ABSTRACT: Determining accurate formation breakdown pressure during hydraulic fracturing operations is one of the major challenges especially for tight sandstone formations in compressional in-situ stress regimes. An accurate estimation of the Breakdown pressure value is critical in determining how much horsepower will be required on site for creating adequate fracture geometry and successful placement of stimulation materials into the created fracture. Overestimation can lead to an inappropriate selection of the well completion type and expenditure loss while underestimation can result in operational failures. This work tries to bridge this gap, and predicts an accurate value of the breakdown pressure taking into account all the underlying physical parameters involved. Specifically, we propose an improved algorithm to predict formation Breakdown Pressure which does not only take into account in-situ stresses and formation strength but also the properties of fluids and permeability of the rock formation. The proposed algorithm is implemented numerically and its results were compared against values obtained from conventional methodology as well as measured breakdown pressure values using data from actual wells. The algorithm utilizes a hybrid analytical and computational approach to compute induced pore pressures during the injection of fluids into the wellbore together with the associated poroelastic stresses as functions of the underlying physical parameters involved (including fracturing fluid compressibility, viscosity, and rock porosity and permeability). The computed quantities are then incorporated into the main tensile wellbore failure equation to compute the Breakdown Pressure. The algorithm was tested using data from two different wells, and the predicted Breakdown Pressure values match well with the measured values during the actual hydraulic fracturing operations.

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