Fluid substitution pane within validates rock properties manager. Practical gassmann fluid substitution in sandshale. Article details practical gassmann fluid substitution in. Whilst the equations and software implementations are straightforward, there are potential. Elastic rock properties change with porosity, fluid type and. When performing fluid substitution on log data gassmanns 1951 model is the general tool of choice. For this purpose, a probabilistic sensitivity analysis of gassmanns fluid substitution equations using a monte carlo approach was carried out. The first stage of this project deals with the application.
So for forward modelling softare for rock physics analysis, look no further than downunder geosolutions. The purpose of this tutorial is to guide the reader through practical gassmann fluid substitution, and. You then use these maps to make a quantitative analysis of the probability of exploration success. Fluid substitution is an important part of seismic attribute work, because it provides the interpreter with a tool for modeling and quantifying the various fluid. Rokdoc rock physics introduction 2 day course 12 may 14. Petrophysical evaluation and fluid substitution modeling for. A gassmannconsistent rock physics template cseg recorder.
Gassmann fluid substitution requires that the porosity remain constant. Summary the most common technique used for modeling and estimating the elastic properties of rocks under various fluid scenarios is gassmanns method gassmann 1951. For the density log, fluid substitution can be written. Reservoir characterization using fluid substitution and. Here, we discuss the sensitivity of the seismic response to uncertainties in the physical parameters of the reservoir rock. Density and acoustic logs are recreated in the fluid saturated. The changes due to fluid substitution are more evid tident inseismograms in dthdepth didomain. Apr 02, 2018 gassmanns fluid substitution formerly known as gassmanns equation is a lightweight software application whose purpose is to help you calculate and generate graphs with seismic velocity changes.
Leon thomsen, delta geophysics and university of houston. Equation 7 is one of the standard forms of the gassmann equation mavko et al. Batzlez abstract gassmanns 1951 equations commonly are used to predict velocity changes resulting from different pore. The slider bar at the bottom can be used to easily change the oilwater or gaswater mixture at any time. The objective of fluid substitution is to model the seismic properties seismic velocities and density of a reservoir at a given reservoir condition e. Despite the popularity of gassmanns equations and their incorporation within most software packages for seismic reservoir interpretation. One gassmann assumption is that the shear modulus, is the same for a dry and fluid saturated rocks.
The work of brown and korringa provides an explicit form for an anisotropic fluid substitution. The first stage of this project deals with the application of the gassmann substitution model using well data and. Fluid substitution and seismic modelling were applied in order to evaluate the paskapoo formation as a potential co 2 geological storage unit and for the purposes of developing seismic monitoring technology. Petrel quantitative interpretation schlumberger software. Afi uses biot gassmann fluid substitution, monte carlo simulation and bayesian estimation to build fluid probability maps. Without leaving the petrel platform, petrel quantitative interpretation provides seamless seismic data conditioning, rock physics, fluid substitution, avoava analysis, and pre and poststack deterministic and stochastic inversion to predict lithology, pore fluid content, and seismic pore pressure modeling. Engineering and manufacturing science and technology, general. Gassmann fluid substitution analysis and forward modeling based on well logs have been carried out to predict the seismic response of a paysand of. It is appreciated in the literature that different porosity choices total or effective exist for gassmann fluid substitution may 2005.
An important issue in using seismic data to physically characterize crustal rocks is the dependence of seismic rock velocity upon the compressibility of the fluid in the pore space. For a fixed porosity, an increase in pore space compressibility increase the sensitivity of the modulus to fluid substitution. The assumption being that, all other things being equal, different saturating fluids should not affect the porosity. However, the input parameters are often crudely estimated, and the resulting estimates of. The gassmann equation once we have computed the dry rock bulk and shear moduli at various porosities, we compute their values at various fluid saturations, using the gassmann equation. The specific surface area is an important parameter related to water retention in reservoir rocks. Gassmanns fluid substitution is a lightweight software application whose purpose is to help you calculate and generate graphs with seismic velocity changes. Seismic modeling of fluid substitution in redwater reef, alberta taher m. Gassmanns fluid substitution paradox on carbonates. Gassmann showed that the shear modulus is independent of fluid content.
