Multipole Sonic-While-Drilling Technology Delivers Quality Data Regardless of Mud Slowness
Authors: Loreto Julio , Saenz Eduardo , Pistre Vivian 
Published: February 2015

Young Technology Showcase
As the pace of exploration and production activity accelerates and the cost of drilling, evaluating, and completing wells continues to rise in complex deepwater and unconventional plays, operators are seeking new logging-while-drilling (LWD) tools that offer real-time measurements comparable to proven wireline logging technologies. Obtaining continuous high-quality data during drilling operations can dramatically improve safety and reduce nonproductive time (NPT) by enhancing an understanding of geomechanical conditions and mitigating uncertainty in borehole stability.
Advanced LWD systems give engineers “eyes down the hole” long before they would normally deploy traditional logging tools. This enables the value of real-time decision making, reduces logging risks, and guarantees data acquisition in challenging wells.
In response to continued advances in LWD technology over the past decade, oil and gas companies are increasingly demanding access to robust real-time and recorded compressional and shear sonic data in both fast and slow formations. In costly deepwater wells, such data can enhance geomechanical models, improve wellbore stability monitoring and pore pressure prediction, and provide sonic-to-seismic tie-in, thereby minimizing drilling hazards and uncertain-ties in well placement and casing positioning. In high-tier horizontal wells in tight gas and unconventional shale plays, having reliable compressional and shear acoustic data while drilling can improve rock mechanics, fracture detection and characterization, perforation design, and hydraulic fracture optimization.
SonicScope Technology
To meet these growing industry needs, Schlumberger released the SonicScope multipole sonic-while-drilling technology (Fig. 1) as part of its suite of expert drilling and measurement services. This new LWD solution is unique in four ways.
Currently it is the industry’s only sonic-while-drilling solution that combines three distinct firing modes in a single tool (Fig. 2): low-frequency monopole for Stoneley acquisition, high-frequency monopole to extract compressional data in all formations and shear slowness data in fast formations, and wideband-frequency quadrupole to extract shear slowness data in slow formations.
As the only tool that provides a dedicated module for the acquisition of Stoneley borehole wave forms while drilling, it provides high-quality acoustic data for fracture evaluation and fluid mobility analysis before washouts can develop.
With more than 35 patents related to this technology, it incorporates innovative acoustic processing techniques for both downhole and surface algorithms, which were developed to compute reliable real-time compressional and shear data without prior knowledge of formation characteristics, and without affecting rate of penetration (ROP).
The new sonic-while-drilling tool includes 48 receivers with the tightest interspacing in the industry (Fig. 3)—just 4 in. of separation between receivers. This arrangement provides superior acoustic sampling for reliable and robust measurements even in noisy environments.