-deep well drilling, the silica suspension was treated with a white carbon black and grounded with sand mill. The particle size of the solids in the suspension was optimized and the properties of the suspension evaluated in laboratory experiment. Basic performance evaluation was performed to evaluate the compatibility of the optimized silica water suspension with cement slurries. Other tests such as compressive strength test, porosity measuring and cementing strength test were performed to evaluate the gas-channeling prevention performance of the silica water suspension. Using XRD and SEM, the gas-channeling prevention mechanisms of the silica water suspension in cement slurries at 180 ℃ were analyzed and explained. It was found in the experiment that the average particle size of the silica was 300 nm, and was compatible very well with cement slurries. Cement slurries treated with 15% silica water suspension had compressive strength that can sustain for a very long time. The porosity of the set cement was less than 0.02 mD and the cementing strength was greater than 4 MPa. The amount of calcium hydroxide produced during hydration of the cement was greatly reduced and the micro structure of the set cement turned from massy to strip-shaped and fibrous. The study showed that the anti gas channeling agent formulated with particlesize optimized silica-water suspension was suitable for use in cement slurries commonly in use and performed better than regular silica water suspension.