Method and system for determining formation porosity
First Claim
1. 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 ofmeasuring 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, anddetermining said porosity of combining said measurements and determinations.
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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.
39 Citations
8 Claims
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1. 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.
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5. 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.
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8. 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: - μ
= ratio of total porosity to the porosity effecting the atmospheric compressive strengthln = natural logarithm of N = rotational speed of bit T = torque Pe = effective confining pressure D = bit diameter R = penetration rate W = weight on bit σ
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.
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Specification
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Current AssigneeTexaco Incorporated (Chevron Corp.)
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Original AssigneeTexaco Incorporated (Chevron Corp.)
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InventorsPittman, Robert W., Hermes, Chester E.
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Primary Examiner(s)Myracle, Jerry W.
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Application NumberUS05/740,998Time in Patent Office411 DaysField of Search73/151, 73/151.5, 73/152US Class Current73/152.02CPC Class CodesE21B 12/02 Wear indicatorsE21B 44/00 Automatic control systems s...E21B 49/003 by analysing drilling varia...
