U.S. patent number 3,905,010 [Application Number 05/406,858] was granted by the patent office on 1975-09-09 for well bottom hole status system.
This patent grant is currently assigned to Basic Sciences, Incorporated. Invention is credited to John Douglas Fitzpatrick.
United States Patent |
3,905,010 |
Fitzpatrick |
September 9, 1975 |
Well bottom hole status system
Abstract
A well bottom hole status system for measuring fluid reservoir
pressure and temperature at the bottom of a well bore. An
instrumentation unit is removably secured to the bottom of the well
tubing for sensing fluid reservoir pressure and temperature and for
transmitting the pressure and temperature data through the well
tubing to the surface using electromagnetic radiation. Receiver and
data processor means are located at the surface for receiving,
processing and displaying said data. The medium for the
transmission of the data may be either the fluid within the tubing
using the said tubing as a wave guide, or by means of fiber optic
wave guides disposed within the said tubing.
Inventors: |
Fitzpatrick; John Douglas
(Tulsa, OK) |
Assignee: |
Basic Sciences, Incorporated
(Tulsa, OK)
|
Family
ID: |
23609695 |
Appl.
No.: |
05/406,858 |
Filed: |
October 16, 1973 |
Current U.S.
Class: |
340/854.4;
340/870.09; 398/109; 340/854.6; 340/870.28 |
Current CPC
Class: |
E21B
47/06 (20130101); E21B 47/13 (20200501) |
Current International
Class: |
E21B
47/12 (20060101); E21B 47/06 (20060101); G01v
001/40 () |
Field of
Search: |
;340/18NC,189
;325/24,26,130,113 ;250/199 ;350/96B ;343/1CS ;178/DIG.2
;179/82 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wilbur; Maynard R.
Assistant Examiner: Birmiel; H. A.
Claims
What is claimed is:
1. A well bottom hole status indicator system for detecting fluid
reservoir pressure and temperature at the bottom of the well bore
having tubing extending from the well head to the well bottom hole
fluid reservoir and comprising bottom hole instrumentation means
removably installed in the well bore in the proximity of the bottom
of the well tubing, said bottom hole instrumentation means
comprising sensing means for sensing fluid reservoir pressure and
temperature, data conversion means operably connected to the sensor
means to produce data corresponding to the output of the sensing
means, electromagnetic transmitting means operably connected to
said data conversion for transmitting data to the well head, said
transmitting means comprising a microwave transmitter having a
microwave antenna operably connected thereto, said antenna being
disposed within the well tubing, power supply means disposed within
the bottom hole instrumentation means and operably connected to the
sensing means, the data conversion means and the transmitting
means; data receiving and processing means disposed at the well
head for receiving and processing data from said instrumentation
means; and wave guide means interposed between the bottom hole
instrumentation means and the data receiving and processing means
for guiding the transmitted data to the well head data receiving
and processing means, said wave guide means being the tubing
itself, the frequency of the microwave transmitter being tuned to
an optimum frequency for transmission through the fluid in the
tubing and along the inside wall of the tubing, and wherein the
data receiver and processing means comprises the microwave receiver
having a receiving antenna operably connected thereto, said antenna
being disposed inside the tubing at the well head.
2. A well bottom hole status indicator system as set forth in claim
1 wherein the microwave transmitter comprises an oscillator which
is operably connected to and keyed by the data conversion means and
a harmonic multiplier for stepping up the output frequency of the
oscillator to a frequency suitable for transmission through the
fluid using said tubing as a wave guide.
3. A well bottom hole status indicator system as set forth in claim
1 wherein the microwave receiver comprises a sum and difference
mixer operably connected to the receiving antenna, a local
oscillator connected to the mixer, an intermediate frequency (IF)
amplifier connected to the output of the mixer for amplifying the
difference frequency whereby lower frequency well head equipment
may be utilized for receiving and processing the bottom hole
data.
