Determination of Multilayer Reservoir Inflow Profiles Using Pulsed Neutron Logs

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThis paper addresses the development and validation of a production logging analysis methodology and associated formation inflow interpretation model for wells that have their production tubing string setting depth below the top of at least the shallowest completed interval in the well. This type of completion technique is commonly utilized in wells that produce formation liquids and in which the tubing is lowered in the well below the top of the shallowest (and possibly additional deeper) completed interval(s) in order to assist in unloading the well of the produced liquids. When this is done, conventional production logging tools and techniques can not be used to measure the inflow profile of the completed intervals that are shallower than the tubing setting depth in the well without raising the tubing above the shallowest completed interval, which can alter the inflow profile of the well.This paper specifically considers the development of a reliable means of performing an equivalent inflow performance analysis, analogous to that which would be obtained with conventional production logging analyses if those inflow profile evaluation techniques could be used in wells with this type of completion. The liquid holdup of the multiphase flow in the well is determined from the Inelastic Ratio measurements of a Pulsed Neutron log and the annular water velocity is directly obtained from the analysis of water flow measurements in the annulus of the well.