低渗灰岩水井常规酸酸化增产工作液的实验研究

利用有机酸缓速、低腐蚀的优点,与盐酸配合形成主酸,结合缓蚀剂等添加剂形成了一套适合于低渗灰岩水井的常规酸酸化工作液体系。通过对秭归县宝塔组灰岩的物化性能分析、静态溶蚀率、岩心酸化流动和静态腐蚀等实验,对该工作液体系进行了综合评价。结果表明:盐酸对岩粉0. 5、1. 0和1. 5 h的平均溶蚀率为95. 1%,乙酸对岩粉1. 5、3. 0和4. 5 h的平均溶蚀率为83. 5%,"8%盐酸+6%乙酸"在4. 5 h后对岩粉的溶蚀率为97. 0%;经"8%盐酸+6%乙酸"酸化后,宝塔组灰岩的岩心渗透率增加了270～1300倍;当酸液注入速度为1 m L/min时,酸液突破体积最小,为343. 6 PV(孔隙体积倍数);咪唑啉类缓蚀剂可同时作为缓速剂和缓蚀剂使用,能减缓酸液与灰岩的反应速度,并减少对钻具的腐蚀。该工作液体系可有效增大灰岩含水层的渗透率,从而提高水井产量,有助于解决部分缺水地区的民生地质问题。

Experimental study on stimulation fluids by regular acidification in low permeable limestone wells

The organic acid has the advantages of slow speed and low corrosion, and it forms a main acid in combination with HCl (hydrochloric acid). The main acid combines with additives such as corrosion inhibitors to form a working fluid system with conventional acids suitable for low permeable limestone water wells. Through the physical and chemical analysis, static dissolution rate, core flooding and static corrosion experiments of the Zigui Baota formation limestone, the working fluid system was comprehensively evaluated. The results showed that the average dissolution rate of HCl on rock powder after 0.5 h, 1 h and 1.5 h was 95.1%, and that of HAC (acetic acid) on rock powder after 1.5 h, 3 h and 4.5 h was 83.5%. The dissolution rate of "8% HCl +6% HAC" after 4.5 h was 97.0%. The core flooding experiment of "8% HCl +6% HAC" on Baota formation limestone core showed that the permeability of the rock sample increased 270-1300 times after acidizing. The minimum breakthrough volume of the acid solution was 343.6 pore volume(PV) when the acid injection rate is 1 mL/min. The imidazoline corrosion inhibitor can be used as both retarder and corrosion inhibitor, which can retard the reaction of acid with limestone and reduce corrosion on the drill. The acid fluid system can effectively increase the permeability of the limestone aquifer thereby increasing the well production and helping to solve the geological problems of the livelihood in some water-deficient areas.