Real-Time Performance Analysis of Water-Injection Wells

Summary This work presents a complete reformulation of the Hall method involving both pre- and post-breakthrough situations. Two approaches involving both transient and pseudosteady-state methods produced very similar solutions, which were verified with the results of coupled geomechanical/fluid-flow simulations. The new formulations allow tracking the expanding water-bank radius from inception to breakthrough. Pressure of this bank at the water/oil interface is evaluated at every timestep, thereby allowing continuous update of the ‘external pressure’ in Hall's formulation. We show that Hall's formulation is a particular case of the proposed approach. Several simulated and field examples demonstrate the value of reformulated Hall analysis. Because Hall formulation involves an integral, the resultant signature, by nature, is insensitive in revealing clues about subtle changes that may occur during formation fracturing or plugging. We observed that the derivative of the modified-Hall integral, obtained analytically, provides definitive signatures about fracturing or plugging. The new interpretation approach is particularly suitable for projects at the inception of flooding. Mature projects can benefit equally from the new tool. Perhaps the biggest appeal of the proposed tool lies in the green fields where real-time data are readily available.