随钻扩眼过程中,领眼钻头与扩眼器前后相随,同步切除岩层.由钻柱施加的钻压为二者共同承担.若钻压分配不当,则易引起钻柱剧烈振动,机械钻速降低,钻具过早损坏等复杂状况.在设计和选配领眼钻头与扩眼器时即应着重考虑钻压分配关系.然而,常规设计方法仅依赖领眼钻头和扩眼器所切除岩层的截面积来确定分配关系,所得结果较为粗糙.故提出钻具锐度的概念以表征破岩工具的切削能力,其值由室内试验测定,值越大,表示工具切削岩层的能力越强；在锐度基础上发展了计算钻压分配关系的常规方法,并说明了锐度对钻压分配关系的影响规律.该结果对随钻扩眼钻具组合的设计和选型具有指导作用.%Reaming while drilling (RWD) technology is used to improve casing program,to enhance cementing quality for side tracking,and to assist in casing drilling as well as solid expandable tubular technology,thus has an extent application scope.The pilot bit and reamer are essential in the RWD process,in which they remove formation materials simultaneously.The weight applied by the drill string is undertaken by the reamer and bit.The ratio of weight distribution between them plays an important role in keeping reaming process stable.If the ratio is unreasonable,there would be sever lateral vibration of the drill string in RWD operation,inducing reduced ROP and even premature malfunction of the cutting tools.Actually,weight distribution should be considered before selecting or designing a proper reamer-bit assembly.However,conventional calculating method only focuses on the cross sectional area cut by the reamer and bit,and supplies a rough result.That is proposed the ability of the cutting tool to penetrate into the formation may influence weight distribution.A concept of cutting tool sharpness is proposed to represent cutting ability.Its value is defined by lab tests,and a largcr value indicates the ability of the tool cutting roch formations.Based on this concept,the conventional method is developed,and a more precise equation is worked out.Results therefrom may be used to guide designing and selecting reamer-bit assembly.
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