Production and recovery chemistry for low-level hydrogen sulfide containing natural gas

低水平含H_2S天然气的生产与回收化学品 加拿大拥有丰富的页岩气储量，横跨7个省。已知至少有两个加拿大页岩区带是酸性的，并且可能含有高达500 ppm的H2S。在运输到市场之前，出于毒性/环境原因，H2S必须减少到小于4ppm，并且CO2减少到小于2%以保持热量含量。H2S含量低于2%的采出液不适用于H2S的常规氧化以回收商业元素硫;因此，加拿大生产商需要替代化学工艺来实现4 ppm的目标。整体研究的重点是通过了解这些低水平的H2S来源和探索替代氧化工艺来满足这一需求。具体的研究目标是：（一）扩大热页岩储层酸化的动力学模型，（二）评价在密相二氧化碳高压催化，和（三）探索工业硫化学联苯和二苯醚的低共熔混合物。 (i)热页岩储层酸化的动力学模拟 我们先前已经证明，非微生物储层酸化可以通过压裂液添加剂（例如，十二烷基硫酸钠）。我们最近的工作主要集中在天然硫化物（H2S或金属硫化物）的快速氧化，以在有限的时间内在储层中产生元素硫。然后，这种元素硫可以氧化其他烃或液压流体添加剂，以热生成H2S。研究将继续在这一领域的重点是凝胶压裂添加剂（与滑溜水添加剂）。这项研究将帮助生产商确定何时H2S将出现在流体中，以及在油井的寿命期间预计会有多少。 (ii)密相CO2高压催化 管理低水平H2S生产的来源是困难的，因为（a）低水平H2S生产不能支持常规克劳斯热反应器中的火焰和（B）替代的低水平选项很少产生商业质量的硫。H2S在压力下的催化直接氧化可以在不需要昂贵的纯CO2再压缩的情况下完成，并提供两种增值产品，即CO2和S8。高压多相催化研究正在被应用于确定这样一个过程的操作条件。 (iii)联苯和二苯醚的低共熔混合物中的硫化学（Dowtherm® A） 烃溶剂如PEG用于一些硫回收工艺;然而，由于与元素硫反应，不能使用更高的温度。对于替代溶剂，我们正在探索在Dowtherm® A中进行常见的工业硫化学反应。 这三个研究领域的进展有助于新兴低碳能源的安全和可持续发展。

PRODUCTION AND RECOVERY CHEMISTRY FOR LOW-LEVEL H2S CONTAINING NATURAL GAS Canada has significant shale gas reserves which span 7 provinces. At least two Canadian shale plays are known to be sour and can contain up to 500 ppm H2S. Before transportation to market the H2S must be reduced to less than 4 ppm for toxicity/environmental reasons and CO2 is reduced to less than 2% to maintain caloric content. Production fluids with less than 2% H2S are not suitable for conventional oxidation of H2S to recover commercial elemental sulfur; therefore, alternative chemical processes are required by Canadian producers to achieve the 4 ppm target. The overall research is focused on addressing this need by understanding these low-level H2S sources and exploring alternative oxidation processes. Specific research goals are aimed at (i) expanding kinetic models for souring of hot shale reservoirs, (ii) evaluating high-pressure catalysis in dense phase CO2, and (iii) exploring industrial sulfur chemistry in a eutectic mixture of biphenyl and diphenyl ether. (i) Kinetic modelling for souring of hot shale reservoirs We have previously demonstrated that non-microbial reservoir souring can occur through the degradation of fracture fluid additives (e.g., sodium dodecylsulfate). Our more recent work has focused on the rapid oxidation of native sulfides (H2S or metal sulfides) to produce elemental sulfur in the reservoir over a finite time. This elemental sulfur can then oxidize other hydrocarbons or hydraulic fluid additives to thermally generate H2S. Studies will continue in this area by focussing on gel fracture additives (versus slick water additives). This research will help producers identify when H2S will appear in the fluids and how much can be expected over the lifetime of a well. (ii) High-pressure catalysis in dense phase CO2 Managing sources of low-level H2S production is difficult, because (a) low H2S production cannot support a flame in the conventional Claus thermal reactor and (b) the alternative low-level options rarely produce commercial quality sulfur. The catalytic direct oxidation of H2S at pressure can be completed without costly recompression of pure CO2 and provide two value-added products; namely CO2 and S8. High-pressure heterogeneous catalysis research is being applied to define the operating conditions for such a process. (iii) Sulfur chemistry in a eutectic mixture of biphenyl and diphenyl ether (Dowtherm® A) Hydrocarbon solvents such as PEG are used in some sulfur recovery processes; however, higher temperatures cannot be used due to reaction with elemental sulfur. For an alternative solvent, we are exploring carrying out common industrial sulfur chemistries within Dowtherm® A. Progress in all three of these research areas help with the safe and sustainable development of emerging low-carbon energy sources.