Electronic Supervisory Control System For Drilling Wells

Abstract

An electronic supervisory control system is disclosed herein wherein rotary power, rotary speed, bit weight, hole size, penetration rate and mud weight ratio are utilized in conjunction with analog and electronic sensing means in order to afford drilling personnel a supervisory control system over drilling operation. Recorded information includes the rate of penetration, corrected d exponent and rotary torque, which may be visually recorded and electronically stored for use for both supervisory control and simultaneous understanding of the monitored drilling variables and their effect upon the drilling operation.

Description

BACKGROUND OF THE INVENTION

This invention relates to a method for supervisory control during the drilling of wells. More particularly, the method of the present invention is an electronic supervisory control system for monitoring various drilling variables and through electronic manipulation of these variables obtaining useful information for the control and observation of the drilling operation.

In applying technology to a drilling operation, it is often a requisite criteria that one obtain a general concept and preferably an exact knowledge of the presence and lithology of formations being encountered or to be encountered by the drilling bit. Various and sundry methods have been proposed for prediction of formations to be encountered or for alarm systems for detecting when a drill bit enters certain formations. In particular, a patent issued to Jordan, et al., U.S. Pat. No. 3,368,400, METHOD FOR DETERMINING THE TOP OF ABNORMAL FORMATION PRESSURES, teaches a process for detecting when a bore hole enters a geopressured shale section, utilizing the penetration rate of the drill bit as the measured variable. The penetration rate of the drill bit is applied over shale sections, to determine the rate of change in penetration rate as the drill bit enters the top of a geopressured shale. The top of the geopressured section is detected by locating the depth at which the rate of change in the rate of penetration distinctly changes. Therefore, through the teaching of Jordon and a determination of the penetration rate, one finds a tool for determining the exact location and depth of the geopressured shale sections so that mud weights and drilling variables may be changed to anticipate well blowouts.

Brown, et al., U.S. Pat. No. 3,541,852, ELECTRONIC SYSTEM FOR MONITORING DRILLING CONDITIONS RELATING TO OIL AND GAS WELLS, teaches the recordation of information by a system, including drilling depth, time, penetration rate, hook load, rotary speed, pump strokes, gas chromatography, and such drilling mud information as weight in-weight out, viscosity, temperature, and flow rates. These data are utilized with the monitoring of drilling rig variables, (for example total depth, rate of penetration, and speed of rotation of the drill bit) to provide a new system for monitoring the rate of penetration of a drill bit used in drilling an oil and gas well.

None of the disclosed prior art have shown a system for the supervisory control of the entire drilling operation where it is particularly advantageous at all times to realize the lithology of the formations being penetrated by a drill bit, and to particularly to understand and control the drilling operation through a knowledge of the lithology being penetrated. What is required is a method for determining in any time period during a drilling operation that lithology which is being encountered by the drill bit or will be encountered a considerable distance ahead of the drill bit. In conjunction with the method are means for monitoring and controlling the drilling variables in order that hazardous conditions may be avoided along with the curtailment of blowouts and other catastrophies.

It is an object of the present invention to provide means for determining the lithological nature of formation encountered by a drill bit.

It is a further object of the present invention to provide means for the supervisory control of a drilling operation.

It is still a further object of the present invention to provide means for the monitoring, recording and supervisory control of a drilling operation through the measurement of specific drilling variables.

With these and other objects in mind, the present invention may be more fully understood through referral to the accompanying drawings and following description.

SUMMARY OF THE INVENTION

The objects of the present invention may be accomplished through an electronic supervisory control system for monitoring and recording of a drilling operation. The electronic supervisory control system comprises computer means for computing means for sensing the rotary motor power, means for sensing the rotary motor speed, means for sensing the weight on the drill bit, and means for sensing the penetration rate of the drill bit. The means for sensing the weight on the drill bit and the means for sensing the penetration rate of the drill bit are utilized in combination with a determination of the drilled hole size and mud weight ratios to compute a corrected d exponent. The means for sensing the rotary motor power and the means for sensing the rotary motor speed are utilized to compute a rotary motor torque. The computed d exponent, rotary motor torque and rate of penetration are simultaneously plotted on an electronic recorder as a function of actual drilled depth.

