天然气井套间气窜自修复技术

井口套间气窜即套间带压一直是困扰天然气井安全生产的技术难题，仅靠固井和修井技术难以从根本上解决问题。基于对天然气井套间气窜原因的分析和水泥基自修复理论，建立了气井井口环空气窜的两种自修复模式。采用在模拟套管的钢管中浸泡钻井液和使用冲击式造缝仪两种方法，来模拟固井水泥环损伤后形成的气窜通道（即微裂缝和微间隙），用GSN渗透结晶型自修复剂配制天然气井套间气窜自修复液，在XAN RC封堵模拟实验流程中进行了水泥环损伤自修复模拟试验。结果表明，GSN自修复剂能够自动渗入气窜通道，形成渗透结晶水化产物，密闭固井水泥环的微间隙和微裂缝，有较好的自修复效果，明显提高了损伤水泥环的抗气窜强度。该研究成果对实现气井井口环空气窜的动态即时自修复，保持水泥环封固的可靠性和耐久性，解决气井环空带压问题有重要的工程运用价值。

On self-healing technology for gas channeling in the cemented annulus

Gas breakthrough or gas channeling in a cemented wellbore annuli has long been a technical challenge threatening the safety of gas production activities. It is not to be radically solved merely by well cementing and workover techniques. Herein in this paper, we proposed two self healing models based on the analysis of causes of gas breakthrough and the cement base self healing theory for annular gas breakthrough at the well head. We simulated the gas channels (i.e., microcracks and microgaps) formed in a damaged cement sheath by injecting drilling fluid into the steel pipes as the casings and by using a fracture generating impact to generate cracks. Then we used GSN penetrative crystallization type self healing agent to prepare the gas breakthrough self healing fluid. Finally we performed cement sheath damage self healing experiment in the process of an XAN RC plugging simulation. As shown in the experiment, the GSN self healing fluid could automatically seep into the gas channels to form a penetrative crystallization type hydration product that sealed the microgaps and microcracks in the cement sheath. This self healing capability obviously helped improve the resistance of the cement sheath to gas breakthrough. The research findings are of significant engineering values to realizing the dynamic and prompt self healing for annular pressure buildup (APB) at gas well heads, maintaining the reliability and durability of cement sheaths, and solving APB problems as a result.