塔河油田奥陶系井底温度高,缝洞发育,极易发生漏失,固井环空间隙小,常规的低密度水泥浆体系不能保证水泥环的密封完整性,不能满足勘探开发的要求。针对以上难点,优选了改性粉煤灰增强水泥石早期强度,复配高抗挤微珠提高水泥浆综合性能,优选高温弹塑性材料降低水泥石弹性模量,结合配套的固井外加剂,评价低密度弹塑性水泥浆体系。该水泥浆体系密度适用范围1.25~1.50 g/cm ³,API失水< 50 mL,流变性好,直角稠化,且水泥浆沉降稳定性好,并具有良好的力学性能,弹性模量可低至7 GPa,抗压强度>14 MPa,增强了水泥环在交变应力作用下的密封完整性。该体系在塔河油田中探1井和TP193井成功运用,整体固井质量良好,说明该体系可满足奥陶系易漏地层小间隙尾管的固井技术要求,应用前景良好。

In Ordovician of Tahe Oilfield, the bottom hole temperature is high, the seam hole is developed, the leakage easily occurs, and the annular clearance of cementing is small. Therefore, the conventional low density cement slurry system cannot guarantee the sealing integrity of cement sheath and meet the requirements of exploration and development. Aiming at the above difficulties, the modified fly ash is optimized to enhance the early strength of cement, the high anti-extrusion microsphere is compounded to improve the comprehensive performance of cement slurry, the high temperature elastoplastic material is optimized to reduce the elastic modulus of cement, and the low density elastoplastic cement slurry system is evaluated combined with the matching cementing additives. The density is applicable in the range of 1.25~1.50 g/cm ³, API water loss is less than 50 mL, the rheological properties is good, the right-angle is thickening, the cement slurry settlement stability is good, and the system has good mechanical properties. Meanwhile, the elastic modulus can be as low as 7 GPa and the compressive strength is greater than 14 MPa. All these things enhance the sealing integrity of cement sheath under the action of alternating stress. The applications of this system in well-Zhongtan-1 and well-TP193 of Tahe Oilfield are successful and the cementing quality are well, which indicate that the system can meet the cementing technical requirements of small clearance liner in the leaky formation of Ordovician and has a good application prospect.