4. A well bottom hole status indicator system as set forth in claim
1 and including alarm means disposed within the bottom hole
instrumentation means and being operably connected between the
sensing means and the transmitting means for keying alarm
transmission signal when the fluid reservoir status exceeds
predetermined conditions.
5. A well bottom hole status indicator system as set forth in claim
4 wherein said alarm means comprises at least one status limiting
means, means for comparing said status limit means to the output of
the sensing means, alarm generator connected to the output of the
means for comparing said status limit means to the output of the
sensing means and the transmitting means.
6. A well bottom hole status indicator system as set forth in claim
5, wherein a delay relay is interposed between the means for
comparing said status limit means to the output of the sensing
means and the alarm generator for intermittently permitting the
alarm generation to conserve power.
7. A well bottom hole status indicator system as set forth in claim
5 wherein the means for comparing the status limit means to the
output of the sensing means comprises an operational amplifier.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to improvements in both method and means for
monitoring the reservoir pressure and temperature at the bottom of
a well bore and more particularly, but not by way of limitation, to
a well bottom hole status monitoring system wherein an
instrumentation sensing unit having electromagnetic radiation
transmission means is installed at the bottom of a well bore at the
lower end of the well tubing for sensing pressure and temperature
and transmitting data to the well head.
2. Description of Prior Art
This invention is related to the means for measuring pressure and
temperature disclosed in the patent to Fitzpatrick U.S. Pat. No.
3,732,728, issued on May 15, 1973, and entitled BOTTOM HOLE
PRESSURE AND TEMPERATURE INDICATOR. As set forth in the patent to
Fitzpatrick (U.S. Pat. No. 3,732,728), for effective management of
producing oil wells, gas wells and the like, it is necessary that
the fluid reservoir pressure and temperature at the bottom of the
borehole be monitored on a regular basis in order to determine
dangerous pressure build-ups, temperature fluctuations, or the need
for treating said wells to increase production therefrom.
Heretofore, the monitoring of these oil and gas wells has been
accomplished by lowering temperature and pressure sensing apparatus
down through the tubing after completely shutting the said well
down which is a time consuming and very expensive process.
The patent to Fitzpatrick (U.S. Pat. No. 3,732,728) addressed this
problem by installing a bottom hole pressure and temperature
instrumentation system within the reservoir and transmitting said
information to the surface by sonic means and magnetic flux means
using the well tubing as an information conductor for the data.
Certain inherent disadvantages are present when using sonic
transmission along the well tubing, the primary one being the
introduction of false or erroneous signals caused from extraneous
sound sources either within the well or within the well head
machinery in contact therewith. The flux method is found to be
inefficient due to flux leakage between the well tubing and the
casing.
SUMMARY OF THE INVENTION
The present invention contemplates a novel method and means for
monitoring the reservoir pressure and temperature at the bottom of
a well bore which is particularly designed and constructed for
overcoming the above disadvantages. The present invention is
particularly suited to free flow wells wherein the pressure within
the reservoir is sufficient to allow flowing of the product to the
well head without the installation of sucker rods or pumps located
within the well tubing. The present invention comprises temperature
and pressure sensing means substantially permanently located at the
bottom of the well tubing within the fluid reservoir, data
conversion means for converting the sensor information into
intelligent signals for keying electromagnetic transmitters also
located in the bottom hole instrumentation unit.
Two basic types of transmission are disclosed herein, one of which
is a microwave transmission which utilizes the fluid within the
tubing as the medium of transmission and is also tuned to a
frequency to permit the use of the inside of the well tubing itself
to act as a wave guide for transmission of the electromagnetic
signal to the surface. A second means for transmitting the said
information to the surface by electromagnetic means is that of the
use of fiber optic strands connecting the bottom hole
instrumentation unit to a well head receiver system. In the case of
the use of fiber optics as a wave guide for the signal, it has been
found that laser transmission is most adaptable. For use with
either means of transmission, a well head receiver, data processor
and an optional alarm system is located at the well head for
receiving and processing the data from the bottom hole
instrumentation unit.
