An Improved Model for Estimating Productivity of Horizontal Drain Hole

Abstract

Abstract Horizontal wells have become a popular alternative for the development of hydrocarbon fields around the world because of their high flow efficiency caused by a larger contact area made with the reservoir. Most of the analytical model existing in the literature on horizontal productivity either assumed that the well is infinitely conductive or the flow is uniform along the entire well length. Guo et al (2007) formulation is one the most recent and accurate models reported in the literatures for predicting production rate in horizontal well considering the frictional pressure drop along long horizontal drain hole. In this paper, an improved predictive model that takes into account the effect of other possible wellbore pressure losses on production rate variation of long horizontal well was developed. Results show that the discrepancies in the predictions of the previous models and field results were not only due to effect of friction pressure losses as opined by previous authors but may also be due to loss due to fluid accumulation experienced by the flowing fluid in a conduit. The effect is most pronounced at the early production time where initial transience at the onset of flow is experienced. The improved model was applied to the same field case study used by Guo et al and results is much more accurate and show that the error of the new model is less than 4% compared to 20% reported by Guo et al. This work provides reservoir engineers an accurate and handy tool for prediction and evaluation of horizontal wells.