During the 2021 EAGE PRM workshop, OCTIO presented results demonstrating the improved gravity and subsidence monitoring accuracy with the gWatch instrumentation. The OCTIO and Equinor authors (abstract) utilised the Snøvhit gas field monitoring case to demonstrate enhanced data value to our customers with the abovementioned improvements.

During a survey, OCTIO gWatch measures gravity and subsidence at predefined locations (stations) at the seafloor. OCTIO conducts repeat measurements at each station to achieve higher accuracy. The repeatability parameter indicates the average uncertainty of individual station measurements and is a crucial element governing the accuracy. Each field’s water depth ranges can impact repeatability, so consecutive surveys from the same field provide the best evaluation baseline to quantify instrumentation driven improvements.

During this workshop, OCTIO demonstrated a 6-fold improvement in gravity and 2.5-fold improvement in depth repeatability using survey data between 2007 to 2019. OCTIO delivered these results by combining the instrumentation hardware upgrades with propriety surveying and processing techniques. gWatch instrumentation offers a compact design, new-generation gravimeters, and patented temperature-stabilised pressure measurements.

2019 survey repeatability stands at 1.7 mm for subsidence and 0.55 microGals for gravity. OCTIO expects to improve this repeatability further during the next survey vintage.

Our customers gain a better insight into critical parameters like pressure depletion or fluid substitution throughout the reservoir at an earlier stage of the field lifetime with improved repeatability and measurement accuracy. A higher accuracy allows detecting subtle changes in reservoir properties and expands the technology envelope to more hydrocarbon fields.

OCTIO gWatch surveys complement or replace 4D seismic at 1 /10 of the price and 1/3 of the delivery time. Our customers reduce the frequency or completely replace 4D seismic surveys, enhance field recovery rates, improve reservoir management, and optimise subsea infrastructure across the shelf and deepwater gas fields. Please find more information about OCTIO gWatch here https://www.octio.com/4d-gravity-at-the-seafloor/

OCTIO provides geophysical monitoring solutions to E&P companies. For more details email us at contact@octio.com

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