磨料射流旋转切割套管试验及工程计算模型

Experiment and mathematical model of rotary cutting of casing with abrasive water jet

针对海洋废弃井口切除的工程需求,在淹没条件下进行射流压力、喷嘴直径、喷嘴个数、切割头转速、切割持续时间、喷距、磨料质量分数、磨料种类等因素对切割影响规律的试验研究,并建立淹没条件下套管切深与时间关系的工程计算模型。结果表明:高射流压力、大直径喷嘴、较多的喷嘴个数、长作业时间、小喷距时切割深度较大;切割头最优转速为7.8r/min;磨料质量分数在26.1%时切割效率最高;铁砂的切割效果最好;工程计算模型可为套管切割深度的预测和套管切断时机的判断提供理论依据。

According to the engineering requirement of cutting abandoned sub sea wellhead,cutting experiments were done in submerged condition,and the influences of various factors including water jet pressure,nozzle diameter,number of nozzles,rotation speed of cutting head,duration of cutting,standoff distance,mass fraction of abrasive,abrasive category on cutting effect were analyzed.And a mathematical model of relationship between the cutting depth of casing and time in submerged condition was established.The results indicate that the cutting depth is bigger in the conditions of high jet pressure,major diameter nozzle,more nozzles,long working time and small standoff distance.The optimum rotation speed of cutting head is 7.8 r/min.The cutting efficiency is the highest when the mass fraction of abrasive is 26.1%,and the cutting efficiency of iron sand is the best.The mathematical model provides theoretical basis for predicting cutting depth of casing and confirmation of whether the cutting job of casing was completed or not.