Retarded acid systems for high-pressure and high-temperature (HPHT) carbonate reservoirs are the key to provide a deep acid penetration and higher acid efficiency. The current study experimentally evaluates a new retarded HCl acid for HPHT carbonate acidizing applications. The acid retardation mechanism is attained by using a polymeric resin-based composition that restricts the proton mobility of the acid species. Ten Indiana limestone cores were used with the dimensions of 6 in (0.15 m) length and 1.5 in (0.038 m) diameter and average permeability of 9 mD (0.009 ). Two sets of experiments were conducted, one at 250°F (394 K) and another at 300°F (422 K), with acid injection rates from 0.5–10 cm³/min (8.3E−9 to 1.67E−7 m³/s). The pore volume of acid required to breakthrough (PVBT) was monitored. Effluent samples were collected to track the pH and the dissolved material. Computed tomography (CT) was used to scan the core before and after the experiment to determine the wormhole propagation along with the core. The optimum injection rate at 250 and 300°F (394 and 422 K) were found to be 2.5 and 6 cm³/min (1.67E−8 and 1.25E−7 m³/s) with PVBT of 0.41 and 0.43 PV, respectively. The 3D CT scan showed an effective wormhole profile featuring a single dominant trajectory with few branches. These results are confirmed by calcium ion concentration profiles through inductively coupled plasma (ICP) analysis. The use of the new acid system will provide deep penetration with low injected acid volume. As a result, the stimulation job efficiency will improve.

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用于 HPHT 碳酸盐酸化应用的新型延迟 HCl 酸系统：实验研究

用于高压和高温 (HPHT) 碳酸盐储层的缓酸系统是提供深度酸渗透和更高酸效率的关键。目前的研究通过实验评估了一种用于 HPHT 碳酸盐酸化应用的新型延迟 HCl 酸。通过使用限制酸物质的质子迁移率的基于聚合物树脂的组合物来实现酸延迟机制。使用了 10 个印第安纳石灰岩岩心，尺寸为 6 in (0.15 m) 长度和 1.5 in (0.038 m) 直径，平均渗透率为 9 mD (0.009  )。进行了两组实验，一组在 250°F (394 K)，另一组在 300°F (422 K)，酸注入速率为 0.5–10 cm ³ /min（8.3E-9 至 1.67E-7 m ³/s)。监测穿透所需酸的孔体积 (PVBT)。收集流出物样品以跟踪 pH 值和溶解物质。计算机断层扫描 (CT) 用于在实验前后扫描岩心，以确定虫洞随岩心的传播。发现 250 和 300°F（394 和 422 K）时的最佳注入速率为 2.5 和 6 cm ³ /min（1.67E-8 和 1.25E-7 m ³/s），PVBT 分别为 0.41 和 0.43 PV。3D CT 扫描显示有效的虫洞轮廓，具有单一的主要轨迹，分支很少。通过电感耦合等离子体 (ICP) 分析，钙离子浓度分布证实了这些结果。新酸系统的使用将以低注入酸量提供深度渗透。结果，刺激工作效率将提高。