RU2036301C1 - Method for determination of wear of drill bit bearing and cutting structure during well drilling by screw downhole motor - Google Patents

Abstract

FIELD: monitoring and control of drilling process. SUBSTANCE: in course of well drilling, frequency and amplitude of electric analogs of hydraulic pulses produced during operation of screw downhole motor and drill bit cutting structure are measured in flow of drilling mud at wellhead by means of piezoelectric detector. Wear of drill bit bearing and cutting structure is determined by comparison at each time moment of values of frequencies and amplitude of electric analogs of hydraulic pulses. EFFECT: higher accuracy of method due to increased body of information from hole bottom which aids in determination of causes of changes of situation at hole bottom in drilling well by screw downhole motor. 3 dwg

Description

 The invention relates to the field of monitoring and control of the drilling process and can be used to optimize the process of drilling wells using screw motors or other hydraulic downhole motors containing in their design a working pair (stator-rotor) of a screw motor.

A known method for determining the wear of the support and armament of the bit, based on the application of the theory of pattern recognition when processing information about the parameters of the drilling process, obtained using the appropriate sensors [1]
In this method, preliminary experimental studies determine the reference values of signals from the sensors about the weight of the drilling tool, the amplitude and frequency of the torsional self-oscillations of the drill string that occur when the bit interacts with the face, the mechanical drilling speed and pressure in the discharge line of the drilling pumps corresponding to other situations. Each of these situations, for example, a chisel support pin, complete wear of its weapons, etc. characterized by certain values of the above drilling parameters. On the reference features for all technological situations, a matrix is compiled and laid in the unit analyzers of the device.

 Subsequently, when drilling wells using the known method, the drilling parameters controlled by sensors are compared at each moment of time with their reference values, the values of which are set based on the probability of deviation detection that is optimal for a given situation. If the signals entering the device during drilling coincide with the reference values, this or that downhole situation is recorded that characterizes the wear of the support or armament of the bit.

 The disadvantage of this method is that to determine the reference values of the parameters characterizing the wear of the support or armament of the bit during drilling, a larger amount of experimental research is required, since the values of these parameters and their combination largely depend on the physicomechanical properties of the drilled rocks, differing, for example, in Western Siberia, a great variety, as well as from a number of technological factors (profile of the well being drilled, type of flushing fluid, etc.).

 The disadvantages of this method also include the use of drill pipe string for transmitting vibrations arising from the interaction of the bit with the face. Recently, when drilling oil and gas wells, combined drillstrings are being used more and more, along with steel pipes which include alloy drill pipes, which have great ability to damp vibrations emanating from the bit during drilling, making it difficult to use this method when drilling deep wells .

 A known method for determining the wear of the support and armament of the bit [2] based on measurements taken on the surface using the corresponding sensors of vibration of the drilling tool and fluctuations of the current load in the circuit of the rotator motor (rig rotor). As a result of comparing the values of the controlled parameters at each moment of time during drilling, certain diagnostic frequencies and relationships between the oscillations of the drilling tool and the fluctuations of the current load in the rotator motor circuit are fixed in the general spectrum of the drilling tool’s oscillations, characterizing the state of the support and armament of the bit.

 The disadvantage of this method is that it cannot be used in turbine drilling, because the number of parameters monitored during its implementation includes the current load in the electric motor circuit, which is possible only with the rotary method of drilling and when drilling using an electric drill.

Closest to the proposed is a method for determining the wear of the arms support bit during drilling [3]
At the heart of this method, along with measurements of the mechanical drilling speed and bit rotation frequency, made on the surface, there are measurements of the frequency and amplitude of hydraulic pulses generated by the downhole emitter, made in the downward flow of flushing fluid using a special sensor installed in the parking lot of the manifold.

 The known method includes a preliminary stage, which consists in carrying out experimental studies, during which initial data are determined to construct a reference curve for the operation of a new bit, which is subsequently needed to determine the wear of the support and armament of a bit working on the bottom, which is a graphical dependence of the dimensionless mechanical speed drilling from dimensionless torque on a bit.