The electronic supervisory control system of the present invention may further comprise a bit time integrator for recording operational drilling time utilized in conjunction with the sensor data recording. Other preferred embodiments of the present invention also comprise the combination of the rotary motor power electrical signal with an electrical signal from the bit time integrator to produce a bit wear and exposure electrical signal, and the combination of the rotary motor power electrical signal with the rate of penetration electrical signal to produce an energy expended per depth interval electrical signal. The bit wear and exposure electrical signal and energy expended for depth electrical signal may also be plotted on an electronic recorder to give exacting monitoring of the drilling operation and allow for the supervisory control thereof.

BRIEF DESCRIPTION OF THE DRAWING

The present invention may be more fully understood by referral to the accompanying drawings in which:

FIG. 1 schematically illustrates the preferred embodiment of the supervisory control system of the present invention with various sensors utilized and the recorded output provided;

FIGS. 2a and 2b represent an electronic schematic of one embodiment of the analog computer utilized in the present invention in order to compute a corrected d exponent for monitoring and supervisory control of the drilling operation;

FIG. 3 represents an analog schematic of one embodiment of an analog computer circuit utilized in order to compute the torque of the rotary table and drill string utilized for recordation in the supervisory control system of the present invention; and

FIG. 4 represents an electronic schematic of one embodiment of a power supply utilized in the supervisory control system of the present invention .

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The present invention may be most easily understood by referral to the FIG. 1 in which the electronic supervisor control system of the present invention is depicted in a schematic representation. It can be readily seen that the supervisory control system consists of the sensing of various drilling variables of the drilling operation, comprising in particular rotary power, rotary speed, weight on drill bit and drill string, drill hole size, and penetration rate in conjunction with a mud weight ratio.

In general, it may be stated that these drilling operation variables are sensed by means for sensing the drilling variables. In particular, the computer means for computing is preferably an analog computer. The means for sensing the rotary motor power is electrically connected to the computer means and may comprise a rotary motor power sensor mounted upon the shaft of the rotary motor in conjunction with means for converting the rotary motion of the shaft measured by the rotary motor power sensor to an electrical signal and electrical circuit means to transmit the electrical signal from the rotary motor power sensor to the other portions of the electronic supervisory control system. Alternatively, the means for sensing the rotary motor power may comprise an electrical rotary motor power sensor connected to the power line of the rotary motor in conjunction with an electrical circuit means to transmit an electrical signal from the electrical rotary motor power sensor. The means for sensing the rotary motor speed is electrically connected to the computer means and may comprise an electrical rotation sensor connected to the drill string or kelly of the drilling rig and an electrical circuit means to transmit an electrical signal from the electrical rotation sensor to other portions of the electronic supervisory control system. In further respect, the means for sensing the weight on the drill bit is electrically connected to the computer means and may comprise an electrical drill bit and drill string weight sensor and electrical circuit means to transmit an electrical signal from the electrical drill bit and drill string weight sensor. In particular, the drill bit and drill string weight sensor may comprise a tension spring connected from the kelly to the drill string, having responsive electrical stops thereupon to convert the flexing of the mechanical spring into an electrical signal which is transmitted to the electronic supervisory control system. Similarly, the means for sensing the penetration rate of the drill bit is electrically connected to the computer means and may comprise an electrical rotation sensor connected to the rotary table and an electrical depth sensor connected to the drill string, to measure vertical movement of the drill string, with means for integrating the electrical signals from the electrical rotary table rotation sensor and electrical depth sensor to produce a rate of penetration electrical signal. An electrical circuit means is provided to transmit the rate of penetration electrical signal to the electronic supervisory control system.

