Acquire VSP data with optimized density and efficiency

An operator wanted to obtain high-quality VSP data on wireline in both the open- and cased hole sections of a vertical well drilled offshore Norway—and in as minimal rig time as possible—to accurately measure the reflectivity response (corridor stack).

Reduce acquisition time from hours to minutes

To optimize VSP density and efficiency, Schlumberger used the Optiq Seismic solution—enabled by high-strength Optiq TuffLINE fiber-optic wireline conveyance and a state-of-the-art optical interrogator—simultaneously with the MDT modular formation dynamics tester. The Optiq Seismic solution significantly improves operations at lower cost because a full well profile is recorded along the cable for each shot in only minutes rather than hours using a conventional surveying tool.

Optimize coupling with the reservoir and improve signal-to-noise ratio

After deploying the toolstring to 1,519 m, cable tension was relieved to optimize coupling while maintaining a tension above the cable weight in mud, and 45 shots were stacked. While pulling out of hole, the MDT tester probe was set at the casing shoe, cable tension was relieved, and 21 shots were stacked. The data was analyzed in near-real time to show that all survey objectives were met. The VSI versatile seismic imager was later run, enabling a full comparison with Optiq Seismic solution data.

A triple G-gun source was deployed at 7-m depth from the rig crane and autotuned with in-sea TRISOR acoustic source control system to ensure perfect synchronization within 0.5 ms of all VSP shots. The source parameters were optimized to improve the signal-to-noise ratio across seismic bandwidth.

Obtain high-quality VSP data while reducing environmental impact

The unique Optiq TuffLINE fiber-optic wireline conveyance enabled recording 4–80 Hz of stacked time-depth and waveform data at the reservoir level and with high-quality look-ahead data of more than 1 km below the deepest sensor while also running the MDT tester toolstring. The acquired data was confirmed with VSI imager data.

The novel Optiq Seismic solution, leveraging high-strength Optiq TuffLINE conveyance, acquired borehole seismic data without a dedicated run and with a reduced number of shots. In this job, operational time was reduced by 95%, reducing energy consumption and carbon emissions by an estimated 28.16 metric tons of CO2e based on average deepwater rig emissions. The Optiq Seismic solution also helped minimize impact to marine mammals, which is often associated with seismic operations. The operation demonstrates the Optiq Seismic solution’s capability to not only capture accurate reflectivity responses in near-real time but also to minimize the environmental impact.