Analytical method for performance evaluation of fractured horizontal wells in tight reservoirs

Abstract

This paper presents an analytical model for horizontal well with multiple hydraulic transverse fractures, producing from a tight oil reservoir. The model combines productivity index model (Guo et al.2009) with non-Darcy flow and fracture heterogeneity.Although there are numerous analytical models have been proposed for fractured horizontal wells performance, either pseudo-steady conditions or pressure-transient phenomenon. They rarely consider the influence of non-Darcy flow and fracture heterogeneity on fractured horizontal wells performance. Non-Darcy flow behavior has been proved to exist in tight reservoirs by many previous investigators. In the meantime, fracture heterogeneity should not be neglected in the process of hydraulic fracturing.In this paper, we deduce an analytical production equation in detail, towards fractured wells in tight reservoirs. Based on productivity index model, three flow region are analyzed by seepage characteristics. We make further analysis of pressure distribution in fractured horizontal well by a commercial numerical simulator. In addition, some critical factors on productivity have been considered.Results show that there are strong correlations between productivity and critical factors by the mathematical model. Further verification of the influences on well productivity is demonstrated. The fractured well productivity with different threshold pressure gradient and deformation coefficient has negative correlation. Fractured well productivity increases as fracture number, half of fracture length, and fracture conductivity increases within a certain range. The effect on fractured well productivity by fracture heterogeneity appears to be complex, not only by the end point influence, but also by fractures of internal interference.