COMPOSITE MATERIALS د. ناظم مجبل فالح تكنولوجيا حفر 7

1. الجامعة المستنصرية كلية الهندسة قسم الهندسة الميكانيكية تكنولوجيا حفر مرحلة 4 COMPOSITE MATERIALSد. ناظم مجبل فالح تكنولوجيا حفر 7

2. Example • Hole size = 7 7/8” • depth = 5000’ • Drillpipe size = 4 1/2” • Anticipated ROP = 30 feet/hr • Qo = 671, N = 65, H = 5000/1000 = 5 • Minimum air rate for dry air = • Qa = Qa +NH = 670 + 65x5 = 995 scfm

3. Example • Liquid injection rate is 6 BPH • Water influx is 3.8 BPH • Total liquid rate is 9.8 BPH • Penetration rate that would give this mass cuttings per hour is 60 ft/hr.

4. Example • The minimum air rate required for dry air drilling at a penetration rate of 90 ft/hr using the value of N for 90 ft/hr, N = 98.3 would be 1162 scfm

5. Wellhead Design - Low pressure • Gas, mist, and foam drilling are normally utilized on low pressure wells • Low pressure wells require simple wellhead designs • Some operators opt for a simple annular preventer alone

6. Wellhead Design - Low pressure • However, a principal manufacturer of such equipment strongly cautions that such use exceeds the design criteria of this equipment. • The minimum setup should consist of a rotating head mounted above a two ram set of manually-operated blowout preventers, consisting of a pipe ram and a blind ram

7. Wellhead Design - Low pressure • Slightly higher pressure systems should also have an annular preventer between the rams and the rotating head. • For added safety the BOP system should be hydraulically operated • Working pressure of these rotating heads is ~400-500 psi

8. Wellhead Design - High pressure • Gasified liquids, flowdrilling, mudcap drilling • Rotating heads on top of conventional hydraulically operated BOP usually suffice • In Canada, nitrified liquids are often used with an RBOP installed atop a conventional BOP stack.

9. Wellhead Design - High pressure • Blind rams should be installed in the bottom set of rams (when a two ram system is used) • Sometimes a third set of rams (pipe rams) is utilized. • In this case the RBOP is installed atop an annular preventer. • The blind ram is placed between the two sets of pipe rams. Harold Vance Department of Petroleum Engineering

10. Wellhead Design - High pressure • The lowermost set of rams should be installed directly atop the wellhead (or an adapter spool if necessary) • You should never place any choke or kill lines below the lowest set of rams. • If one of these lines cuts out, there is no way to shut in the well. Harold Vance Department of Petroleum Engineering

11. Wellhead Design - High pressure • Care must be taken to utilize a rig with a substructure high enough so that the wellhead is not below ground level, with space enough to put the entire desired BOP stack below the rig floor Harold Vance Department of Petroleum Engineering

12. Wellhead Design - Snub drilling • Snub drilling and CT drilling have BOP stacks that allow tripping at much higher pressures than other forms of UBD (routinely up to 10,000 psi) • Snubbing and CT units can be used for UBD at pressure that cannot be managed by conventional surface equipment. Harold Vance Department of Petroleum Engineering