Axial motion drill bit model

Patent metadata

Field	Value
Publication number	US-9951560-B2
Application number	US-201414517445-A
Country	US
Kind code	B2
Filing date	Oct 17, 2014
Priority date	Oct 18, 2013
Publication date	Apr 24, 2018
Grant date	Apr 24, 2018

Abstract

A method for predicting an amount of axial motion of a drill bit having one or more cutters for drilling formation rock includes: receiving lithology data for the formation rock; receiving drilling parameters; calculating confined compressive strength (CCS) of the rock using the received information; calculating an area of cut into the formation rock by each of the one or more cutters; calculating an effective back rake of each of the one or more cutters; calculating a force applied to each of the one or more cutters using the CCS, the area of cut and the effective back rake of the one or more cutters, and by accounting for an orientation of each cutter with respect to a surface of the rock to be cut; and summing the calculated forces applied to each of the one or more cutters to calculate the weight on bit and torque on bit.

First claim

What is claimed is:

1. A method for predicting an amount of axial motion of a drill bit having one or more cutters for drilling a borehole into a formation rock, the method includes:
receiving lithology data for the formation rock;
receiving drilling parameters that include mud weight and drill bit depth for a drill rig that will operate a drill tubular coupled to the drill bit and drill bit design information;
calculating confined compressive strength of the formation rock using the received lithology data, drilling parameters, and drill bit design information;
calculating an area of cut into the formation rock by each of the one or more cutters;
calculating an effective back rake of each of the one or more cutters;
calculating a force applied to each of the one or more cutters using the calculated confined compressive strength of the formation rock, the area of cut and the effective back rake of the one or more cutters, and by accounting for an orientation of each of the one or more cutters with respect to a surface of the rock to be cut; and
summing the calculated forces applied to each of the one or more cutters to calculate the weight on bit (WOB) and torque on bit (TOB);
wherein the above method is implemented by a processor.

2. The method according to claim 1 , further comprising calculating the WOB and TOB to provide a prescribed rate of penetration.

3. The method according to claim 1 , further comprising calculating a rate of penetration (ROP) to provide a prescribed WOB.

4. The method according to claim 1 , further comprising representing the drill bit with a first set of virtual pickets and the formation rock with a second set of virtual pickets.

5. The method according to claim 4 , wherein the first set of pickets lines up with the second set of virtual pickets at the interface of the drill bit with the formation rock.

6. The method according to claim 4 , wherein the area of cut of each of the one or more cutters, the effective back rake of each of the one or more cutters, and the force applied to each of the one or more cutters are calculated on a picket by picket basis.

7. The method according to claim 6 , wherein summing comprises summing the forces on each of the pickets.

8. A non-transitory computer-readable medium comprising computer-executable instructions for predicting an amount of axial motion of a drill bit having one or more cutters for drilling a borehole into a formation rock that when executed by a computer processing system implements the following steps:
receiving lithology data for the formation rock;
receiving drilling parameters that include mud weight and drill bit depth for a drill rig that will operate a drill tubular coupled to the drill bit and drill bit design information;
calculating confined compressive strength of the formation rock using the received lithology data, drilling parameters, and drill bit design information;
calculating an area of cut into the formation rock by each of the one or more cutters;
calculating an effective back rake of each of the one or more cutters;
calculating a force applied to each of the one or more cutters using the calculated confined compressive strength of the formation rock, the area of cut and the effective back rake of the one or more cutters, and by accounting for an orientation of each of the one or more cutters with respect to a surface of the rock to be cut; and
summing the calculated forces applied to each of the one or more cutters to calculate the weight on bit (WOB) and torque on bit (TOB).

Assignees

• Spencer Reed W
• Hanson Jonathan M
• Baker Hughes A Ge Co Llc

Inventors

• Spencer Reed W
• Hanson Jonathan M

Classifications

• E21B7/00 Primary

  Special methods or apparatus for drilling · CPC title

• E21B10/00

  Drill bits (specially adapted for deflecting the direction of boring {E21B7/064}; with means for collecting substances E21B27/00) · CPC title

• E21B44/00 Primary

  Automatic control systems specially adapted for drilling operations, i.e. self-operating systems which function to carry out or modify a drilling operation without intervention of a human operator, e.g. computer-controlled drilling systems; Systems specially adapted for monitoring a plurality of drilling variables or conditions · CPC title