水泥环和混凝土对储气井的加强与固定作用

The reinforcement and cementation of cement sheath to gas storage well

通过建立储气井受力模型,对水泥环与井筒界面之间的界面压力进行计算,得到了储气井固井水泥环与井筒之间的摩擦力和储气井固井临界长度:理想固井状态下,对于φ177.8和φ244.48储气井,固井长度超过0.7m,则井筒不会脱离水泥环从地面窜出。在水泥环与地层不脱离的情况下,当地层土为粉细砂时,φ177.8和φ244.48储气井地面以下连续固井长度分别需要达到43m和60m。针对储气井上部腐蚀减薄和固井不合格的情况,分析了加固混凝土对储气井井筒的加强作用:若储气井井口段采取有效加固处理和充分的防腐措施,即使储气井壁厚的减薄量超过腐蚀裕量,正常工作压力下储气井井筒的实际应力也低于许用应力。

In this paper, the friction resistance between cementation process＇s cement sheath and well bore of gas storage well and the critical length of gas storage well cementation is obtained through establishing a stress model for gas storage well to calculate the pressure on the interface between cement sheath and well bore. In an ideal well cementing state, the well bore will not separate with cement sheath and run out from the ground if the well cementing length exceeds 0.7 m for gas storage well at Ф177.8 and Ф244.48. In the case of the cement sheath not separating from the formations, the continuous well cementing length for Ф177.8 and Ф244.48 gas storage wells should reach 43 m and 60 m respectively when the formation soil is fine sand. The reinforcement of reinforced concrete to the well bore of gas-storage well is analyzed according to the situation of well wall reduction due to corrosion and unqualified cementation. If efficient reinforcement treatments and sufficient anti-corrosion measures are taken for well head interval of gas-storage well, even if the reduction of wall thickness of gas storage well exceeds the corrosion allowance, the actual pressure of gas storage well bores under normal working pressure is also lower than the allowable stress. （1 Table, 2 Figures, 6 References）