Hydraulic Fracture Model Sensitivity Analyses of a Massively Stacked, Lenticular, Tight Gas Reservoir

Green, Christopher Anthony; Barree, R.D.; Miskimins, Jennifer

doi:10.2118/106270-ms

Cited by 6 publications

References 13 publications

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Analysis of microseismic events during a multistage hydraulic stimulation experiment at a shale gas reservoir

Kaka

Reyes-Montes

Al-Shuhail

et al. 2017

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Despite the current easing in demand for increased oil production linked to the global downturn in crude prices, energy demand continuously increases and the long-term demand will require maximizing the productivity of reservoirs and a search into the exploitation of new resources in increasingly challenging environments. In this study, we present the results from the monitoring of the very first multistage stimulation experiment at a shale gas reservoir in Saudi Arabia, presenting an analysis of the microseismicity induced during the treatment. Our aim was to analyse microseismic events to better understand fracture growth and the role of pre-existing fractures in these reservoirs. Microseismic (MS) event monitoring is used to track the creation of fractures during and after the stimulation, and therefore to evaluate the effect of the reservoir stimulation. The monitoring includes a downhole array of 12 3C-sensors that were deployed in a vertical well with a 30.5 m level spacing. A total of 415 MS events were located and analysed, with the results outlining induced fractures extending consistently with an average azimuth of N335° E, normal to the horizontal section of the treatment well. This implies that there are no changes in the local stress direction along the treatment well either in situ or induced along the treatment. There are significant changes in total length and aspect ratio (length/width) of the fractures induced in the different stages. These variations could be attributed to in situ fracturing, local rock heterogeneity or the influence of the treatment parameters. In general, early and late stages of stimulation show the longest fracture networks, with events induced further away from the initiation point. We found no immediate relationship between treatment parameters (peak pressure and pumping rates) and fracture extension. Sensitivity analysis using Monte Carlo simulation methods shows a higher location uncertainty for events located at the early stages, thus limiting the interpretation from monitored seismicity in the early stages. An analysis of magnitude distribution with distance shows a decrease in sensitivity of one degree of magnitude for every 375 m, and a maximum viewing distance of approximately 700 m for the current set-up. The low number of located events does not provide a complete enough dataset for a robust analysis of changes in b -value (slope in linear part of magnitude distribution) during the treatment: however, magnitude distributions, corrected for array sensitivity, provide a useful variable for the validation of geomechanical models currently being developed for the reservoir.

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Analysis of microseismic events during a multistage hydraulic stimulation experiment at a shale gas reservoir

Kaka

Reyes-Montes

Al-Shuhail

et al. 2017

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3D geomechanical modeling of a tight‐gas reservoir, Rulison field, Piceance Basin, Colorado

Wikel

Davis

Bratton

2007

SEG Technical Program Expanded Abstracts 2007

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Evidence of Strong Fracture Height Containment Based on Complex Shear Failure and Formation Anisotropy

Barree

Conway²,

Gilbert

et al. 2010

SPE Annual Technical Conference and Exhibition

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For years, uncontrolled fracture heights have been modeled for layered reservoirs using Mode-I tensile failure driven threedimensional (3D) and pseudo-three-dimensional (P3D) fracture geometry models. In these models stress contrast between layers has been assumed to provide the dominant height containment mechanism. Meanwhile, many of the completion diagnostic tools were revealing more contained fracture heights and were thus being discounted. As more diagnostic tools have been employed, it has become apparent that the frac models may have been incorrectly over-predicting fracture heights in many cases. Mine-backs and post-frac coring revealed more contained fracture heights, as did radioactive tracer logs, treating pressure profiles, fall-off data, production modeling, and the absence of perforated interval communication. This paper will present some of the diagnostic data that support more contained fracture height development. These will include case histories from tight gas sands and shales in which restricted fracture height observations are supported by diagnostic observations. It will also go one-step further, by proposing mechanisms which contribute to fracture height containment. These include poroelasticity, abnormally high "trapped" pore pressure, and complex shear in layered or anisotropic media. It will present some modeling methodologies that place more emphasis on poroelasticity and Mode-II shear failure than current conventional fracture models. The need for investigation, and adoption, of these methodologies will be corroborated by diagnostic data.

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Hydraulic Fracture Model Sensitivity Analyses of a Massively Stacked, Lenticular, Tight Gas Reservoir

Cited by 6 publications

References 13 publications

Analysis of microseismic events during a multistage hydraulic stimulation experiment at a shale gas reservoir

Analysis of microseismic events during a multistage hydraulic stimulation experiment at a shale gas reservoir

3D geomechanical modeling of a tight‐gas reservoir, Rulison field, Piceance Basin, Colorado

Evidence of Strong Fracture Height Containment Based on Complex Shear Failure and Formation Anisotropy

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