ROGII Advances Reservoir Mapping with Ultra-Deep Azimuthal Resistivity Data Inversion

A Case Study from Offshore Australia*

ROGII Inc., in collaboration with industry partners, has successfully demonstrated the power of ultra-deep azimuthal resistivity (UDAR) data inversion in reducing reservoir structural uncertainties. This groundbreaking case study, conducted in the Thylacine raw gas and condensate field in offshore Australia’s Otway Basin, highlights how UDAR technology, combined with advanced vendor-independent inversion in StarSteer software, optimizes geosteering and well placement in complex geological environments.

Addressing Complex Geological Challenges

The Thylacine field presents significant geological challenges, including rapidly changing formation dips, lateral discontinuities, and inter-fingered stratigraphy. These factors create high reservoir structural uncertainty, complicating field development strategies. Traditional well placement methods often struggle to provide the accuracy needed for optimal hydrocarbon recovery. By leveraging a modern logging-while-drilling (LWD) UDAR tool and advanced multi-parametric inversion techniques, ROGII and its partners successfully delineated reservoir boundaries and identified key pay zones in the Thylacine West 2 well.

Key Benefits of UDAR Technology

• Real-time Decision Making: UDAR technology enables operators to make immediate adjustments to well trajectory based on real-time data analysis.
• Increased Wellbore Stability: Accurate reservoir mapping reduces drilling risks associated with unexpected geological formations.
• Enhanced Hydrocarbon Recovery: Precise identification of pay zones maximizes reservoir drainage efficiency.
• Cost Reduction: Improved well placement minimizes the need for costly sidetracks and re-drilling efforts.

Optimizing Well Placement with UDAR Technology

UDAR technology empowers operators with real-time data, enabling precise well trajectory adjustments, reducing geological uncertainty, and maximizing reservoir contact. By integrating high-resolution inversion algorithms, drilling teams can proactively respond to subsurface challenges, enhancing hydrocarbon recovery while minimizing non-productive time. This innovative approach improves operational efficiency, reduces drilling risks, and optimizes resource extraction, making UDAR a vital tool for modern geosteering strategies.

Advanced Inversion Techniques

The study showcases two key approaches—stochastic and deterministic inversion, implemented in StarSteer software. The stochastic approach provided an unbiased mapping of formation layers, confirming real-time UDAR results, while the deterministic method offered a clearer, high-resolution resistivity distribution map, further improving reservoir delineation. The results enabled operators to make confident well placement decisions, ultimately enhancing field development efficiency.

Industry Implications

The success of UDAR technology in the Thylacine West 2 well has broad implications for the oil and gas industry:

• Standardization of Geosteering Techniques: Vendor-independent inversion methods contribute to a more consistent approach across different operators and service providers.
• Application to Other Complex Reservoirs: The methodology can be replicated in similar structurally complex reservoirs worldwide.
• Improved Collaboration Between Disciplines: Integration of seismic data, UDAR measurements, and advanced inversion techniques enhances cross-disciplinary decision-making.

Enhancing Field Development Efficiency

By integrating UDAR technology with seismic interpretations, ROGII’s approach helps oil and gas operators mitigate uncertainty, standardize geosteering workflows, and optimize drilling operations in structurally complex reservoirs. This technology not only improves well placement accuracy but also enhances overall operational efficiency and economic viability.

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‍* This article is presented by Kushnir, D., Sviridov, M., Mosin, A., Sarmiento, J., Thompson, R., and J. Sage. "A Case Study from Offshore Australia: Reducing Reservoir Structural Uncertainties with the Help of Ultra-Deep Azimuthal Resistivity Data Inversion." Paper presented at the ADIPEC, Abu Dhabi, UAE, November 2024. doi: https://doi.org/10.2118/222906-MS