CN102998699A

CN102998699A - Casing-harmonic-containing vertical seismic profile data interval velocity inversion method

Info

Publication number: CN102998699A
Application number: CN2011102650867A
Authority: CN
Inventors: 张庆红; 张固澜; 蔡志东
Original assignee: China National Petroleum Corp; BGP Inc
Current assignee: China National Petroleum Corp; BGP Inc
Priority date: 2011-09-08
Filing date: 2011-09-08
Publication date: 2013-03-27
Anticipated expiration: 2031-09-08
Also published as: CN102998699B

Abstract

The invention relates to a casing-harmonic-containing vertical seismic profile data interval velocity inversion method. The method is used for suppressing casing harmonics by low-pass filtering and F-K filtering in seismic prospection, and includes steps of obtaining amplitude spectrums by means of 15-Hz low-pass filtering, obtaining F-K spectrums by converting the amplitude spectrums in a track direction, clearing all F-K spectrums of up-going waves and down-going waves of the speed higher than 5000 m/s, obtaining a second wave field of time domain by means of inverse Fourier transform, picking a continuous event from the down-going waves of the wave field to obtain first break I of each track, picking the first break on an original interference-less track and translating the same, obtaining the first break II by adding the first break I of each track with the translation value, obtaining the adjacent difference by subtracting the depth of the previous track from the depth of the next track, obtaining the first break difference of the adjacent track by subtracting the record first break of the first track from the record first break II of the next track, and finally dividing the depth difference of the adjacent track by the first break different of the adjacent track. By the method, interference to the interval velocity from the casing harmonics can be avoided, so that accurate first break and interval velocity are acquired. Accordingly, the method is easy and convenient to use, and high in computational efficiency.

Description

A kind of vertical seismic profile data Interval Velocity Inversion method that contains the sleeve pipe harmonic wave

Technical field

The present invention relates to the Seismic Exploration Data Processing technology, be a kind of low-pass filtering of utilizing frequency field and F-K (frequency-wavenumber domain) thus the accurate method of inverting interval velocity of filtering compacting sleeve pipe harmonic wave.

Background technology

Vertical seismic profile (VSP) (VSP) data is owing to special acquisition mode, and wave detector need to be positioned in the well, and needs good coupling between the sleeve pipe of wave detector and well cementation, just can be recorded to reliable record.But when do not have cementing between the sleeve pipe or between sleeve pipe and the stratum or glue pure when bad, these multilayer sleeves will cause the singing of high amplitude, thereby produce the sleeve pipe harmonic wave relevant with the sleeve pipe natural frequency.Its energy is decayed hardly, and frequency runs through the whole frequency band of significant wave, continues whole writing time, make follow the trail of upward traveling wave and descending ripple become impossible.Those woodss of jar (unit of capacitance) studies show that to this copper pipe ripple they are larger on the particle movement impact of vertical direction, and are little on the particle movement impact of horizontal direction. less on transformed wave and shear wave impact namely to the compressional wave serious interference, but its physical process is still understood not.Disturb for the singing that this superficial part multilayer sleeve causes, the solution in the field acquisition is: near the VSP inspection well, bore again a bite shallow well, and running casing, and well cementing, observe with the superficial part that replaces original VSP inspection well.

In the field acquisition, affected by various factors, near inspection well, bore shallow well and cased method, also almost can't implement.When the sleeve pipe harmonic energy is very strong, no matter be vertical component or horizontal component, all can't pick up accurately first arrival, thereby deeply concern in the time of can't obtaining accurately, more can't obtain interval velocity.

By the end of at present, during the VSP data is processed, when compacting sleeve pipe harmonic energy is more intense can't first break picking the time, generally all be considered as this road signal and be useless road, no longer process, the dark relation and interval velocity reduced the using value of VSP data greatly in the time of therefore can't obtaining accurately.

Summary of the invention

The present invention seeks in vertical seismic profile (VSP) (VSP) data, provide a kind of low-pass filtering of utilizing frequency field and F-K (frequency-wavenumber domain) thereby filtering compacting sleeve pipe harmonic wave accurately first break picking and inverting interval velocity, simultaneously easy to use succinct, the Interval Velocity Inversion method that operation efficiency is high.

