CN104155693A - Angle gather seismic response numerical computation method of reservoir fluid fluidity - Google Patents

Abstract

The invention discloses an angle gather seismic response numerical computation method of reservoir fluid fluidity, and relates to a petroleum seismic exploration data processing and explanation technology. According to the angle gather seismic response numerical computation method of reservoir fluid fluidity, pre-stack angle gather seismic normalization of reservoir fluid fluidity is achieved. First, on the basis of petrophysics and the theory of elasticity of holes containing fluid mediums, frequency relevancy longitudinal wave and transverse wave speed parameters of all the segments or layers of log data or a synthetic geologic model, and a reservoir physical parameter geologic model containing different levels of fluid fluidity is obtained; second, a two-dimensional angle and frequency domain AVO seismic reflection coefficient distribution formula is utilized for obtaining an incident angle and frequency domain AVO reflection coefficient distribution model changing along with the incident angle and the frequency at the same time; third, a scalar diffusion viscosity equation is used for performing forward calculation of a seismic wave field to obtain pre-stack angle gather data. The angle gather seismic response numerical computation method of reservoir fluid fluidity can be used for describing influences of reservoir fluid fluidity on a pre-stack angle gather seismic response and the corresponding relation between the reservoir fluid fluidity and the pre-stack angle gather seismic response, and provides more reliable guidance for recognition of oil gas in reservoirs in oil gas seismic exploration.

Description

Reservoir fluid mobility Jiao road collection seismic response numerical computation method

Technical field

The present invention relates to oil seismic exploration data processing and interpretation field, a kind of hole theory of elasticity and wave equation method of utilizing petrophysics, containing fluid media (medium), realize road, the prestack angle collection Seismic forward of reservoir fluid mobility, for describing seismic response features and the rule on road, prestack angle collection containing fluid reservoir mobility, for fluid identification of reservoir in oil-gas seismic exploration provides the technology of guidance.

Background technology

Reservoir fluid mobility is the physical parameter of fluid mobility in reflection pore media, be defined as the ratio of reservoir permeability and pore fluid viscosity, it has reflected the perviousness (or connective) of reservoir rock skeleton mesoporosity structure and the type of pore fluid, viscosity, the acting in conjunction of saturation degree, therefore, reservoir fluid mobility is for the elastic parameter of determining reservoir rock, inner structure and significant containing fluid properties etc., utilize numerical computation method to analyze the seismic response features of reservoir fluid mobility on road, prestack angle collection, can instruct the inverting of reservoir fluid mobility parameter in actual exploration, for oil-gas seismic exploration provides technical support more reliably.

Fluid in pore media can cause significant seismic attenuation and frequency dispersion abnormal, and the pore fluid flow that seismic event excites (wave-induced fluid flow---WIFF) be major reason (Chapman, 2003 that cause seismic attenuation and frequency dispersion; Maultzsch et al., 2003; Chapman & Odebeatu, 2005; 2006; M ü ller, 2010), at present, the groundwork of numerical simulation that contains fluid pore media elastic parameter and seismologic record is as follows: utilize the numerical method based on Biot hole theory of elasticity to carry out numerical analysis (Carione & Picotti to the velocity dispersion of fractional saturation thin film model and decay, 2006), or utilize similar approach to carry out numerical analysis on the elasticity alternating layers model of hole, and obtain its seismic response (Quintal et al, 2012) by finite element method; The low frequency fractal of the permeability formation dependent Frequency that the filtering theory of take is derived as basis, can reflect the effect (Silin & Goloshubin, 2010) of reservoir fluid mobility; Utilize the theoretical reflection coefficient that calculates single-layer model dependent Frequency of localized ejection stream, considered the response of earthquake spectrum and AVO feature (Chapman and Odebeatu etc., 2006) containing fluid reservoir simultaneously.

Because reservoir fluid mobility and seismic amplitude (are that Amplitude Versus Offset---AVO) both exist interrelated and complicated acting in conjunction with the variation of geophone offset, thereby show unique seismic response features and rule on the road, prestack angle of oil and gas reservoir collection, yet, how to simulate and portray the seismic response of reservoir fluid mobility on road, prestack angle collection, still the numerical computation method that lacks at present system, and this is the seismic anomaly features such as Dispersion and attenuation of Study In Reservoir fluid mobility on road, prestack angle collection, instruct reservoir fluid mobility parametric inversion on road, actual seismic prestack angle collection, realize the important foundation work of reservoir description and fluid detection.

