METHOD OF FIXED DEPTH OF INVESTIGATION MEASUREMENTS FOR MULTI-LATEROLOG INSTRUMENT
Publication Date: 2008-Jul-18
The IP.com Prior Art Database
Multi-laterolog (----) is a newly Baker Hughes developed wireline galvanic tool that provides the formation resistivity surrounding a borehole drilled with conductive mud. It is an extension of a conventional hardware focused laterolog device (LL7) with 4 operation frequencies to obtain four independent measurements simultaneously. Four focused curves (From shallow to deep: Mlr1, Mlr2, Mlr3, and Mlr4) are generated to reflect the resistivity variation outside the borehole in the radial direction. In order to obtain the true information of formation outside the borehole, a standard borehole correction algorithm (BHC) is used to remove the borehole effects in each curve. The BHC under-corrects the borehole effects when the size of the borehole is large or the formation and borehole resistivity contrast is high. To solve the problem, a new fixed depth of investigation measurements (FDM) algorithm is invented for those difficult situations.