中心分区式PDC钻头流场数值模拟

为证实φ215.9 mm中心分区式PDC钻头具有更好的冷却和携岩性能,根据钻头底部轮廓包络面建立了φ215.9 mm中心分区式与常规PDC钻头刀翼流道流场模型,对模型大压力梯度区域运用非均匀结构网格技术进行了局部细化,模拟了两种水力结构对井底流场及各流道内流量的影响。结果表明,中心分区水力结构形成的弱连通区域,使各流场区域的流量分配更加合理,并可缓解流体对钻头冠部的冲蚀,有利于流体及时冷却切削齿,减小钻头热磨损可能性,提高携岩能力和降低原生泥包发生概率。PDC钻头采用中心分区水力结构不会增加钻头布齿及刀翼等结构设计和加工制造的难度,并能提高水力效率,推荐在适用PDC钻头地层的中深井段常规钻井和复合钻井中使用。

Numerical Simulation of Flow Field of Center Partition-Type PDC Bit

In order to proveφ215.9 mm center partition-type PDC bit's cooling and cuttings carrying performance,the blades channel model forφ215.9 mm center partition-type and conventional PDC bit was developed according to bit envelope profile.The region with high pressure gradient was refined by local grids and non-uniform structure meshing.The impacts of two bit hydraulic types on bottom hole flow field were simulated.The results showed that the center partition-type bit formed a weak hydraulic connected region,so that the flow distribution was more rational which can ease the erosion of the bit profile,help cutter teeth cooling,reduce thermal wear,increase carrying capacity and reduce the risk of native rock balling. PDC bits with central partition structure will not increase the difficulties of bit design and manufacturing, while it can improve water efficiency.It was recommended in the application of PDC bits in mid-deep well drilling and comblined drilling.