Correcting for Frictional Pressure Drop in Horizontal-Well Inflow-Performance Relationships

摘要

This paper presents the development of a correlation that corrects for error in single-phase horizontal-well productivity calculations made by neglecting frictional pressure drop in the wellbore. Frictional pressure drop within the wellbore is frequently a controlling factor on the performance of long horizontal wells. Frictional pressure drop could be especially significant in wells completed with screens and slotted liners. This pressure loss is neglected in traditional inflow-performance (IPR) calculations, such as those developed by S.D. Joshi and by D.K. Babu and A.S. Odeh. This study develops a correction that can be added to these analytical IPR relationships to account for friction. This correction is based on a dimensionless group that combines well and reservoir information. It is easy to evaluate and can be readily used in nodal analysis. The correction was developed on the basis of more than 5,000 finite-difference-simulation runs, using a simulator with the capability to model wellbore friction. These runs spanned a wide range of well and reservoir parameters. The results are presented in terms of productivity errors (PEs); that is, the flow rate without friction minus the flow rate when friction is included in the model, divided by the flow rate reported without friction. The study found PEs as high as 90% in some cases (usually long wells with a small well-bore radius). These errors could lead to poor decisions on field development and production facilities. This paper presents a simple way to improve well-productivity predictions without requiring a reservoir-simulation model to take account of frictional pressure drops in the wellbore.