Summary of the invention

The present invention will provide a kind of hole theory of elasticity and wave equation method that fully utilizes rock physics, contains fluid media (medium), realize the technology of road, reservoir fluid mobility prestack angle collection Seismic forward numerical evaluation, it can be for Study In Reservoir fluid mobility seismic anomaly feature and the rules such as Dispersion and attenuation on road, prestack angle collection, instruct reservoir fluid mobility parametric inversion on actual seismic Die Jiao road collection, for fluid identification of reservoir in oil-gas seismic exploration provides support.

Reservoir fluid mobility Jiao of the present invention road collection seismic response numerical computation method, first fully utilize petrophysical data, logging trace, log analysis data, geology, earthquake and development data etc., the reservoir physical parameter geologic model that foundation comprises different fluid mobility, makes geologic model more approach geology and the geophysical character of true reservoir.

Reservoir fluid mobility Jiao of the present invention road collection seismic response numerical computation method, adopt dynamic EFFECTIVE MEDIUM THEORY, the frequency dependence elastic tensor matrix of the reservoir physical parameter geologic model that calculating comprises different fluid mobility, and then the frequency dependence that obtains each stratum speed parameter in length and breadth, effectively portray the parameters such as p-and s-wave velocity of oil and gas reservoir with the physics law of fluid mobility and frequency co-variation, make the earthquake Dispersion and attenuation feature of reservoir fluid mobility and dependent Frequency set up direct corresponding relation.

Reservoir fluid mobility Jiao of the present invention road collection seismic response numerical computation method, conventional AVO reflection coefficient formula is expanded to incident angle-frequency field, set up frequency dependence AVO reflection coefficient distribution formula, by this formula, can utilize the frequency dependence frequency dependence AVO reflection coefficient distribution that speed parameter calculates each layer of reflecting interface in length and breadth, thereby can reflect that, in two dimension angular-frequency plane, fractal is with the co-variation of different incidence angles degree and frequency.

Reservoir fluid mobility Jiao of the present invention road collection seismic response numerical computation method, employing has considered that the wave equation of reservoir fluid dispersivity, fluid viscosity realizes, the earthquake prestack angle Dao Ji that generation comprises frequencfy-dependent behavior, make the concentrated seismic wave field in road, earthquake prestack angle fully reflect effect and the contribution of fluid mobility, the features such as Dispersion and attenuation that can portray oil and gas reservoir dependent Frequency.

Reservoir fluid mobility Jiao of the present invention road collection seismic response numerical computation method, has following superiority:

(1) set up two dimension angular-frequency field frequency dependence AVO reflection coefficient distribution formula, the computing method of utilizing dynamic EFFECTIVE MEDIUM THEORY and frequency dependence AVO reflection coefficient to distribute, obtain reservoir physical parameter geologic model, make it can embody acting in conjunction and the contribution of frequency dependence and incident angle, more meet the geophysics objective law of oil and gas reservoir;

(2) utilize the wave field extrapolation of scalar disperse viscous equation to carry out the numerical evaluation of Seismic forward, make the prestack angle road energy collecting generating comprise the seismic wave field information relevant with reservoir pore space fluid mobility feature, be conducive to analysing fluid mobility to the impact of seismic response and the mechanism of action thereof;

(3) road, the frequency dependence prestack angle collection generating mainly reflects primary seismic wave information, interference and impact without transformed wave and interformational multiples, do not exist because of moving school and draw the interference of stretching the low-frequency effects causing on road, prestack angle collection, be conducive to accurately determine effect and the corresponding relation of oil and gas reservoir fluid mobility to the concentrated seismic response in road, prestack angle simultaneously.

