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CA2127809A1 - High temperature stabilized time base - Google Patents

High temperature stabilized time base

Info

Publication number
CA2127809A1
CA2127809A1 CA002127809A CA2127809A CA2127809A1 CA 2127809 A1 CA2127809 A1 CA 2127809A1 CA 002127809 A CA002127809 A CA 002127809A CA 2127809 A CA2127809 A CA 2127809A CA 2127809 A1 CA2127809 A1 CA 2127809A1
Authority
CA
Canada
Prior art keywords
time base
isolation enclosure
predetermined temperature
stabilized time
temperature range
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
CA002127809A
Other languages
French (fr)
Inventor
Kenneth L. Jones
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Western Atlas International Inc
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of CA2127809A1 publication Critical patent/CA2127809A1/en
Abandoned legal-status Critical Current

Links

Classifications

    • HELECTRICITY
    • H03ELECTRONIC CIRCUITRY
    • H03LAUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
    • H03L1/00Stabilisation of generator output against variations of physical values, e.g. power supply
    • H03L1/02Stabilisation of generator output against variations of physical values, e.g. power supply against variations of temperature only
    • H03L1/04Constructional details for maintaining temperature constant
    • GPHYSICS
    • G05CONTROLLING; REGULATING
    • G05DSYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D23/00Control of temperature
    • G05D23/19Control of temperature characterised by the use of electric means
    • G05D23/1906Control of temperature characterised by the use of electric means using an analogue comparing device
    • GPHYSICS
    • G05CONTROLLING; REGULATING
    • G05DSYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D23/00Control of temperature
    • G05D23/19Control of temperature characterised by the use of electric means
    • G05D23/20Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Oscillators With Electromechanical Resonators (AREA)
  • Geophysics And Detection Of Objects (AREA)
  • Measurement Of Unknown Time Intervals (AREA)
  • Control Of Temperature (AREA)

Abstract

To provide stable, accurate time reference signals for control and operation of a well logging instrument (12), a temperature isolation enclosure (14) defines an internal cavity (16) for containing and protecting an electronic time base (10). An electronic timer (10) such as a crystal oscillator is located within the oven cavity (16) and is electronically stable at a predetermined temperature range slightly higher than the highest ambient temperature encountered within the wellbore. A heating element (18), control circuit (22), and a temperature sensor (24) are provided within the oven cavity (16) to maintain the timer (10) within the predetermined temperature range. An automatically energized cooling element (20) may also be provided within the oven cavity (16) for additional temperature control.

