First Revision to the IADC Fixed Cutter Dull Grading System

Abstract

This paper is one of two describing changes to the IADC Classification and Dull Grading Systems for fixed cutter bits. Dull grading system revisions, described herein, were implemented to improve utilization and effectiveness of the dull grading system. Classification system changes were required as a result of improvements in bit technology and applications, and are detailed in the companion paper SPE 23940.

Geometry and force modeling, and mechanical properties study of polycrystalline diamond compact bit under wearing condition based on numerical analysis

“…And then, the projection position of the eight cutting edges can be obtained during the PDC bit drilling. In (4)- (6) can be translated into equations (7)- (9). And then, the cutting parameters of each cutter during rock breaking can be solved by these equations.…”

“…The first step in this process is to find the zero point P 0 of the ith cutting edge (in block 1). Set n equal to i, and u equal to zero in equations (7)- (9). Then, the coordinate value (r, h) of zero point P 0 can be obtained by equation 7. In the following steps, make a traversal along the ith cutting edge from zero point P 0 to left.…”

“…2 The unworn part looks like a three-quarter moon. Combined with the wear model in the fixed cutter dull grading system 9 made by the International Association of Drilling Contractors (IADC), the model of the worn cutter can be abstracted to the model in Figure 2(b). A Cartesian coordinate system OX 4 Y 4 Z 4 is built, and origin of coordinates is the center of tooth surface, and axis OZ 4 is perpendicular to the wear surface.…”

“…Figure3(e), the cutting edges which are numbered i 2 1#, i + 1#, i# are the projection of i 2 1th, i + 1th, ith cutters through the plane M in the previous cycle. At this point, equations (4)-(6) can be translated into equations (7)-(9). And then, the cutting parameters of each cutter during rock breaking can be solved by these equations.…”

New PDC Technology Significantly Improves Performance in Drilling Deep Khuff Wells for a Major Operator in Abu Dhabi

“…A comprehensive study was performed on the 12 ¼" sections drilled in the US and ABK fields in which forty-six drill bits, mostly PDC designs, were evaluated and graded for their dull conditions based on the current IADC dull grading system utilized in the oil and gas drilling sector. 1 It was noted that more than 40% of the PDC dull bits had worn cutters (WT) and approximately 50% of PDC drill bits have shown either chipped cutters (CT) or broken cutters (BT) as primary dull conditions Figures 2.…”