控压固井候凝阶段井口回压控制方法研究与应用

Research and application of wellhead back pressure control method during the waiting stage of managed pressure cementing

控压固井可以降低窄安全压力窗口井固井漏失的风险,同时还能在一定程度上提高顶替效率。但是目前控压固井在候凝期间还是基于经验来施加井口回压,井口回压控制不够精确,容易导致井漏或气窜。为此,根据水泥水化、失水以及胶凝作用建立了井口回压计算模型,并形成了候凝压力控制方法,用于指导井口回压控制。通过与目前的控制方法相比表明该方法能够精确指导井口回压控制,保证井筒安全。

Pressure controlled cementing can reduce the risk of cementing leakage in narrow safety pressure windows,while also improving displacement efficiency to a certain extent.However,at present,during the waiting period of pressure control cementing,the application of wellhead back pressure is still based on experience,and the control of wellhead back pressure is not precise enough,which can easily lead to well leakage or gas channeling.To this end,a wellhead back pressure calculation model was established based on cement hydration,water loss and cementation,and a waiting pressure control method was developed to guide wellhead back pressure control.Compared with current control methods,it is shown that this method can accurately guide wellhead back pressure control and ensure wellbore safety.