活化粉煤灰低密度水泥浆体系研究及应用

Research and Application of Low-density Slurry with Activated Fly Ash

粉煤灰本身的化学组成与微观颗粒形态决定了其活性低、水化慢。通过对其进行物理活化，破坏玻璃体表面致密保护层，改善颗粒圆球度，增加颗粒细度；再进行颗粒分级，窄化粒径分布，90％的活化粉煤灰颗粒粒径小于5μm；配合使用化学激活剂，可有效提高粉煤灰活性。扫描电镜显示，活化粉煤灰水泥浆养护24h的水化产物均匀，其间未有未反应的粉煤灰颗粒。以活化粉煤灰为主要减轻材料，研制开发出性能优良的活化粉煤灰低密度水泥浆体系，其密度在1．45-1．55g／cm^3可调，API失水〈50mL，SPN值〈3，48h水泥石抗压强度大于15MPa，水泥浆上下密度差小于0．01s／cm^3。该体系在塔河油田应用30多井次，固井优良率达到80％，有效解决了塔河油田二叠系低压易漏层固井难题。

The chemical composition and micro particle shape of fly ash make it has low activity and slow hy- dration. By physical activation, compact coating layer of vitreous was broken, particle sphericity was improved, and grain fineness was increased. Then grain classify was followed, narrowing size distribution, 90% activated fly ash particle size were less than 5 μm. In alliance with chemical activation agent to increase fly ash activity effec- tively. SEM showed that the hydration product were uniform and compact after cured 24 h, without unhydrated fly ash particles. The low-density slurry with activated fly ash as the main lightening admixture was studied, which had adjustable density （ 1.45 - 1.55 g/cm^3 ）, API fluid loss 〈 50 mL, SPN value 〈 3, compressive strength 〉 15 MPa/48 h, the density of slurry between top and bottom were less than 0. 01 g/cm^3. Low-density slurry with activa- ted fly ash had been applied more than 30 wells for solving the low pressure and leakage cementing problem of per- mian strata in Tahe oilfield, the excellent rate was 80%.