磨料水射流破岩射孔孔道形成机制

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中图分类号：O347;TE248 国标学科代码：13015;440.54 文献标志码：A

On formation mechanism of perforation channel during rock breaking by abrasive water jet

XU Peng， SHENG Mao， TIAN Kejun， TIAN Shouceng， HUANG Zhongwei， LI Gensheng （State Key Laboratory of Petroleum Resources and Engineering， China University of Petroleum （Beijing），Beijing 102249，China）

Abstract：Abrasivewater jet（AWJ）perforationisanefectivemeanforstimulation inoilandgaswels.However，the mechanism ofperforation formationand theregulationof its parameterremain poorlyunderstood.This study investigates the variation in holeshape duringAWJ perforation through aseries of experimental designs and analyses.Byanalyzing the variationinperforationshapewith injectiontime，therock-breakingdamagecausedbyAWJandtheflowcharacteristicsinthe perforation were quantitativelycharacterized.The results showthatthe process of perforation formation is govemed bythe couplingofthree physicaleffects.Theinflowincreasestheholedepthbyverticallyimpactingtheholetip，whilethebackflow enlarges thehole diameter by eroding the hole wall As the fluid mechanical energy disipates along the path，theevolution of theperforationslows downduring thelaterperforationperiod.Because therock breakingabilityofinflow is strongerthanthat ofbackflow，theratio of hole depth to hole diameterofAWJ perforation increases with the increase of injection time. Specifically，when the injection time ranges from 5s to 300s ，theratio increases from7to 28.The rock breakingability of the backflowdecreases fromthe tiptotheorifice，whereas the durationof the backflow’saction on the hole wall increases inthe samedirection.Underthecombined influenceofrock breaking abilityandrock breaking time，the holeevolves fromaconical shape to a spindle shape，and the degreeof spindle increases.Withthe increaseof injection time andhole depth，the fluid mechanical energy loss becomes more severe. The change rate of hole depth decreased to 11.3% and the change rate of hole diameter decreased to 4.3% .The evolution of the AWJ perforation became slow.

Keywords： abrasive water jet; rock breaking; perforation; fluid-structure interaction

磨料水射流射孔在油气完井增产领域应用效果显著，其原理是工作液携带一定浓度的磨料颗粒，经喷嘴加速后冲击穿透井壁、破碎储层岩石，形成具有一定深度和形状的孔道[1-2]。（剩余17984字）