Description

WO ~4Jl1763 PC~US93/10932 -1- 2 l 2~

RIGlEI TEM[PERA~URE STABILlZED TIME BASE ``
~. ~
This inv~n~on relates generally to the provision of a stabilized dming refaence such as is pro~rided by solid state timers, ~ystal oscill~ors and le lil~e.
More par~cularly, ~e present invention is directed to ~e provision of a stable timing refe~ence in downhole well logging ins~uments for provision of a stabilized ~me S refe~enæ signal for effective instrument ope~ation over a large spectrum of ope~ating t~:mp~a~res w~e eli~tillg ~ypical loss of acculaey due to tempe~ature va~iations, L~ne loss and ~ew caused ~y ~e resistance and capac:itance of the lengthy wireline rsquir~d for a well logging ~pera~on.
'Timing devices (i.e., solid state ~mers, such as crystal oscillators and the li~) are well Ic~own to be quite sensitive to changes in tempe~ture. Though stable at a ce~in tempesa~re, changing the temperature deg~des ~eir stabili~,r. It is d~able, ~e~efors, to pro~ide means for maintaining the ~ming device within a designated, quite nanow temperature ~nge that permits tSe timing device to ope~ate st ma~umum efficiency and accu~acy.
~ ~ : It is well hloun ~at the ambient tempe~ature of ~e downhole well : = Dment varies with depth and well loca~on. ~hus, during a downhole well O~Ulg:apO~Dd, the loggin~ ins~ment will t~pically encou~ter a wide variety of ambieDt ~elah~les dq~nding upon its loca~on in the well bore. Some of these b~pahL~ ~y be above or below the stable operating tempe~ure~ Tange of c~ys~
oseillators and other tin~ing devices. It is desirable, ~erefore, to p~ide novel means fo~ p~viding a stable ~dIri~n~g refe~w by maintaining ~e timi~g device at a f~Rd, d~ Oemp3ab~re above ~at of ~he maximum ambient tempeIature of use, while op~ting in a well logging environment where the ambient ~mperatuJe v~ies witb depth and well location.
It is a principal feature of the present invention to provide a novel high temperature stabilized time base for well logging operations which generates a stable Wo 94/11763 Pcr/us93/lo932 2127~9 referenee signal at the logging ins~ument and maintains ~e signal generating device of the log~ng instrument witllin a predetern~i~ arrow temperature range within which the ~ming device maintains its operational st~bility.
It is another feature of this inven~orl to provide a no~lrel high tempe~
S stab~d ~me base for well logging instruments which maintains ~e ~ming device or dev~ces thereof w~thin a predetermined, na~Tow tempe~ature lange regardless of the ambient temperah~re that is encountered at any paIficular depth within the well bore.
It is an even filrther feature of ~is invention to provide a novel high tempe~ure s~abilized time base for logging ins~uments wherein ~e timing device or devices are ~aintained within a ~a~row tempe~ture range which is an elevated tempe~ature r~nge above that of the ma~imum ambient temperature of use while ~peratin~ in a well logging environment where the ambient temperature va~ies with depth and well location.
It is also a fe~ture of the present inven~on to provide a novel stabilized timing base system for o~etational control of well logging instruments which permits controlled maintenance of a tining device such as a crystal osciL~ator within a temperatwe range that is less ~an the highest tempe~re that will be enoountered by a logging instrument at ope~atioDal depth within a well bore.
Bdefly, the various feahlres of the present invention are achieved ~ough the provision of a sy~tem for maintaining a high temperature stabilized ~me base which comprises a low thermal~onduction oven or isolation enclosur~ of sufficieJ~t dimension to accommodate the ~dme base and con'aol circui~y. l~e lowthermal conduc~on o~ien is provid~ a hea~ng and/or ~oling dement cy~able of mainl~ining a ~equired mass within a predete~mined temperature ~ange. The hea~nglcooling oven is provided wi~ a con~ol ~it having a tempe~atwe sensor ~at is designed to mo~itor intemal oven temperature and regulate ~e supply of ele~ical power to ~e heater or to ~e cooling element as the case may be. To provide ~or stability of the timing device, such as a c~ystal oscillator for example, a ~ming device is p~ovided which is s~ecifically design~d to have frequency stabili~r at a predetermined elevated temperature ~ange. The circuit components of the time base is maintained at :`

wo g4/1 1763 Pcr/lJS93/10932 ~l21~0~
. 3 ~he pr~de~mined ele~ted tempelature regardless of well ~empe~ e to thus ensure ~he s~abili~ of ~e ~me b~e in the downhole envir~nment. Where excessively ho~ well condi~ons are encountered, or if ~e ~me base circuitry is stable only at a tempe~ature lower ~an the ambient temperatwe of the well the protective enclosure for the circui~
S may also be provided with con~olled cooling to maintain ~e tempe~atwe of ~e ~me base wi~in the range of its stabili~
So ~at ~e manner in which the above recited features, advantages and objects of the present invention are attained and can be understood in detail, a more par~cular descrip~oD of the invendon, briefly summarized above, n~y be had by refe~ence to ~t' embodiments ther~of which are illus~ated in the ap~ended drawiDgs.
Xt is ~o be noted, however, that the appende~ drawings illustrate ~nly ~pical embodime~ts of this invention and are the~efore not to be considered limiting of îts scopc, for the invention may admit to o~er ~qually eff~ve embodiments.
Pig. 1 is a block diag~m schema~c illustration of a high tempe~
stabilized time base for well logging instruments which is constructed in accordance with ~e fea~s of the present invention.
Pi~. 2 is a sectional view of the beat maint~ining oven of the stabilized ~me base of ~ig. 1, showing the temperature generation and ¢ontrol devices together with the time base signal genera~ng device being located within ~e tempe~ature control overl.
Pig. 3 is a bloclc dia~ elec~onic schemadc re~resen~ng an altemative en bodiment of ~e ~nt invell~on, for selectively heating or cooling the e~ectronic Girt:111tFy.
Refemng now to Figs. 1 and 2 of ~e d~awings, a stabilized time base system shown generally at 10 is provided for incolpora~on within a downhole welllogging i~strument, a portion of which is sllown at 12. The stabilized time baseincludes a low ~ennal~onductive oven or isolation enclosure 14 is located wi~in the logging instrument 12 and functions as a thermal isolator which is used to contain heat for the pu pose of maintaining the efficiency of elec~onic circuitry disposed within an inte~nal compartment 16 thereof. The low thermal- conductive oven also functions to WO 9~/11763 Pcr/u~93~10932 212~809 ~