 The dimensionless mechanical drilling speed is the square root of the ratio of the current mechanical drilling speed to the product of the current bit rotation frequency and the bit diameter.

 For dimensionless torque, the ratio of the current bottomhole torque on the bit to the product of the current bottomhole axial load on the bit and the diameter of the bit is taken.

 Downhole information about the current values of torque and axial load on the bit are transmitted during drilling to the surface in the form of hydraulic pulses generated by the modulator valve, which is part of the downhole layout of the system with which this method is implemented.

 The graphical dependence of the dimensionless mechanical drilling speed on the dimensionless torque on the bit for a new bit is almost a straight line.

 When the bit is operated at the bottom, its weapons are worn out and the actual curve of the dimensionless mechanical drilling speed versus dimensionless torque, which is built on the basis of the above measurements made during drilling at any time, deviates down from the reference. This deviation increases with the increase in the working time of the bit at the bottom. At the same time, the performance of the bit is evaluated by a parameter that depends only on the degree of wear of the bit's armament and lithological changes of the drilled geological section. As a result of a constant analysis of this parameter and the magnitude of the torque on the bit with the help of a computer device, the state of the bit is determined.

 The disadvantages of this method include the low accuracy of recognition of downhole situations associated with wear of the support and armament of the bit during drilling, which is caused by the low information content of the controlled downhole parameters, and therefore, to determine the cause of the change in the downhole situation, pre-built reference graphic dependences of dimensionless mechanical speed on dimensionless torque moments for the construction of which, taking into account the existing variety of types of bits and lithological heterogeneity and drilled geological dimensions, a large amount of preliminary experimental research is required, which reduces the efficiency of the method.

 Measurement of hydraulic pulses generated by a downhole emitter in a downward flow of flushing fluid, which has significant noise interference due to the operation of ground-based drilling equipment, reduces the quality of downhole information.

 The aim of the invention is to increase the accuracy of the method by increasing the information obtained from the bottom hole, helping to determine the cause of the change in the bottom hole situation during drilling of a well with a screw motor.

 The goal is achieved by the fact that in the known method of determining the wear of the support and armament of the bit, based on measuring downhole information about the work of the bit, formed in the form of hydraulic pulses, and its analysis, in the process of drilling a well, hydraulic pulses generated during the operation of the screw are used as downhole information the engine and armament of the bit, at the wellhead in the flow of flushing fluid, simultaneously measure the frequency and amplitude of their electrical counterparts, and analyze the downhole information t by comparing the measured values at each instant of time.

 A comparative analysis of the proposed solution with the prototype shows that the claimed method differs from the known one in that hydraulic pulses are used instead of hydraulic pulses modulated by means of a specially designed device for using downhole information about changes in the state of support and armament of the bit and lithological composition of the drilled geological section generated during the operation of the screw engine, as well as hydraulic pulses resulting from the operation of weapons chisels. Thus, the claimed method meets the criteria of the invention of "Novelty."

 The measurement of the frequency and amplitude of hydraulic pulses generated during the operation of the armament of the bit, carried out in the proposed method simultaneously with the measurements of the frequency and amplitude of hydraulic pulses generated during the operation of the screw engine, gives the well-known technical solution a new technical property to increase the accuracy of determining the wear of the support and armament of the bit due to the allocation the reasons for the change in the bottomhole situation, which allows, during the drilling process, to identify signs of downhole situations that characterize wear on pores and armaments of the bit, which gives reason to conclude that the technical solution meets the criteria of the invention "Significant differences".

 In FIG. 1 shows a diagram of a system for operational control of drilling mode parameters.

 Hydraulic impulses generated during the operation of the armament of the bit 1 and the screw engine 2 act on the piezoelectric receiver 3 installed in the flow of flushing fluid at the mouth of the well being drilled. Due to the action of hydraulic pulses on the piezoelectric receiver, variable electromotive forces (EMF) arise in it, the nature of the dynamics of which, i.e. frequency and amplitude are determined by the operational parameters of the downhole emitter.

