Defining irreducible water saturation using global characteristics envelopes and novel correlations

2016 ◽  
Vol 56 (1) ◽  
pp. 1 ◽  
Author(s):  
Peter Behrenbruch ◽  
Chengzhi Yuan ◽  
Nhan B. Truong ◽  
Phil Do Huu ◽  
Tuan G. Hoang
Keyword(s):  
Grain Size ◽  
Pore Structure ◽  
Water Saturation ◽  
Laboratory Data ◽  
Great Promise ◽  
Flow Zone ◽  
Structure Characteristics ◽  
Irreducible Water Saturation ◽  
Universal Correlation ◽  
Group Flow

Irreducible water saturation plays a significant role in estimating hydrocarbon initially-in-place and petroleum recovery. Yet, laboratory measurements for determining irreducible water saturation take considerable time and money. For this reason available data may not cover all requirements, giving rise to the practise of using correlations to fill in gaps. Described in this paper are the reasons for irreducible water saturation being an elusive parameter that not only depends on pore structure characteristics but also the type of experiment and laboratory procedures, as well as changing plug conditions during experimentation. This paper reviews traditional methods, as well as recent and novel approaches to quality assure laboratory data and for correlating irreducible water saturation for prediction. To gain insight into the dependence of irreducible water saturation on detailed pore structure characteristics, most notably grain size and sorting, the usefulness of global characteristics envelopes is explored (Behrenbruch and Biniwale, 2005). In this multidimensional plot, irreducible water saturation is plotted against porosity, permeability, hydraulic radius, porosity group, flow zone indicator (grain size) and sorting, giving an insightful overview of the interdependence of parameters. The second part of this paper compares novel correlations with commonly used correlations. Traditional and more recent correlations are covered, from simple correlations versus the logarithm of permeability to more sophisticated approaches using more variables, including porosity and others. Most notably, it is shown that an approach of correlating irreducible water saturation with grain size (or flow zone indicator [FZI]) and sorting shows great promise. Data from two Australian fields are used to demonstrate the methodology, showing a significant increase in fitting accuracy. This approach may eventually lead to a universal correlation.

scholarly journals Insights, Trends and Challenges Associated with Measuring Coal Relative Permeability

2019 ◽  
Vol 89 ◽  
pp. 01004
Author(s):  
Dylan Shaw ◽  
Peyman Mostaghimi ◽  
Furqan Hussain ◽  
Ryan T. Armstrong
Keyword(s):  
Relative Permeability ◽  
Effective Stress ◽  
History Matching ◽  
Water Saturation ◽  
Laboratory Data ◽  
Stress Regime ◽  
Cross Point ◽  
Irreducible Water Saturation ◽  
Relative Permeability Curves ◽  
The Right

Due to the poroelasticity of coal, both porosity and permeability change over the life of the field as pore pressure decreases and effective stress increases. The relative permeability also changes as the effective stress regime shifts from one state to another. This paper examines coal relative permeability trends for changes in effective stress. The unsteady-state technique was used to determine experimental relativepermeability curves, which were then corrected for capillary-end effect through history matching. A modified Brooks-Corey correlation was sufficient for generating relative permeability curves and was successfully used to history match the laboratory data. Analysis of the corrected curves indicate that as effective stress increases, gas relative permeability increases, irreducible water saturation increases and the relative permeability cross-point shifts to the right.

Assessment on Pore Structure of Western Sichuan Reservoir through Mercury Intrusion Porosimetry

2012 ◽  
Vol 226-228 ◽  
pp. 2082-2087
Author(s):  
Chi Guan ◽  
Zhang Hua Lou ◽  
Hai Jian Xie
Keyword(s):  
Pore Structure ◽  
Mercury Intrusion Porosimetry ◽  
Water Saturation ◽  
Absolute Permeability ◽  
Tight Gas ◽  
Gas Reservoir ◽  
Western Sichuan ◽  
Mercury Intrusion ◽  
Irreducible Water Saturation ◽  
Tight Gas Reservoir

Mercury intrusion porosimetry injection is important in assessing microscopic pore structure of reservoirs. This paper introduces an estimated function for investigating the pore characteristic of western Sichuan tight gas reservoir based on VG model. Better correlations between the measured and estimated results have been obtained using VG model. Representative parameters were obtained by fitting the predictions of VG model to the experimental data, and then the estimated formulation was proposed for the studied reservoir. Correlation analysis of the parameters of VG model confirms that absolute permeability and irreducible water saturation are important in mercury injection porosimetry. The approach applied in this paper is helpful in investigating tight reservoirs, especially in the common cases when measurement is difficult to carry out, partly because of complicated variability in the field, and partly because measuring is time-consuming and expensive.

An Approach for Exploring the Application of the Flow Zone Index Concept in Describing Petrophysical Properties Using Available SCAL Data Relative Permeability

2021 ◽  
Author(s):  
Efeoghene Enaworu ◽  
Tim Pritchard ◽  
Sarah J. Davies
Keyword(s):  
Relative Permeability ◽  
Water Saturation ◽  
Petrophysical Properties ◽  
Residual Oil ◽  
Flow Zone ◽  
Oil Saturation ◽  
Residual Oil Saturation ◽  
Core Samples ◽  
Irreducible Water Saturation ◽  
Permeability Data