By the use of electromagnetic radiation transmission, the chances
of interference or extraneous signals being introduced into the
data information is greatly lessened and as a result thereof the
information received at the well head is highly reliable.
A bottom hole pressure and temperature alarm system is also
contemplated as an optional part of this invention whereby both the
upper and lower pressure and temperature bounds may be monitored so
that if the pressure or temperature goes outside these bounds, an
alarm signal is transmitted to the surface of the well. This is
desirable so that preventive measures may be taken to prevent
reservoir wall cracking, the pumping of a dry hole which burns out
pumping equipment, and the like.
DESCRIPTION OF THE DRAWINGS
Other and further advantageous features of the present invention
will hereinafter more fully appear in connection with a detailed
description of the drawing in which:
FIG. 1 is an elevational sectional view of a well bore having an
instrumentation unit installed at the bottom thereof and a receiver
and data processing unit installed at the upper end thereof.
FIG. 2 is an elevational section view of the bottom hole
instrumentation unit having microwave transmission equipment
installed therein.
FIG. 3 is an electrical schematic of the microwave transmitter of
FIG. 2.
FIG. 4 is a block diagram schematic of the well head receiver and
data processing unit of FIG. 1.
FIG. 5 is a sectional elevational view of a well bore depicting an
instrumentation unit located at the bottom thereof and a receiver
and data processing unit located at the upper end thereof.
FIG. 6 is a sectional elevational view of the instrumentation unit
of FIG. 5 depicting a laser, receiver and transmission system
located therein a fiber optic means located within the tubing
thereof.
FIG. 7 is an electrical schematic diagram of the laser and receiver
system located in the bottom hole instrumentation unit of FIG.
6.
FIG. 8 is an electrical and block diagram schematic of the well
head receiver data processing and transmission system of FIG.
5.
FIG. 9 is an electrical and block diagram schematic of an optional
temperature or pressure alarm system which may be disposed within
the bottom hole instrumentation units.
DETAILED DESCRIPTION OF THE INVENTION
Referring to the drawings in detail, reference character 10
generally indicates a well bore in the earth 12 connecting the
surface thereof with a fluid reservoir 14 of oil, gas and the like.
Normally, the well bore is lined with a casing 16 which extends
from the surface of the earth 12 down to and into the reservoir 14.
The area between the casing and the rough borehole 10 is normally
filled with a concrete or the like substance 18 to support the said
casing. Disposed within the said casing is an elongated vertically
disposed tubing 20 which extends from the surface of the well into
the reservoir pool 14 at the bottom of the oil well bore. Reference
character 22 generally indicates a bottom hole instrumentation unit
which is secured to the bottom of the tubing 20 by means of a
threaded or sealed attachment means 24 as depicted in FIG. 2. The
lower end of the tubing itself is provided with a plurality of
spaced holes, not shown, therearound to allow the fluid from the
reservoir to enter the tubing and rise to the surface of the well.
An information receiver means 26 is disposed at the well head and
is operably connected to a data process means 28 connected thereto.
The output of the data processing means 28 may also be connected to
an optional alarm means 30.
The bottom hole instrumentation unit 22 generally comprises an
elongated vertically disposed housing 32 which is secured to the
bottom of the tubing 20 by the attachment means 24. The housing 32
comprises a lower compartment 34 having a pressure transducer 36
and a temperature transducer 38 disposed therein, the sensing
elements 40 and 42 of the pressure transducer and the temperature
transducer, respectively, being exposed to the reservoir 14 through
the bottom of the housing 22. Another compartment 44 is provided
for housing a power supply 46 which may be a battery operated
supply or even a long life nuclear power supply. The unit 22 also
comprises a third electronics bay compartment 48 which is
surrounded by insulation 50 and houses a data conversion means 52
and transmitter means 54. The data conversion means 52 is operably
connected to the output of the pressure and temperature transducers
36 and 38 and to the power supply 46. The output of the data
conversion is operably connected to the input of the transmitter
means 54. The data conversion means may be any electronic means for
converting the pressure and temperature outputs of the transducers
36 and 38 into either a frequency or amplitude modulated signal
which is proportional to the pressure and temperature sensed by the
transducers 36 and 38 or to a binary coded signal or the like.
