堵漏和废弃（P&A）是石油天然气行业油井退役流程的一部分。一旦油井不再用于生产或被认为不经济，就会对井筒进行堵塞和密封，以阻止进一步泄漏。P&A 可以防止甲烷等温室气体和其他有害原油产品泄漏到环境中，保护生态系统和近海海洋生物。
Traditionally, cement has been the primary material used for plugging and sealing wellbores. However, cement is not completely impermeable and will deteriorate over time due to factors such as temperature fluctuations, chemical reactions, and mechanical stresses. Unfortunately, several instances of cement plugs leaking and releasing harmful substances into the environment have been reported. To ensure the long-term integrity and stability of these abandoned wells, bismuth alloys have recently emerged as groundbreaking plugging material.
为什么使用铋合金？
凝固时膨胀：铋合金可在凝固时轻微膨胀 3-6%，这不同于一般水泥的收缩和随之而来的圆周裂缝。这就确保了与井筒套管以及套管外环形空间内的紧密机械结合，提高了密封效果。
Melting point: The melting point of bismuth-based alloys for different compositions can range from 124 °C to 330 °C. This characteristic allows more efficient and controlled deployment of the alloy without affecting the wellbore-casing, and also temporary plugging and maintenance. The choice of a specific alloy with an appropriate melting point can be based on the wellbore temperature, casing material, and the heating technology employed.
Composition variability: Bismuth alloys offer flexibility in terms of composition. By adjusting the percentage of individual metals, such as tin, silver, antimony, and indium, different variations of bismuth alloys can be created. This allows the customization of physical, mechanical, and chemical properties of the alloys to suit varying wellbore characteristics.
渗透性：铋合金的体积渗透率为零，可确保整个体积完全密封。
Long-term durability: Bismuth alloys exhibit resistance to corrosion, brine, CO2, and crude oil, and maintain structural integrity at high temperatures. These properties ensure the longevity and effectiveness of the plugging material.
High density and low viscosity: The combination of high density and low viscosity allows the melted alloy to penetrate narrow and hard-to-reach areas of the wellbore without the need for a pump. Voids, irregularities, and fractures within the wellbore are filled more effectively with melted alloy than with cement.
无毒： 铋合金与水泥不同，无毒且环保，水泥中的添加剂和化学物质会造成土壤和地下水污染。
Economical: The cost of well-decommissioning ranges from $100,000 per well onshore to $1-10M per well offshore. Cementing and rig costs alone account for more than 25% of the total decommissioning cost for offshore wells. The higher cost of alloy to cement is overshadowed by the elimination of cementing and rig cost.
此外，铋基合金的低热膨胀性、改善的热疲劳、高机械强度、耐压等级和抗蠕变性使其成为近年来最受欢迎的潜在气井封堵和废弃材料。石油和天然气公司的领导者们对其开发的资助表明，它对未来的堵漏和弃井工艺至关重要。
Indium Corporation has carried out a huge amount of in-house research on fusible alloys. We have the ability and expertise to fine-tune the characteristic of bismuth-based alloys as per customer and industry needs. If you are interested in working with the application of bismuth-based alloys in P&A and any other industry, please share with us your needs, and problems if you are facing any. Let’s plug the wells together.
