Fluid Leakoff Delineation in High-Permeability Fracturing

Economides, M.J.

doi:10.2523/37403-ms

Cited by 11 publications

(19 citation statements)

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“…Most of the developed analysis techniques presented so far concentrate on the analysis of the before-closure data. [2][3][4][5][6][7][8][9][10][11][12][13][14] Recently, analysis techniques for after-closure data have been introduced. 15 The various diagnostic techniques include the conventional methods whose goal is to determine closure pressure and leakoff coefficient, and the latest development of the area leading to calculation of reservoir properties such as pressure and permeability.…”

Section: Introductionmentioning

confidence: 99%

After-Closure Analysis to Determine Formation Permeability, Reservoir Pressure, and Residual Fracture Properties

Soliman

Craig

Bartko

et al. 2005

SPE Middle East Oil and Gas Show and Conference

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractA minifrac test is usually performed before a fracture stimulation treatment to calculate formation and fracture properties. Recently the analysis techniques were extended to the after-closure period. The after-closure data are analyzed to calculate formation permeability and reservoir pressure.Technology developers have hypothesized the existence of either pseudo-radial or linear flow behavior during the afterclosure region. Identifying the presence of the flowing regime is an awkward process at best. The roots of the linear flow equations are different from those of the pseudo-radial flow equations. Many tests do not follow either flow regime.In this paper, we have created a general approach for analysis of after-closure pressure decline data. Because the determination of the flow regime and type of fracture depends only on time and monitored pressure, the analysis may even be performed in real time. The technique determines whether sufficient data have been obtained to perform a reliable analysis. The calculated parameters would be used to update the fracture design and, in turn, for performing the fracture treatment.The new technique is simpler and more generalized than what currently exists. The technique initially determines whether analyzable data exist. It shows that three flow regimes may dominate the after-closure region, depending on the reservoir properties and residual fracture conductivity. The technique presented not only determines the type of regime, and consequently, the type of residual fracture, it also determines the formation permeability and reservoir pressure.There is no reason to restrict the application of this test to minifrac test analysis. We believe the approach is also applicable to analysis of data after performing a fracture stimulation treatment. A numerical simulator was used to model the pumping and closure process and to validate the new approach.The paper also presents a detailed discussion and analysis of several field cases, demonstrating the various flow regimes and, ultimately, the validity of the developed technique.

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Section: Introductionmentioning

confidence: 99%

After-Closure Analysis to Determine Formation Permeability, Reservoir Pressure, and Residual Fracture Properties

Soliman

Craig

Bartko

et al. 2005

SPE Middle East Oil and Gas Show and Conference

View full text Add to dashboard Cite

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“…2,5,6,8 With the closure stress determined from G-function derivative analysis, reservoir pore pressure can be estimated by use of the uniaxial-strain relationship, Poisson's ratio, and the overburden stress (assuming Biot's constants set equal to one): 3 and the modified Mayerhofer method 9 can be used to estimate permeability to the mobile reservoir fluid using before-closure pressure-falloff data. The modified Mayerhofer method, which was proposed by Valkó and Economides, 9 is a simplified form of the Mayerhofer et al 3 method. Both methods differ significantly from conventional leakoff analysis.…”

Section: Fracture-injection/falloff Test Methodologymentioning

confidence: 99%

“…3 Valkó and Economides 9 simplified the Mayerhofer method by assuming either a confined-height or radial-fracture geometry and solving for fracture half-length (area) using Nolte-Shlyapobersky analysis of the pressure-falloff data. 9 Consequently, a history match of the pressure falloff is not required to determine fracture area. The estimated permeability and fracture-face resistance can be determined directly from a specialized plot.…”

Section: Fracture-injection/falloff Test Methodologymentioning

confidence: 99%

Permeability, Pore Pressure, and Leakoff-Type Distributions in Rocky Mountain Basins

Craig

Eberhard

Ramurthy

et al. 2005

SPE Production &Amp; Facilities

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The permeability, pore pressure, and leakoff type interpreted from more than 1,200 diagnostic fracture-injection/falloff tests were collected in a database and statistically evaluated for four Rocky Mountain basins. The statistical analysis includes the range of observed permeability and pore pressure and the fracture leakofftype distribution.The analysis reveals that pressure-dependent leakoff, fracturetip extension during shut-in, and fracture-height recession during shut-in are the most common leakoff types. Overall, pressuredependent leakoff, which can be indicative of highly productive fractured reservoirs, is the most common leakoff type in all Rocky Mountain basins. The analysis also shows orders-of-magnitude variation in gas permeability within all basins, with observed gas permeability ranging from less than 0.001 to greater than 0.10 md. G-FunctionDerivative Analysis. G-function derivative analysis is used to identify a leakoff type and provide a definitive indication of fracture-closure stress. The graphical technique, which was proposed by Barree and Mukherjee, 8 requires a graph of bottomhole pressure, the derivative of pressure (dp/dG), and the superposition derivative (Gdp/dG) vs. the G-function.The leakoff type is identified using the characteristic shape of the pressure-derivative and superposition-derivative curves. Fig. 1

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“…The before-closure model relied heavily on the models presented by Economides (1995, 1999). The dimensionless wellbore pressure equation developed by Valkó and Economides (1999) was used by Marongiu-Porcu et al (2011) to model the before-closure period.…”

Section: Log-log Derivative Approach: Conventional Formulationmentioning

confidence: 99%

Testing Tight Gas and Unconventional Formations and Determination of Closure Pressure

Soliman

Gamadi

2012

All Days

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Experience indicates that applying the conventional testing techniques such as drawdown-buildup tests to unconventional reservoir may lead to non-unique answers. Diagnostic testing approach is now more commonly used in tight gas formations and unconventional reservoirs. Testing unconventional reservoirs, particularly hydrocarbon-bearing shale formations, presents considerable challenges. In addition determination of the fracture closure pressure is sometime elusive. This paper reviews those challenges faced in analysis of testing of tight gas and unconventional reservoirs both liquid and gas. Conventional testing and analysis methods, although applicable, are often impractical because of excessive test duration. Diagnostic fracture injection test (DFIT) has become the preferred option for unconventional formations. Several methods may be used for interpreting DFIT data. We examine those methods in detail and explore their relative strengths while interpreting field data. We also show ways to determine the fracture closure pressure under various reservoir and fracture conditions.

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Fluid Leakoff Delineation in High-Permeability Fracturing

Cited by 11 publications

References 0 publications

After-Closure Analysis to Determine Formation Permeability, Reservoir Pressure, and Residual Fracture Properties

After-Closure Analysis to Determine Formation Permeability, Reservoir Pressure, and Residual Fracture Properties

Permeability, Pore Pressure, and Leakoff-Type Distributions in Rocky Mountain Basins

Testing Tight Gas and Unconventional Formations and Determination of Closure Pressure

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