Horizontal Drilling and Stimulation Processes in Shale Exploration

Introduction

• Horizontal drilling and stimulation processes are crucial for successful shale exploration.
• Combination of technologies has improved efficiency and yield in gas extraction.

Drilling Process

Initial Steps

• Drill Bit and Mud:
  • Drill bit mounted on end of drill pipe.
  • Grind away rock, mud mixture pumped in to cool the bit.
  • Flush cuttings to surface and coat well bore walls.
• Vertical Drilling:
  • Drill to just under deepest freshwater near the surface.
  • Remove drill pipe and bit.

Surface Casing

• Installation:
  • Insert surface casing to isolate freshwater zone.
  • Acts as foundation for blowout preventer (safety device).
• Cementing:
  • Pump cement down casing, out through shoe opening at bottom.
  • Cement forced up between casing and well bore, sealing off fresh water.

Continuation

• Drilling Process:
  • Drill through plug and cement for vertical section up to 500 feet above planned horizontal leg (kickoff point).
  • Remove pipe and bit.
• Angle Building:
  • Use downhole drilling motor with instruments to begin angle building.
  • Distance for curve: just under a quarter mile.
  • Complete curve, start drilling horizontal section (lateral).

Horizontal Drilling

• Pipe Specifications:
  • Each pipe: 30 feet long, ~495 pounds.
  • Total: 350 pipes, ~87 tons for 10,500-foot well.

Production Casing and Cementing

• Final Drilling:
  • Remove drill pipe and bit at target distance.
  • Insert production casing for entire well bore length.
• Final Cementing:
  • Pump cement down casing, out through shoe hole.
  • Cement forced up, filling annulus (open space).

Preparation for Production

• Once drilling rig no longer needed:
  • Install temporary well head.
  • Prepare location for service crew to perf, frack, and prepare well.

Perforation and Fracturing (Fracking)

• Perforation:
  • Lower perforating gun into casing, to targeted section of horizontal leg.
  • Send electrical current to perf gun, set off charge.
  • Small holes shot through casing, cement, into shale.
  • Remove perf gun.
• Hydraulic Fracturing:
  • Pump water, sand, additives into well bore, down casing at high pressure.
  • Pressure forces mixture through perforations into shale, causing fractures.
  • Creates pathways for gas flow from reservoir to well bore.

Staging and Flow

• Temporary Plug:
  • Place plug at heel/left side of first stage frack.
  • Isolate sections for multi-stage fracking.
• Multi-Stage Fracking:
  • Repeat perforating and fracking for entire horizontal well bore.
• Completion:
  • Drill out plugs after fracking.
  • Allow gas flow up well bore.