As an alternative to cement, the feasibility of bismuth-tin (BiSn; contains 58 wt% Bi and 42 wt% Sn, abbreviations are not in stoichiometric ratio) as a low melting-point plug has been tested by Zhang et al. (2020) for rigless plug-and-abandonment (P&A) service of offshore wells. Similar to BiSn, bismuth-silver (BiAg; contains 97.5 wt% Bi and 2.5 wt% Ag, abbreviations are not in stoichiometric ratio) also exhibits desirable properties compared with Portland cement. However, because of its greater melting point, BiAg has potentially a wider application than BiSn, especially in deep formations. In the present study, we investigate the feasibility of BiAg alloy for P&A. The bond quality of the alloy-shale cores is evaluated through shear, tensile, push-out, and permeability tests, and compared with those of BiSn alloy-shale and cement-shale cores. To avoid phase change-induced shale damage at elevated temperature while setting BiAg plugs, water was first extracted with supercritical carbon dioxide (CO₂). For shear and tensile tests with pinhole-anchored BiAg, the ultimate strength and modulus were measured as a function of anchor points at different temperatures (21, 80, and 110°C). For the push-out tests, shale samples of smooth, rough, and pinholed surfaces were prepared with the BiAg alloy plug. In general, we find that, without anchors, bond failure precedes shale failure. Results for cement-shale cores are also reported for comparison. We contrast the performance of BiAg and BiSn alloys at 21, 65, 80, and 110°C to determine the crossover temperature for deployment suitability.

作为一种替代水泥的方法，Zhang等人还测试了铋锡（BiSn； Bi含量为58 wt％，Sn含量为42 wt％，缩写不是化学计量比）的可行性。（2020）进行海上钻井的无钻即插即用（P＆A）服务。与BiSn相似，铋-银（BiAg；包含97.5 wt％的Bi和2.5 wt％的Ag，缩写不是化学计量比）与波特兰水泥相比也显示出理想的性能。但是，由于其熔点较高，BiAg的应用范围可能比BiSn广泛，尤其是在深层地层中。在本研究中，我们调查了BiAg合金用于P＆A的可行性。通过剪切，拉伸，推出和渗透性测试来评估合金-页岩核的粘结质量，并与BiSn合金页岩芯和水泥页岩芯进行比较。为了避免在设置BiAg塞时在高温下因相变引起的页岩破坏，首先用超临界二氧化碳（CO₂）。对于使用针孔锚定的BiAg进行的剪切和拉伸测试，在不同温度（21、80和110°C）下，测量最终强度和模量与锚固点的关系。对于推出测试，使用BiAg合金塞制备了光滑，粗糙和针孔表面的页岩样品。通常，我们发现，在没有锚的情况下，粘结破坏先于页岩破坏。还报告了水泥页岩岩心的结果用于比较。我们对比了BiAg和BiSn合金在21、65、80和110°C时的性能，以确定用于部署适用性的交叉温度。