An antenna 56 is disposed within the lower end of the tubing 20 and
is operably connected to the output of the transmitter 54 by means
of a coax cable 58 which is sealingly disposed through the housing
attach means 24 and the insulation means 50.
Assuming that the output of the data conversion means 52 is in the
form of serial square wave pulses, FIG. 3 represents a schematic
diagram of a microwave transmitter means suitable for transmitting
the serial information from the data conversion means to the well
head.
Referring now to FIG. 3, reference character 54, generally
indicates the transmitter means and comprises an oscillator circuit
60, the output of which is connected to a harmonic tripler circuit
62. The power supply unit 46 is generally indicated by a battery
symbol in the circuit.
The oscillator circuit 60 generally comprises a transistor Q.sub.1
having the base thereof connected to the output of the data
conversion means 52 through a resistor R.sub.1. The emitter of the
transmitter Q.sub.1 is connected to ground or the negative output
terminal of the power supply 46 and the collector thereof is
operably connected to the emitter of a second transistor Q.sub.2
through an inductor L.sub.1 in series therewith. The collector of
the transistor Q.sub.1 is also connected to ground through a
resistor R.sub.2 and the emitter of the transistor Q.sub.2 is
connected to ground through a variable capacitor C.sub.1. The base
of the transistor Q.sub.2 is connected to ground through a resistor
R.sub.3 and a fixed capacitor C.sub.2 in parallel therewith. The
base of the transistor Q.sub.2 is also connected to the positive
output terminal of the voltage power supply 46 through a resistor
R.sub.4 and the collector of the transistor Q.sub.2 is connected to
the positive output of the terminal of the power supply 46 through
an inductor L.sub.2.
The output of the oscillator circuit 60 or more specifically the
output at the collector of the transistor Q.sub.2 is connected to
the harmonic tripler circuit 62 which comprises a pair of parallel
connected inductors L.sub.3 and L.sub.4 connected between the
collector of the transistor Q.sub.2 and the negative output
terminal of the power supply 46 through variable capacitors C.sub.3
and C.sub.4, respectively, in series therewith. The output of the
oscillator 60 is also connected to the antenna 56 through an
inductor L.sub.5 and a variable capacitor C.sub.5 connected in
series therewith.
In operation, data from the data conversion means 52, in serial
form, is applied to the input or base of the transistor Q.sub.1
through the resistor R.sub.1 thereby saturating the transistor
Q.sub.1 which places the emitter of the microwave transistor
Q.sub.2 near DC ground. This allows oscillation at the fundamental
oscillator frequency determined by the values of capacitors C.sub.1
and C.sub.2. The oscillator at fundamental frequency then feeds the
harmonic tripler network 62 which is tuned to pass the third
harmonic of the oscillator. The tripler 62 then feeds a coax to
wave guide antenna 56, the wave guide being formed by the tube or
pipe string 20 which is continuous from the bottom hole of the well
to the well head.
The optimum frequency of radiation for utilizing the well string or
pipe string 20 as a wave guide is found by the equation: ##EQU1##
where f is the frequency, c is the speed of light in the medium,
which in this case would be the reservoir product, and d is the
inside diameter of the pipe string 20. The speed of light in the
medium is found by: ##EQU2## where C.sub.o is the speed of light in
a vacuum (3.0 .times. 10.sup.10 cm/sec) and N is the index of
refraction of the medium or reservoir product which yields ##EQU3##
For example in the case of a 2 inch ID pipe string 20 (5.08 cm) and
a medium such as Benzene having index of refraction N = 1.5 the
output frequency from the tripler 62 would be ##EQU4## Therefore
the frequency of the oscillation 60 would be 1/3f or 8.75 .times.
