Derived Equation for Skin Due to Restricted Fluid Entry into ICD

Abstract

The use of inflow control devices (ICD) have been used to balance flux around wellbores and also delay breakthrough of unwanted fluid into completions.1-2. Inflow-control devices (ICDs) were developed to avoid coning problems in long horizontal wells. The model for the ICD consists of pressure-drop equations from the reservoir, through the screen, the flow conduit, the ICD nozzle, and into the production tubing, along with pressure drop through the lower-completion system.1-2. This technology has been a common practice in the petroleum industry for many years now. This procedure though has been beneficial especially in highly heterogenous small formations, but however causes some pressure drop which does not contribute to additional fluid inflow into the wellbore and this is seen to be an impairment to the productivity of horizontal wells to some extent. In wells that are equipped with ICD, a precise quantification of this additional pressure drop is of paramount importance to completely identify the existence of damage created around the well bore. Many authors have proposed mathematical solutions that can be used to estimate various pseudoskin factor caused by damage, partial completion, slanted well and perforation. No author has researched about productivity loss or skin that may result from the use of inflow control devices. In this work, a 3D numerical model which includes inflow control devices along horizontal wells was used to investigate reservoir and production performances of various ICD nozzle sizes. Different productivity losses from different nozzle sizes were seen as skin. Consequently, a simple equation for calculating this skin due to restricted fluid entry through ICD nozzles was derived. The skin results obtained from this new equation is compared with the result obtained using existing skin equation and the variance is within acceptable limit.