Schlumberger

Technical Paper: Next Generation LWD Sonic Tool

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Presentation Date: 2008
Download: Next Generation LWD Sonic Tool (1.14 MB PDF)

 

Abstract

LWD technology has progressed rapidly in recent years to address the need for saving rig time, making real-time decisions for drilling efficiency and risk managements, and accurate geosteering. Real-time LWD sonic measurements provide timely analysis for borehole stability problems, drilling optimization, and assisting with pore-pressure prediction and seismic well ties. The sonic measurement can provide data to accurately determine well placement on the seismic sections and can create direct ties between downhole and seismic measurements.

A new LWD sonic tool is under development. Requirements of the new tool are the robust measurements of compressional and shear slownesses in fast and slow formations, thus enabling advanced sonic applications. The tool can acquire multipole modes (monopole and quadrupole) with 48 sensors (12 axial and 4 azimuthal positions). It has a large acoustic aperture with a short inter-receiver spacing that enhances the slowness processing in terms of quality and resolution. The tool has a large downhole computing capability, enabling more complex processing and leading to broader applications in real-time.

Field test data in different formation and borehole conditions show the tool can acquire high-quality waveforms in a wide frequency band, providing reliable compressional and shear slownesses equivalent to the latest wireline sonic measurement. Additionally the tool has the capability to acquire low-frequency Stoneley data, thus enabling applications such as formation damage indicators and fracture evaluation.

High-quality waveform data combined with advanced processing will provide the robust compressional and shear slowness logs and further expand the applications of LWD Sonic measurements.

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