10.sup.8 Hz.
Referring now to FIG. 4, reference character 64 generally indicates
a microwave receiver antenna which is located near the well head
but still disposed in the fluid medium. The antenna 64 extends into
the pipe string 20 through an aperture 66 therein, the aperture 66
having an insulated plug 68 therein with suitable seals 70 for
maintaining a fluid seal around the antenna 64. The antenna 64 is
coax connected by means of a coax cable 72 to the receiver means
generally indicated by reference character 26.
An ordinary microwave receiver may be used to receive the signal
but since high frequency receivers are relatively expensive, lower
cost components as indicated by the block diagram (FIG. 4) may be
used to reduce the effective frequency of the signal without
degrading the quality thereof. The receiver 26 generally comprises
a doubly balanced mixer 74, one input of which is operably
connected to the antenna 64 through the coax cable 72, a local
oscillator 76 being operably connected to the other input of the
doubly balanced mixer 74. The output of the mixer 74 may be either
tha sum of the signal frequency from the bottom hole and the local
oscillator frequency or may be the difference therebetween. By
utilizing the difference output, a substantially reduced frequency
may be utilized. The output of the mixer is then fed into an
intermediate frequency (IF) amplifier 78 which in turn is operably
connected to a detector 80. The output of the detector 80 is fed
into a data processing unit for converting the data into a readable
quantity which is proportional to either the pressure or
temperature of the bottom hole reservoir fluid 14. This data
processing unit may also be provided with a display means for
displaying said temperature or pressure indication and/or may be
provided with recording means for recording such information if the
well head unit is not attended.
It is readily apparent that the microwave system or instrumentation
unit at the bottom hole may be varied such as by the adoption of a
clock (not shown) for periodically operating the transmitter system
for conserving power in the power supply unit 46.
Referring now to FIGS. 5, 6, 7 and 8, FIG. 5 depicts an oil well
bore which is substantially identical to that of FIG. 1 and for
ease of description will carry the same reference character numbers
as that in the description of the borehole of FIG. 1.
The data instrumentation unit of the embodiment described in FIGS.
5, 6, 7 and 8 may be substantially identical to that hereinbefore
described and contains a power supply 46, pressure and temperature
transducers 36 and 38, which have elements 40 and 42, respectively,
exposed to the reservoir fluid 14. The electronics compartment 48
which is insulated by insulation material 50 also contains a data
conversion means 82 for providing a modulation signal which is
proportional to the pressure or temperature sensed by the
transducers 36 and 38. The output of the data conversion means 82
is operably connected to the input of a laser means 84. The output
of the laser is directed into one end of a fiber optic strand 86.
The instrumentation compartment also is provided with a light
sensitive or laser receiving means 88 which is likewise connected
to the end of a fiber optic strand 90. The fiber optic strands 86
and 90 extend through the bottom hole unit attach means 24 and the
insulation material 50.
Referring now to FIG. 7, the power supply 46 is operably connected
to the data conversion means and to the receiver 88. The receiver
88 may comprise any well known photo sensitive device having a
switching means 92 therein so that when a signal is received
through the fiber optic strand 90 into the receiver 88, the switch
92 will close thereby providing power through the receiver to the
laser 84. The laser 84 comprises a data input transistor Q.sub.3
and a diode laser D.sub.1. The base of the transistor Q.sub.3 is
connected to the output of the data conversion means 82 and the
collector thereof is connected to the power output of the receiver
88. The base of the transistor Q.sub.3 is operably connected to the
input of the diode laser D.sub.1 whereby upon the receipt of a
signal or serial data from the data conversion means 82, the
transistor Q.sub.3 will saturate thereby applying power from the
receiver means 88 through the said transistor Q.sub.3 to the diode
laser D.sub.1. A collimating lens 94 is connected to the end of the
fiber optic strand 86 so that the photo emission from the diode
laser D.sub.1 is collimated to be directed into the fiber optic
strand 86 for subsequent travel therealong to the well head.
