CN102322999B - Ergometer for downhole load survey tool - Google Patents

Abstract

The present invention describes a kind of ergometer for downhole load survey tool.This ergometer includes the multiple strain gauges being arranged to the balanced array of such as Wheatstone bridge.The array of strain gauge is arranged in a fluid, and this fluid is in use under the pressure identical with the downhole fluid of surrounding.Owing to balanced array is in the pressure identical with the fluid around this, it is not necessary to ergometer is carried out pressure calibration.Preferably it is arranged to ergometer measure the shear strain crossing over this ergometer.

Description

Ergometer for downhole load survey tool

Technical field

The present invention relates to the ergometer (load cell) for downhole load survey tool, such as, survey Measure and applied the tension force to oil well Well logging rope or pressure by steel wire rope or drafting tool.

Background technology

Drilling well Well Logging Engineering teacher often needs load measure sensor is arranged on logging tool rope Between the bottom of top and steel wire cable, such as in cable head.This has monitored and has been applied directly to The axial load of instrument rope.This is used to determine that instrument rope the most blocks and/or steel in down-hole Whether the tension force in cord is close to the important measurement of breakaway poing of cable head.Cable head load-transducing Device also helps Well Logging Engineering teacher to determine in the drilling well of highly deviated at run duration by steel wire rope It is applied to the power on instrument rope with traction apparatus.

Design lines cable end load unit time institute facing challenges is by independent by down-hole hydrostatic pressure The axial load produced separates from the load applied by steel wire rope or traction apparatus.In deep-well, quiet Water pressure will cause applying the tens thousand of pounds of axial compressive force to instrument rope, and this compression stress compares Big potential steel wire rope power is order of magnitude greater.

US 2008/0216554 discloses acquisition down-hole pressure and the subsurface dynamograph of temperature information. This down-hole pressure and temperature information are for calibrating the reading of subsurface dynamograph.It would be desirable, however, that Be need not to obtain temperature and pressure measured value and then ergometer be carried out temperature and pressure Calibration, because which increasing manufacturing time and requiring that ergometer has needs when measuring The compensation file prepared and use.

Summary of the invention

According to the present invention, it is provided that for the ergometer of downhole load survey tool, this ergometer Including multiple strain gauges of the balanced array being arranged to such as Wheatstone bridge, and wherein strain The balanced array of meter is arranged in a fluid, and in use, this fluid is in the down-hole stream with surrounding Under the pressure that body is substantially the same.

Owing to being compensated by the balanced array of strain gauge, thus do not require ergometer is carried out pressure or Temperature correction.Therefore, manufacturing time significantly shortens and needs not compensate for file.

Ergometer is preferably arranged to for measuring the shear strain crossing over ergometer.Use and shear Strain gauge rather than uniaxially gauge also allow for the raising of precision because ergometer without resolve bore The steel wire rope load at the top of well pressure.

Strain gauge ergometer is firm, simple, has good sensitivity and is highly linear.

Ergometer preferably has beam, is provided with the balanced array of strain gauge thereon, and should Beam preferably has at least one bool, and this bool is arranged to when axial force is applied to survey Power timing bends.

The downhole tool including ergometer can be provided.Downhole tool may be included in and which provided survey The cable head of power meter.

Accompanying drawing explanation

Now only with reference to appended figure, embodiments of the invention will be described by example, wherein:

Fig. 1 shows the downhole unit in the well being positioned at drilling well；

Fig. 2 shows the ergometer of an example of the present invention；

Fig. 3 is the more detailed see-through view of the ergometer shown in Fig. 2；And

Fig. 4 schematically illustrates the elastic strain that ergometer is experienced under load effect.

Detailed description of the invention

Fig. 1 illustrates the downhole unit 10 in the well 20 being positioned at drilling well.

Downhole unit 10 is from the steel passed through from cylinder 40 via the pulley 50 being arranged at earth's surface Cord 30 is suspended in midair.Ergometer may be provided at any suitable position, such as in cable head 11. Being schematically illustrated as in Fig. 1, downhole unit 10 may be blocked in the wellbore.

