Schlumberger Ngi Tool Fix May 2026

Schlumberger NGI Tool: Near-bit Gamma Imaging for Geosteering and Formation Evaluation

1. Overview & Purpose

While modern iterations of the technology have evolved into the NeoScope and IMPulse families (which add resistivity and imaging), the legacy and fundamental principles of the "NGI" remain the gold standard for near-bit measurements. schlumberger ngi tool

High Environmental Tolerance: The tool is designed to operate reliably under high-pressure and high-temperature (HPHT) conditions common in deepwater and unconventional wells. Confirm lithology changes immediately after drilling

• Confirm lithology changes immediately after drilling.
• Identify radioactive markers (e.g., volcanic ash, organic-rich shales) for correlation.

• Conductive Mud Issues: In oil-based mud (OBM), which is the standard for shale plays, the NGI tool performs exceptionally. However, in very high-salinity water-based mud (WBM), signal attenuation can reduce the depth of detection. Mitigation: Use non-conductive mud additives or reduce the operating frequency.
• Resistivity Contrast Dependency: The tool requires a minimum resistivity contrast (usually 2:1) to see a boundary. If a sand has R=20 ohm-m and a shale has R=18 ohm-m, the NGI will not see the boundary. Mitigation: Use with high-resolution density imaging (e.g., LithoScanner*).
• Cost: The NGI tool is premium technology. It costs significantly more than a standard GR/resistivity suite. Justification: The cost of a sidetrack due to exiting the reservoir is usually 10x the cost of running the NGI tool.