Referring now to FIG. 8, reference character 96 indicates a well
head laser which may consist of a laser diode similar to that used
in the bottom hole instrumentation unit but which is used for
sending a signal into the upper end of the fiber optic strand 90 to
be directed to the bottom hole receiver means 88. The upper end of
the fiber optic strand 90 extends through the pipe string 20
utilizing appropriate sealing means 92, the end of the said fiber
optic strand being provided with a colliminator lens 98 for
collimating the photo emission therefrom and directing said
emission into the fiber optic strand 90. The well head
instrumentation system is provided with a receiver 100 which
comprises a photo sensitive switching transistor 102, the
sensitivity of which is controlled by a resistor R.sub.2 and a
potentiometer R.sub.3 which is connected to a negative output power
supply (not shown). The output of the photo sensitive transistor
switch 102 is operably connected to the emitter of a transistor
Q.sub.4. The transistor Q.sub.4 has the base thereof connected to
ground and the collector thereof operably connected to the positive
output terminal power supply (not shown) and thereby acts as a
current amplifier. The collector of the transistor Q.sub.4 is also
connected into a preamplifier 104 through a capacitor C.sub.6. The
output of the preamplifier 104 is then fed into a data processing
unit 106 for processing the temperature and pressure data and
reconverting the same back into a readable form which is
proportional to the actual pressure and temperature of the fluid
reservoir. The photo sensitive transistor switching means 102 of
the receiver 100 is positioned in alignment with the upper end of
the fiber optic strand for receiving the signal from the bottom
hole laser 84. The fiber optic strand 86 is also passed through the
pipe string 20 and is provided with a suitable sealing device
108.
In operation, when it is desirable to obtain pressure and
temperature readings from the bottom hole indicator unit, the laser
96 is turned on and photo emission therefrom is transmitted through
the fiber optic strand 90 to the bottom hole unit and into the
receiver means 88 therein. So long as the photo emission is present
at the receiver 88, the switch 92 thereof will be closed, thereby
applying power to the laser means 84 therein. Information from the
pressure and temperature transducers through the data conversion
means is applied to the laser 84, thereby modulating the said
signal or by creating coded pulses from the laser 84. The signal is
transmitted through the fiber optic strand 86 to the well head
where it is received by the receiver unit 100. There are obvious
modifications apart from those shown herein, such as by utilizing a
latching type switch in the receiver means 88 which would allow the
keying signal and the data information signal to utilize the same
fiber optic strand thereby eliminating one of the strands
thereof.
Referring now to FIG. 9, reference character 110 generally
indicates a pressure or temperature alarm system which may be
located with the bottom hole instrumentation unit 22 for providing
an alarm signal whenever the pressure or the temperature of the
product reservoir 14 either becomes too high or too low. The alarm
system 110 derives its power from the power source 46 and generally
comprises a status limit means or voltage divider type transducer
112 which is substantially identical to and represents either the
transducer 36 or the transducer 38 hereinbefore described. There
will normally be two alarm systems 110, which are exactly identical
and, hence, only one such system is described herein. Stated
another way, the alarm system 110 may be a pressure alarm system
and, if so, the transducer 112 would be one and the same transducer
as that of 36 having the voltage divider pressure sensitive element
40 exposed to the reservoir 14.
The transducer 112 is connected across the power source 46 in
parallel with a potentiometer R.sub.4 and a second potentiometer
R.sub.5 is connected in parallel therewith. The output of the
transducer 112 is connected to the positive terminal of an
operational amplifier A.sub.1 and is likewise connected to the
negative terminal of an operational amplifier A.sub.2. The output
or wiper element of the potentiometer R.sub.4 is connected to the
negative input terminal of the operational amplifier A.sub.1 and
the output or wiper element of the potentiometer R.sub.5 is
connected to the positive input terminal of the operational
amplifier A.sub.2. A delay action relay 114 is connected to the
power source 46 and a substantially identical delay action relay
116 is likewise connected to the power source 46. The output of the
operational amplifier A.sub.1 acts as the actuator of the delay
action relay 114 while the output of the operational amplifier
A.sub.2 acts as the actuator for the delay action relay 116. The
delay action relays 114 and 116 are for the purpose of conserving
electrical power during the alarm phase of operation. The relays
will energize the alarm generators 118 and 120 for a brief period
and then lock out further transmission for another period. The
delay time periods may be preselected by the user.
