Contents
- Background
- Basic model; probability equation
- Direct hit (DH) probability: method + results
- Unintentional crossing (UC) probability: method + results
- Conclusions
Background
- Wellbore collision: unplanned and negative event
- direct hit (DH)
- unintentional crossing (UC)
- Cause (here): uncertainty in wellbore positions
- What is acceptable probability?
- depends on consequences (HSE / non-HSE)
- Existing analysis methods:
- approximate; suited for simple geometries only
- complex, time consuming
Basic Model
- Offset well = existing; Reference well = planned, or being drilled
- Standard position (N, E, V) and uncertainty (Cov) data; passed QC
- Can interpolate all NEV and Cov data at any desirable MD
- Uncertainties are combined (=> relative uncertainty) and assigned to the reference well
- Wellbore dimensions are combined and assigned to the offset well
Direct Hit Probability: Method
- Taylor expansion
- Symmetric segment
- Integration
- Contributing terms:
- Any reasonable pdf distribution
- Any Segment orientation
What Boundary Should be Used?
- Closest approach: minimum spatial distance
...
View the entire Presentation:
Quantification of Wellbore Collision Probability by Novel Analytic Methods
Jon Bang, Gyrodata
First presented at: SPE/IADC Drilling Conference and Exhibition, 14-16 March 2017, The Hague, The Netherlands