CN104133982A - Elimination method of slurry pulse signal pump stroke noise - Google Patents

Abstract

The invention discloses an elimination method of slurry pulse signal pump stroke noise. The order formula (N=Fs/Fo) of a comb filter is utilized, wherein Fs is the sampling frequency of a slurry signal, and Fo is a product of the movement rate of a single slurry pump piston and the number of slurry pumps, and the order of the comb filter is determined; when the pump stroke noise is eliminated, a filtering process of a slurry pulse signal is realized by utilizing MATLAB software, and comprises the following steps: 1) collecting the slurry pulse signal on site; 2) according to the signal to noise ratio of the signal, determining the bandwidth (BW) of the comb filter, designing the required comb filter according to the BW and the determined order; 3) converting the slurry pulse signal to enable a signal value to be within an interval (-1,1), and obtaining a signal X(n); 4) loading the signal X(n) into the comb filter to carry out convolution filtering to obtain a filtered signal Y(n); and 5) plotting, and observing a signal filtering situation. The invention breaks through the restriction of a hardware circuit, the MATLAB software is utilized to effectively realize the filtering process of the slurry pulse signal, and meanwhile, the comb filter is applied to the slurry pulse signal so as to further enhance a filtering effect.

Description

A kind of mud pulse signal pump rushes the removing method of noise

Technical field

The present invention relates to the technical field of oil drilling well logging while drilling, refer in particular to a kind of mud pulse signal pump and rush the removing method of noise.

Background technology

At present, in oil well logging while drilling field, conventional signal filtering is to be completed by hardware circuit, general passive filter circuit or the active filter circuit of adopting, this method realizes simple, but in the time being applied to well logging while drilling mud pressure pulse signal, because its transmission frequency is lower, comparatively approaching with the frequency of interference source, the precision and the effect that adopt the method for hardware filtering to carry out filtering like this all do not reach requirement, in different environment interfering signal type differences, the parameter of change filtering is also very inconvenient simultaneously.The wave filter that this just makes to need in system equipment some high Inhibitory signal processing, improves the channel quality of whole system.In addition, in mud pulse signal generation systems, because mud need to transmit by outside pressure, therefore mud piston needs continuous to-and-fro movement, in this to-and-fro movement process, can produce pump and rush noise, the signal data therefore collecting for underground instrument signal, carry out correct signal decoding, just must eliminate pump rushes noise.

Summary of the invention

The object of the invention is to overcome the deficiencies in the prior art and shortcoming, provide a kind of effective, reliable mud pulse signal pump to rush the removing method of noise, can obviously improve signal quality, be convenient to follow-up signal transmission, decoding and process.

For achieving the above object, technical scheme provided by the present invention is: a kind of mud pulse signal pump rushes the removing method of noise, first, according to the sample frequency of single mud piston movement rate and steam piano number and mud signal, utilize the exponent number formula of comb filter: N=Fs/Fo, the sample frequency that Fs is mud signal, Fo is mud piston period of motion frequency, be the product of single mud piston movement rate and steam piano number, determine the exponent number of comb filter; When needs carry out pump rush noise eliminate time, utilize MATLAB software to realize the filtering of mud pulse signal, comprise the following steps:

1) the standpipe pressure sensor signal in well logging while drilling is gathered, and convert the simulating signal collecting to digital signal, the digital signal obtaining is the mud pulse signal that collection in worksite arrives;

2) be the bandwidth BW that signal to noise ratio (S/N ratio) is determined comb filter according to the quality of mud pulse signal, be conventionally defaulted as 3dB, and then according to the comb filter of the exponent number N design of bandwidth BW and calculating gained;

3) by collection in worksite to mud pulse signal change, make signal value be positioned at (1,1) interval, the result obtaining is X (n);

4) comb filter that the signal X (n) after conversion is loaded into design is processed, and does convolutional filtering, draws filtered signal Y (n);

5) mapping, observation signal filtering situation, sees that pump rushes noise and whether is eliminated, the elimination work that so far just completes mud pulse signal pump and rush noise.

In step 3) in, original signal is deducted to mean value, then after absolute value divided by signal peak, just obtain mud pulse signal X (n).