isola~e the heat contained ~erein to lessen the ef~ects of thennal ~ansience to which the ins~ument 12 m~ght be subjected. The oven stlucture is ~Iso employed as ~e means of mounting the hardware to a backbone. The cavi~r or compartment 16 of the o~en structure is of a dimension and design for effec~ve support of the elec~oluc time S base and heat control circuit~y. The oven structu~e i5 composed of a mate~ial such as polyether ethe~ Icetone having a low th~ conductivity and having a c~cteristic of acceptable thermal expansion. The oven structure is composed of a ma~erial that is easily macbinable or molded for the complex shapes that ~nay be required wi~in the oven cavity 16.
Withiin the oven cavity 16 is located an elec~iically ene~gized heating element 18 ha~ing the capabiliq of producing sufficient heat to maintain an internal oven temperature at the lowest required ambient temperatuge t~t is expe~d to be encoon~ed v~i~iin the well bare. l~e electroniic hea~ng element has the capabili~ of being energiized ~om an ele~ic power ciircuit 23 by elec~iical energy from a suitable lS source 25 such æ a sup~ly cable, onboard battery, etc.
As sbown in the alternative embodiment of Fig. 3, in additial to the heating element 18, there is provided in the oven cavi~ 16 a cooling element 20 which is electrically energized and controlled through a control ciircuit 22. The cooling elemerlt is utili~ed whe~ the ambient borehole t mperature is abo~le ~at of ~e osciL~ator's stable ~ ating tempe~atu~, thus requiriDg ~ling in order to maint~in ~e o~e~ cavity 16 witbin a p~ede~ermined tempelature sange ~or stabili~r and efficiency of ~e timing d~ce. The coolirlg element may employ Pel~er- Junc~on cooling to lower ~e oscillator's temperature when required to maintain its opera~onal stabili~
Within the oven cavi~ is provided a temperature sensor 24 which provides temperature signals via conductor 26 to the control circuit 22. In &e embodiment of Fig. 1 ~ae con~aol ci~cuit induces ener~ization of ~e heating element 18 periodically in or~er ~ maintain ~e tempeIaturc of the cavity 16 and its circuit components wi~in a na~w predetennined temperature range, being ~e temperahure ~ange within whicb ~e ~ming signal generator is stable. As shown in Pig. 3, the control circuit 22 is selectiYely coupled via con~ol conductors 28 and 30 to the cooling , WO 94/11763 Pcr/uss3/lo932 8 ~

