A workflow for navigating thermal oil sands wells
Resistivity geosteering has been on our radar for some time. With ROGII releasing a resistivity forward modeling module as part of Starsteer, the use of resistivity for geosteering complex reservoirs such as the McMurray became applicable for operators and third party service providers such as Chinook.
We have demonstrated and refined the workflow on a number of projects, beginning with CNRL in one of their thermal oil sands developments, using Weatherford GuideWave LWD tools. We have further demonstrated the approach on projects using Halliburton, Weatherford and Schlumberger tools.
For this presentation we used publicly available data from PetroNinja, with well information (surveys, LWD curves, offset logs) covering Statoil‘s development in Leismer around township 78-10W4. This acreage was taken over by Athabasca Oil in 2016.
The workflow includes a series of steps:
- Data loading
- Top picking
- Log squaring
- Earth model generation
- Resistivity forward modeling
- Geosteering interpretation (correlation)
- Curve correlation
- Apparent dip and stand-off determination
- Reservoir navigation and target prediction
A more complex workflow involves the use of combined earth models whereby the resulting model used is much closer to “real” reservoir geology and will reflect the variable nature of the McMurray and distinct resistivity profiles along the lateral length of the well.
It is worth mentioning that while a single profile interpretation is easy to perform (just run the resistivity module in Starsteer), using combined models is more laborious. This is where thorough geological understanding of the play is leveraged alongside Starsteer’s heavy mathematical computations.
Preparation (including mapping, top picking, display setup, format and colors) and then log squaring, earth model generation, tool and curve setup, is all done prior to the main processes of geosteering and curve correlation. Correlation is where we spend most of our time as geosteeres. We do curve correlations in order to project targets ahead of the bit by using calculated apparent dips and stand-off determination.
Use of resistivity modeling gives precise stand-off values, while correlation on the MD scale gives apparent dip a precision within 0.5 degrees (in our evaluation, compare this with 0.1 degrees precision in traditional correlation on the vertical scale).
We have used this project as a training ground and have developed a few additional workflows in the process, related to data loading, automatic calculations, data analysis, batch processing, data export and analysis. We would like to acknowledge our team of geosteerers (Oana C., Adrian D. and Tibi M.) for their help with expanding the scope of this project. Their hard work and dedication allowed us to analyze the entire pool, with 7 pads, 85 delineation wells and 101 lateral wells. Special thanks to ROGII’s Sergey Lebedev (product owner for the resistivity module in StarSteer) for his insight, technical assistance and patience in developing this workflow.
Find a recording of the presentation on out YouTube channel https://youtu.be/tuXPjjLjmP8 or play below:
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