Means are provided for inputting a drilled hole size into the computer means. The drilled hole size may be manually measured and fed through a potentiometric electronic indicator into the supervisory control system, or it may actually be measured through electronic sensors contained within the drill bit or drill string with appropriate electronic potentiometric circuit means to transmit the electrical signal from the sensors to the supervisory control system. Means are also provided for inputting a mud weight ratio into the computer means. The mud weight ratio may be measured by the electronic measurement of mud pit sensors showing the change in mud weight-in versus mud weight-out of the wellbore or in a preferred embodiment, the normal gradient for the mud density in the geographical area of the well being drilled may be utilized in conjunction with the returned mud weight in order to derive the mud weight ratio utilized in combination with the potentiometric signal of the weight on the bit, the predetermined hole size, and the electrical signal of penetration rate in order to compute a d exponent value. Means for recording is electrically connected to the computer means for recording computed values and penetration rate, and is preferably a depth driven electronic recorder.

Therefore, in the supervisory control system, the various components of rotary power, rotary speed, weight on the drill bit, hole size, and penetration rate are introduced into a buffer system of the supervisory control system. The amplifiers are depicted in FIG. 1 as rotary power-buffer amplifier 101, rotary speed-buffer amplifier 104 and penetration rate-buffer amplifier 105. The amplifiers are utilized to convert the electrical signals to those signals required for the computation of the various drilling indicators. These drilling indicators are computed within an analog computer 106 in which the electrical signal for torque of the drilling operation, which represents the rotary power times a predetermined constant divided by the rotary speed, is produced through electrical circuit 107. The d exponent is an empirical exponent represented by the following equation:

d = [log(R/60N)]/[log(12W/10.sup.6 D)]

wherein

R = rate of penetration, feet per hour

N = rotary speed, revolutions per minute

W = weight on drill bit, pounds

D = drill bit diameter, inches

The numerator computed portion of the d exponent is calculated by taking the natural logarithm of the penetration rate divided by the rotary speed times 60 (in order to convert to hours). The denominator computed portion of the d exponent is calculated by taking the natural logarithm of 12 times the weight on the drill bit and drill string divided by 10.sup.6 times the hole size (in order to reduce to feet). Dividing the numerator computed portion by the denominator computed portion produces an electrical signal for the d exponent which is transmitted through electrical circuit 108. A penetration rate signal is produced through electrical circuit 109. The computed torque signal is fed to a driver gain amplifier 110 through electrical circuit 107 to transmit an appropriate electrical through electrical circuit 111 to be received by the recorder 112 and plotted on a strip chart 113. The display of this signal is indicative of various operations, shown on the synthetic trace, such as a pipe jointing operation and washing operation. The computed d exponent signal produced through circuit 108 is fed to gain amplifier 115 which works through a potentiometer 114 having the mud weight ratio programmed therein to form a system which yields a corrected d exponent signal which is subsequently fed through electric circuit 116 to the recorder 112 in order to be recorded on the strip chart 113. Similarly, the rate of penetration signal is also fed through electrical circuit 109 to a gain amplifier 117 to transmit an appropriate electrical signal through electrical circuit 118 to be recorded on the strip chart 113 by the recorder 112.

A continuous monitoring of rate of penetration, d exponent, and rotary torque is given for the drilling operation by the electrical log of these various drilling operations provided by the supervisory control system of the present invention. In conjunction with the present apparatus, an electrical signal of finite time may be fed through electric circuit 119 to a bit time integrator 120 in order to record actual drilling time of the operation shown on the depth drive recorder 112.

FIG. 2, which embodies FIG. 2a and FIG. 2b, typifies the analog computer circuitry utilized in order to compute the corrected d exponent value from the electrical signals of rotary speed N, weight-on the drill bit and drill string, W, hole size, D, penetration rate, R, and mud weight ratio. The various components of the analog circuitry are comprised of the major amplifier sections shown in detail with the various and sundry resistors, capacitors, voltage inputs and circuitry depicted and numbered accordingly with each of the values of the component parts corresponding to those illustrated in FIGS. 2a and 2b shown in the following Table I:

