Pressure interference data between fractured wells in tight formations during fracturing 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 tools that can guide the staff and engineers on location with insight into the position and geometry of the propagating fractures. In this work, we present a new analytical model that provides a quick analysis of the fracture responses during treatment and validate it with observed field cases and fully 3-D coupled numerical modeling.
This new analytical model uses the fundamental stress equations for simple fracture geometries (KGD, PKN, and radial fractures) and captures critical characteristics observed in field pressure interference observations. Multiple field stages with offset pressure responses were captured from bottom-hole gauges, interpreted, and detailed in this study. A python code for these analytical stress predictions was developed to make the process user-friendly and adaptable to ever-changing industry needs.
The model closely ties these observed field responses to predicted stresses reported from the model and allows for timely interpretation of the pressure data. To further validate the characteristic stress responses observed in the field, fully coupled 3-D poroelastic simulations were also performed which tie these results closely with the analytical predictions showing less than 2% error between the results. Insights to well spacing, fracture geometry, fracture overlap, and stress shadow with varying distances are obtained from the results.
This workflow can be employed for near real-time analysis and yield estimates of fracture geometry to greatly advance the field capabilities for on the fly fracture design optimization. In an industry with increasing complexity in nearly every model, we show that simple ground truth physics and analytical results can be extremely useful tools to make quick effective decisions with minimal computational resources.
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