Pdf application of modelbased inversion technique in a. Highresolution reservoir characterization by 2d modeldriven. Integrating seismic acoustic impedance inversion and. Chapter 4 joint seismic inversion and localization comparing simulated annealing and metropolis hasting, extends the findings in chapter 3 to apply the combination of elastic wavefield model and bayesian inversion to solve a joint bayesian inversion problem to determine the tunnel position in the ground and also. Model based inversion produces a blocky output that contains more geological detail than bandlimited inversion. This paper describes a successful application of model based seismic inversion technique and probabilistic neural. Highresolution reservoir characterization by 2d model. In a seismic inversion the original reflectivity data, as typically recorded routinely, is converted from an interface property i. By continually modifies and updates the geological model through model selective. Stochastic reservoir characterization based on seismic inversion data are also utilized for better spatial description of reservoir eidsvik et al. We introduce a new opensource toolkit for model based bayesian seismic inversion called delivery. Seismic inversion the best tool for reservoir characterization.
Some other alternatives are spaceadaptive and discrete spike inversions. Extracting seismic uncertainties from tomographic velocity inversion and their use in reservoir risk analysis. In addition to the work flow of a model based inversion, a brief illustration of other inversion. Simultaneous model based inversion parametrization. Geophysical inversion versus machine learning in inverse. Research of model based imaging and wave impedance. Nov 14, 2016 seismic inversion aims to reconstruct a quantitative model of the earth subsurface, by solving an inverse problem based on seismic measurements. Typically, a reflection coefficient series from a well within the boundaries of the seismic survey is used to estimate the wavelet phase and frequency. The fullwaveform inversion problem is to infer the velocity map from a given set of seismic data. Smooth logs are used to choose model bounds in the stochastic inversion.
Cloetingh3,6 1german research centre for geosciences gfz potsdam, germany, 2schmidt institute of physics of the earth, moscow. Horizon top and bottom are marked by blue line shows zone of. Seismic reservoir characterization using model based poststack seismic inversion. Seismic inversion is a procedure that helps extract underlying models of the physical characteristics of rocks and fluids from seismic and welllog data. Model based inversion 1 optimally process the seismic data 2 build model from picks and impedances 3 iteratively update model until output synthetic matches original seismic data. Highresolution clinoform characterization by 2d modeldriven. Both recursive and model based inversion use the assumption that we have extracted a good. After the initial qc of the input data, the well data is correlated with the seismic data and a zero phase wavelet is extracted. Modelbased inversion modelbased inversiontypically starts with a low frequency model of the pimpedance and then the model is perturbed until a good fit is obtained between the seismic data and a synthetic trace using the recursive formula. Geophysical inversion and machine learning methods both are useful for solving inverse problems. P245 model based seismic inversion using nongaussian. Therefore, seismic wavefield modeling may be viewed as the reverse process of seismic migration. The software described in this paper is a tracebased inversion routine, and is designed to draw stochastic samples from the posterior distribution of.
Well toseismic match, zerophasing of data in zone of interest and extraction of the wavelet. Inversion is defined as mapping the physical structure and properties of the subsurface of the earth using measurements made on the surface, creating a model of the earth using seismic data as input. Inversion of differences in frequency components of azimuthal seismic data for indicators of oilbearing fractured reservoirs based on an attenuative cracked model huaizhen chen, junxiao li, and kristopher a. Modelbased inversion of amplitudevariationswithoffset data using a genetic algorithm subhashis mallick. Composite seismic loops a impedance cube inversion output 3d seismic data seismic wavelet initial impedance model input picked horizons in twt b figure 1b the input for a model driven seismic inversion consists of time migrated seismic data, a seismic wavelet, an optional impedance model and picked time horizons. Full waveform inversion fwi is nonlinear datafitting procedure that aims at obtaining detailed estimates of subsurface properties from seismic data, which can be the result of either passive or active seismic experiments.
By applying this recursive equation, seismic data can be directly. Inversion methodsacasestudyfromblackfootfield,canada. A possible workflow for performing a modelbased seismic inversion consists of loading three types of data. Acoustic impedances are produced in thin microlayers. Pdf modelbased amplitude versus offset and azimuth. We introduce a new opensource toolkit for modelbased bayesian seismic inversion called delivery. Under such a framework, the model parameters and the physics of the forward problem are used to generate synthetic data. A simplistic initial stratigraphic model macro and micro is convolved with the wavelet to obtain a synthetic response that can be compared with the actual seismic trace. Modelbased inversion introduction to seismic inversion. In the petrophysical seismic inversion, we use the petroelastic model during the inversion process. Comparing deterministic and probabilistic approaches. Figure 1b the input for a modeldriven seismic inversion consists of time migrated seismic data, a seismic wavelet.
