Interpreting Inter-Well Poroelastic Pressure Transient Data: An Analytical Approach
- R. Manchanda (The University of Texas at Austin) | B. Elliott (The University of Texas at Austin) | P. Seth (The University of Texas at Austin) | M. M. Sharma (The University of Texas at Austin)
- Document ID
- American Rock Mechanics Association
- 53rd U.S. Rock Mechanics/Geomechanics Symposium, 23-26 June, New York City, New York
- Publication Date
- Document Type
- Conference Paper
- 2019. American Rock Mechanics Association
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- 45 since 2007
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ABSTRACT: Pressure interference data between fractured wells in tight formations during hydraulic fracturing (fracing) has been shown to reflect the geometry of propagating fractures. Interpretation of such data can be used to estimate fracture parameters such as azimuth, length, width and height of the fracture. This pressure interference is ascribed to the poroelastic impact of the propagating fracture's stress shadow. Numerical modeling of this observation using fully-coupled geomechanical simulators has been shown to capture field observations. Numerical modeling, however, can be time consuming and not feasible for application to on-the-fly solutions during the frac treatment. There is a need for fast simple models or simulation tools that can provide a very quick, near real-time interpretations of the position and geometry of the propagating fractures. In this work, we present a new analytical model that provides a quick method of fracture diagnostics during a frac treatment.
This new analytical model uses the fundamental stress shadow equations for simple fracture geometries and computes the impact of fracture opening on the pressure response at pressure gauge locations in surrounding wells. The model captures critical characteristics observed in field pressure interference observations. For example, the model predicts the downward slope of the observed pressure data and associates it with the region of lower compression ahead of the propagating fracture. A reduction in the observed pressure response with increasing distance from the observation well is also observed. Such predictions allow us to quickly and quantitatively interpret pressure interference data in terms of estimates of fracture location, orientation and geometry so that changes to a fracture pumping schedule can be made in near real-time.
As multi-well pad operations become more complex and the natural variability of the formations is better recognized there is a continual need to advance tools utilized for fracture characterization. Pressure interference between wells induced by poroelastic interactions (not by pressure diffusion) during fracturing has been well documented in recent literature to estimate fracture parameters such as azimuth, length, width, and height of the fracture (Kampfer et al., 2016; Roussel and Agrawal, 2017; Seth et al., 2018). There have been extensive studies of numerical modeling of this poroelastic phenomenon using fully coupled geomechanical simulators (Roussel and Agrawal, 2017; Seth et al., 2019c, 2019a, 2019b, 2018). These results have been compared to field observations and validated with diagnostics. However, numerical modeling of this process is time consuming and does not lend itself to a near real-time, or real-time explanation of offset pressure signals. It is almost always done post mortem as a matching effort with field data. The efforts in this work show a new, analytical model that will better fit the expectations of speed and accuracy that modern unconventional completions require.
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