--> Improved Geomechanical and Hydraulic Fracture Calibration Workflow for Unconventional Wells

AAPG ACE 2018

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Improved Geomechanical and Hydraulic Fracture Calibration Workflow for Unconventional Wells

Abstract

Hydraulic fracture calibration in an unconventional environment is a complex process inconsitently practiced. Automated calibration methods are not effective or efficient in accounting for the heterogeneity and variation of constraining parameters. However, it is important to build a consistent methodology to calibrate hydraulic fractures incorporating the observed data. This paper covers the systematic Seismic to Simulation workflow for unconventional reservoirs to constrain a hydraulic fracture models to obtain a calibrated result.

For the hydraulic fracture calibration, injection fall-off tests, sonic logs and image logs are commonly used as the primary inputs to calibrate the geomechanical model. A new workflow is developed to be used consistently incorporating the learnings from the traditional fracture calibrations methods. Impact of high stress barriers and height and pitchouts of fractures are incorporated in a geomechanical-flow model. Simultaneous matching of the observed net pressure trend, incorporating the effect reservoir laminations in fracture height growth is made using a complex fracture model. Impact of the natural fracture networks (NFN) on pressure losses, proppant transport is also accounted for the fracture geometry. Further, hydraulic fracture geometry is calibrated using the microseismic data. The production behavior was validated using a numerical simulation to do production history matching.

Case studies from the Permian basin are considered for the study. The fracture geometry and footprint obtained using the calibration workflow matches very closely the observed downhole measurements. In the first case, we constrained the model by matching the net pressures and achieved simulated production within 12% error of the actual oil and gas production. In the second case, we constrained the fracture extent and height using laminations. This workflow successfully demonstrates hydraulic fracture model calibration using pressure matching, microseismics and production history match. Systematically and consistently using this workflow provides solutions for infill well planning and well spacing for asset optimization.

This paper explains a systematic fracture calibration procedure which can be easily adopted by the operators to obtain reliable results in unconventional wells. Effect of reservoir laminations and impact of natural fracture in calibrating the fracture geometry and fracture pressure trend is uniquely demonstrated in this study.