CN103576189B - A kind of drilling earthquake direct wave group searching method - Google Patents

Abstract

The invention belongs to the field in field of seismic exploration, drilling earthquake data processed, particularly relate to a kind of drilling earthquake direct wave group searching method based on surface seismic section.The present invention utilizes reflective information that surface seismic section provides and bell cosine function to obtain surface seismic echo " template ", the energy of recycling drilling earthquake ripple and homophase degree calculate direct wave and there is probability, then be there is probability in surface seismic echo template and direct wave and make cross-correlation, finally determine drilling earthquake direct wave sequence according to cross-correlation magnitude variations.

Description

A kind of drilling earthquake direct wave group searching method

Technical field

The invention belongs to the technology neck in field of seismic exploration, drilling earthquake data processed Territory, particularly relates to a kind of drilling earthquake direct wave group searching method based on surface seismic section.

Technical background

Drilling earthquake technology is that seismic exploration technique combines with petroleum drilling engineering technology Seismic technology in kind emerging well, have do not disturb wellbore construction, can be continuous at depth direction Measurement, exploration efficiency high, be a new and high technology with strategic importance.

Drilling earthquake used " focus " is in drilling process produced by bit hits formation rock Vibration, this signal is compared with ground environment noise, and energy is the most weak.And seismograph while drilling leans on Nearly drilling well site, around atural object is changeable, circumstance complication, the most for a long time, outdoor, without warning Record condition, the noise types causing drilling earthquake record is many, and noise energy is strong, the faintest Effective direct wave and echo be substantially submerged among various types of noise, signal to noise ratio Extremely low.It addition, bit vibration signal is the stochastic signal of continuous print non-pulse, data volume is big, The conversion extremely unstable of energy and frequency, it is impossible to when determining the generation of significant wave from mass data Between, character and source.

Summary of the invention

The problem that it is an object of the invention to exist for prior art, it is provided that one utilizes ground The reflection sequence information that earthquake is provided searches for searching of drilling earthquake direct wave group quickly, in high precision Suo Fangfa.

Technical scheme includes: described method utilizes the reflection that surface seismic section provides Information and bell cosine function obtain surface seismic echo " template ", recycle drilling earthquake The energy of ripple and homophase degree calculate direct wave and there is probability, then by surface seismic echo template There is probability with drilling earthquake direct wave and make cross-correlation, finally determine according to cross-correlation magnitude variations Drilling earthquake direct wave sequence.Concrete steps include:

1. utilize surface seismic to cross well achievement section, obtain reflection wave groups R below designated depth_i；

2. calculate reflection coefficient ζ (t) of surface seismic；

ζ (t)=R_iT=Tr_iTime

ζ (t)=0 t ≠ Tr_iTime

In formula: Tr_iZero shot-geophone distance TWT for i-th reflection.

Wherein, offset distance is that the zero shot-geophone distance TWT in virtual road of 0 is:

Tr₀=(VT₀-Z)/V

In formula: T₀It it is the surface interface round trip of the echo at a certain interface below designated depth Hourage, V is formation velocity, and Z is bit depth.

The zero shot-geophone distance TWT of i-th reflection is:

${\mathrm{Tr}}_i=\sqrt{{({\mathrm{VT}}_0-Z)}^2+X_i^2}/V$

In formula: X_iIt it is the offset distance in the i-th road.

3. reflection coefficient ζ (t) and bell cosine function C (t) are done cross-correlation, obtain ground, ground Shake echo " template "；

$H\left(\mathrm{\τ}\right)=\underset{0}{\overset{T}{\∫}}C\left(t\right)\mathrm{\ζ}(t+\mathrm{\τ})d\mathrm{\τ}$

Wherein, bell cosine function C (t) is:

$C\left(t\right)=cos\left(2\mathrm{\π}ft\right)e^{-{\mathrm{\βt}}^2}$

4. obtain drilling earthquake protocol；

5. pair drilling earthquake protocol carries out various Filtering Processing, obtains drilling earthquake and initially cuts open Face；

6. use drilling earthquake initial profile, along optimal time control curvilinear path, calculate drilling earthquake ripple Energy and homophase degree；

