Improved Production Log Interpretation in Horizontal Wells Using a Combination of Pulsed Neutron Logs Quantitative Temperature Log Analysis Time Lapse LWD Resistivity Logs and Borehole Gravity

摘要

A novel combination of logs and their unique interpretations are used to improve the understanding of production in horizontalrnwells on the North Slope of Alaska. Two techniques using Pulse Neutron Capture (PNC) logs to identify and quantify liquidrnproductive intervals were previously presented in a paper by Brady et. al1. These techniques are compared and combined with twornadditional techniques: 1) the use of time lapse LWD resistivity to determine productive intervals and liquid flow profiles whilerndrilling, and 2) a non trial-and-error method to determine quantitative gas production using temperature logs in a two-phase flow.rnFinally, modeling shows borehole gravity logs can be used to track the vertical movement of gas or water tens of feet above orrnbelow horizontal wells.rnIntegrating the time lapse differences between the shallow LWD resistivity logs run while drilling and logs run several hours afterrndrilling shows a strong correlation with PNC liquid flow profiles for wells producing at solution GOR. Additionally, combining arnquantitative gas flow rate analysis from the temperature log with the liquid profiles provides a complete analysis of the productionrnprofile for two-phase flow in horizontal wells. Finally by combining the production profile analysis from a horizontal well with thernmodeled time-lapse borehole gravity data, a complete understanding of the fluid movements in the well borehole as well as tens torntwo hundred feet into the formation can be obtained.rnThese techniques can be applied to both horizontal and vertical wells with both slotted liner and cemented perforated completionsrnto obtain a quantitative production profile. The LWD resistivity data is collected while drilling to better understand the productivernreservoir rock before the well is completed. Time lapse borehole gravity provides an understanding of the reservoir fluidrnmovements affecting the wellbore flow profiles after the well has been put on production.