Shi Jiangang，Li Gensheng，Liu Weiji，etal.Numerical simulation oncuttingand breaking of heterogeneous conglomerate by special-shaped PDC cutter[J].China Petroleum Machinery，2O25，53（6）：44-51.

Numerical Simulation on Cutting and Breaking of Heterogeneous Conglomerate by Special-Shaped PDC Cutter

Shi Jiangang1.²LiGensheng1Liu Weiji3.4Wu Desheng²Zhang Nan²Deng Kaichuang³ （1.CollegeofPetroleumEngineering，China UniversityofPetroeum（Beijing）；2.PetroChinaXinjiangOilfieldCompany;3.Sch -oolofMecanicalEngineingouhuestPetroleUiesity；4KeyLbortoryofOilamp;GsEquipment，inistryoEdutio

Abstract：When the PDC bit is used to drillconglomerate formations，the frequent impact loads reduce the expected lifeofPDC cutter，leading to frequent bit changes and ultimately affecting drilling effciency.Specialshaped cutter can change the impact situation on the cuter surface，so choosing an impact-resistant cutter surface is one of the effective methods to deal with such formations.To studythe performance ofPDC cuter with diffrent structures in cuting conglomerate，the conglomerate cores taken from deep formation of the Junggar Basin were selected for analysis.Based on a finite element model of heterogeneous conglomerate，the parameters of the conglomerate model were calibrated through uniaxial compresson test，and rock cutting and breaking simulation of special-shaped cutter was carried out.Moreover，the cutting efects of 12 types of PDC cutters were discussed under the same rake angle and cuttng depth，andthe cuting forcefluctuation and rock-breaking specific energy of them werecompared.The study results show that although theaverage cutting forces of axe-shaped cutter and three-plane cutter are relatively large，the overallfluctuations are more stable.The cuting force fluctuations of planar cuter，concave cuter，convex cutter and hyperboloidal cutter are relatively large，and the cutter surfaces are subjected to significant impact.The rock-breaking specific energy determines therock breaking eficiency of thecuter，by means of comparing the values，the rock-breaking specific energy of hyperboloidal cutter is the smallest，while thatof wedge-shaped cuttr is thelargest.Withoutconsidering therigidityof PDCcuttr，by means of comparing cuting force fluctuation and rock-breaking specific energy，the axe-shaped cutter and threeplane cutter are the beter choices among alltypes of PDC cutters.The study results provide some reference for the cutter shape selection of PDC bit when drilling conglomerate formations.

Keywords： heterogeneous conglomerate; specical-shaped PDC cuter;rock cutting and breaking simulation finite element； cutting force；rock-breaking specific energy

0 引言

砂砾岩油气藏是我国非常规油气资源开采领域的重要目标[1-2]，尤其在准噶尔盆地玛湖油田，其储量更是超过12亿t[3]，具有极高的开发潜力。但是由于储层沉积和成岩的作用程度不同，岩相类型复杂，导致砂砾岩储层的非均质性很强，在钻井过程中易造成钻头失效快、钻进速度低等问题[4]。

PDC钻头耐磨性强、受载稳定，是当前钻进砾岩地层的主要钻头种类[。砾岩的砾石含量、粒径和分选情况，以及基质胶结程度均会影响PDC钻头受到的冲击载荷大小，而较大的冲击载荷易导致PDC齿产生磨损、断裂和崩齿等失效现象[6-7]。研究表明，将平面PDC齿改为非平面齿（即异形PDC齿）可以改变钻齿在受到局部冲击时的影响，诸如使用斧形齿、三平面齿等异形齿可以增强钻齿的抗冲击能力[8-9]。这类齿具有脊形结构，其通过点载荷和拉剪作用的方式破坏前方岩石，减轻切削齿受到的冲击[10]。为了揭示在切削过程中PDC齿和砾岩的相互作用关系，众多学者开展了关于单齿切削砾岩的试验和仿真。程书婷等[]、徐卫强等[1]通过室内切削试验研究平面齿、锥形齿、斧形齿在切削砾岩时的表现，指出平面齿的切削力波动范围最大，而斧形齿可以有效降低切削力的波动程度。对于单齿切削破岩仿真的探究，主要采用有限元方法和离散元方法。有限元方法以讨论齿和岩石的相互作用机理为主，刘伟吉等[8通过单齿切削破岩仿真模拟讨论了多种个性化PDC齿的切削效果，并根据破岩比功指标讨论齿的破岩效率；……