TABLE I ______________________________________ Component Number Value ______________________________________ 1 10,000 ohms, 1/2 watt, 1% 2 10,000 ohms, 1/2 watt, 1% 3 10,000 ohms, 1/2 watt, 1% 4 10,000 ohms, 1/2 watt, 1% 5 20,000 ohm, 1/2 watt, 1% 6 10,000 ohm, 1/2 watt, 1% 7 10,000 ohm, 1/2 watt, 1% 8 10,000 ohm, 1/2 watt, 1% 9 10,000 ohm, 1/2 watt, 1% 10 2,700 ohm, 1/2 watt, 5% 11 200 ohm, potentiometer 12 510 ohm, 1/2 watt, 5% 13 3,600 ohm, 1/2 watt, 5% 14 200 ohm, potentiometer 15 510 ohm, 1/2 watt, 5% 16 10,000 ohms, 1/2 watt, 1% 17 6,200 ohm, 1/4 watt, 5% 18 6,200 ohm, 1/4 watt, 5% 19 100,000 ohm, 1/4 watt, 5% 20 10,000 ohm, 1/2 watt, 1% 21 5,000 ohm, 1/2 watt, 1% 22 5,000 ohm, 1/2 watt, 1% 23 10,000 ohm, 1/2 watt, 1% 24 10,000 ohm, 1/2 watt, 1% 25 6,200 ohm, 1/4 watt, 5% 26 6,200 ohm, 1/4 watt, 5% 27 100,000 ohm, 1/4 watt, 5% 28 10,000 ohms, 1/2 watt, 1% 29 10,000 ohms, 1/2 watt, 1% 30 6,200 ohm, 1/4 watt, 5% 31 100,000 ohm, 1/4 watt, 5% 32 6,200 ohm, 1/4 watt, 5% 33 5,100 ohm, 1/2 watt, 5% 34 100,000 ohm, 1/4 watt, 5% 35 82,000 ohm, 1/2 watt, 5% 36 10,000 ohm potentiometer 85 9432 monolithic op amps. (5) O.E.I. 86 2457 monolithic universal logarithmic module O.E.I. 87 2457 monolithic universal logarithmic module O.E.I. 88 2457 monolithic universal logarithmic module O.E.I. 89 395 anti-logarithmic module O.E.I. 136 10,000 ohm potentiometer ______________________________________

Referring to FIG. 2a which schematically illustrates the circuitry for a partial solution of the equation

d = [log (R/60N)]/[log (12W/10.sup.6 D)].

The electronic solution requires scaling of the original equation to restrict the electrical values to be within the dynamic range of the electronic modules. The scaled equation is:

[(log 2 R - log N/2) - (log 240)]/[(log W - log D) - (log 83.333)]

The solution for the numerator (log 2 R - log N/2) - (log 240) is schematically illustrated by FIG. 2a.

It should be appreciated that with this particular type of operational amplifier module 85 there are five operational amplifiers enclosed within module 85. These are available through Optical Electronics Inc., in Tucson, Ariz. and are identified as amplifier module 9432.

FIG. 2a shows electrical input R 97 coupled through input resistor 20 to the inverting input of an operational amplifier having a fixed gain of two, developed by feedback resistor 5 being coupled from inverting input to output. This output is representative of inverted 2 R in the equation and is coupled through resistor 24 to the input of the logarithmic amplifier module 86.

Looking at input N 99, an electrical input is connected to a balanced voltage divider. The junction voltage between resistors 21 and 22 is equal to N/2 and coupled to the input of another logarithmic amplifier contained in module 86 through resistor 23. The outputs of the two logarithmic amplifiers are connected to resistors 25 and 26 which together comprise a summing junction that is connected to the inverting input of an operational amplifier also included in module 86. The gain of this amplifier is adjusted by feedback resistor 27 to cause the output at junction 202 of this amplifier to be the electrical representation of (log 2 R - log N/2). The junction 202 is coupled back to an operational amplifier contained in module 85 through resistor 3 to the inverting input. Also coupled to this inverting input through resistor 9 and adjusted by potentiometer 11 is a voltage equal to 2.38 volts which represents the log of 240. The junction of input summing resistors 3 and 9 is connected to the inverting input of an operational amplifier in module 85 and resistor 2 connected from output to inverting input sets the gain at one. This output is shown at point C on FIG. 2a and is the electrical representation of (log 2 R - log N/2) - (log 240).