${\mathrm{Td}}_i=\frac{1}{V}\sqrt{Z^2+X_i^2}$

The energy of drilling earthquake ripple is:

$E_{sum}=\underset{j=1}{\overset{L}{\Σ}}\underset{i=1}{\overset{N}{\Σ}}{S}_i^2({\mathrm{Td}}_i+j)$

In formula: window width when L is, N is number of channels, S_iFor offset distance X_iThe i-th channel amplitude The homophase degree of drilling earthquake ripple；

$F_{sum}=\underset{j=1}{\overset{L}{\Σ}}\underset{i=1}{\overset{N-1}{\Σ}}{S}_i({\mathrm{Td}}_i+j)S_{i+1}({\mathrm{Td}}_{i+1}+j)$

7. utilize drilling earthquake wave energy and homophase degree to calculate direct wave and there is probability；

P=w₁E_sum+w₂F_sum

In formula: w₁For energy weight coefficient, w₂For homophase degree weight coefficient

8. surface seismic echo sequence " template " and drilling earthquake direct wave are existed probability to make Cross-correlation；

$M\left(t\right)=\underset{0}{\overset{T}{\∫}}H\left(t\right)P\left(t\right)dt$

9. the existence of drilling earthquake direct wave sequence is judged according to cross-correlation magnitude variations.

It is an advantage of the current invention that to make full use of surface seismic echo sequence " template " and with brill There is probability to search for drilling earthquake direct wave group in Seismic Direct Wave.The method has search speed Hurry up, accuracy rate high, it is possible to meet the on-the-spot needs processed in real time in drilling engineering field. On-the-spot application result shows: the method is applicable to the quick of all seismic prospecting data direct wave groups Search, it is possible to increase the precision that data processes, hence it is evident that improve section resolution.

Accompanying drawing explanation

Fig. 1 is that surface seismic crosses well profile

Fig. 2 is to utilize this invention calculated surface seismic echo sequence " template "

Fig. 3 is that drilling earthquake gathers protocol

Fig. 4 is the drilling earthquake initial profile processed after filtering

Fig. 5 is that the energy of drilling earthquake ripple, homophase degree and direct wave exist probability curve

The left figure of Fig. 6 is that surface seismic echo sequence " template " exists with drilling earthquake direct wave Probability cross-correlation curve；Right figure is that the set during drilling earthquake utilizing this invention to obtain is straight Reach ripple.

Detailed description of the invention

The data used in the embodiment of the present invention are the drilling earthquake records from field actual observation The part data of middle extraction.

Place seismograph while drilling by design on earth's surface and receive the bit vibration through earth-layer propagation Signal, the i.e. drilling earthquake of this signal gathers protocol (Fig. 3).

First obtained surface seismic achievement section (Fig. 1) of this well, found out under designated depth Each prominent reflector R of side_i, therefrom extract reflection coefficient ζ (t) of each layer, and with bell Cosine function C (t) cross-correlation, obtains surface seismic echo sequence " template " H (τ) (figure 2), its amplitude is the most corresponding with the intensity of echo.Then drilling earthquake protocol is carried out Compacting earth's surface direct wave, eliminates the various Filtering Processing such as low frequency large time difference face ripple, obtains with boring ground Shake initial profile (Fig. 4), the drilling earthquake initial profile after utilization process, along optimal time control The ENERGY E of drilling earthquake ripple in curvilinear path computation window_sumWith homophase degree F_sum, to energy and Homophase degree is weighted, and obtains drilling earthquake direct wave and there is probability P (Fig. 5), at lineups Going out now, there is probability and all obtains extreme value in its energy, homophase degree and direct wave.Next will There is probability P and carry out cross-correlation in surface seismic echo sequence H (τ) and drilling earthquake direct wave, Extreme value change (the left figure of Fig. 6) according to cross-correlation curve determines drilling earthquake direct wave group, figure 6 right figures are for utilizing the calculated one group of direct wave of this invention.If direct wave sequence occurs Time interval, energy, speed each side are obtained for confirmation, and this sequence can serve as next The basic data of step reflection wave imaging.