An upper limit alarm generator 118 is operably connected to the
delay action relay 114 so that whenever a signal is applied from
the delay action relay 114 to the high alarm generator thereby
causing an alarm signal to be generated thereby. A lower limit
alarm generator 120 is likewise connected to the delay action relay
116 so that power is applied thereto whenever an actuator signal is
generated by the operational amplifier A.sub.2. The output of the
high alarm generator 118 and the low alarm generator 120 are
applied as inputs to a transmitter 122 which may constitute the
microwave transmitter 54 of the first embodiment herein described
or the laser transmitter 84 of the second embodiment herein
described.
An example of operation for the alarm system 110, operational
amplifiers A.sub.1 and A.sub.2 are selected which will provide a
switching signal to the delay relays 114 and 116 only if the
voltage at the negative input terminals thereof exceeds the voltage
at the positive input terminals thereof. Under this theory of
operation, the potentiometer R.sub.4 is set at a point which is
representative of the highest reservoir pressure desired in the
working well, so that the voltage drop across that portion of the
potentiometer R.sub.4 between the positive output terminal of the
power supply 46 and the wiper arm of the potentiometer R.sub.4 is
always less than the potential drop across that respective portion
of the resistive element of the transducer 112 so long as the
pressure within the reservoir is less than the prescribed upper
limit. When the pressure within the reservoir exceeds the upper
limit, the wiper arm of the transducer 112 will move toward the
positive power terminal thereof thereby reducing the voltage at the
positive input terminal of the operational amplifier A.sub.1. When
this pressure exceeds the upper limit, the voltage applied at the
positive input of the operational amplifier A.sub.1 will be less
than that at the negative input terminal thereof which will cause
the amp. A.sub.1 to generate an output signal to the delayed relay
mechanism 114 which will in turn after a predetermined delay, close
the switch therein and apply power to the high alarm generator.
This alarm generator will then key the transmitter 122 to send an
alarm signal to the well head, either by microwave signal or by
fiber optics, whichever embodiment is being used.
Likewise, the lowest desired pressure limit may be set into the
potentiometer R.sub.5 so that so long as the pressure in the
reservoir 114 is greater than the lower limit prescribed by the
setting of the potentiometer R.sub.5 no signal will be produced
from the operational amplifier A.sub.2. However, when the pressure
of the reservoir 14 becomes too low, the voltage level at the
negative input terminal of the operational amplifier A.sub.2 will
become higher than the voltage present at the positive input
terminal thereof which causes an actuator signal to be transmitted
to the delay relay mechanism 116 thereby applying power to the low
alarm generator, said alarm signal being transmitted by the
transmitter 122 to the well head.
As hereinbefore stated, it is readily apparent that the same
identical alarm circuit may be used for a temperature alarm system
which could work in parallel with the system hereinbefore described
and the alarm system could be easily connected to work with the
microwave and laser measuring system hereinbefore described.
From the foregoing, it is apparent that the present invention
provides a novel well bottom hole status system for measuring fluid
reservoir pressure and temperature at the bottom of a well bore.
This measuring system may also embody a unique alarm system for
providing an alarm at the well head whenever the fluid reservoir
exceeds the prescribed temperature or pressure levels.
Whereas, the present invention has been described with particular
relation to the drawings attached hereto, it is readily apparent
that other and further modifications apart from those shown or
suggested herein, may be made within the spirit and scope of this
invention.
* * * * *