Referring again to FIG. 2a and to the denominator portion of the scaled equation (log W - log D) - (log 83.333) and electrical input, D 98 is shown connected to the inverting input of another operational amplifier of module 85 through input resistor 7. The output of this amplifier is coupled back to the input through feedback resistor 8 which sets the gain at one. The output shown as point E on FIG. 2a is also shown as point E on FIG. 2b.

Referring now to FIG. 2b, there is illustrated circuitry for solving the remaining portion of the equation:

[(log 2 R - log N/2) - (log 240)]/[(log W - log D) - (log 83.333)]

Point E is representative of D in the equation and is shown connected to the input of a logarithmic amplifier of module 87 through resistor 16. Point W is representative of W in the equation and is shown connected through resistor 1 to another logarithmic amplifier of module 87. The outputs of these log amplifiers are connected to the input of an operational amplifier in module 87 through summing resistors 17 and 18. The gain of this amplifier is fixed by feedback resistor 19 to be the electrical representation of (log W - log D) in the equation. Referring back to FIG. 2a at point 201, a voltage of - 1.92 volts (the electrical representative of -(log 83.333),) is adjusted by potentiometer 14 and connected through resistor 96 to the inverting input of an operational amplifier again contained in module 85. Point A on FIG. 2b is the electrical output representing (log W - log D) and it is shown on FIG. 2a as point A connected through resistor 6 to the junction of resistor 96. This provides a summing junction for the operational amplifier input. The gain of this amplifier is fixed by feedback resistor 4 coupled from output to inverting input. The output voltage of this operational amplifier 85 is the sum of (log W - log D) - (log 83.333). This concludes the solution for the denominator portion of the scaled equation and this portion of the equation is represented on FIG. 2a and FIG. 2b as point B.

Referring to FIG. 2b, point B is connected through resistor 28 to the input of a logarithmic amplifier contained in module 88. Point C is connected to the input of a second logarithmic amplifier in module 88 through resistor 29. Note that point B is the electrical solution of (log W - log D) - (log 83.333) and point C is the solution of (log 2 R - log N/2) - (log 240). The next logarithmic amplifier in module 88 is utilized to divide point C by point B. Point C is divided by point B by subraction of log point B from log point C. The output of the logarithmic amplifier producing log point B is connected through resistor 30 to the input of an operational amplifier contained in module 88. The output of the logarithmic amplifier producing log C is connected through resistor 32 to the same input junction as resistor 30. The voltage of log C is of opposite polarity to that of log B and the output of the operational amplifier 203 will be a voltage representing the logarithm of log C - log B. At the point 203 of FIG. 2b the scaled equation has been electrically solved to a point where we have:

log [(log 2 R - log N/2) - (log 240)]/[(log W - log D) - (log 83.333)]

and the scaled equation for log d is:

d = [(log 2 R - log N/2) - log 240]/[(log W-log D) - log 83.333]

by taking the anti-log of point 103 the equation is solved. Point 103 is connected through resistor 33 to the input of anti-logarithmic amplifier 89. The output of 89 is adjusted to the proper level by potentiometer 36 and offset resistor 34 to give a voltage output that is equal to the anti-log of the input voltage. This output voltage is then applied to potentiometer 104 which is set as a voltage divider proportional to the ratio of normal mud weight used in a particular area (region) to the measured mud weight actually being used in the drilling operation.

It should be understood that many of the component parts of the apparatus used in this invention must be carefully selected to minimize error and that the selected values for electrical components used in specific embodiments such as those described herein, may be critical to proper operation of the apparatus.

Referring to FIG. 3, the analog circuitry utilized for computing the torque T for recordation from the electrical signals of rotary speed N, rotary power P and the predetermined constant K is depicted with the following Table II listing the values and component parts corresponding to the illustrated FIG. 3.

