GT-04 · Aerated Drilling Control

Hole depth 2,846 m MD · Formation: Andesite fractured zone

Blind drilling active · 8½ in open hole

Total loss at 2,460 m MD. No measurable surface return; injected liquid and air are entering the fractured formation. Continue only inside the approved hydraulic and mechanical envelope.

0 GPM RETURN
285 GPM
318 scfm
142 bar
0.910 sg

GT-04 well schematic

As-drilled · not to scale
0 m80 m600 m1,800 m2,460 m2,846 m MD20 in casing13⅜ in casing9⅝ in casing shoe8½ in open holeTOTAL LOSSBit + motor + MWDTD 2,846 m MD
Flow path: aerated fluid travels down the drill string, exits through the bit, cleans the bottom-hole interval, and is discharged into the fracture network. No annular return reaches surface during the blind-drilling phase.

Directional trajectory

MD · TVD · departure
05001,0001,5002,0002,6000300600900 mTVD (m)Horizontal departureKOP · 700 m MDBuild 2.0°/30 mHold · 22°Blind intervalTD · 2,846 m MDTrajectory summaryTVD: 2,600 mInclination: 22°Azimuth: 128°
Survey control: MWD surveys every stand in the build section and every 90 m in hold. Blind drilling does not remove the requirement to monitor inclination, azimuth, dogleg severity, torque, and drag.

Blind-drilling pressure window

Pore ECD Fracture
0.910 sgTD operating point05001,0001,5002,0002,6000.750.850.951.051.15TVD (m)Equivalent density (sg)LOSS / BLIND-DRILLING ZONE
TD margins: ECD 0.910 sg; pore equivalent 0.860 sg; fracture gradient 1.020 sg. Lower margin 0.050 sg and upper margin 0.110 sg. Live response overrides the static model when the formation takes fluid.

Drilling parameters by hole section

GT-04 blind-drilling program
Interval MDHole / bitModeWOBRPMLiquid flowAirSPPTarget ROPECD
0–80 m26 in · triconeConventional5–10 klbf40–60800 GPM0 scfm25–45 bar20–35 m/h1.08–1.12 sg
80–600 m17½ in · PDCConventional20–35 klbf80–100750 GPM0 scfm55–85 bar20–30 m/h1.08–1.12 sg
600–1,800 m12¼ in · PDCAerated transition20–32 klbf70–90500 GPM0–120 scfm90–125 bar15–24 m/h0.96–1.04 sg
1,800–2,846 m8½ in · PDC + motorBlind / total loss12–22 klbf55–70285 GPM318 scfm132–152 bar8–14 m/h0.89–0.94 sg

Current blind-drilling parameter envelope

Control-room action limits
Mechanical set pointWOB 18 klbf · RPM 62 · torque 14.8 kft·lbf · ROP 11.8 m/h. Adjust one parameter at a time and observe at least one connection cycle.
Hydraulic set point285 GPM liquid · 318 scfm air · SPP 142 bar · ECD 0.910 sg. Ramp air in controlled steps; confirm pressure stabilization.
STOP / reassess triggersSPP ±20 bar from baseline, torque +25%, severe vibration, gas/H₂S escalation, unexpected pit gain, compressor trip, or loss of pressure telemetry.