Fluidseis users guide a matlab fluid substitution program crewes. The fact that the gassmann equation falls out so naturally from a derivation of the dry and saturated pore space stiffnesses suggests that these physical quantities are fundamental to the way in which porosity. Recent advances in rock physics and fluid substitution cseg. Fluid substitution and seismic modelling in a sandstone aquifer. Whilst the equations and software implementations are straightforward, there are. Understanding gassmann fluid substitution the mechanics of fluid substitution on the density and shear logs is simple. He also showed that the bulk modulus of the various. The most widely used fluid substitution procedure is based on gassmanns 1951 equations, which predict velocity changes resulting from variations of porefluid saturation. Rock lithology rock physics analysis forward modelling. The results are used to tie wells to seismic and hopefully gain an understanding of what properties of the formation are responsible for the observed seismic traces. Modelling the seismic responses of amangihydrocarbon field. Note green log portions showing depth interval over which the calculation is taking place and the fluid subbed values.
A tutorial on gassmanns fluid substitutions, by pierreolivier lys gassmanns equations are widely used in the industry to address the fluid substitution problem during. Integrated rockphysics library and gassmann fluid substitution. To estimate the effect of the pore fluid on the elastic properties, the gassmann fluid substitution approach was used to model different scenarios and to make reliable estimates of v p, v s and density. Integrated interpretation with gassmann fluid substitution. Lawton abstract fluid substitution and seismic modelling were applied in order to evaluate the paskapoo formation as a potential co2 geological storage unit. Poststack and prestack seismic inversion have been done over the area, utilizing the seismic data set along with the well log data to better understand the lithology and fluid distribution in the channel. Intended for new and intermediate users who require an introduction to rokdoc and the rock physics theories behind the software. Sign up gassmann fluid substitution for seismic properties computation. More evident changes in the wavelet character 21m coalbed. The gassmann equation is a widely used model as fluid substitution. Accentuated changes in wavelet character 21m coalbed. Gassmannager fluid substitution in reservoir rocks. Testing the new gassmann solidfluid substitution on the.
The objective of fluid substitution is to model the seismic. Sensitivity analysis of gassmanns fluid substitution. Given reservoir conditions after fluid substitution, it calculates new bulk. The gassmann equation is the most common way of performing a fluid substitution model from one known parameter. Pdf gassmanns fluid substitution paradox on carbonates. The fluid substitution process is a fundamental part of any rock physics workflow. Gassmanns fluid substitution formerly known as gassmanns equation is a lightweight software application whose purpose is to help you. This is a safe assumption since for fluids and gases is zero.
Rock provides a powerful, intuitive workflow for interactive depthdependent endmember lithology trend interpretation and stochastic forward modelling. Seismic modeling of fluid substitution in redwater reef, alberta. Lawton abstract the objective of this study is to analyze and undertake seismic modeling of co2 saturation of the devonian leduc reservoir characterization at the redwater reef by using gassmann fluid substitution seismic modeling. Applied modified gassmann fluid substitution method for laminated sand shale sequences on log data completed a rock physics diagnostics study with fluid substitution test. The substitution is done using the gassmanns relations obtained from mavko 2000 equations 5 and 6. For this purpose, a probabilistic sensitivity analysis of gassmann s fluid substitution equations using a monte carlo approach was carried out. Afi uses biotgassmann fluid substitution, monte carlo simulation and bayesian estimation to build fluid probability maps. Modeling based on a userdefined, hierarchical framework that integrates stratigraphy, lithology and rockphysics. I will then discuss the importance of biots work, which i first. In this study, we have analyzed the complexity of pore structure and its interaction with pore fluid. When performing fluid substitution on log data gassmann s 1951 model is the general tool of choice. Gassmanns fluid substitution equation fluid substitution is an important part of the rock physics, which provides a way to identify fluid saturated rock.