TABLE II ______________________________________ Component Number Value ______________________________________ 74 10,000 ohm, 1/2 watt, 1% 75 10,000 ohm, potentiometer K input 76 10,000 ohm, 1/2 watt, 1% 77 10,000 ohm, 1/2 watt, 1% 78 6,200 ohm, 1/4 watt, 5% 79 6,200 ohm, 1/4 watt, 5% 80 100,000 ohm, 1/4 watt, 5% 81 10,000 ohm, potentiometer 82 15,000 ohm, 1/2 watt, 5% 83 10,000 ohm, potentiometer 90 2457 Optical Electronics, Inc. logarithmic module 91 395 Optical Electronics, Inc. anti-logarithmic module 92 709 operational amplifier 93 0.001 mf. 50 volt condenser 94 1,500 ohm, 1/2 watt, 5% 295 rotary power input 296 R.P.M. input T torque output ______________________________________

The electrical signal representing rotary power P is obtained from junction 295 and is coupled to the inverting input of operational amplifier 92 through resistor 74. The gain of amplifier 92 is adjustable to a gain of one or less by the connection of variable resistor 75 coupled from the output to the inverting input. The variable resistor 75 also represents the constant K. The output voltage of amplifier 92 will be the inverted product of electrical signal input P times the predetermined constant K. The output of amplifier 92 is coupled to the input of a logarithmic amplifier contained in the monolithic module 90 through resistor 77. The electrical signal representing rotary speed N is obtained from junction 296 and is coupled to a second logarithmic amplifier contained in module 90 through resistor 76. The inputs of these two logarithmic amplifiers are of opposite polarity. The outputs of the two logarithmic amplifiers are coupled to an amplifier input through the summing resistors 78 and 79. The output of the summing module amplifier 90 is a voltage representative of log PK-log N. The output of module 90 is coupled to an anti-log module 91 through trimming potentiometer 81. Potentiometer 83 is used as offset and trimming of the anti-log module. The anti-log of the difference between log PK and log N is arithmetically equal to PK divided by N, or PK/N. Proper adjustment of potentiometers 81 and 83 will result in an electrical voltage output of anti-log module 91 that is representative of Torque when the equation Torque = PK/N is considered.

FIG. 4 is a typical schematic representative of any "off-the-shelf" well-filtered, well-regulated, direct-current power supply adjustable to plus and minus 13.3 volts. The various components depicted in FIG. 4 are listed in Table III giving the values of the components of FIG. 4 as enumerated.

TABLE III ______________________________________ Component Number Value ______________________________________ 37 120 volt, 60 Hz primary, dual secondary 15 volts each 38 1 amp silicon rectifier GE 509 39 1 amp silicon rectifier GE 509 40 1 amp silicon rectifier GE 509 41 1 amp silicon rectifier GE 509 42 1 amp silicon rectifier GE 509 43 1 amp silicon rectifier GE 509 44 1 amp silicon rectifier GE 509 45 1 amp silicon rectifier GE 509 46 100 mf 50 volt 47 100 mf 50 volt 48 2,200 ohm 5%, 1/2 watt 49, 61 2N1305 Transistor 50, 62 2N1305 Transistor 51 12 volt, 1 watt Zener diode 52 0.001 mf condenser 53 5,100 ohm 5%, 1/2 watt 54 GE 3 Transistor 55 6,800 ohm 5%, 1/2 watt 56 50 mf 50 volt condenser 57 1,500 ohm 5% 1/2 watt 58 2,000 ohm potentiometer 59 250 ohm 5% 1/2 watt 60 100 mf 50 volt condenser 63 0.001 mf condenser 64 5,000 ohm 5%, 1/2 watt 65 2,200 ohm 5%, 1/2 watt 66 12 volt, 1 watt Zener diode 68 6,800 ohm 5%, 1/2 watt 69 50 mf 50 volt condenser 70 1,500 ohm 5% 1/2 watt 71 2,000 ohm potentiometer 72 250 ohm 5% 1/2 watt 73 100 mf 50 volt condenser ______________________________________

Therefore, through the various sensors described herein, it can be seen how the supervisor control system may be utilized in order to convert electrical signals from the electronic sensors into useful supervisory control data for both monitoring and use with other systems. The simulated chart on FIG. 1 depicts a typical recording of rate of penetration, corrected d exponent and torque for use in order to control the actual drilling operation such that the drilling operator is afforded a greater continuous recording of drilling information and the opportunity to store the data and utilize it further for optimal drilling and prevention of catastrophies.

