庆深气田水平钻井水基泥浆中套管磨损机理实验研究

水平井钻井过程中,钻杆与技术套管的接触力较大,套管磨损比较严重,套管强度降低较多,给后续试油及完井投产作业留下隐患。为了深入了解水平井水基泥浆中钻杆-套管的磨损机理,为准确评价庆深气田套管磨损程度及剩余强度提供依据,在西安石油大学创新研制的环块式钻杆-套管磨损实验机上,模拟实际钻进参数,进行了该气田常用的水基泥浆中钻杆-套管磨损实验,考察了接触压力、转盘转速、磨损时间等因素对套管磨损效率的影响。利用试件磨损表面扫描电镜(SEM)图片进行了形貌分析,确定了水基泥浆中套管的磨损机理。实验结果表明:水基泥浆中,套管的磨损类型兼有粘着磨损、疲劳磨损和犁沟磨损等。黏着磨损是最主要的类型,采用基于黏着磨损机理的White磨损效率模型预测井下套管的磨损是可信的。水基泥浆中P110套管的磨损效率在(2~8)×10-131/Pa之间,稍大于钻井手册中的套管磨损效率(2×10-131/Pa);磨损效率随接触压力和转速的增加而增加,前期增长速率小,后期增长速率大;磨损效率随磨损时间的增加先增加,后逐渐减少,最后趋于稳定。

Experiment on the Abrasive Mechanism of Drill Pipe and Casing in Water-based Mud in Horizontal Well of Qingshen Gas Field

Because of the large contact force between drill pipe and technical casing in horizontal well, the casing may be worn seriously, and the intensity of it will be decreased correspondingly, which may be a security threat for well testing and well completion. To make known the abrasion mechanism of drill pipe and casing, and then provide reference for the degree of wear and remaining strength, by the using of the ring block wear tester, the abrasive experiment of drill pipe and casing in water-based mud was done with the parameters same as that in actual drilling process. The relationship between the abrasive efficiency and the contact stress, abrasion time, rotary speed were analyzed. Then, to determine the abrasive mechanism of casing, the abrasive morphologies of casing were analyzed by the scanning electron microscopy (SEM). We can find from the experiment that among adhesive wear, fatigue wear and abrasive wear, adhesive wear is the main abrasive type between the drill pipe and casing in the water-base mud. It is creditable to predict the abrasive mechanism of downhole casing using the White wearing efficiency model. The abrasive efficiency of P110 casing in water base mud is 2 to 8×10-13 1/Pa, which is slightly larger than that in drilling manual (2x10-13 1/Pa). The abrasive efficiency increased with the increment of contact pressure as well as the rotate speed between drill pipe and casing. The increasing rate is small first, and then it becomes larger. But, it firstly increases, then decreases, and finally tends to be stable with the increase of time.