渗透固结型环氧树脂基油气井常温固泥材料

Penetrating Consolidating Epoxy-Based Oil and Gas Well Cementing Additives for Use at Ambient Temperature

在油气井钻井过程中固井二界面胶结强度低是导致固井环气窜问题的重要原因。采用含可反应稀释剂的低黏度、高渗透性的环氧树脂(HP环氧树脂)与水泥浆共混,混合水泥浆中的环氧树脂在高压下可以渗透扩散至泥饼中,经固化后可明显改善水泥浆和泥饼之间的界面胶结强度。实验结果表明,HP环氧树脂自身固化具有较高的抗压性能,加入表面活性剂Tween-80可提高其与水泥浆的相容性,形成均一的体系,HP环氧改性水泥浆的各项性能指标符合工程需求。通过接触角、SEM等测试验证了环氧树脂通过“渗入-扩散-胶结”来增强界面黏接力的机理。结果表明,HP环氧树脂占比为5%的共混水泥浆,其1 d的抗压强度为24.3 MPa,用其进行泥饼胶结时,固化1 mm厚泥饼的胶结强度可达0.45 MPa,如果将HP环氧树脂的含量升至10%,胶结强度还能进一步提升至0.55 MPa。从微观形貌中可以看出,HP环氧树脂从水泥浆中渗透扩散至泥饼中,使得形成的泥饼界面更加致密,从而提高改性水泥浆-泥饼界面的胶结强度。

In oil and gas well drilling, the low bond strength between the cement sheath and the borehole wall(mud cakes) is an important factor causing gas channeling along the interfaces between the cement sheath and the borehole wall. In laboratory experiment, a low viscosity high penetrating capacity epoxy resin(HP epoxy resin) containing reactive thinner was mixed with a cement slurry. The epoxy resin in the mixed cement slurry can penetrate and diffuse into the mud cakes under high pressures. The epoxy resin, after becoming consolidated, greatly improved the bond strength between the cement sheath and the mud cakes. The experimental results have shown that the consolidated epoxy resin have high compressive strength and can be uniformly mixed with cement slurry with the aid of Tween-80, a surfactant. The properties of the cement slurry modified with the HP epoxy resin meet the requirements of field operations. By contact angle measurement and SEM analysis, it was found that the epoxy resin improved the bond strength between the cement sheath and the borehole wall through a “penetration-diffusion-bonding” process. A cement slurry containing 5% HP epoxy resin had 1 d compressive strength of 24.3 MPa. When this cement slurry was bonded with mud cakes, the bond strength of the solidified mud cake of 1 mm in thickness can be as high as 0.45 MPa. When the content of the HP epoxy resin in the cement slurry was increased to 10%, the bond strength was raised to 0.55 MPa accordingly. From the micromorphology of the consolidated mud cakes it was found that the HP epoxy resin penetrated and diffused into the mud cakes from the cement slurry, making the surface of the mud cakes denser, hence improving the bond strength of the interfaces between the modified cement slurry and the mud cakes.