Presenter
Karol Riofrio from Halliburton
Co-authors
Aker BP
Abstract
- OBJECTIVES/SCOPE
The complexity of injectite reservoirs, which show steep geometries, complex distribution and thicknesses represents a challenge for their development, resulting in limited exploitation of the hydrocarbon reserves that they contain. Recent advances in technology and approaches to exploration have made it possible to reconsider them as important hydrocarbon sources, especially in sectors like the Norwegian Continental Shelf. The presence of injectites cause increased seismic uncertainty, and as a result their predictability is difficult, therefore well planning is problematic using seismic data even in combination with shallow Logging While Drilling Logs offset data. The deployment of 1D and 3D Ultra-Deep Azimuthal Resistivity tools (UDAR) and adaptive workflows decrease the uncertainty associated with their development.
- METHODS PROCEDURES, PROCESS
The deployment of UDAR technologies provides the bridge to link the spread of seismic interpretations with shallow electromagnetic measurements to decrease uncertainty. The formation of injectites results in 3D geometries that can be mapped with 1D UDAR inversions where they are intersected or are distributed above or below the wellbore, however, to assess their lateral distribution 3D electromagnetic inversion has proven to provide accurate sand distribution around the wellbore, providing a more complete picture of their distribution. Due to the 3D nature of the geology 1D inversion has shown an acceptable definition of geobodies, but it still gets highly affected by fitting a 1D solution to the 3D injectite elements. Different methodologies can be applied to improve the definition of the 1D electromagnetic inversion to improve the results.
- RESULTS, OBSERVATIONS, CONCLUSIONS
In addition to the 3D inversion approach, a new gradient slope-based inversion was used to define in better detail thinner dykes or sills that can be common in this environment. This newer gradient slope approach for 1D electromagnetic inversion has proven to be more sensitive to gradational resistivity changes focused on lower resistivity profiles and used successfully to define thinner layers of contrasting resistivity. The results of the application of the gradient slope approach in injectites has shown a better shape identification of the geobodies, indicating that this gradient slope inversion is less affected by 3D geological/fluid effects. In comparison to the original 1D square-log boundary formation model. The strongest approach is to run the 1D square boundary, 1D gradient boundary, and 3D inversions in areas of severe complexity to decrease uncertainty and provide more accurate modelling of the geobodies.
- NOVELTY OR ADDITIVE INFORMATION
A comparison of geobody mapping in a complex injectite system using traditional 1D electromagnetic inversion against the gradient slope or high-definition mapping inversion and 3D Inversions, allows the strengths of each approach to be demonstrated. The new high definition inversion has proved to be successful in defining gradational resistivity profiles in low resistivity environments, in thinner intercalated layers in turbidite systems, and in this case study it proves to be less sensitive to distortion caused by a 3D geology in complex geologies like injectite systems. This latest gradational-slope inversion has been compared against 3D inversion to prove its efficiency, but also against the original 1D electromagnetic inversion for consistency.
Biography
Karol Riofrío is the Geosteering Regional Manager for Europe and Sub-Saharan at Halliburton, based in Norway. Riofrío joined the Oil and Gas industry in 2010 as Consultant Geologist for Landmark Software and Services and then moved in 2014 onto Geosteering Geologist at Sperry Drilling, both Halliburton departments. She has worked in different countries from South America, Mexico. From 2018 she started as Geosteering Geologist in Norway and subsequently as geosteering team lead for Aker BP, specializing in applications of ultra-deep resistivity tool. Riofrío holds a Master’s degree in Reservoir Geology and Geophysics from the University of Barcelona.