碳酸盐岩储层完井铝基耐酸易钻油管性能评价

Performance Evaluation of Aluminum-Based Acid-Resistant and Easy-Drilling Tubing for Carbonate Reservoir Completion

在碳酸盐岩储层采用钢质支撑油管完井,可以解决井壁坍塌问题,但是带来钻磨时间长、费用高的难题。铝合金的强度、硬度较钢低,是最有潜力的易钻油管材料。但是,铝合金在盐酸溶液中会剧烈反应,不适用于酸化工况。设计了在6061T6铝合金管内、外表面涂覆耐酸涂层的铝基耐酸易钻油管。基于标准拉伸试样实测的6061T6铝合金强度值,借鉴ISO/TR 10400—2018中钢质油管强度计算方法,结合内压强度、外挤强度试验,建立并验证了铝基耐酸易钻油管的强度与厚度的数学模型。该模型计算的6061T6铝合金油管的内压强度、外挤强度与实测结果的误差分别为8.6%、0.2%。采用失重法及交流阻抗法评价6061T6铝合金油管的耐酸性能,结果表明,在100℃、质量分数20%的盐酸溶液中浸泡12 h,该油管内、外表面涂层无开裂、无破损、无脱落,因吸水使质量略微增加,增加速率为0.008%/h。采用钻磨试验对比测试了6061T6铝合金油管、P110钢质油管的钻磨性能,结果表明,在钻压为10 kN、转速为300 r/min时,6061T6铝合金油管的钻削速度是P110油管钻磨速度的3.5倍。

Completion with steel supporting tubing can effectively solve the problem of the easy collapse of unsupported tubing completion in carbonate reservoirs,but at the same time,it brings the problems of long drilling and grinding cycles and high drilling and grinding costs.Aluminum alloys are the most promising alternative to steel tubing materials because of their low strength and hardness but it is not suitable for acidification condition because aluminum will react violently in hydrochloric acid solution.An acid-resistant easy-drilling oil pipe coated with a self-developed acid-resistant coating on the inner and outer surfaces of the 6061T6 aluminum alloy pipe was designed.The mathematical model of strength and wall thickness of aluminum alloy tubing is established based on the strength value of aluminum alloy obtained from the measured aluminum alloy standard tensile specimen and the ISO/TR 10400:2018 and verified by the internal pressure strength and external extrusion strength experiments.The results show that the errors of theoretical calculation results and actual measurement results of internal pressure strength and external extrusion strength of 6061T6 tubing are 8.6%and 0.2%respectively.The acid resistance of the 6061T6 tubing was evaluated by the weightlessness method and the AC impedance method,and the results show that after immersing in a 20%hydrochloric acid solution at 100℃for 12 h,the inner and outer surface coatings of the tubing have no cracking,damage,or shedding.The quality of the tubing is slightly increased due to water absorption at a rate of 0.008%/h.The results of grinding experiments of 6061T6 tubing and P110 steel tubing show that the drilling speed of 6061T6 tubing was 3.5 times that of P110 tubing when the weight on the bit is 10 kN at speed of 300 r/min.