Specific implementation principle of the present invention is as follows:

First import and comprise p-and s-wave velocity, density, the isoparametric logging trace of factor of porosity, each interval fluid type and saturation parameters of well logging interpretation, calculate the viscosity of reservoir pore space fluid, in conjunction with core and rock physics information, as data such as permeability, rock particles size, hole ellipticity, fracture density and length, (viscosity by permeability divided by pore fluid, unit is m to calculate reservoir fluid mobility ⁴/ (Ns), wherein m is rice, N is newton, s is second).Utilize dynamic EFFECTIVE MEDIUM THEORY (Chapman etc., 2003), calculate the frequency dependence elastic tensor matrix of each interval, and then obtain the frequency dependence p-and s-wave velocity of each interval, thereby make the elastic parameter on each stratum embody effect and the contribution of fluid mobility.

Based on the dynamic EFFECTIVE MEDIUM THEORY of Chapman (Chapman etc., 2003), first build frequency dependence elastic tensor Matrix C (f), this entry of a matrix element C _ijklby following, calculate:

$C_{\mathrm{ijkl}}=C_{\mathrm{ijkl}}^0-{\mathrm{\φ}}_p{C}_{\mathrm{ijkl}}^1-{\mathrm{\ϵ}}_c{C}_{\mathrm{ijkl}}^2-{\mathrm{\ϵ}}_f{C}_{\mathrm{ijkl}}^3$

Wherein, C ⁰the isotropy background elastic tensor of elastic tensor matrix, C ¹, C ²and C ³be respectively and rock porosity φ _p, crack density ε _cwith fracture density ε _fcorresponding elastic tensor correcting value.

Utilize the existing parameter in above-mentioned logging trace, as the compressional wave shear wave velocity (frequency f of known measurement ₀) with density p, rock porosity φ _pwith crack density ε _c, fluid mobility calculation of parameter given frequency initial background elastic tensor C ⁰(Λ, Μ), wherein elastic constant Λ and Μ calculate as follows

Λ＝λ ₀+φ _p(λ ₀,μ ₀,f ₀)+ε _c(λ ₀,μ ₀,f ₀),

Μ＝μ ₀+φ _p(λ ₀,μ ₀,f ₀)+ε _c(λ ₀,μ ₀,f ₀)

Wherein ${\mathrm{\λ}}_0=\mathrm{\ρ}{\left(v_p^0\right)}^2-2{\mathrm{\μ}}_0,{\mathrm{\μ}}_0=\mathrm{\ρ}{\left(v_s^0\right)}^2.$ Can calculated rate correlativity elastic tensor matrix:

$C_{\mathrm{ijkl}}\left(f\right)=C_{\mathrm{ijkl}}^0(\mathrm{\Λ},M,\mathrm{\ω})-{\mathrm{\φ}}_p{C}_{\mathrm{ijkl}}^1({\mathrm{\λ}}_0,{\mathrm{\μ}}_0,f)-{\mathrm{\ϵ}}_c{C}_{\mathrm{ijkl}}^2({\mathrm{\λ}}_0,{\mathrm{\μ}}_0,f)-{\mathrm{\ϵ}}_f{C}_{\mathrm{ijkl}}^3({\mathrm{\λ}}_0,{\mathrm{\μ}}_0,f)$

Wherein, f is frequency.

Obtained considering the frequency dependence elastic tensor Matrix C (f) of reservoir fluid mobility feature, then calculated rate correlativity p-and s-wave velocity v accordingly _pand v (f) _s(f).

The AVO reflection coefficient that calculates two-dimentional incident angle-frequency field distributes, on the basis of the people's such as Wiggins (1983) P-wave AVO reflection coefficient approximate formula, expanded to angle-frequency field, set up angle-frequency field AVO reflection coefficient distribution computing formula as follows:

R(f,θ)＝A(f)+B(f)sin ²θ+C(f)tan ²θsin ²θ

Wherein:

$A\left(f\right)=\frac{1}{2}[\frac{\mathrm{\Δ}{V}_P\left(f\right)}{V_p\left(f\right)}+\frac{\mathrm{\Δ\ρ}}{\mathrm{\ρ}}],$

$B\left(f\right)=\frac{1}{2}\frac{\mathrm{\Δ}{V}_P\left(f\right)}{V_p\left(f\right)}-4{\left[\frac{V_s\left(f\right)}{V_P\left(f\right)}\right]}^2\frac{\mathrm{\Δ}{V}_s\left(f\right)}{V_s\left(f\right)}-2{\left[\frac{V_s\left(f\right)}{V_P\left(f\right)}\right]}^2\frac{\mathrm{\Δ\ρ}}{\mathrm{\ρ}},$

