Method and system for determining formation porosity
AssigneeTexaco Inc.
InventorsRobert W. Pittman, Chester E. Hermes
Life of this patent
Estimating the term…
Abstract
A method and/or system for measuring formation porosity from drilling response. It involves measuring a number of drilling parameters and includes determination of tooth dullness as well as determining a reference torque empirically. One of the drilling parameters is the torque applied to the drill string.
Claims8
Method for determining porosity of a formation from drilling response, wherein a bit is attached to the lower end of a drill string that is rotated while the downward force on said bit is controlled, comprising the steps of
- measuring the revolutions of said bit,
- measuring the depth of said bit in the borehole,
- measuring the weight on said bit,
- determining the tooth dullness of said bit,
- measuring the torque applied to said drill string,
- determining a reference torque empirically, and
- determining said porosity of combining said measurements and determinations.
A system for determining porosity of a formation from drilling response, wherein a bit is attached to the lower end of a drill string that is rotated while the downward force on said bit is controlled, comprising in combination
- means for measuring the revolutions of said bit,
- means for measuring the depth of said bit in the borehole,
- means for determining the tooth dullness of said bit,
- means for measuring the torque applied to said drill string, and
- means for correlating said measurements and determination in conjunction with an empirical reference torque to provide a porosity log.
A system for determining porosity of a formation from drilling response, wherein a bit is attached to the lower end of a drill string that is rotated while the downward force on said bit is controlled and wherein the torque applied to rotate said drill string is measured, comprising in combination
- means for measuring the revolutions of said bit comprising a tachometer,
- means for measuring the depth of said bit in the borehole,
- means for determining the tooth dullness of said bit,
- means for correlating said measurements and determination in accordance with the equation ##EQU6## wherein:
- .mu. = ratio of total porosity to the porosity effecting the atmospheric compressive strength
- ln = natural logarithm of
- N = rotational speed of bit
- T = torque
- P.sub.e = effective confining pressure
- D = bit diameter
- R = penetration rate
- W = weight on bit
- .sigma.ca max = atmospheric compressive strength extrapolated back to zero porosity, to represent a porosity parameter of the formation,
- means for recording said porosity parameter on a record medium as it is advanced, and
- means for advancing said record medium in accordance with the depth of said bit.
Dependencies are inferred from the claim text.