一种长封固段固井用缓凝剂的制备及性能评价

Preparation and performance evaluation of a kind of retarder used in long cementing interval

通过硼酸与共沉淀法制备的镁铝型层状双氢氧化物(Mg/Al-CO_(3)-LDH)进行离子交换反应合成了一种层状复合缓凝剂——硼酸根插层水滑石(Mg/Al-BA-LDH)。采用XRD、FTIR、SEM对其结构进行了表征。评价了其用量对水泥浆体系综合性能的影响。结果表明,制备的Mg/Al-BA-LDH结晶度较好,在pH=4.5下其层间距最大,为0.92 nm。Mg/Al-BA-LDH在90~170℃下能有效调节水泥浆稠化时间,其稠化曲线平稳且呈直角稠化。含Mg/Al-BA-LDH的水泥石24 h低温抗压强度大于14 MPa,掺量为0.5%(以水泥质量为基准,下同)时,7 d强度可达33.97 MPa。在不同温差条件下养护后,顶部水泥石抗压强度正常发展,满足长封固段固井施工要求,Mg/Al-BA-LDH的填充效应以及晶体效应在水泥水化后期起主导作用,促进水泥的水化,有效缓解了因缓凝作用而导致的浆体抗压强度下降。

A kind of layered composite retarder,borate-intercalated hydrotalcite(Mg/Al-BA-LDH)was synthesized by ion exchange reaction between boric acid and magnesium-aluminum lamellar dihydroxide(Mg/Al-CO_(3)-LDH)prepared by coprecipitation method.Mg/Al-BA-LDH was characterized by XRD,FTIR and SEM and its dosage on the comprehensive performance of the cement slurry system was evaluated.The results showed that the prepared Mg/Al-BA-LDH had a good crystalline with an interlayer spacing of 0.92 nm at pH=4.5.The Mg/Al-BA-LDH retarder could effectively adjust the thickening time of cement slurry at90~170℃.The thickening curve was stable,indicating right-angle thickening.The compressive strength of cement stone sample containing Mg/Al-BA-LDH was greater than 14 MPa at low temperature for 24 h.The strength of the sample with a dosage of 0.5%(based on the mass of cement,the same below)reached 33.97 MPa after 7 d.After curing under different temperature difference conditions,the compressive strength of the top cement stone samples developed normally and met the construction requirements,which could be applied to long cementing and large temperature range cementing operation.The filling of Mg/Al-BA-LDH and the crystal effect played a leading role in the process of cement hydration,thus promoting cement hydration and effectively alleviating the slurry compressive strength decline caused by retarding effect.