$C\left(f\right)=\frac{1}{2}\frac{\mathrm{\Δ}{V}_P\left(f\right)}{V_p\left(f\right)}.$

Wherein R (f, θ) is that two dimension angular-frequency field AVO reflection coefficient distributes, and θ and f are respectively incident angle and frequency, V _p(f), V _s(f) and ρ be respectively the frequency dependence p-and s-wave velocity of reflecting interface levels and the mean value of density, and Δ V _p(f), Δ V _s(f) and Δ ρ be respectively the frequency dependence p-and s-wave velocity of reflecting interface levels and the difference of density.

The Seismic forward numerical evaluation of road, prestack angle collection, is to calculate by wave equation continuation, adopts as the realization of subscript quantity disperse viscous equation:

$\frac{{\∂}^{2}u}{{\∂t}^2}+\mathrm{\ζ}\frac{\∂u}{\∂t}-\mathrm{\η}\frac{{\∂}^{3}u}{{\∂z}^2\∂t}-v^2\frac{{\∂}^{2}u}{{\∂z}^2}=0$

Wherein, u is displacement, and ζ is disperse attenuation parameter, and η is fluid viscosity, and v is velocity of wave propagation.The phase shift continuation of calculating proportion-wavenumber domain wave field of this equation realizes:

$u(z+\mathrm{\Δz},\mathrm{\ω})=u(z,\mathrm{\ω})e^{{\mathrm{ik}}_z\left(\mathrm{\ω}\right)\mathrm{\Δz}}$

Wherein, angular frequency=2 π f, z is the degree of depth, Δ z is the step-length of degree of depth continuation, vertical wave number k _zbe calculated as follows:

$k_z\left(\mathrm{\ω}\right)={\left[\frac{-{\mathrm{\ω}}^2+\mathrm{i\ζ\ω}}{v_p^2\left(f\right)+\mathrm{i\η\ω}}\right]}^{1/2}$

The AVO reflection coefficient of the reservoir physical parameter geologic model that comprises different fluid mobility is distributed and the input of each layer of frequency dependence velocity of longitudinal wave as above-mentioned scalar disperse viscous equation, by the numerical evaluation of wave field extrapolation, can obtain reservoir fluid mobility Jiao road collection, for the pre-stack seismic response characteristic of fluid mobility, analyze.

Accompanying drawing explanation

Fig. 1 is the reservoir fluid mobility geologic model of design, and wherein first and third layer is that the second layer is for containing fluid hole sand layers not containing the mud stone of fluid.The thickness of ground floor is 2.07 grams/cc of 248 meters, velocity of longitudinal wave 2755 meter per seconds, shear wave velocity 1402 meter per seconds, density; The thickness of the second layer is 90 meters, velocity of longitudinal wave 2830 meter per seconds, shear wave velocity 1470 meter per seconds, 2.09 grams/cc of density, factor of porosity 25%; The thickness of the 3rd layer is 2.2 grams/cc of 172 meters, velocity of longitudinal wave 2975 meter per seconds, shear wave velocity 1595 meter per seconds, density.

Fig. 2 is corresponding with Fig. 1 geologic model, and when the second layer is relatively low containing the fluid mobility of fluid hole sand layers, now fluid mobility is 7.8 * 10 ^-11m ⁴/ (Ns), prestack angle road composite section and full angle stacked section thereof that Seismic forward numerical evaluation of the present invention obtains.Wherein: (a) being road, prestack angle composite section, is (b) full angle stack seismic trace.

Fig. 3 is corresponding with Fig. 1 geologic model, and when the second layer is relatively high containing the fluid mobility of fluid hole sand layers, now fluid mobility is 1.95 * 10 ^-9m ⁴/ (Ns), prestack angle road composite section and full angle stacked section thereof that Seismic forward numerical evaluation of the present invention obtains.Wherein: (a) being road, prestack angle composite section, is (b) full angle stack seismic trace.

Fig. 4 is corresponding with Fig. 2, the reservoir fluid mobility attribute that utilizes a kind of reservoir fluid mobility inversion method (Chen Xuehua etc., 2012) based on seismic data to calculate the section in Fig. 2; Utilize same method to calculate.