Fig. 2 shows the ergometer 12 can being used together with the downhole unit 10 shown in Fig. 1. In this example, ergometer 12 is arranged between top connection 13 and lower contact 14.Strain gauge 15 be attached to bool 16 and whole ergometer be immersed in be in identical with the drilling fluid of surrounding Hydrostatic pressure under fluid 17 in.Strain gauge 15 is specifically designed weighs bool 16 In shear strain, and bool be arranged as axial load apply to ergometer 12 time curved Bent.Ergometer 12 includes some groups of four stress gauges.Each group is disposed to measure in beam 18 Shear strain, and all strain gauge is arranged to the balanced array of such as Wheatstone bridge.And All strain gauges 15 of non-constitutive Wheatstone bridge show the most in fig. 2, because some strains Meter is by other side of beam 18.Owing under outer well, hydrostatic pressure is passed through can be such as piston, The pressure compensator 19 of barrier film etc. applies, and the material experience of bool 16 is produced quiet Water stress, the four stress gauges in each group of balanced array stands the strain of equivalent, and balances Unaffected.Similarly, downhole temperature change affect the most equally in balanced array all answer Become meter, and do not affect the balance of array.But, when axial load applies to ergometer, curved Bent part 16 occurs shear strain and bridge balance correspondingly to change.This changes by embedding this single The electronic device (not shown) sensing of unit.

Fig. 3 shows the more detailed see-through view of ergometer 12.Visible two strain gauges 15 Orient perpendicular to each other.Similarly, two other strain gauge (not shown)s are the most same Sample is arranged on the opposition side of beam 18.In this example, each strain gauge 15 is resistive element, And four individual resistors elements use suitable electrical connection 20 to be arranged to Wheatstone bridge.

Beam 18 can be made up of any suitable material.In this example, beam 18 is by stainless steel Become.Beam material is preferably chosen to the springform with material that is basic and that make strain gauge 15 The elastic modelling quantity that amount matches.In this example, beam 18 is made up of 17-4PH rustless steel.No Rust steel can carry out heat treatment to provide enough intensity, thus stands subsurface environment.

Fig. 4 schematically illustrates when ergometer 12 stands the load of 12000N by beam 18 The elastic strain stood.As can be seen from Figure 4, cross over ergometer and can experience answering of varying level Becoming, particularly maximum strain is experienced around bool 16.During use, at beam 18 Different piece in experience these different strains detected by multiple strain gauges 15.Produce Electronics output (strain gauge 15 by being arranged to Wheatstone bridge produces in this example) is by such as Microprocessor or the suitable controller detection of circuit (not shown), thus provide ergometer 12 Indicating of that suffer and that therefore downhole unit 10 is suffered load.

It is as noted previously, as strain gauge 15 and is arranged to balanced array and via pressure compensator 19 Suffering down-hole pressure, this causes ergometer 12 due to down-hole pressure the most equably Strain so that the balanced array of strain gauge will actually due to the overall strain that down-hole pressure records It is zero.

Use full Capella oil on the ergometer that stress test is shown in fig. 2 encloses rusting Bottle is carried out, and this ergometer immerses in Capella oil.Before using DVM to read, Wheatstone bridge uses the reality with the balanced voltage being amplified 100 times by operation amplifier circuit Test room power supply and supply power to +/-5 volts.Construct with this and by the full load of 12000N, find The sensitivity of this ergometer 12 is 11.7N/mV.Experimental result find, from 0 to 20000psi(1.38×105kN/m²) change the Wheatstone bridge that ambient pressure causes some millivolts Balanced voltage on maximum change, it represents less than 0.5%, is more typically 0.2% or more The little error recording load so that without down-hole pressure change is compensated, it is provided that more Simply, control more reliable and more at a low price is arranged.

Also carry out experiment to determine whether there is in the temperature owing to being caused by downhole fluid The change any impact on the sensitivity of the balanced array of strain gauge, ergometer will be in this down-hole Fluid uses.

Record ergometer balanced voltage and the data logger of ergometer temperature being attached to simultaneously Time, in Fig. 2 diagram ergometer be baked in an oven, and temperature from room temperature cycles until 177℃.Have been found that error that the change of thus environment temperature experienced less than 0.5%, more typical Ground is 0.2% or less.This deviation sufficiently small thus without mending in sensor electronics Repay, it is provided that control simpler, more reliable and more at a low price is arranged.