The pdf is assumed to have a gaussian distribution in a. Highresolution clinoform characterization by 2d model. Geophysical inversion versus machine learning in inverse problems. In other words, seismic attributes at a specific time may represent the convolution of the desired reservoir element with neighboring. The milton dobrin lecture april, 2010 brian russell. The inversion process is then applied to the entire data set. Pdf seismic inversion methods and some of their constraints. Single loop inversion of facies from seismic data based on. In this study, a 3d low frequency model lfm is proposed which can be estimated by kriging interpolation of resultant impedance values from well log data. The original problem of seismic inversion is a leastsquare problem, however, the seismic inverse problem is ill posed. Model based poststack seismic inversion in modelbased inversion we start with a low frequency model of the pimpedance and then perturb this model until we obtain a good fit between the seismic data and a computed synthetic trace.
The proposed avoa inversion algorithm is tested on real 3d prestack seismic data from the tarim basin, china, the inverted fracture density show good agreement with well log data, except that. Modelbased inversion of lowfrequency seismic data earthdoc. Inversion results at seismic scale can also be downscaled to reservoir properties in a second inversion step through a petroelastic model. Seismic migration is a process of estimating earths reflectivity from a recorded seismic wavefield using a velocitydepth model. Highresolution clinoform characterization by 2d model driven seismic bayesian inversion ranging from hundreds to millions of years. Interwell seismic inversion and reservoir characterization. In this study, we compare geophysical inversion based on a leastsquares method and a neural network as a supervised machine learning method with examples of reflectivity inversion and make clear the similarities and differences between them. The process of imaging through modeling the velocity structure is a form of inversion of seismic data, and the term inversion is often used to imply building a velocity model which is iteratively improved until it and the seismic data are optimally in agreement. The hussar experiment was carried out in central alberta, canada, in september 2011 with the purpose of acquiring low frequency seismic data to be used in inversion methods. Model based inversion, colored inversion, sparsespike inversion, bandlimited impedance inversion. A twostep inversion approach for seismicreservoir characterization and a comparison with a singleloop markovchain monte carlo.
In the past sections of the course, we have derived reflectivity information directly from the seismic section and used recursive inversion to produce a final velocity versus depth model. Extracting seismic uncertainties from tomographic velocity. Model based beamforming and bayesian inversion signal. Threeparameter prestack seismic inversion based on l12 minimization, lingqian wang, hui zhou, yufeng wang, bo yu, yuanpeng zhang. Highresolution clinoform characterization by 2d modeldriven seismic bayesian inversion ranging from hundreds to millions of years.
Reservoir characterization using model based inversion and. Porosity prediction from seismic inversion, lavrans field. The bayesian inversion method through the probability density function permits the incorporation of a priori information about the parameters, and also allow for. Stochastic vs deterministic prestack inversion methods cgg. The software described in this paper is a tracebased inversion routine, and is designed to draw stochastic samples. In one of the modeldriven methods we support, the simplicity term is implemented by limiting the solution. Interwell is a seismic inversion and characterization software for reservoir and exploration geophysicists, available in linux and windows environments. This new solution can fully use seismic data and logging or pseudologging data to establishing an initial model.
In the study, model based poststack inversion technique was used to create pseudo logs at each seismic trace at the well location to constitute high resolution acoustic inverted impedance models. Bandlimited inversion is a robust method that produces a smooth and continuous output. Comparison of post stack seismic inversion methods. I cast the inversion of amplitudevariationwithoffset avo data into the framework of bayesian statistics. Direct reservoir property estimation based on prestack. Because the internal layers of the sediments of the clinoform do not differ much from an acoustic point of view, such features do not tend to show up very well on seismic images. Highresolution reservoir characterization by seismic inversion with. This study presents the result of a modelbased seismic inversion technique which was used to invert an acoustic impedance structure within a reservoir interval by intergrating well logs and 3d post stack seismic data obtained from xy field offshore niger delta. There are at least three fundamental issues to be solved simultaneously. Modelbased inversion of amplitudevariationswithoffset.
Accelerating 2d frequencydomain fullwaveform inversion via fast wave modeling using a model reduction technique. A deterministic modelbased inversion will output just one earth impedance model that fits the seismic data being inverted, and the user of that deterministic inversion has a risk of being proven wrong by the drill bit. All modern seismic inversion methods require seismic data and a wavelet estimated from the data. Reservoir characterization using avo and seismic inversion. Accurate wavelet estimation is critical to the success of any seismic inversion. Different methods of seismic inversion, including deterministic and stochastic approaches, have been. In order to find a better inversion solution suitable for special gas hydrate exploration area with distinctive geological conditions, this paper proposed model based wave impedance inversion.