Fig. 5 is the reservoir fluid mobility attribute corresponding with Fig. 3.

Embodiment

The specific embodiment of the present invention is as follows: (1) input comprises p-and s-wave velocity, density, the isoparametric log data of factor of porosity, and each interval fluid type and saturation parameters of well logging interpretation, calculate the viscosity of reservoir pore space fluid, in conjunction with core and rock physics information, as data such as permeability, rock particles size, hole ellipticity, fracture density and length, calculate reservoir fluid mobility; (2) utilize dynamic EFFECTIVE MEDIUM THEORY, calculate each element of each interval frequency dependence elastic tensor matrix, then with this, calculate the frequency dependence p-and s-wave velocity parameter of each interval, in the depth range of setting, along depth-logger direction node-by-node algorithm, until all sampled points calculating of appointment interval are complete, obtain the reservoir physical parameter geologic model that comprises different fluid mobility; (3) utilize two dimension angular-frequency field AVO reflection coefficient distribution formula, frequency dependence p-and s-wave velocity and density to each interval, depth direction node-by-node algorithm incident angle-frequency field AVO reflection coefficient along reservoir physical parameter geologic model distributes, and obtains the angle-frequency field AVO reflection coefficient distributed model simultaneously changing with frequency and incident angle of each interval; (4) utilize scalar disperse viscous equation, what the reservoir physical parameter geologic model that comprises different fluid mobility and angle-frequency field AVO reflection coefficient distributed model were carried out to pre-stack seismic wave field just drills calculating, obtains road, prestack angle collection data.(5) utilize geological data Become the picture software, the prestack road collection data of generation are changed into profile image or carry out visual demonstration, or utilize the collection data analysis of road, prestack angle to specify the reservoir fluid mobility of interval road, prestack angle to be concentrated to impact and the corresponding relation thereof of seismic response.

Embodiment explanation of the present invention:

Fig. 1 is the reservoir fluid mobility geologic model (concrete physical parameter is shown in above-mentioned accompanying drawing explanation) of design, Fig. 2 is when given this model second layer relatively low containing the fluid mobility of fluid hole sandstone, and (Fig. 2 a) and full angle stack seismic trace (Fig. 2 b) to utilize the prestack angle Dao Ji that reservoir fluid mobility Jiao of the present invention road collection seismic response numerical computation method obtains.From Fig. 2 a, be positive reflection line-ups containing top, the end of fluid hole sandstone, and amplitude incident angle increases and reduce, and the frequency ratio top of bottom reflection lineups is low, there is decay in seismic wave explanatorily.Fig. 3 is corresponding with Fig. 1, when the Given Graph 1 model second layer relatively high containing the fluid mobility of fluid hole sandstone, (Fig. 3 a) and full angle stack seismic trace (Fig. 3 b) to utilize the prestack angle Dao Ji that reservoir fluid mobility Jiao of the present invention road collection seismic response numerical computation method obtains, from Fig. 3 a, containing top, fluid sand rock stratum, it is positive reflection homophase, its amplitude incident angle increases and slightly reduces, but all there is obvious phase distortion in its bottom reflection lineups, illustrate and occurred obvious earthquake frequency dispersion, especially in incident angle, be greater than in the seismic trace of 25 degree more remarkable, and the frequency of bottom reflection lineups is starkly lower than the reflection line-ups at top, there is decay in seismic wave explanatorily, in Fig. 3 b, also can be observed containing the obvious phase distortion feature in fluid hole sand layers bottom.In addition, comparison diagram 2 and Fig. 3 are visible, in the situation that both fluid mobilities are different, containing fluid hole sand layers top, end reflection line-ups, all shown different features, Fig. 2 containing fluid hole sand layers bottom reflection than obviously the moving down of Fig. 3, and the phase distortion of Fig. 3 more obviously, frequency is also lower.Therefore, Fig. 2 and Fig. 3 illustrate reservoir fluid mobility Jiao of the present invention road collection seismic response numerical computation method, can simulate and reflect in different reservoir fluid mobility situation, different characteristic and the rule of seismic response concentrated in road, prestack angle, while effectively portraying the variation of reservoir fluid mobility, the off-note of the seismic response changing with incident angle.