Ergometer mentioned above is used to cause strain gauge 15 in down-hole pressure and temperature environment All somewhat shorten under the acting by external hydrostatic pressure raised, and the temperature owing to raising somewhat becomes Long.But, although the pressure and temperature that ergometer 12 is raised, but the battle array of strain gauge 15 The balance of row is maintained.But, as illustrated in our Fig. 4, when ergometer 12 (employ the load of 12000N in the example of fig. 4) when being loaded, cross over ergometer There are differences in the strain of 12.This difference creates one of principal vector in sensing, the most outwardly Other point make two strain gauges 15 become longer, other two become shorter simultaneously, change Become the balance of Wheatstone bridge.Change in this balance creates what instruction ergometer was suffered The output voltage of load.

Ergometer 12 is calibrated, so that the controller of association provides ergometer 12 to be suffered The instruction of load, such as, such as map to corresponding negative by use by the output voltage of balanced array The inquiry table carried or similar algorithm.The load that ergometer 12 is suffered, and therefore instrument The instruction of load that rope is suffered can show the suitable operator at earth's surface, or storage with For analysis after a while, or for both.

The favorable factor of embodiments of the invention is to use to shear in pressure balanced environment to answer Becoming meter, strain gauge stands from the directive full hydrostatic pressure of institute in this context.

Use this to construct another advantage to be, under the influence of temperature and hydrostatic pressure, should Dependent element all produces same amount of deformation, in theory will not be in the balance of such as Wheatstone bridge Array produces the change of entirety.Only it is supported in ergometer when do not associate with pressure and temperature The change in balance is just produced during appearance.In practice, due to the defect in strain gauge 15, Some error deviations will be had.Ignore however it has been found that this deviation is sufficiently small to being thought of as.

It is notable that the ergometer using one embodiment of the present of invention creates in Measurement Resolution Improve, and the calibration process being greatly simplified.The output of ergometer is substantially linear, therefore Available three measurement points are calibrated.Temperature or pressure calibration is carried out also without to instrument, because This is compensated by the balanced array of the wheatstone bridge arrangement of such as strain gauge.This is significantly reduced Manufacturing time, and eliminate the need being supplied to client together with instrument and compensating file Want.

Above-mentioned example can be made a lot of change and still fall within the scope of the present invention.Such as, Although illustrating two bools, but one or three or more bool can be used.Additionally, In use, any suitable pressure compensator of such as piston, barrier film, bellows etc. can be used Hydrostatic pressure under outer well is applied the fluid to ergometer by 19, pacifies in this ergometer Put the balanced array of strain gauge.

Claims (9)

1., for an ergometer for downhole load survey tool, described ergometer includes:

Being arranged to multiple shear strain meters of balanced array, wherein shear strain meter is described flat Weighing apparatus array is arranged in a fluid, and in use, described fluid is in the downhole fluid with surrounding Under essentially identical pressure；And

Pressure compensator, it is configured to hydrostatic pressure be applied in described balanced array, its Described in balanced array be configured to each institute of described balanced array when by hydrostatic pressure State shear strain meter as one man to strain.

Ergometer the most according to claim 1, it is characterised in that described ergometer is arranged Become to measure the shear strain crossing over described ergometer.

3. according to the ergometer described in claim 1 or claim 2, it is characterised in that institute State ergometer and there is beam, described beam is provided with the described balanced array of strain gauge, and Described beam includes being arranged as when applying axial load to described ergometer bending at least one Bool.

Ergometer the most according to claim 3, it is characterised in that described beam has layout Two bools on the not homonymy of described beam.

Ergometer the most according to claim 4, it is characterised in that the springform of described beam Amount substantially matches the elastic modelling quantity of described strain gauge.

Ergometer the most according to claim 1, it is characterised in that described balanced array is Wheatstone bridge.

Ergometer the most according to claim 1, it is characterised in that the institute of shear strain meter Stating array to arrange in a fluid, in use, described fluid is also in and described well around At a temperature of lower fluid is essentially identical.

8. a downhole load survey tool, including according to described in arbitrary aforementioned claim Ergometer.

Downhole load survey tool the most according to claim 8, it is characterised in that described Downhole load survey tool has cable head, and described ergometer is arranged in described cable head.