Methods for modeling wear of fixed cutter bits and for designing and optimizing fixed cutter bits

• US 8,589,124 B2
• Filed: 07/09/2004
• Issued: 11/19/2013
• Est. Priority Date: 08/09/2000
• Status: Expired due to Fees

• Current Assignee: Smith International Incorporated (SLB)
• Original Assignee: Smith International Incorporated (SLB)
• Inventors: Huang, Sujian
• Primary Examiner(s): Saxena, Akash
• Application Number:
  US10/888,354
• Publication Number:
  US 20050015229A1
• Time in Patent Office: 3,420 Days
• Field of Search: 703/2, 703/7, 703/10, 175/24, 175/57, 175/431, 702/151
• US Class Current: 703/2
• CPC Class Codes: E21B 10/00 Drill bits specially adapted for deflecting the direction of boring E21B7/064; with means for collecting substances E21B27/00
• CPC Class Codes: E21B 10/16 characterised by tooth form or arrangement
• CPC Class Codes: G06F 30/17 Mechanical parametric or variational design

Abstract

In one aspect, the invention provides a method for modeling the wear of a fixed cutter bit drilling earth formations. A method for determining wear of a fixed cutter drill bit includes simulating the fixed cutter drill bit drilling an earth formation; determining a cutter-formation interaction force and a relative sliding velocity of a selected area on a cutting surface on a cutter of the fixed cutter drill bit during the drilling; and calculating a wear rate of the selected area based on the cutter-formation interaction force and the relative sliding velocity.

Claims

1. A method for determining wear of a fixed curer drill bit, comprising:

(a) simulating the fixed cutter drill bit drilling an earth formation;

(b) determining a cutter-formation interaction force and a relative sliding velocity of a selected area on a cutting surface on a cutter of the fixed cutter drill bit during the drilling, wherein the selected area comprises an interface between the curing surface on the cutter and the earth formation;

(c) calculating a wear rate of the selected area based on the cutter-formation interaction force and the relative sliding velocity;

(d) converting the wear rate into a visual representation;

(e) applying the calculated wear rate to at least one cutter of the simulated fixed curer drill bit;

(f) continuing to simulate the fixed cutter drill bit with the at least one worn cutter drilling the earth formation;

(g) ending the simulation and displaying output data;

wherein the cutter-formation interaction force is determined as a function of a depth of cut; and

wherein the calculating the wear rate is according to;

WR=a1×

10^a2×

d^a3×

v^a4×

T^a5

where WR is the wear rate, d is the depth of cut, v is the relative sliding velocity, T is a temperature, and a1-a5 are constants.

2. The method of claim 1, wherein the a1-a5 constants are determined based on laboratory test or field test data.

3. A method for designing a fixed cutter drill bit having a plurality of cutters, comprising:

(a) selecting initial bit design parameters;

(b) simulating drilling an earth formation using the fixed cutter drill bit;

(c) determining wears on the plurality of cutters, wherein the determining the wears comprises determining a cutter-formation interaction force and a relative sliding velocity for each contact area on each of the plurality of cutters during the drilling, and calculating a wear rate of the each contact area based on the cutter-formation interaction force and the relative sliding velocity;

(d) displaying a graphical display of the wears on the plurality of cutters;

(e) applying the calculated wear rate to at least one cutter of the fixed cutter drill bit;

(f) continuing to simulate the fixed cutter drill bit with the at least one worn cutter drilling the earth formation;

(g) adjusting at least one bit design parameter based on the graphical display;

(h) repeating the simulating, the determining, the displaying, the applying, the continuing to simulate, and the adjusting until an optimal bit design parameters is reached;

wherein the cutter-formation interaction force is determined as a function of a depth of cut; and

wherein the calculating the wear rate is according to;

WR=a1×

10^a2×

d^a3×

v^a4×

T^a5

where WR is the wear rate, d is the depth of cut, v is the relative sliding velocity, T is a temperature, and a1-a5 are constants.

4. The method of claim 3, wherein the a1-a5 constants are determined based on laboratory test or field test data.