 The frequency of pulses generated during the operation of the armament of the bit is determined by the rotational speed of the output shaft of the screw engine, the number of teeth (teeth) on the bit, the amplitude is mainly the physicomechanical properties of the drilled rocks and the flight of teeth (teeth) above the roller cutter body (wear of the weapon).

 The frequency and amplitude of the pulses generated during the operation of the screw motor are determined by its operating parameters, the output shaft rotation frequency, and the net power developed during drilling.

 The useful power developed by a screw engine is directly dependent on the moment of resistance to rotation of the bit during drilling, design features of the bit (type of weapon, design of supports), its physical condition (wear of supports, wear of weapons) and physical and mechanical properties (drillability, torque capacity) of the drilled mining rocks.

 The hydraulic pulses converted in the piezoelectric receiver to alternating EMF are fed to the input of the mode parameter indicator (IRP), consisting of amplifiers 4, frequency filters 5 and equipped with magnetoelectric indicating devices 6, the scales of which are graded in pulses per second (frequency characteristics) and in volts (amplitude characteristics ) Information about the parameters monitored during the drilling process enters the recording unit 7, equipped with a multi-channel self-cleaning device, where the current values of the monitored parameters are recorded in parallel on the chart tape.

 Determining the wear of the support and armament of the bit is based on a comparison of the controlled parameters and their operational analysis during the drilling of the well.

 In FIG. 2 shows fragments of diagrams with recording of controlled parameters that were obtained while drilling a well at the Sutorminskoye oil field of the Noyabrskneftegaz production association in 1987 during field tests of a prototype of the downhole parameter monitoring system used to implement the inventive method. Drilling was carried out using a downhole screw motor D1-195.

 Fragments of diagram tapes are presented that reflect the final stage of bit development 215, 9MZ-GNURO4 while drilling well N 454 of cluster 4A in the depth interval 2521-2525 m.

 The values of controlled parameters recorded at the first to sixth minute of fragments characterize the normal, without drastic changes, drilling process.

 At the seventh minute of the fragment, the drilling process is characterized by an increase in the amplitude (curve 1) of the electrical analogues of the hydraulic pulses generated during the operation of the screw motor from 6 to 10 V with a decrease in their frequency (curve 2) from 16.5 to 13.5 imp / s, which indicates a sudden increase in torque (moment of resistance force) on the output shaft of the engine. At the same time, the frequency (curve 4) of the electrical analogs of the hydraulic pulses generated during the operation of the armament of the bit significantly decreased. From 42 imp / s, its value dropped to 30 imp / s, i.e. almost 1/3. The amplitude (curve 3) of the electrical analogues of these pulses changed slightly (from 8 to 9 V).

 An analysis of the described changes in the controlled downhole parameters made it possible to conclude that one of the bit cone bits was jammed, after which the axial load on the bit was reduced and drilling was carried out with a reduced axial load on the bit in order to avoid the bit cone jamming, which corresponds to the sections of the diagrams presented in the ninth to twelfth minutes fragments (Fig. 2). The value of the amplitude of the signal generated during operation of the screw motor was 5-6 V, and the frequency increased to 18 pulses / s. Accordingly, the dynamic characteristics of the signal generated during the operation of the armament of the bit also changed. The amplitude decreased to 7-8 V, and the pulse frequency increased to 43-45 rms / s.

 At the twelfth minute of the fragments, changes in the controlled downhole parameters were re-recorded, similar to those that were recorded at the seventh minute, indicating a repeated, despite a reduced axial load, chisel chisel.

