Underbalanced Drilling (continued)

UBD – Case History – Keystone Holt* Unit (combination Glorieta and the Clearfork) Kermit, Texas

Glorieta (Upper Holt) discovered in 1943
Clearfork (Lower Holt) discovered in 1947
Glorieta Gas Injection from 1958 – 1968
Glorieta Waterflood from 1968 - present
Original pressures = 2145 psi @ 4700 TVD 137
Active wells, 81 producers, 56 injectors
20 – 80 Acre Spacing
K = 3-20 mD, F = 5-15%
+/- 800 psi BHP in gas cap, 2000 psi in oil leg
Several producers w/both zones open - Drill Gas Cap only

KHU Case History Comparison

KHU Case History Comparison CONCLUSIONS 

When compared to “conventional horizontal wells”, the UBD horizontal was 29% less to drill roughly the same hole size and length 

Completion costs were about the same, but the UBD completion was high due to logistics whereas the Conventional horizontal was high due to low production and the need for clean up 

UBD is great, but the real benefit comes from the ability to complete the well in the underbalanced mode