Integrated Interpretation for Pressure Transient Tests in Discretely Fractured Reservoirs

Morton, Kirsty Lorna; Nogueira, P. de B.; Booth, Richard; Kuchuk, Fikri J.

doi:10.2118/154531-ms

Cited by 18 publications

(4 citation statements)

References 8 publications

(7 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is consistent with the fracture characterization methodology proposed by Morton et al (2012). Our analysis of a simulated pressure response of a fracture model realization with a conventional dualporosity model showed the difficulty of obtaining usable parameters for conditioning or validating the fracture model.…”

Section: Discussionsupporting

confidence: 85%

Global Sensitivity Analysis for Natural Fracture Geological Modeling Parameters from Pressure Transient Tests

et al. 2013

Self Cite

View full text Add to dashboard Cite

We have observed that pressure transient data gathered in most naturally fractured reservoirs tend not to exhibit the wellknown characteristic behavior, including pressure derivative, of the Warren and Root (1963) dual-porosity reservoir model. In reality, there are a rich variety of flow regimes dependent on the fracture distribution, spatial intensity and fracture conductivity. A semi-analytical solution for pressure transient behavior of fractured reservoirs has recently been presented that can be used to model the pressure response of formations with an arbitrary fracture distribution, density, and conductivity. The fractured system can be distributed discretely or continuously (network) with conductivities ranging from very low to infinite. Using the semi-analytical solution for fractured reservoirs, we perform a sensitivity analysis to identify which reservoir and geological parameters can be estimated from pressure transient test data collected from single or multiple well locations.We employ principal component analysis to explore the model parameterization as a pre-screening step. The global sensitivity analysis (GSA) methodology is then employed to determine how the uncertainty of each parameter influences the uncertainty in the output from the reservoir model. This methodology avoids the need to apply a linearized model. Our results indicate that near-wellbore region fracture conductivities have the largest contribution to the total variance of the ensemble of output pressure responses whether the well intersects fractures or not. While this is an intuitive result, GSA indicates that this parameter may be estimated independently from other geomodeling parameters unlike interpretations based on the dualporosity pressure transient solutions. This study describes how GSA is used to design a pressure transient well test for uncertain reservoir parameters.

show abstract

Section: Discussionsupporting

confidence: 85%

Global Sensitivity Analysis for Natural Fracture Geological Modeling Parameters from Pressure Transient Tests

et al. 2013

Self Cite

View full text Add to dashboard Cite

show abstract

“…The integrated pressure transient interpretation methodology for naturally fractured reservoirs given by Morton et al (2012) can also be applied to rate transient analysis and production forecasting. Of course, there will be some modifications, particularly if high-precision downhole pressure data and its diagnostic derivatives are not available.…”

Section: Figure 12-dimensionless Rate Of a Fracture-intersecting Wellmentioning

confidence: 99%

Rate Transient and Decline Curve Analyses for Continuously (Dual-Porosity) and Discretely Naturally Fractured Reservoirs

