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Enhanced-Clarity Imaging of High-Resistivity Formation Despite Hypersaline Mud System, Oman FMI-HD high-definition formation microimager provides high-quality images where extreme resistivity contrast prevented conventional image logging CHALLENGE Acquire microresistivity images of a high- resistivity formation in a highly conductive mud environment, where conventional imaging logs cannot provide detailed data. SOLUTION Deploy the new FMI-HD* high-definition formation microimager with improved operating range and image quality to provide clear, high-fidelity images even in extreme resistivity conditions. RESULTS Visualized the borehole with excellent- quality static and dynamic images from the FMI-HD microimager to support structural and sedimentological interpretation. CASE STUDY Formation Evaluation High-resistivity formation, high-conductivity mud Drilling high-resistivity tight sandstone formations with hypersaline (240,000-ppm) mud systems was causing an extreme contrast between the true formation resistivity and the mud resistivity (R t /R m ). The downhole mud resistivity of 0.02 ohm.m in comparison with the formation resistivity of 80 to 100 ohm.m resulted in an R t /R m ratio exceeding 4,000:1. This high contrast posed a challenging logging environment for Petroleum Development Oman (PDO) to use conventional microimaging. Diligent real-time analysis of image quality and repeated log passes with carefully optimized parameters would be required. High-definition microimaging The new FMI-HD* high-definition formation microimager greatly improves operating range, reliability, and image quality through the addition of all-new electronics to the field-proven FMI* sonde. The enhanced analog-to-digital circuitry and parallel signal processing increase the measurement signal-to-noise ratio and image clarity fourfold. The tool’s tolerance of R t /R m in excess of 2,000:1 results in excellent image quality in challenging logging environments, with images successfully acquired at R t /R m contrasts up to 200,000:1. Sixteen-bit data acquisition further enhances the image contrast, even with very low signals. High-detail, high-clarity images The FMI-HD microimager delivered excellent-quality images in the challenging pairing of high- conductivity mud and high-resistivity formation. Fracture trends and thin laminations with subtle variation in dip and texture are well detailed on the images. Image-based interpretation of the present-day stress regime and natural fractures was used to plan an optimized completion design. The images at 0.2-in vertical resolution from the FMI-HD microimager can be displayed on a virtual 3D core by the Techlog* wellbore software platform at any scale down to 1:1.
Transcript
Page 1: Enhanced-Clarity Imaging of High-Resistivity …/media/Files/evaluation/case_studies/fmi_hd...Enhanced-Clarity Imaging of High-Resistivity Formation Despite Hypersaline Mud System,

Enhanced-Clarity Imaging of High-Resistivity Formation Despite Hypersaline Mud System, OmanFMI-HD high-definition formation microimager provides high-quality images where extreme resistivity contrast prevented conventional image logging

CHALLENGEAcquire microresistivity images of a high-resistivity formation in a highly conductive mud environment, where conventional imaging logs cannot provide detailed data.

SOLUTIONDeploy the new FMI-HD* high-definition formation microimager with improved operating range and image quality to provide clear, high-fidelity images even in extreme resistivity conditions.

RESULTSVisualized the borehole with excellent- quality static and dynamic images from the FMI-HD microimager to support structural and sedimentological interpretation.

CASE STUDY

Formation Evaluation

High-resistivity formation, high-conductivity mud Drilling high-resistivity tight sandstone formations with hypersaline (240,000-ppm) mud systems was causing an extreme contrast between the true formation resistivity and the mud resistivity (Rt /Rm). The downhole mud resistivity of 0.02 ohm.m in comparison with the formation resistivity of 80 to 100 ohm.m resulted in an Rt /Rm ratio exceeding 4,000:1. This high contrast posed a challenging logging environment for Petroleum Development Oman (PDO) to use conventional microimaging. Diligent real-time analysis of image quality and repeated log passes with carefully optimized parameters would be required.

High-definition microimaging The new FMI-HD* high-definition formation microimager greatly improves operating range, reliability, and image quality through the addition of all-new electronics to the field-proven FMI* sonde. The enhanced analog-to-digital circuitry and parallel signal processing increase the measurement signal-to-noise ratio and image clarity fourfold. The tool’s tolerance of Rt /Rm in excess of 2,000:1 results in excellent image quality in challenging logging environments, with images successfully acquired at Rt /Rm contrasts up to 200,000:1. Sixteen-bit data acquisition further enhances the image contrast, even with very low signals.

High-detail, high-clarity images The FMI-HD microimager delivered excellent-quality images in the challenging pairing of high-conductivity mud and high-resistivity formation. Fracture trends and thin laminations with subtle variation in dip and texture are well detailed on the images. Image-based interpretation of the present-day stress regime and natural fractures was used to plan an optimized completion design.

The images at 0.2-in vertical resolution from the FMI-HD microimager can be displayed on a virtual 3D core by the Techlog* wellbore software platform at any scale down to 1:1.

Page 2: Enhanced-Clarity Imaging of High-Resistivity …/media/Files/evaluation/case_studies/fmi_hd...Enhanced-Clarity Imaging of High-Resistivity Formation Despite Hypersaline Mud System,

www.slb.com/fmi-hd

CASE STUDY: Clear, detailed microimages in high resistivity contrast, Oman

*Mark of SchlumbergerOther company, product, and service names are the properties of their respective owners.Copyright © 2013 Schlumberger. All rights reserved. 13-FE-0015

Comparison of images from a conventional imager (left) and the FMI-HD high-definition microimager (right) shows the step-change improvement in image quality despite extreme resistivity conditions.


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