Abstract:With the increasing demand of deep-sea and deep-earth drilling, the wear of downhole drilling tools using traditional PDC bit is serious, which cannot fully meet the drilling requirements of deep wells in hard formation, so the special-shaped cutter PDC bit, especially the V-shaped cutter PDC bit, become the focus of research. At present, there are few studies on the influence of wear on rock contact area of V-shaped cutter PDC bit, so it is very important to study the influence of V-shaped cutter wear on its ROP. In order to calculate the contact area between the V-shaped cutter and the rock in the wear stage, by using the method of plane inclined intercepting the cylindrical surface where the composite piece is located, we deduce the expression of the contact area as a function of the wear height and the geometric parameters of the V-shaped cutter, such as chord length and tangent angle, and we analyze the influence of the geometric parameters of the V-shaped cutter and the wear height on the contact area and the contact pressure. The results show that: in the early stage of wear, the contact area of cylindrical cutter and V-shaped cutter is the same, when the composite piece wears to a certain stage, the contact area of V-shaped cutter is smaller, and the smaller the chord length and tangent angle are, the smaller the contact area is; under the same load, when the wear reaches to a certain stage, the contact pressure of the V-shaped cutter is larger compared to that of the cylindrical cutter, and it have the ability to cut deeper into the rock. When drilling rock formations, V-shaped teeth PDC drills can be used, by measuring the height of the cutting teeth wear and accurately calculating the contact area between the cutting teeth of the drill bit and the rock, it is convenient to adjust the drilling pressure in time to maintain a higher drilling speed; or optimize the geometric parameters of the V-shape teeth when designing, which is also conducive to improving the drilling efficiency.
