The DLT provides the deep resistivity measurement (LLD) and the shallow resistivity measurement (LLS). Under normal conditions, the LLS will be the resultant of the flushed, invaded and transition zones. The LLD, although affected by the previous zones, will respond to mainly the virgin zone. The accuracy of the measurement requires that the undisturbed formation have the largest contribution on the reading. Therefore, the mud resistivity must be low relative to the formation resistivity.
|Pressure||20,000 PSI||1,379 bar|
|Temperature||325° F||163° C|
|Weight||353 lbs||160.12 kg|
|Length||14.85 ft||4.562 m|
|Transport Length*||16.67 ft.||5.08 m|
|Tool OD||3.625 in||9.2 cm|
* From end of top thread protector to end of bottom thread protector.
|LLS||26 in||66 cm|
|LLD||26 in||66 cm|
|Depth of Investigation|
|LLS||30 in||67 cm|
|LLD||72 in||183 cm|
|LLS & LLD||0.2-40 KW|
|Maximum Logging Speed|
|LLS & LLD||60 ft/min||18.2 m/min|
|LLS & LLD||±20%<1 W, ±5%1-1000 W, ±10%>1000 W|
|Minimum||6.0 in||15.24 cm|
|Maximum||16.0 in||40.64 cm|
Open hole and fluid filled. The Dual Laterolog Tool (DLT) cannot run in non-conductive mud such as oil-based mud. In a large-diameter hole, it is recommended the DLT be run centralized.
If the mud is conductive relative to formation water, i.e., Rmf/Rw<2, the DLT should be used. Because the DLT is accurate at higher resistivities, it is ideal when fresh mud with resistivity readings above 200 ohms is encountered. Use the DLT in borderline cases of large boreholes (>12 in) or deep invasion (>40 in).