Fig. 4, Fig. 5 are the fluid mobility attributes that utilizes respectively Fig. 2 and Tu3Zhong Jiao road collection data to calculate, this attribute is to utilize a kind of reservoir fluid mobility inversion method (Chen Xuehua etc. based on seismic data, 2013) realize, can extract the reservoir parameter relevant with fluid mobility, from Fig. 4 and Fig. 5, the fluid mobility attribute containing fluid hole sandstone of the second layer is all shown as relative value extremely greatly, and cover with the fluid mobility attribute of the shale layer of bottom on it, be zero, this conforms to initial reservoir parameter geologic model; In addition, comparison diagram 4 and Fig. 5 are visible, in Fig. 4, the second layer is starkly lower than Fig. 5 containing the fluid mobility attribute of fluid hole sandstone, and reservoir parameter geologic model when the numerical evaluation conforms to Fig. 2 and Fig. 3 for this: in Fig. 2 the second layer containing the fluid mobility of fluid hole sandstone relative low, that Fig. 3 second layer contains fluid hole sandstone fluid mobility is relatively high.Therefore, the fluid mobility attribute specification in Fig. 4 and Fig. 5, reservoir fluid mobility Jiao of the present invention road collection seismic response numerical computation method accurately and reliably simulation reservoir fluid mobility at road, prestack angle concentrated seismic response and off-note thereof.

Claims (5)

1. a reservoir fluid mobility Jiao road collection seismic response numerical computation method, is characterized in that adopting following concrete steps: input comprises p-and s-wave velocity, density, the isoparametric log data of factor of porosity, and each interval fluid type and saturation parameters of well logging interpretation, calculate the viscosity of reservoir pore space fluid, in conjunction with core and rock physics information, as data such as permeability, rock particles size, hole ellipticity, fracture density and length, calculate reservoir fluid mobility; utilize dynamic EFFECTIVE MEDIUM THEORY, calculate each element of each interval frequency dependence elastic tensor matrix, then with this, calculate the frequency dependence p-and s-wave velocity parameter of each interval, in the depth range of setting, along depth-logger direction node-by-node algorithm, until all sampled points calculating of appointment interval are complete, obtain the reservoir physical parameter geologic model that comprises different fluid mobility; utilize two dimension angular-frequency field AVO reflection coefficient distribution formula, frequency dependence p-and s-wave velocity and density to each interval, depth direction node-by-node algorithm incident angle-frequency field AVO reflection coefficient along reservoir physical parameter geologic model distributes, and obtains the angle-frequency field AVO reflection coefficient distributed model simultaneously changing with frequency and incident angle of each interval; utilize scalar disperse viscous equation, what the reservoir physical parameter geologic model that comprises different fluid mobility and angle-frequency field AVO reflection coefficient distributed model were carried out to pre-stack seismic wave field just drills calculating, obtains road, prestack angle collection data; utilize geological data Become the picture software, the prestack road collection data of generation are changed into profile image or carry out visual demonstration, or utilize the collection data analysis of road, prestack angle to specify the reservoir fluid mobility of interval road, prestack angle to be concentrated to impact and the corresponding relation thereof of seismic response.

2. a kind of reservoir fluid mobility Jiao according to claim 1 road collection seismic response numerical computation method, it is characterized in that: utilized log data, well logging interpretation and rock physics information simultaneously, Fluid Computation mobility and frequency dependence p-and s-wave velocity thereof, set up the reservoir physical parameter geologic model that comprises different fluid mobility stratum.

3. a kind of reservoir fluid mobility Jiao according to claim 1 and 2 road collection seismic response numerical computation method, it is characterized in that: set up incident angle-frequency field AVO reflection coefficient and distributed, embodied reservoir fluid mobility to the impact of the seismic response of different incidence angles degree and frequency and effect.

4. a kind of reservoir fluid mobility Jiao according to claim 1 road collection seismic response numerical computation method, is characterized in that: utilized the phase shift wave field extrapolation algorithm of scalar disperse viscous equation, calculated the seismic wave field data of road, prestack angle collection.

5. a kind of reservoir fluid mobility Jiao according to claim 1 road collection seismic response numerical computation method, it is characterized in that: in road, the prestack angle collection data of acquisition, comprised the seismic wave field Dispersion and attenuation feature relevant with reservoir fluid mobility, embodied both corresponding relations.