The forward model the physics takes a map of seismic wave velocity as input and by simulating the physics of wave propagation in this subsurface, produces as output what seismic data would be measured over this surface. The model inversion results revealed four distinct sedimentary packages based on the. The purpose was to delineate lateral and vertical alternations in subsurface rock properties which is caused by difference in. Swr ai mai v p ai v p in acoustic impedance inversion the seismic, model and output are as shown here. Pdf seismic reservoir characterization using model based post. Inversionmethodsacasestudyfromblackfootfield,canada. The inversion result is qcd using time slices of a window centered about the target horizon. Both recursive and modelbased inversion use the assumption that we have extracted a good. The geosi method that i will discuss today combines both a gaussian pdf and. One method chosen to better understand the amplitude variations was 3d seismic inversion. Building a geologic modelbased inversion for the stratton field 3d survey. This data set has dense well coverage with 19 wells in the twomile by onemile seismic survey, an important feature for testing inversion techniques,several techniques for mapping reservoir elements using the seismic data have been proposed, they generally correlate a specific sand to.
In the absence of well data, the properties can also be inferred from the inversion of seismic data alone 10. Pdf in the study, model based poststack inversion technique was used to create pseudo logs at each seismic trace at the well location to. Quality control and preconditioning of the input data. Highresolution reservoir characterization by 2d modeldriven seismic bayesian inversion. We have also seen that these methods can be severely affected by noise, poor amplitude recovery, and the bandlimited nature of seismic data. Predicting porosity by multivariate regression and. Microlayers are automatically introduced into the macromodel to define a grid cell volume based on inline, crossline. Modelbased inversion of broadband seismic data crewes. The macro layers are formed by the mapped twt horizons. Filtered seismic data 10156085 hz and an initial model with a 1015 hz cutoff were used for this test.
Seismic inversion is essentially a very simple procedure. Highresolution reservoir characterization by 2d model driven seismic bayesian inversion. Figure from seismic inversion methods and some of their. Earthworks seismic inversion plugin for decisionspace. With a probabilistic modelbased inversion, all acceptable earth impedance models are output.
The acoustic impedance ai inversion aims to obtain a highresolution impedance volume by integrating welllog and bandlimited seismic data. Horizon top and bottom are marked by blue line shows zone of interest. Furthermore, seismic inversion is adopted for extracting correlated attributes to merge with the lfm so as to better construct a pseudo log volume. Poststack seismic data used in inversion, red curves show available three well logs. The inspection of the a posteriori probability density function pdf through the.
The prior model in delivery is a tracelocal layer stack, with rock physics information taken from log analysis and layer times initialised from picks. Detection of thin beds is based on subtle changes in the shape of a specific seismic loop doublet, a feature that is usually. Seismic inversion methods and some of their constraints. Three wells located close to the seismic line and a dynamitesource dataset, acquired with threecomponent 10 hz geophones, were used for a poststack inversion test using commercial software.
Model based inversion of acoustic impedance from seismic. Modelbased inversion of amplitudevariationswithoffset data using a genetic algorithm. This book covers the basic theory and techniques used in seismic inversion, corresponding to these three issues, emphasising the. Seismic inversion aims to reconstruct a quantitative model of the earth subsurface, by solving an inverse problem based on seismic measurements. Given an initial guess of the subsurface parameters, a model the data are predicted by solving a waveequation. Estimation of acousticimpedance model by using modelbased. Since seismic data is bandlimited and well data has highfrequency information, a lowfrequency component within the seismic band of the model based on well data is needed. Seismic inversion a work flow for modelbased inversion. Show full abstract the opo field, western niger delta using a modelbased seismic inversion technique. This was carried out using cggs 3d inversion package tdrov gluck et al. It handles a large range of seismic data in dedicated workflows from data conditioning to quantitative property estimation. Model based poststack seismic inversion in model based inversion we start with a low frequency model of the pimpedance and then perturb this model until we obtain a good fit between the seismic data and a computed synthetic trace. Modelbased mbi, colored ci, sparsespike ssi, and bandlimited bli inversions are applied to the poststack seismic data from the blackfoot field, alberta.
The input to seismic modeling is a representation of the earths reflectivity and a velocitydepth model. Avo inversion based on inverse operator estimation in. An example of such a process and the one we will discuss in this. Single loop inversion of facies from seismic data based on sequential simulations and probability perturbation method dario grana, jack dvorkin department of geophysics stanford university tapan mukerji department of energy resources engineering stanford university abstract the main objective of this work is to present a new methodology for. Modelbased inversion 1 optimally process the seismic data 2 build model from picks and impedances 3 iteratively update model until output.
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