Concrete steps of the present invention comprise:

1) acquisition and recording earthquake raw data;

The low-pass filtering below 15 hertz of 2) raw data being carried out frequency field obtains the first wave field;

3) to the Fourier transform of the advanced line time direction of the first wave field, thereby transform to frequency field, obtain its spectral amplitude; Then spectral amplitude is carried out Fourier transform in the Taoist monastic name direction, thereby transform to wavenumber domain, obtain its frequency-wave number (F-K) spectrum;

4) in step 3) in frequency-wave number (F-K) of obtaining spectrum, with all up F-K spectrum zero clearings that involves the descending ripple of speed more than 5000m/s; Then carry out the inversefouriertransform of wave number direction, obtain its spectral amplitude; Again the spectral amplitude that obtains is carried out the inversefouriertransform of frequency direction, obtain the second wave field of time domain;

5) the descending ripple in the second wave field picks up continuous lineups, obtains the first arrival one of per pass;

6) first break picking time on glitch-free seismic trace in raw data, the first arrival one that this first break time deducts this road obtains shift value, and the first arrival one of per pass is all added this shift value, obtains first arrival two;

7) deduct the depth difference that the degree of depth corresponding to last trace record obtains the phase neighboring trace with the degree of depth corresponding to a rear trace record, it is poor that the first break time two that deducts last trace record with first break time two degree of depth of a rear trace record obtains the first arrival of phase neighboring trace; And with the depth difference of phase neighboring trace divided by the poor interval velocity that obtains of the first arrival of phase neighboring trace.

The present invention can avoid the sleeve pipe harmonic wave to the interference of interval velocity, obtains accurately first arrival and interval velocity.Simultaneously easy to use succinct, operation efficiency is high.

Description of drawings

Fig. 1 is the real VSP data;

Fig. 2 is 15 hertz of wave fields after the following low-pass filtering;

Fig. 3 is the descending ripple after F-K separates;

Fig. 4 is the accurately first arrival of picking up;

Fig. 5 is the speed of inverting of the present invention.

Embodiment

The present invention seeks in vertical seismic profile (VSP) (VSP) data, provide a kind of low-pass filtering of utilizing frequency field and F-K (frequency-wavenumber domain) thereby filtering compacting sleeve pipe harmonic wave accurately first break picking and inverting interval velocity.

Describe the present invention in detail below in conjunction with accompanying drawing.

1) acquisition and recording earthquake raw data; Be the sleeve pipe harmonic wave entirely more than 1800 meters in the real VSP data of Fig. 1, red line is final accurate first arrival among the figure.

The low-pass filtering below 15 hertz of 2) raw data being carried out frequency field obtains the first wave field; Among Fig. 2, after the low-pass filtering below 15 hertz, it is continuous that the lineups of descending ripple become.But the situation of the lineups changing of the relative positions still appears in the seismic trace that the partial resonance energy is too strong.

3) to the Fourier transform of the advanced line time direction of the first wave field, thereby transform to frequency field, obtain its spectral amplitude; Then spectral amplitude is carried out Fourier transform in the Taoist monastic name direction, thereby transform to wavenumber domain, obtain its frequency-wave number (F-K) spectrum; Among Fig. 3, through after the F-K filtering, occur in the seismic trace of the lineups changing of the relative positions, descending ripple lineups also well are connected with neighboring trace mutually.

5) the descending ripple in the second wave field picks up continuous lineups, obtains the first arrival one of per pass; Among Fig. 4, first arrival is smooth continuously.

Among Fig. 5, interval velocity meets the regional geology situation, and the interval velocity and not containing that contains the stratum of sleeve pipe harmonic wave change between the interval velocity on stratum of sleeve pipe harmonic wave mild, without bad break.

Claims

1. vertical seismic profile data Interval Velocity Inversion method that contains the sleeve pipe harmonic wave, characteristics are that the specific implementation step is as follows:

1) acquisition and recording earthquake raw data;

3) to the Fourier transform of the advanced line time direction of the first wave field, thereby transform to frequency field, obtain its spectral amplitude; Then spectral amplitude is carried out Fourier transform in the Taoist monastic name direction, thereby transform to wavenumber domain, obtain its F-K spectra;

4) in step 3) in the F-K spectra that obtains, with all up F-K spectrum zero clearings that involves the descending ripple of speed more than 5000m/s; Then carry out the inversefouriertransform of wave number direction, obtain its spectral amplitude; Again the spectral amplitude that obtains is carried out the inversefouriertransform of frequency direction, obtain the second wave field of time domain;