In step 4) in, need first the comb filter of design to be exported as to single order response matrix H (n), then just in time domain, do process of convolution with mud pulse signal X (n), draw filtered signal Y (n), wherein,

$Y\left(n\right)=\underset{m=-\∞}{\overset{m=+\∞}{\mathrm{\Σ}}}X\left(m\right)H(n-m)$

After this multiplying each other, the computing method of summation is called convolution, in formula, m is the signal response number that at every turn participates in summation operation, n makes the H (m) amount of displacement, in the time of sequential n=0, (m) be the result of H (m) in sequential negate, sequential negate makes H (m) centered by the longitudinal axis, turn over turnback to sequence H;

The number of supposing signal X (n) is n1, the element number of single order response matrix H (n) is n1, the Y (n) of output has (n1+n2-1) individual point, due to single order response matrix H be less than 0 or be greater than n2 in be all 0, so simplified formula is above:

$Y\left(n\right)=\underset{m>n-n2}{\overset{m<n}{\mathrm{\&Sigma;}}}X\left(m\right)H(n-m)$

According to above formula, draw filtered signal Y (n).

Compared with prior art, tool has the following advantages and beneficial effect in the present invention:

1, broken through the restriction that realizes filtering accuracy and effect with hardware circuit, utilize MATLAB Software for Design to go out wave filter, be applied in the process software of measurement while drilling signal, effectively realize the filtering of mud pulse signal, compared with hardware circuit, filter parameter is convenient to regulate, and has expanded the scope of application of wave filter;

2, the comb filter that is usually used in high quality graphic processing is applied to mud pulse signal, compare with other wave filters, when filtering pump rushes noise, can be by the high fdrequency component of signal yet filtering, precision and effect are further improved, improve the channel quality of whole system, be convenient to follow-up signal transmission, decoding and process.

Brief description of the drawings

Fig. 1 is the schematic diagram of comb filter of the present invention.

Fig. 2 is the frequency response chart of comb filter.

Fig. 3 is the signal spectrum figure before filtering.

Fig. 4 is filtered signal spectrum figure.

Fig. 5 is that mud pulse signal pump rushes noise eradicating efficacy figure.

Embodiment

Below in conjunction with specific embodiment, the invention will be further described.

Mud pulse signal pump described in the present embodiment rushes the removing method of noise, and its concrete condition is as follows:

First, according to the sample frequency of single mud piston movement rate and steam piano number and mud signal, utilize the exponent number formula of comb filter: N=Fs/Fo, Fs is the sample frequency of mud signal, Fo is mud piston period of motion frequency (being the product of single mud piston movement rate and steam piano number), determines the exponent number N of comb filter.

When needs carry out pump rush noise eliminate time, utilize MATLAB software to realize the filtering of mud pulse signal, comprise the following steps:

1) the standpipe pressure sensor signal in well logging while drilling is gathered, and convert the simulating signal collecting to digital signal, the digital signal obtaining is the mud pulse signal that collection in worksite arrives.

2) be the bandwidth BW that signal to noise ratio (S/N ratio) is determined comb filter according to the quality of mud pulse signal, be conventionally defaulted as 3dB, and then according to the comb filter of the exponent number N design of bandwidth BW and calculating gained.

Suppose frequency acquisition Fs=100Hz, F _o=1.66Hz, in the design of filter instrument FDATOOL of MATLAB, select IIR-Comb wave filter, respond style is Nothing trapper, the exponent number of determining comb filter is about 60Hz, the filter quality factor of acquiescence is 3dB, and the wave filter amplitude-frequency response obtaining so as shown in Figure 2.

3) by collection in worksite to mud pulse signal change, make signal value be positioned at (1,1) interval, the result obtaining is X (n), specifically original signal is deducted to mean value, after absolute value divided by signal peak, just obtain mud pulse signal X (n) again.

4) comb filter that the signal X (n) after conversion is loaded into design is processed, do convolutional filtering, draw filtered signal Y (n), as shown in Figure 1, Xn is input, through being added with input signal Xn after time delay and amplifier am, deduct the output signal through time delay and amplifier bn, obtain Yn output.Its concrete condition is as follows:

The comb filter of design is exported as to single order response matrix H (n), then just in time domain, do process of convolution with mud pulse signal X (n), draw filtered signal Y (n), wherein,

$Y\left(n\right)=\underset{m=-\&infin;}{\overset{m=+\&infin;}{\mathrm{\&Sigma;}}}X\left(m\right)H(n-m)$

After this multiplying each other, the computing method of summation is called convolution, in formula, m is the signal response number that at every turn participates in summation operation, n makes the H (m) amount of displacement, in the time of sequential n=0, (m) be the result of H (m) in sequential negate, sequential negate makes H (m) centered by the longitudinal axis, turn over turnback to sequence H.

