Reasons for Using Cementing Plugs

• Remove mud sheath

• Separate cement and Mud

• Prevent over displacement

• Surface indication

• Pressure test casing

Five Wiper Cementing Plugs

• Available with:– aluminum inserts

– plastic inserts

– non-rotating (NR) plastic inserts

• 350 psi rupture diaphragm in bottom plugs

• Surface release or sub-surface release (SSR)

• Compatible with water-based or oil-based muds

NR Cement Plug System

• Reduces drillout time

• PDC drillable

• 350 psi rupture diaphragm

• Use with NR float collar

• All plastic inserts

Top & Bottom Plugs with NR Float Collar

NR Cement Plugs

Cementing in process Cementing complete Ready for drillout

Pumping Cement without Cement Plugs

• Much cement contamination

• No surface indication of cement placement

Displacement fluid

Cement

Casing

Mud sheath

Drilling mud

Pumping Cement with Top Plug Only

• Top plug wipes mud sheath from casing ID

• Separates cement from displacement fluid

• Surface indication when cement placement is complete

• Require additional shoe track length

Casing

Top plug

Accumulatedmud

Mud sheath

Drilling mud

Accumulated Mud Volume Ahead of Cement Plug

Fill up per 1,000 ft. casing

1/16 51 ft. 40 ft. 28 ft. 20 ft.

1/32 25 ft. 20 ft. 12 ft. 10 ft.

1/64 13 ft. 10 ft. 7 ft. 5 ft.

Mudsheath

thickness(Inches)

5-1/2 inchcasing

7 inchcasing

9-5/8 inchcasing

13-3/8 inchcasing

Pumping Cement with Top & Bottom Plugs

• Preferred method

• Bottom plug wipes mud sheath from casing ID

• Surface indication when cement placement is complete

• Maximum cement/mud separation

Displacementfluid

Top plug

Accumulatedmud

Casing

Drilling mud

Cement

Bottom plug

Polycrystalline Diamond Compact Bits (PDC)

• Soft – medium formations

• Improves rate of penetrate (ROP)

• Longer service life

Concave PDC Bit

Illustrates aggressive nature of PDC bits