 At the nineteenth minute of the fragments of FIG. Figure 2 shows a sharp decrease in the amplitude of the signal generated during operation of the screw engine from 9.5 to 1.0 V, accompanied by a decrease in its frequency to 10 pulses / s with a corresponding change in the frequency of pulses generated during the operation of the armament of the bit, which characterizes the transition of the screw engine in the brake mode of operation due to an increase in torque on the output shaft of the engine, after which the engine stopped completely (twenty-first minute of fragments).

 An assumption was made about the spell of the second bit cutter. Drilling was suspended in order to replace the bit.

 An external inspection of the spent bit, performed at the mouth of the rig after its lifting, confirmed the presence of two jammed cones with operational weapons.

 In FIG. Figure 3 shows fragments of diagram tapes with graphical images of the values of controlled parameters recorded during drilling of well N 2006 on the Kukuiskaya area of the Permneft production association with a bit Ш215, 9СЗ-ГНУ using a screw engine D2-195 in the interval 1602-1604 m.

 The sections of the diagrams corresponding to the first to twentieth minutes of the fragments are characterized by fluctuations in the dynamic characteristics of the signal generated during the operation of the screw engine (amplitude curve 1 from 1.5 to 3.0 V, frequency curve 2 from 18 to 20 pulse / s), and the signal a bit formed during the operation of the weapon (curve 3 amplitudes from 3.5 to 5.5 V, curve 4 frequencies from 40.5 to 42.0 imp / s). Such fluctuations in dynamic characteristics indicate the operational state of the armament of the bit.

 In the normal state of armament of the bit, an effective drilling process is characterized by the values of the amplitude of electrical analogues not lower than 3V (Fig. 2). At lower values, drilling is not effective either because of the wear of the armament of the bit or the screw engine. A specific reason is established taking into account the values of the dynamic characteristics of analogues of hydraulic pulses generated during the operation of the armament of the bit.

 The sections of the fragments of the diagrams corresponding to twenty-fifth to ninety minutes differ in stabilization of the dynamic characteristics of the monitored signals while reducing the amplitude of the electrical analogs of the pulses generated during operation of the screw motor to 1 V, and the amplitudes of the electrical analogs of the pulses generated during the operation of the armament of the bit to 2 V. changes in the controlled parameters are explained by the wear of the armament of the bit. External examination of the bit raised from the well showed that the carbide teeth of the bit had wear from 1/2 to 2/3 of their original height. The cone supports were in working order.

 The application of the proposed method, compared with the prototype, provides the following advantages.

 Improving the accuracy of the assessment of downhole situations associated with wear of the support and armament of the bit during drilling, by increasing the information obtained from the bottom, significantly reduces the amount of preliminary experimental research, since there is no need to build reference graphic dependencies.

 The use of hydraulic pulses of information on the downhole process parameters of the bit of hydraulic pulses generated during the operation of the screw engine and armament of the bit, allows to increase the reliability of the method, since its implementation does not require additional specially made devices for forming a bottomhole information carrier, i.e. modulation of hydraulic pulses.

 The possibility of using an ascending stream, which has less noise interference due to the operation of mud pumps and other ground equipment, can be used as a hydraulic communication channel with the bottom of a well being drilled, along with a downward flow of flushing fluid, which allows improving the quality of downhole information.

 The energy costs for drilling mud drive are reduced due to the fact that the formation of hydraulic pulses carrying downhole information occurs without the use of special devices that cause additional hydraulic resistance in the circulating system of the drilled well.

Claims (1)

 METHOD FOR DETERMINING THE SUPPORT WEAR AND WEAP WEAPONS IN THE PROCESS OF DRILLING A WELL WITH A SCREW ENGINE, based on measuring downhole information about the operation of a bit, formed in the form of hydraulic pulses, and its analysis during drilling, characterized in that, in order to increase the accuracy of determination due to information obtained from the bottom hole, hydraulic pulses generated during the operation of the screw engine and the armament of the bit at the wellhead in the flow of flushing fluid are used as bottomhole information and simultaneously measure the magnitude of the frequency and amplitude of their electrical analogues, and the analysis of downhole information is carried out by comparing the measured values at each moment of time.

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