Abstract
A new comprehensive model of hydraulic fracturing is presented which has been developed for the Gas Research Institute (GRI) mobile fracture monitoring and analysis facility. The main purpose of the model is to simulate the hydraulic fracturing process in real-time, that is on-site during the fracturing operation, but the model can also be used for pre-fracture design and post-fracture analysis. Sensor data obtained during the course of the job — such as wellhead pressure, flow rates, frac-fluid viscosity, and proppant staging — can be received directly by the model as input, superceding the pre-frac job design schedule, and making possible more accurate model estimates of current fracturing conditions and predictions of final fracture geometry, as the job proceeds.
The overall model has four major components describing:
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flow of fluids and slurry in tubular goods
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creation and propagation of the hydraulic fracture
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transport of proppant, deposition, and fracture closure
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heat and fluid exchange between fracture and reservoir.
This fully-integrated, numerically robust model of the hydraulic fracturing process takes directly into account as much of the essential physics as possible, given the computational limitations of the real-time application. Additional information, pertaining to very complex reservoir characteristics, can be indirectly supplied to the model through data-based results obtained prior to the job from other more comprehensive (e.g., 3D, cross-sectional) fracture simulations. Having thereby embedded more elaborate fracture analysis into a simple lumped model, accurate predictions are achieved at execution speeds faster than real-time, allowing on-the-job analysis and even real-time history matching for unknown reservoir parameters.
Sample results are presented from model simulations of a fracture treatment performed in the Travis Peak formation of East Texas. Actual sensor data from the job was used as input and model predictions are compared with field measurements.
