Relief-Well Ranging & Intercept Design, Sour-Gas Blowout

Central Asia · 2025

Relief-well engineering for an H₂S sour-gas surface blowout, ranging and intercept design in a multi-company alliance

The challenge

→A fatal multi-well sour-gas blowout event; H₂S-rich gas broke through to surface.
→Gas surfacing across ~20 locations around the field; a complex multi-well event.
→Targets must be located and intercepted by relief wells through thick salt.

Our solution

As ranging & interception lead in a multi-company well-control alliance, Gunnar designed the survey-management and ranging program: advanced multi-station MWD survey correction to sharpen both target- and relief-well positions, a locate-follow-intercept strategy (active magnetic ranging, with active acoustic as backup through salt), and an optimized 3–6° intercept above the 9⅝" casing shoe.

Relief-well drilling, ranging, intercept & dynamic kill assessed technically feasible

The result

Feasible

relief well, ranging · intercept · dynamic kill

·Advanced multi-station MWD correction cut positional uncertainty, fewer ranging runs
·Locate-follow-intercept plan; active acoustic ranging as backup through salt
·Optimized intercept just above the 9⅝" shoe at a 3–6° incidence angle
·Dynamic kill: 2.10 SG mud, ~30 bpm, ~588 m³, within rig and pump capability

Ranging

AMR + PMR

Deployment

BHA While Drilling

Re-entry

Yes

Location

Central Asia

Year

2025

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