Abstract This paper describes a unique approach for exploring the Flow Zone Index (FZI) concept using available relative permeability data. It proposes an innovative routine for relating the FZI parameter to saturation end-points of relative permeability data and produces a better model for relative permeability curves. In addition, this paper shows distinct wettabilities for various core samples and validated functions between FZI and residual oil saturation (Sor), irreducible water saturation (Swi), maximum oil allowed to flow (Kro, max), maximum water allowed to flow (Krw, max),and mobile/recoverable oil (100-Swi-Sor). The wettability of the core samples were defined using cross-plots of relative permeability of oil (Kro), relative permeability of water (Krw), and water saturation (Sw). After classifying the data sets into their respective wettabilities based on these criteria, a stepwise non-linear regression analysis was undertaken to develop realistic correlations between the FZI parameter, initial water saturation and end-point relative permeability parameters. In addition, a correlation using Corey's type generalised model was developed using relative permeability data, with new power law constants and well defined curves. Other parameters, including Sor, Swi, Kro, max, Krw,max and mobile oil, were plotted against FZI and correlations developed for them showed unique well behaved plots with the exception of the Sor plot. A possible theory to explain this unexpected behaviour of the FZI Vs Sor cross plot was noted and discussed. These derived functions and established relationships between the FZI term and other petrophysical parameters such as permeability, porosity, water saturation, relative permeability and residual oil saturation can be applied to other wells or reservoir models where these key parameters are already known or unknown. These distinctive established correlations could be employed in the proper characterization of a reservoir as well as predicting and ground truthing petrophysical properties.

Determination of nuclear magnetic resonance T2 cutoff value based on multifractal theory — An application in sandstone with complex pore structure

Geophysics ◽  
2015 ◽  
Vol 80 (1) ◽  
pp. D11-D21 ◽  
Author(s):  
Xinmin Ge ◽  
Yiren Fan ◽  
Xuejuan Zhu ◽  
Yiguo Chen ◽  
Runze Li
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Pore Structure ◽  
Water Saturation ◽  
Influential Factors ◽  
Structure Characterization ◽  
Cutoff Value ◽  
Irreducible Water Saturation ◽  
Multifractal Theory ◽  
Nuclear Magnetic

The cutoff value of nuclear magnetic resonance (NMR) transversal relaxation time [Formula: see text] is vital for pore structure characterization, permeability prediction, and irreducible water saturation calculation. Conventional default values often lead to inaccurate results for rocks with complex pore structure. Based on NMR experiments and multifractal theory, we have developed an effective statistical method to predict [Formula: see text] cutoff values without other petrophysical information. The method is based on multifractal theory to analyze the NMR [Formula: see text] spectrum with the assumption that the [Formula: see text] spectrum is an indicator of pore size distribution. Multifractal parameters, such as multifractal dimension, singularity strength, and mass exponent, are calculated to investigate the multifractal behavior of [Formula: see text] spectrum via NMR experiments and a dyadic scaling-down algorithm. To obtain the optimal [Formula: see text] cutoff value, the rotation speed and time of centrifugation are enlarged increasingly to optimal centrifugal state. A predicating model for [Formula: see text] cutoff value based on multiple linear regressions of multifractal parameters was proposed after studying the influential factors. On the basis of the multifractal analysis of NMR [Formula: see text] spectrum, a reasonable predication model for [Formula: see text] cutoff value was rendered. Upon testing, the predicted results were highly consistent with the experimental results.

scholarly journals Scaleup of Laboratory Data for Surfactant-Alternating-Gas Foam Enhanced Oil Recovery

SPE Journal ◽  
2020 ◽  
Vol 25 (04) ◽  
pp. 1857-1870
Author(s):  
Rodrigo O. Salazar-Castillo ◽  
William R. Rossen
Keyword(s):  
Enhanced Oil Recovery ◽  
Oil Recovery ◽  
Water Saturation ◽  
Gas Injection ◽  
Laboratory Data ◽  
Mobility Control ◽  
Model Parameters ◽  
Fractional Flow ◽  
Foam Model ◽  
Irreducible Water Saturation

Summary Foam increases sweep efficiency during gas injection in enhanced oil recovery processes. Surfactant alternating gas (SAG) is the preferred method to inject foam for both operational and injectivity reasons. Dynamic SAG corefloods are unreliable for direct scaleup to the field because of core-scale artifacts. In this study, we report fit and scaleup local-equilibrium (LE) data at very-low injected-liquid fractions in a Bentheimer core for different surfactant concentrations and total superficial velocities. We fit LE data to an implicit-texture foam model for scaleup to a dynamic foam process on the field scale using fractional-flow theory. We apply different parameter-fitting methods (least-squares fit to entire foam-quality scan and the method of Rossen and Boeije 2015) and compare their fits to data and predictions for scaleup. We also test the implications of complete foam collapse at irreducible water saturation for injectivity. Each set of data predicts a shock front with sufficient mobility control at the leading edge of the foam bank. Mobility control improves with increasing surfactant concentration. In every case, scaleup injectivity is much better than with coinjection of gas and liquid. The results also illustrate how the foam model without the constraint of foam collapse at irreducible water saturation (Namdar Zanganeh et al. 2014) can greatly underestimate injectivity for strong foams. For the first time, we examine how the method of fitting the parameters to coreflood data affects the resulting scaleup to field behavior. The method of Rossen and Boeije (2015) does not give a unique parameter fit, but the predicted mobility at the foam front is roughly the same in all cases. However, predicted injectivity does vary somewhat among the parameter fits. Gas injection in a SAG process depends especially on behavior at low injected-water fraction and whether foam collapses at the irreducible water saturation, which may not be apparent from a conventional scan of foam mobility as a function of gas fraction in the injected foam. In two of the five cases examined, this method of fitting the whole scan gives a poor fit for the shock in gas injection in SAG. We also test the sensitivity of the scaleup to the relative permeability krw(Sw) function assumed in the fit to data. There are many issues involved in scaleup of laboratory data to field performance: reservoir heterogeneity, gravity, interactions between foam and oil, and so on. This study addresses the best way to fit model parameters without oil for a given permeability, an essential first step in scaleup before considering these additional complications.

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