砂岩酸化过程中铁离子沉淀研究

随着油气勘探开发的进行,新发现的碳酸盐岩储层越来越复杂,如储层非均质性强,储层井段较长等。转向酸具有变黏转向、均匀布酸的优点,在此类储层酸化(压)改造中得到了广泛的应用。虽然实验室开展了转向性能、变黏过程和耐温性能等实验评价,但以往的评价结果并没有和现场施工紧密结合。通过转向范围评价出较宽和较窄的两类转向酸体系,并进行转向过程性能评价,压力差表现出1次峰值和3次峰值的两类特征;针对裂缝储层开展纤维转向剂转向性能评价,室内封堵压力差达到3.2MPa。依据实验结果探索了转向酸及纤维转向剂对储层及施工要求的适应性;利用初步建立的适应性选择方法,优选出适宜于Y5井的转向酸体系,在施工中表现出明显的快速变黏转向和多次转向的特征,改造后产量为施工前的3.95倍,油压为施工前的2.7倍。

Research of iron precipitation in sandstone acidizing

With the oil and gas exploration and development, the newly discovered carbonate reservoir is more and more complex, such as the strong heterogeneity, long interval, and compli- cated construction technological process. With the advantages of viscosity variation and acid dis- tribution uniformly, the self-diversion acid was applied in such reservoir. Although researchers carried out many experimental evaluations, such as diverting performance, viscosity variation process and temperature endurance etc, the study results have not been combined with the acid- fracturing operation on site. Through the experiment of diverting range, the acid is divided into two categories which are a wide system and a narrow system, and the diverting performance was also tested. The result of pressure differential demonstrated two types of characteristics： one peak and three peaks. The performance evaluation experiments using degradable fiber diverting agent were carried out for plugging the fracture reservoir, whose plugging pressure reached 3.2MPa. According to the research result, the adaptability of self-diversion acid and fiber diverting agent to the reservoir and operation requirements were obtained. Based on the initial obtained a- daptability, we selected the suitable self-diversion acid for Y5 well. During the acid-fracturing on site, the acid demonstrated rapid and repeated diverting trend. After the acid-fracturing, the well output was 3.95 times and the pressure is 2.7 times than before respectively.