Gassmanns equation for fluid substitution petrowiki. Practical gassmann fluid substitution in sandshale sequences. Whilst the equations and software implementations are straightforward, there are potential pitfalls. The use of fluid substitution modeling for correction of mud. The transform from brine saturated to dry is as follows. Although gassmanns equations are widely popular in commercial software packages, a significant limitation which is often. When performing fluid substitution on log data gassmanns. At the heart of the fluid substitution problem are gassmanns 1951 relations, which predict how the rock bulk modulus changes with a change of pore fluids, with the companion result that the shear modulus is independent of the pore fluids. Delegates are guided through a typical rokdoc workflow, comprising data loading and qc, predicting missing data with calibrated rock physics models, blocky modelling, logbased rock physics analysis and 2d forward modelling. Gassmann has shaped both hampsonrussells software and my own scientific development over the last 27 years. Seismic software downloads coggins geosciences, inc. I will start with a discussion of gassmanns work, and how it influenced version 1.
This does not take into account diagenetic processes, such as cementation or dissolution, that vary with changing geochemical conditions in the pores. Gassmann s fluid substitution formerly known as gassmann s equation is a lightweight software application whose purpose is to help you calculate and generate graphs with seismic velocity changes. In the present study, an integrated approach of seismic, petrophysics, and gassmann fluid substitution has been applied on goru sands of sanghar area, pakistan, for optimum field development. Zoeppritzbased forward synthetic seismogram generator to create pre and poststack seismic products, optionally with mode. Estimation of dryrock elastic moduli based on the simulation. The gassmann equation, first described by fritz gassmann, is used in geophysics and its relations are receiving more attention as seismic data are increasingly used for reservoir monitoring. Introduction well log data are commonly used to create synthetic seismograms that are then compared to real seismic data.
A tutorial on gassmanns fluid substitutions, by pierreolivier lys gassmanns equations are widely used in the industry to. Sabrina aliyeva deep learning engineer synopsys inc. The fluid substitution method is the most commonly used technique using the application of gassmanns equation. Geosyn 2d enables geoscientists to get a complete depth and time perspective. Fluid substitution is a process which provides a tool for fluid identification and quantification in a reservoir during the development phase. The substitution is done using the gassmann s relations obtained from mavko 2000 equations 5 and 6. Although gassmanns equations are widely popular in commercial software packages, they have a significant, albeit often overlooked. Gassmann fluid substitution on top of incompressible two phase flow matlab simulator with nonlinear solver taken from aarnes, gimse and lie martemyevincompressible nonlineargassmann. Testing the new gassmann solid fluid substitution on the triassic sandstone reservoirs in the southern north sea basin.
Gassmanns fluid substitution on thinly bedded sandshale. Gassmanns fluid substitution formerly known as gassmanns equation is a lightweight software application whose purpose is to help you calculate and. Several authors have noted the need for quality control qc of gassmann input parameters. In this process, users can target the correction of the formation invasion, and calculate the replacement of the reservoir fluids by a combination of brine, oil or gas. Build your structural and stratigraphic model using ihs markit digital logs or your own las files, fill in features like faults and reefs and plot and modify interwell curve zones and log readings to develop a likely geological scenario.
Avo fluid inversion afi avo fluid inversion afi estimates the uncertainty in the fluid predictions from avo. Poststack and prestack seismic inversion have been done over the area, utilizing the seismic data set along with the well log data to better understand the lithology and. Testing the new gassmann solidfluid substitution on the triassic sandstone reservoirs in the southern north sea basin. Freeware python software for scopinglevel seismic modeling. Generally, gassmann relations reflect the variations in pwave and swave. Subtle changes after fluid substitution 10m coalbed. Rock physics templates for 4d seismic reservoir monitoring.
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