水泥浆凝结过程的气窜问题

BREAKTHROUGH DURING CEMENT SLURRY COAGULATION

水泥浆在凝结过程，因失重而造成的油、气、水窜问题是影响固井质量的重要因素之一。针对深井，温度高、压力大，油、气、水活跃的特点，从机理研究和现场应用相结合的方法入手，对水泥浆失重、气侵压力的测定，影响因素，防气窜机理和防气窜方法，进行了深入的研究，提出了采用水泥浆阻力变化值、稳定性、失水量以及保证水泥浆凝固过程的压力平衡关系等措施，从而达到防止油、气、水窜的目的。防窜试验表明，研究的６种水泥浆配方，都具有较好的防气窜效果，分别适宜于不同压力梯度井深的要求，其中３Ｓ水泥浆防气窜能力最好。

Gas, oil or water breakthrough caused by weightlessness during cement slurry coagulation is one of the most important factors, which influences cementing quality. In connection with characteristics of high temperature, high pressure and active oil gas and water in deep well, and combining mechanism study and field application, the factors affecting cement slurry weightlessness and gas breakthrough, and the mechanism and method of preventing gas breakthrough is studied, and presents the measures of monitoring cement slurry's resistance, stability, and water loss, and assuring the pressure balance in the procedure of cement slurry coagulation is presented, so as to reach the goal of preventing oil, gas and water breakthrough. Tests shows that six types of cement slurry compounding are capable of preventing gas breakthrough, and are separately suitably for hole depth of various pressure gradients, of which 3-S slurry is of the best capability for preventing gas breakthrough.