While the invention as has been described above with respect to certain embodiments thereof, it will be understood by those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention as set forth herein.

Claims

Therefore, we claim:

1. An electronic supervisory control system for monitoring and recording of a drilling operation wherein a drill string having a kelly and a drill bit is turned by means of a rotary motor said control system comprises:

a. computer means for computing;

b. means for sensing the rotary motor power electrically connected to said computer means;

c. means for sensing the rotary motor speed electrically connected to said computer means;

d. means for sensing the weight on the drill bit electrically connected to said computer means;

e. means for sensing the penetration rate of the drill bit electrically connected to said computer means;

f. means for recording electrically connected to said computer means;

g. means for inputting a drilled hole size into said computer means;

h. means for inputting a mud weight ratio into said computer means; and

in which the means for sensing the weight on the drill bit and the means for sensing the penetration rate of the drill bit are utilized in combination with the input of the drilled hole size and mud weight ratio to compute by said computer a corrected d exponent; and simultaneously the means for sensing the rotary motor power and means for sensing the rotary motor speed are utilized to compute by said computer a rotary motor torque, and the corrected d exponent, rotary motor torque and rate of penetration are plotted on said means for recording.

2. The electronic supervisory control system of claim 1 in which the means for sensing the rotary motor power comprise:

a. a rotary power sensor mounted upon the shaft of the rotary motor;

b. means for converting the rotary motion of the shaft measured by the rotary motor power sensor to an electrical signal; and

c. electrical circuit means to transmit the electrical signal from the rotary motor power sensor to said computer means.

3. The electronic supervisory control system of claim 1 in which the means for sensing the rotary motor power comprise:

a. an electrical rotary motor power sensor connected to the power line of the rotary motor; and

b. an electrical circuit means to transmit an electrical signal from the electrical rotary motor power sensor to said computer means.

4. The electronic supervisory control system of claim 3 in which the means for sensing the rotary motor speed comprise:

a. an electrical rotation sensor connected to the kelly; and

b. an electrical circuit means to transmit an electrical signal from the electrical kelly rotation sensor to said computer means.

5. The electronic supervisory control system of claim 4 in which the means for sensing the penetration rate of the drill bit comprise:

a. an electrical rotation sensor connected to the rotary table;

b. an electrical depth sensor connected to the drill string;

c. means for integrating the electrical signals from the electrical rotary table rotation sensor and electrical depth sensor to produce a rate of penetration electrical signal; and

d. an electrical circuit means to transmit the rate of penetration electrical signal to said computer means.

6. The electronic supervisory control system of claim 5 in which the computation by said computer means of a corrected d exponent is conducted by an analog computer receiving the electrical signals of rate of penetration, weight on the bit, hole size and mud ratio in formation.

7. The electronic supervisory control system of claim 6 in which the corrected d exponent, rotary motor torque and rate of penetration computed signals are received from the appropriate sensors and analog computer and are recorded on said means for recording.

8. The electronic supervisory control system of claim 7 further comprising a bit time integrator for recording operational drilling time in conjunction with the sensor data recording.

9. The electronic supervisory control system of claim 8 further comprising:

a. means for combining the rotary motor power electrical signal with an electrical signal from the bit time integrator to produce a bit wear and exposure electrical signal;

b. means for combining the rotary motor power electrical signal with the rate of penetration electrical signal to produce an energy expended per depth electrical signal and for recording of the bit wear and exposure electrical signal and the energy expended per depth electrical signal on said means for recording.

10. The electronic supervisory control system of claim 9 wherein said means for recording is a depth driven electronic recorder.