.. .
elemellt 20 and to ~e heating element 18. Thus the hea~ng and cooling elements a~e `. selectively energized by ~e control circuit æ to in~u~ hea~ng or cooling into the ~ m 16 to compensate for heat gain or loss and ~ereby maintain a prede~ermined , typically quite narrow tempe~ature ~nge within ~e cavity. Within ~e oven cavity is S also located a signal generator circuit 32 which may convenien~y take the form of a c~stal oscillator circuit having a predete~ed timing frequenc3r ou~ut signal viaoutput conductor 34 which extends ~rough the oven wall structure. As shown in Fig.
. 2 the oont~ol ci~cuit 22 may convenien~y be defined by a circuit bd having ~
appropriate elec~ical components for receiving ~e temperature signal of the sensor 24 ~ -and pro~nding ~pera~on and control signals to the hea~ng element t8 or cooling -element 20. The temperature sensor of the o~nt~ol circuit will t~rpically sense temperatu~e of the time base substrate ~thin a ~ange of about 1 C. ~e temperature '. is mon~tored and f~back signals of the tempelature sensor are used to control ~e heater/cookr circuits, thus maintaining the desired tempe~ature within the oven . lS compartment. To maintaisl the accuracy of the control circuit, the power source for the temp~ature sensor must also be maintained at the elevated temperature of the oven compartment to eliminate circuit temperature induce~l circuit drift. Temperaturefluctua~ons outside the oven affect the heat loss of the oven. 'rhe control circui~y must sense ~is change and compensate ascordingly.
~ The crystal oscillator is a ~Iy designed part that has integrated ten~alule stabilit!y at lhe desired elevated tempe~at~. The specific crystal oscillator design is not a pa~t of tbis invention e7~cept to the eJctent ~at it and its tempe~ature for effative stabili~ of op~on are ~tained wi~in an appropriate typically narrow prede~ed temperature ~nge and it thus provides a stable timing ~eference ove~ a large spectrum of c~ting tempe~atures ~anging from 20~ C to 30~ C and above, wbich temperature ~anges are common in dee~ petroleum wells. Tbe c~ystal osciLator or other frequency output generator is ~us capable of providing a consistent and stable output signal which maintains its accu~r ~ven though the apparatus is subjected to tempe~ature ~ariations. Since the electronic timing signal is generated at ~e downhole well logging inst~ument, it is not subjected to temperature varia~dons, line loss and Wo 94~11763 pcrJuss3/1o532 2~21~09 : ~

skew that might otherwise be caused by the resistance and capaeitance of the lengthy wireline that is ordinarily ~equired for well logging opaa~ons. Even ~ough significaslt changes in ambient tempe~ature are encountered by the well logging instrument during its trave~se of ~e borehole, or its use a~ different borehole depths, the crystal oscillator or other frequency ou~put device is capable of maintaining a consistent and a~cu~
timing frequency output signal ~ause it is not adw~sely influenced by ambient temperatu~e changes. Typically, the temperature within the internal cavity of the low thermal conductive oven is maintained at a narrow temperature range ~at is above ~e maximum temperature that is expected to be encountered by the logging instrument at any depth in the well bore. In sircumstances where the well bore temperature exceeds the predetermined tempera~ure range for which the crystal oscillator is designed to have its ~equency st~bility or time base circuitry is employed which is stable only at a tempe~ature range that is lower than the ambient wellbore temperature at forma~on _ . depths, the temperahlre control system will be also provided with a cooling element lS capable of cooling ~e tempe~atwe of the oven compartment and its circuit components tothede~rednarrowtemperaturerange.
In view of the foregoing, it is evident that the present invention is one well adapted to attain all of the objects and fe~tures hereinabove set ~or~, together with other objects and feah~es which are inherent in the apparatus disclosed herein.
As will be ~adily apparent to those sldlled in ~e art, ~e present invention may be produoed in other specific forms wi~out depar~ng f~m its spirit or essential cbalac~cs. Ihe present embodiment, is ~erefore, to be considered as illustrative and not ~estrictive, ~e sco~e of the invention being indicated by the claims rather ~an the foregoing descnpdon, and all changes which come wi~in the me~u~ing and ;ange of ~e equivalence of ~e claims are therefore intended to be embraced ~erein.

~Vhat ~ im~d is:

Claims (16)

