Optimization of borehole measurements in highly deviated gas wells of the NW german rotliegend (Examples for the application of modern LWD-technology)

摘要

LWD (Logging While Drilling) measurements are a potential alternative to conventional wireline logging for the optimisation of log data acquistion strategies in highly deviated or horizontal deep wells, and to safeguard petrophysical informations e.g. from partly depleted tight gas sands in the German Rotliegend formations. In this paper the results of the first sonic LWE "slimhole" measurements in 57/8" boreholes in Germany are presented and compared with conventional wireline logs and core data. Since 1996, BEB has meanwhile successfully run the Halliburton/Pathfinder SCLSS (Slimhole Compensated Long Space Sonic LWD tool in four deep highly deviated, partly depleted wells as a cost effective and reliable alternative to conventional Coiled Tubingor pipe conveyed wireline logging. In addition to a potentially reduced risk of operational problems (e.g. by differential sticking) in difficult wells, the LWD measurements have the further advantage to provide real time measurements at nearly "virgin" reservoir conditions, i.e. before a potential formation damage or saturation change by a deep invasion of drilling muds. This is especially relevant for the saturation evaluations from resistivity data.