The number of supposing signal X (n) is n1, the element number of single order response matrix H (n) is n1, the Y (n) of output has (n1+n2-1) individual point, due to single order response matrix H be less than 0 or be greater than n2 in be all 0, so simplified formula is above:

$Y\left(n\right)=\underset{m>n-n2}{\overset{m<n}{\mathrm{\&Sigma;}}}X\left(m\right)H(n-m)$

According to above formula, draw filtered signal Y (n).

5) mapping, observation signal filtering situation, sees that pump rushes noise and whether is eliminated, the elimination work that so far just completes mud pulse signal pump and rush noise.As shown in Figure 3 and Figure 4, wherein in Fig. 3, near noise signal 1.66Hz has obtained weakening in Fig. 4 in the contrast of signal in frequency domain.As shown in Figure 5, the signal that amplitude is larger is the signal X (n) that comprises noise to the comparison diagram of signal in time domain, and what amplitude was less is that filtering pump rushes noise signal Y (n) afterwards.The effect of filtering is very directly perceived.

In sum, adopting after above scheme, the pump that the inventive method can effectively be eliminated in mud pulse signal rushes noise, this compared to existing technology, the inventive method has broken through the restriction of hardware circuit, utilize MATLAB software effectively to realize the filtering of mud pulse signal, improve filtering accuracy and effect, the comb filter that is usually used in high quality graphic processing is applied to mud pulse signal simultaneously, further strengthen filter effect, improve the channel quality of whole system, be convenient to follow-up signal transmission, decoding and process, be worthy to be popularized.

The examples of implementation of the above are only the present invention's preferred embodiment, not limit practical range of the present invention with this, therefore the variation that all shapes according to the present invention, principle are done all should be encompassed in protection scope of the present invention.

Claims (3)

1. a mud pulse signal pump rushes the removing method of noise, it is characterized in that: first, according to the sample frequency of single mud piston movement rate and steam piano number and mud signal, utilize the exponent number formula of comb filter: N=Fs/Fo, Fs is the sample frequency of mud signal, Fo is mud piston period of motion frequency, i.e. the product of single mud piston movement rate and steam piano number is determined the exponent number of comb filter; When needs carry out pump rush noise eliminate time, utilize MATLAB software to realize the filtering of mud pulse signal, comprise the following steps:

1) the standpipe pressure sensor signal in well logging while drilling is gathered, and convert the simulating signal collecting to digital signal, the digital signal obtaining is the mud pulse signal that collection in worksite arrives;

2) be the bandwidth BW that signal to noise ratio (S/N ratio) is determined comb filter according to the quality of mud pulse signal, be conventionally defaulted as 3dB, and then according to the comb filter of the exponent number N design of bandwidth BW and calculating gained;

3) by collection in worksite to mud pulse signal change, make signal value be positioned at (1,1) interval, the result obtaining is X (n);

4) comb filter that the signal X (n) after conversion is loaded into design is processed, and does convolutional filtering, draws filtered signal Y (n);

5) mapping, observation signal filtering situation, sees that pump rushes noise and whether is eliminated, the elimination work that so far just completes mud pulse signal pump and rush noise.

2. a kind of mud pulse signal pump according to claim 1 rushes the removing method of noise, it is characterized in that: in step 3) in, original signal is deducted to mean value, then after absolute value divided by signal peak, just obtain mud pulse signal X (n).

3. a kind of mud pulse signal pump according to claim 1 rushes the removing method of noise, it is characterized in that: in step 4) in, need first the comb filter of design to be exported as single order response matrix H (n), then just in time domain, do process of convolution with mud pulse signal X (n), draw filtered signal Y (n), wherein

$Y\left(n\right)=\underset{m=-\&infin;}{\overset{m=+\&infin;}{\mathrm{\&Sigma;}}}X\left(m\right)H(n-m)$

After this multiplying each other, the computing method of summation is called convolution, in formula, m is the signal response number that at every turn participates in summation operation, n makes the H (m) amount of displacement, in the time of sequential n=0, (m) be the result of H (m) in sequential negate, sequential negate makes H (m) centered by the longitudinal axis, turn over turnback to sequence H;

The number of supposing signal X (n) is n1, the element number of single order response matrix H (n) is n1, the Y (n) of output has (n1+n2-1) individual point, due to single order response matrix H be less than 0 or be greater than n2 in be all 0, so simplified formula is above:

$Y\left(n\right)=\underset{m>n-n2}{\overset{m<n}{\mathrm{\&Sigma;}}}X\left(m\right)H(n-m)$

According to above formula, draw filtered signal Y (n).