CLAIMS:
1. A stabilized time base for a well logging instrument utilized for conducting logging operations, comprising:
(a) an isolation enclosure being disposed within said well logging instrument;
(b) heating means being disposed within said isolation enclosure;
(c) control circuitry for said heating means being operative for monitoring the temperature within said isolation enclosure and for regulating electrical power to said beating means to maintain the temperature of said isolation enclosure within a predetermined temperature range; and (d) an electronic timing device being located within said isolation enclosure and having timing stability when maintained within said predetermined temperature range to provide stable timing reference signals for operation of said well logging instrument.
2. The stabilized time base of claim 1, wherein said electronic timing device comprises:
a solid state electronic timer capable of supplying a stable reference signal when maintained within said predetermined temperature range.
3. The stabilized time base of claim 1, wherein said timing device comprises:
a crystal oscillator capable of supplying a stable reference signal when maintained within said predetermined temperature range.
4. The stabilized time base of claim 1, wherein said heating means comprises:
an electrically energized heating element being disposed within said isolation enclosure having sufficient heating capacity to maintain said predetermined temperature within said isolation enclosure.
5. The stabilized time base of claim 1, wherein:
said predetermined temperature is higher than the highest temperature expected to be encountered within said well bore.
6. The stabilized time base of claim 1, including:
cooling means being disposed within said isolation enclosure for controlled energization by said control circuitry for maintaining the temperature within said isolation enclosure within said predetermined temperature range.
7. The stabilized time base of claim 1, wherein said control circuitry includes:
(a) a temperature sensor for detecting the temperature of said isolation enclosure and having an electronic temperature signal output; and (b) a heating controller being responsive to said electronic temperature signal output for selective energization of said heating means.
8. The stabilized time base of claim 1, wherein said isolation enclosure comprises:
(a) a low thermal conductive enclosure being located within said well logging instrument and defining an oven cavity;
(b) said heating means, control circuitry and electronic timing device being located within said oven cavity; and (c) a frequency output conductor being coupled in signal transmitting relation with said electronic timing device and extending through said low thermal-conductive enclosure.
9. A stabilized time base for a well logging instrument utilized for conducting logging operations, comprising:
(a) an isolation enclosure being disposed within said well logging instrument;
(b) heating means being disposed within said isolation enclosure;
(c) control circuitry for said heating means and said cooling means being operative for selectively regulating electrical power to said heating means and said cooling means to maintain the temperature of said isolation enclosure within a predetermined temperature range;
(d) a temperature sensor being located within said isolation enclosure and having an electronic temperature signal output being coupled in signal transmitting relation with said control circuitry; and (e) an electronic timing device being located within said isolation enclosure and having timing stability when maintained within said predetermined temperature range to provide stable timing reference signals for said well logging instrument.
10. The stabilized time base of claim 9, including:
cooling means being disposed within said isolation enclosure and being energized by said control circuitry for cooling said isolation enclosure to said predetermined temperature range.
11. The stabilized time base of claim 9, wherein said electronic timing device comprises:
a solid state electronic timer capable of supplying a stable reference signal when maintained within said predetermined temperature range.
12. The stabilized time base of claim 9, wherein said timing device comprises:
a crystal oscillator capable of supplying a stable reference signal when maintained within said predetermined temperature range.
13. The stabilized time base of claim 9, wherein said heating means comprises:
an electrically energized heating element being disposed within said isolation enclosure having sufficient heating capacity to maintain said predetermined temperature within said isolation enclosure.
14. The stabilized time base of claim 9, wherein:
said predetermined temperature is higher than the highest temperature expected to be encountered within said well bore.
15. The stabilized time base of claim 9, including:
cooling means being disposed within said isolation enclosure for controlled energization by said control circuitry for maintaining the temperature within said isolation enclosure within said predetermined temperature range.
16. The stabilized time base of claim 15, wherein said cooling means comprises:
a Peltier-Junction cooling element being located within said isolation enclosure and being coupled for power and control by said control circuitry.
CA002127809A 1992-11-13 1993-11-11 High temperature stabilized time base Abandoned CA2127809A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US97588292A 1992-11-13 1992-11-13
US07/975,882 1992-11-13

Publications (1)

Publication Number Publication Date
CA2127809A1 true CA2127809A1 (en) 1994-05-26

Family

ID=25523531

Family Applications (1)

Application Number Title Priority Date Filing Date
CA002127809A Abandoned CA2127809A1 (en) 1992-11-13 1993-11-11 High temperature stabilized time base

Country Status (4)

Country Link
EP (1) EP0635137A4 (en)
CA (1) CA2127809A1 (en)
NO (1) NO942573L (en)
WO (1) WO1994011763A1 (en)

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Also Published As

Publication number Publication date
WO1994011763A1 (en) 1994-05-26
NO942573D0 (en) 1994-07-08
EP0635137A1 (en) 1995-01-25
NO942573L (en) 1994-07-08
EP0635137A4 (en) 1995-04-19

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