深井塑性水泥浆体系研究

在深井的固井过程中经帮会面临大段盐膏层固井问题。深井本身具有井深、温度高、水泥环薄的特点，再加上地层盐水的侵入而使水泥浆性能发生变化，加大了固井难度；而且一般水泥石本身具有硬和脆的性质，易受后续施工、射孔或地下复杂作用力的影响而发生脆裂，或与套管、井壁剥离。采用以改性纤维为主要材料的早强增塑剂QA研究出了深井抗盐塑性水泥浆体系。对塑性水泥浆的惜规性能和抗盐、抗温能力及密度可调性进行了试验分析研究。试验结果表明，加入QA的水泥浆的惜规性能指标与不加QA的水泥浆接近，但水泥石抗裂程度明显提高，抗压强度增加25％～30％，7d的抗冲击韧性提高16．6％～22．3％，抗折强度提高18％～21％，弹性模量降低约17％；而且水泥浆抗盐性能优良，使用温度和密度范围宽，与各类外加剂配伍性好，流变性好，直角稠化，强度发展快，粘接强度高，有利于复杂地层的固井施工；工艺简单，操作方便，适宜现场推广运用。

Plastic cement slurry in deep wells

The thick salt and gyps layers are frequently encountered during cementing in deep or ultra deep wells, and the characteristics of deep hole, high temperature, and thick cement loop exist in the wells. In addition, cement slurry performances can be changed by the invasion of formation brine. All these lead to difficulty of cementing. Furthermore, owing to conventional cement stone has the properties of rigidity and fragility, it is frequently embrittlement cracking or peeling off from the casing or well wall -caused by the influence of the next working, shooting and complex formation force. Thus, salt resistance plastic cement slurry has been developed by the study on the early strength plasticizer QA which using modified fiber as the main material. The general performances such as salt resistance, thermostability and density adjustability of the slurry have been tested and the results showed that with the adding of QA, the general performances of the slurry were close to that of the conventional cement slurry, and the rupture strength, compressive strength, toughness (in seven days) and breaking strength of the cement stone have increased by 25%-30%, 16. 6%-22. 3% and 18%-21%, respectively. Meanwhile, the elastic modulus has reduced by about 17%; the salt resistance property of the slurry is excellent and the using ranges in temperatures and densities are wide. Therefore, with properties of good compatibility, good rheology, right angle thickening, strong strength and cementation, the slurry is useful for cementing in complex formation wells and it is convenient to operated in field.