南堡油田玄武岩个性化高效钻头的设计与应用

Design of high-efficiency PDC bit and its application to basalt drilling in Nanpu Oilfield

南堡油田馆陶底埋藏着垂直厚度十几米至几百米不等的玄武岩,其可钻性极差,长期以来只能使用牙轮钻头,钻井速度慢,制约了南堡油田优快钻井。利用实钻岩心和测井资料对玄武岩可钻性和抗压强度等进行了分析,结果表明玄武岩可钻性级别为5-7级,抗压强度为91-221MPa,压入硬度为435-1 322MPa,属于中到中硬地层。设计中优选应用了Z3、AC型切削齿,采用6刀翼和浅内锥、加长外锥冠部形状,中高密度布齿设计,利用计算流体动力学技术对钻头水力结构进行优化,采用螺旋保径结构,设计研制出了FM2653Z、FMH3653ZZ和M1666SS3种高效PDC钻头。现场应用表明：单只钻头钻穿300-500m玄武岩;与牙轮钻头相比,机械钻速和钻井进尺提高了1.7-3.3倍;解决了南堡油田火成岩钻速慢的问题。

There are basalt layers with the thickness from tens to hundreds meters at the bottom of Guantao Formation in Nanpu Oilfield,so the drillability of those layers was bad.Only cone bit could be used in those layers,and the drilling speed was very low.The core samples and well log information were used to analyze the drillability and compressive strength of the basalt.The results demonstrate that the drillability level of the basalt in Nanpu Oilfield is from 5 to 7,and the compressive strength is from 91 to 221 MPa, and the indentation hardness is from 435 to 1 323 MPa. The basalt belongs to medium hard rock. Three kinds of high-efficiency PDC bits including FM2653Z, FMH3653ZZ and M1666SS bits were designed by using Z3 and AC types of cutting and fixed teeth with the disposition of six blades, superficial inner cone, extending cone crown profile and medium-high density mode, optimizing the hydraulic compositions of bits through CFD technology adopting screw gauge figure. Field application of the new bits demonstrated that a single high-efficiency bit could drill out basalt from 300 to 500 meters in thickness. Compared with the cone bit, the speed and footage of drilling were increased by 1.7-3.3 times in Nanpu Oilfield.