Claims (3)

1. a searching method for drilling earthquake direct wave group, is characterized in that described method utilizes surface seismic section The reflective information provided and bell cosine function, do reflection coefficient ζ (t) and bell cosine function C (t) mutually Relevant, obtain surface seismic echo " template ", the energy of recycling drilling earthquake ripple and homophase degree calculate through There is probability in ripple: P=w₁E_sum+w₂F_sum, w in formula₁For energy weight coefficient, w₂Weight for homophase degree , then there is probability by surface seismic echo " template " and drilling earthquake direct wave and make cross-correlation, root in coefficient Drilling earthquake direct wave sequence is finally determined according to cross-correlation magnitude variations.

The searching method of a kind of drilling earthquake direct wave group the most according to claim 1, is characterized in that institute The method of stating comprises the steps:

(1) utilize surface seismic to cross well achievement section, obtain reflection wave groups R below designated depth_i；

(2) reflection coefficient ζ (t) of surface seismic is calculated；

ζ (t)=R_iT=Tr_iTime

ζ (t)=0 t ≠ Tr_iTime

In formula: Tr_iZero shot-geophone distance TWT for i-th reflecting layer

(3) reflection coefficient ζ (t) and bell cosine function C (t) are done cross-correlation, obtain surface seismic echo " template "；

$H\left(\mathrm{\τ}\right)=\underset{0}{\overset{T}{\∫}}C\left(t\right)\mathrm{\ζ}(t+\mathrm{\τ})d\mathrm{\τ}$

Wherein, bell cosine function C (t) is an even resonance function exponentially decayed:

$C\left(t\right)=cos\left(2\mathrm{\π}ft\right)e^{-{\mathrm{\βt}}^2}$

(4) drilling earthquake protocol is obtained；

(5) drilling earthquake protocol is carried out various Filtering Processing, obtain drilling earthquake initial profile；

(6) utilize drilling earthquake initial profile, along optimal time control curvilinear path, calculate drilling earthquake ripple Energy and homophase degree；

If being the hourage of direct wave:

${\mathrm{Td}}_i=\frac{1}{V}\sqrt{Z^2+X_i^2}$

In formula: V is formation velocity, Z is bit depth, X_iIt is the offset distance in the i-th road,

The energy of drilling earthquake ripple is:

$E_{sum}=\underset{j=1}{\overset{L}{\Σ}}\underset{i=1}{\overset{N}{\Σ}}{S}_i^2({\mathrm{Td}}_i+j)$

In formula: window width when L is, N is number of channels, S_iIt is X for offset distance_iThe amplitude in the i-th road,

The homophase degree of drilling earthquake ripple is:

$F_{sum}=\underset{j=1}{\overset{L}{\Σ}}\underset{i=1}{\overset{N-1}{\Σ}}{S}_i({\mathrm{Td}}_i+j)S_{i+1}({\mathrm{Td}}_{i+1}+j)$

(7) utilize drilling earthquake wave energy and homophase degree to calculate direct wave and there is probability；

P=w₁E_sum+w₂F_sum

In formula: w₁For energy weight coefficient, w₂For homophase degree weight coefficient,

(8) be there is probability in surface seismic echo " template " and drilling earthquake direct wave and make cross-correlation；

$M\left(t\right)=\underset{0}{\overset{T}{\∫}}H\left(t\right)P\left(t\right)dt$

(9) existence of drilling earthquake direct wave group is judged according to cross-correlation magnitude variations.

The searching method of a kind of drilling earthquake direct wave group the most according to claim 2, is characterized in that In described step (2), the calculation procedure of the zero shot-geophone distance TWT in i-th reflecting layer is:

Offset distance is that the zero shot-geophone distance TWT in the virtual road of 0 is:

Tr₀=(VT₀-Z)/V

In formula: T₀It is the two-way travel time of a certain reflecting interface below drill bit,

The zero shot-geophone distance TWT in i-th reflecting layer is:

${\mathrm{Tr}}_i=\sqrt{{({\mathrm{VT}}_0-Z)}^2+X_i^2}/V.$