SU1686109A1 - Method for determination of bit wear in drilling - Google Patents

Abstract

The invention relates to a technique for monitoring and measuring parameters for drilling oil and gas wells, and can be used to determine the degree of wear of a rock-breaking front. The goal is to improve the accuracy of determining the degree of bit wear by reducing the effect of interference. For this, the amplitudes of different frequency ranges of the vibrations of the bits are measured by a vibration sensor. Then, a normalized correlation function is obtained from the amplitudes of different frequency ranges of the vibration of the bit by the calculator. After that, the value of its maximum is determined by a maximum analyzer. The degree of bit wear / g is determined from the expression / g (-d Ri / d E): (- d Ri / d E) dachshund, the value / g close to unity indicates the minimum wear of the bit, and the value close to zero for maximum wear. The value of /.I is indicated on the wear indicator 5 Il. cl

Description

The invention relates to a technique for monitoring and measuring the parameters of drilling oil and gas wells and can be used to determine the degree of wear of a rock cutting tool in order to achieve its effective development.

The aim of the invention is to improve the accuracy of the method by reducing the effect of interference.

FIG. Figure 1 shows a view of the normalized correlation function of the drill bit vibration signal; in fig. 2 - dependence of the maximum value (normalized correlation function on the energy E, spent by the bit on the destruction of the bottom rock; in Fig. 3, the derivative taken with a minus sign, the maximum value of the normalized correlation function

on the energy spent on the destruction of the rock slag; in fig. 4 - dependency

d ri

and hch, / and HI rank, - -j- | - / i - -pjr} max on energy,

the bit spent on the destruction of the slaughter rock; in fig. 5 is a block diagram of a device implementing the method.

The method is based on the property of the normalized correlation function to separate and determine the fraction of the power of a periodic signal from the total signal against the background of random interference.

The signal of the vibrations of the bit has a pronounced periodic character due to the rotational movement of the bit, the cutters and the geometrical arrangement of the bit teeth. The teeth of the chisel, moving along the face and interacting with the tributaries of the rock, create a vibration.

00

about

oh oh

The signal of the latter is transmitted through a string of drill pipes and is perceived from the well surface as a vibration signal of the drilling tool. The vibration signal of a drilling tool is then a periodic sequence of pulses, where each pulse reflects the interaction of each tooth with a rock heterogeneity.

Frequency destruction of a tooth causes a decrease in amplitude, that is, an average power of the corresponding pulse, and complete destruction 3} is the disappearance of the pulse. However, direct analysis of the vibration signal is difficult due to the high level of the block caused by the friction of the drill bit against the walls of the squash, noise from the movement of the washing fluid, etc. This obstacle is largely allowed by the use of correlation analysis.

According to the properties of the normalized correlation function, the presence of a pronounced periodic component in the vibration signal causes the occurrence of maximum 1 (Fig. 1), and its RI value characterizes the proportion of the periodic component power in the total signal power, Thus, the decrease in the average power of individual pulsop or their the disappearance leads to a decrease in the value of RI — the maximum of the normalized correlation function. The value of RI in the process of chiseling monotonously decreases in full accordance with the degree of bit gear.

In FIG. 2, the 0-Ei section reflects the period of effective rhythm and the accumulation of fatigue by the material of bits a. At one time, Ei-Eg sows the process of active wear of the bit, is characterized by a high rate of decline of Pi in the initial part of the section and a decrease in the rate of decline to zero by the end of the section. Thus, the point EI corresponds to a practically izobredennom long and can be determined by the highest rate of decay of the dependence of RI from E. equal to the derivative of RI with respect to argument E, with a minus sign

i d Ri.

dE

-). The resulting relationship is shown in fig. 3, where the point II corresponds to the beginning of active wear of the bit teeth, and the point III corresponds to the maximum wear.

Determine the value of / g by the formula

/

d Ri, / d Ri

d E

- /

dRi

/ - i UE /

where ----- is taken with a minus sign derived from the value of the maximum of the normalized correlation function RI with respect to the energy E spent on the destruction of the bottomhole rock;

(d

(- -) max - the highest value since the beginning of dolving at the moment of drilling

specified derivative, excluding the one with a minus sign.

The dependence of the magnitude / and, which characterizes the wear of the bit, on E is shown in FIG. 4. At the same time, minimum bit wear

is determined by the value of / - close to unity, and the maximum wear-no value of / g is close to zero.

The block diagram (Fig. 5) contains the sensor 1 of the vibration of the drilling tool, the band

filter 2, unit 3 for calculating the normalized correlation function 3, first analyzer 4 maxima, unit 5 for measuring the energy expended in breaking down rock, unit 6 for differentiating with

by inversion, the second CHI converter 7 of the maximum, block 8 division, indicator 9 of the degree of wear.

The method is implemented as follows.

The vibrations of a drilling tool are sensed by a nut 1. The electrical signal from sensor 1 passes through a band-pass filter 2 Filter 2 passes only those frequency components of the vibration signal,

which lie in the range of possible frequencies of vibrations of the drilling tool, due to the interaction of the teeth of the bit with the rock slab. From the output of filter 2, the received signal is fed to the input of block 3

calculating the normalized correlation function. The signal corresponding to RL) is the result of the calculation, is fed to the input of the first analyzer 4 max, the output of which receives the current RI value of the maximum of the normalized correlation function. From the output of the first analyzer 4 max the signal goes to the first input of the differentiation unit b with inversion the second input of which receives a signal from block 5 from the measurement of the energy expended on the destruction of the bottomhole rock.

At the output, block 6 of differentiation with other rations receives a signal corresponding to (- --Ј-) In the second analyzer 7

the maximum at the input of which the received signal arrives is determined by the greatest chiseling of the derivative from the beginning.

(-) Max. From the output of the inversion differentiation unit 6, the signal also goes to the first input of the dividing unit 8, to the second input of the dividing unit 8 a signal comes from the second analyzer 7 maximum. At the output of block 8 division receive a signal corresponding to the value

dRt d E

- /

(dRi TE /

Max,

which is indicated in the bit wear indicator 9. The indicator determines the degree of wear of the bit.

Claims (1)

The method allows to significantly improve noise immunity and reduce the effect of drilling conditions on the measurement result, which leads to an increase in accuracy in determining the degree of bit wear. Claim Method A method for determining the degree of bit wear during a drilling process, including measuring drill bit vibrations using a vibration sensor, characterized in that, to improve the accuracy of the method by reducing the influence of interference, a normalized drill bit vibration signal is obtained the value of its maximum, and the degree of bit wear, ft, is determined from the expression dRi  dRix  d E} max where RI is the maximum value of the normalized correlation function; E is the energy expended by the chisel on the destruction of the bottom; j p - - derivative; d fc (- - p) max - the largest since the beginning of dolbeleni value of the derivative with a minus sign; the minimum bit wear is determined by the value of //, close to one, and the maximum wear - by value / g, close to zero. FIG. five