Overview:
- Passive ranging is technically useable, but has poor performance in most circumstances.
- The limitations of passive ranging and reliance upon it as a primary detection method invite cost increase and operational failure.
- A more robust and systematic approach uses active ranging which can be complimented with passive ranging (in the limited number of circumstances where it is appropriate)
- Success in a relief well ranging operation is not defined as identifying or tracking a well, but instead by the ability to intersect and establish hydraulic communication with the target.
Lessons Learned
- Active Ranging measurements, an accurate relief well survey, and a predicted/successful intersection allowed the target well position to be established with great accuracy
- The target well position was within a few meters of the original survey supplied to all directional drilling and magnetic ranging service providers
- A proximity scan of the 11 sidetracks on the first relief well attempt against the actual position of the target well reveal that the first relief well sidetracks were never closer than 30 meters from target well.
Observations
- It is unlikely that low target signal on the first attempt was caused by corrosion.
- Active ranging would likely have identified the target well at or near the sidetrack #1 kick off point.
- The limited range of passive techniques in general greatly complicates the process of locating and intersecting a target well
- The surveying process and sidetracks associated with passive methods can amount to a dramatic increase in project time and cost.
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View the entire Presentation:
Comparison of Active and Passive Magnetic Ranging Techniques
Clinton Moss - Halliburton