2014

View full text Add to dashboard Cite

Forecasting production rates and reserves is important for reservoir management. Analysis of long-term production data has traditionally been performed using the empirical Arps (1945) decline curves to predict future production. Fetkovich (1980) combined Arps decline curves with constant-wellbore pressure solutions to offer a new method for decline-curve analysis. Furthermore, both rate-transient and declinecurve analyses for naturally fractured reservoirs were performed using Arps (1945) decline curves or Warren and Root (1963) dual-porosity-type models. These approaches have yielded unsatisfactory results for naturally fractured reservoirs. Recent studies show that the Warren and Root (1963) dual-porosity-type models, which do not contain fractures, cannot characterize highly diverse transient behaviors of continuously and discretely fractured reservoirs because they are inappropriate and incomplete for most naturally fractured reservoirs. Furthermore, no investigation has been performed on rate-transient behavior of discretely fractured reservoirs.We investigate rate-transient behavior of continuously (dual-porosity) and discretely naturally fractured reservoirs using semianalytical solutions. These fractured reservoirs can contain periodically or arbitrarily distributed finite-and/or infinite-conductivity fractures, of different lengths and orientations. Our results demonstrate that, in terms of rate transients, neither continuously nor discretely fractured reservoirs behave like the Warren and Root (1963) dual-porosity type model. There are many factors that dominate the rate-transient behavior of naturally fractured reservoirs, such as fracture conductivities, dip angles, lengths, and distributions, as well as whether or not fractures intersect the wellbore. Rate transients associated with these factors are shown for a few continuously and discretely fractured reservoirs with different well and fracture configurations.The inverse of the dimensionless pressure (p D ) is not a good approximation for the dimensionless rate (q D ), but for most cases, their derivatives behave similarly, and exhibit same or similar flow regimes. For some cases, they behave very differently. The similarities or variations are true for any type of reservoirs. For any reservoir, Arps' decline curves yield unreasonably high production rates and cumulative productions, except the exponential decline curve. The exponential decline curve should not be used without taking into account the change of the wellbore pressure as a function of time. Arps' decline curves analysis should not be used for both discretely and continuously fractured reservoirs. An integrated interpretation methodology is outlined for rate transient analysis in fractured reservoirs.A few examples for the rate transient behavior of the continuously and discretely fractured fractured reservoirs are presented. They exhibit different flow regimes depending on fracture distribution, intensity, and conductivity. We also compare the rate transient derivatives with pressure...

show abstract

“…For example, Morton et al (2012) presented a field case study from Brazil for which neither a homogeneous single porosity model nor a Warren and Root-type (1969) dual porosity model presented a good pressure match. For example, Morton et al (2012) presented a field case study from Brazil for which neither a homogeneous single porosity model nor a Warren and Root-type (1969) dual porosity model presented a good pressure match.…”

Section: Grid-based Inversion For Parameter Estimationmentioning

confidence: 99%

Design of Objective Function for Interference Well Testing

et al. 2013

View full text Add to dashboard Cite

Multi-well interference tests are performed among neighboring wells for reservoir characterization, to assess heterogeneity, and to estimate formation mobility and storativity in the area of these wells. Interference tests are particularly useful where there is some uncertainty in the geology between two wells, such as the conductivity of a fault, fracture corridors in naturally fractured media, or other sources of significant heterogeneity. However, the analysis of such interference tests can be challenging. During an interference test, a volume of influence develops around and between the wells, and the dynamic pressure response from the two wells may be used for interpretation. Reservoir transmissibility and borehole storage are the main elements affecting the attenuation of the pressure response. Accurate, high resolution, pressure measurements become more important for smaller pressure responses, to enable the data to be used for reservoir description. The relative size of the pressure differences observed at each well and the small absolute pressure change at the observation well(s) may become a challenge to the interpretation of the data.In this paper we review the methods available to quantitatively interpret interference test data from multiple wells simultaneously. Concentrating on grid-based parameter estimation methods, we propose an objective function that is designed to effectively combine data from source and observation wells. Combining data from different wells requires weighting and scaling of the measurement errors in the objective function to ensure the relative impact of each data set is correctly accounted for. Different weighting strategies are tested to explore the impact on pressure match.Our objective function permitted us to simultaneously incorporate the data from both the observation and source wells. This allowed us to more effectively apply methods grid-based parameter estimation for the inversion of reservoir properties from pressure transient test data for interference tests. By determining what values of measurement error used in the objective function lead to the best interpretation, we are able to suggest an acceptable level of noise in test design.

show abstract

Integrated Interpretation for Pressure Transient Tests in Discretely Fractured Reservoirs

Cited by 18 publications

References 8 publications

Global Sensitivity Analysis for Natural Fracture Geological Modeling Parameters from Pressure Transient Tests

Global Sensitivity Analysis for Natural Fracture Geological Modeling Parameters from Pressure Transient Tests

Rate Transient and Decline Curve Analyses for Continuously (Dual-Porosity) and Discretely Naturally Fractured Reservoirs

Design of Objective Function for Interference Well Testing

Contact Info

Product

Resources

About