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PETE 411 Well Drilling

PETE 411 Well Drilling. Lesson 6 Drilling Structures. Types of Drilling Structures. Conventional Rotary Rig for drilling on Land Alternate Drilling Structures Structures for deep Water or Arctic Drilling Hydrogen Sulfide and RULE 36. Homework. Read:.

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PETE 411 Well Drilling

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  1. PETE 411 Well Drilling Lesson 6 Drilling Structures

  2. Types of Drilling Structures Conventional Rotary Rig for drilling on Land Alternate Drilling Structures Structures for deep Water or Arctic Drilling Hydrogen Sulfide and RULE 36

  3. Homework Read: Applied Drilling Engineering, Ch.5 (bits) HW #3: Posted (due Sept. 18, 2002) Find HW #3 and Lessons at: http://pumpjack.tamu.edu/~juvkam-wold/

  4. Standard Derrick - Engines close to derrick - Mechanical Transmission

  5. 700 hp ENGINE COMPOUND 700 hp ENGINE 700 hp ENGINE

  6. Drilling Structures: • Conventional Land Rig • Jack-up Rig • Drillship • Semisubmersible • Jacket Platform • Gravel Island • Ice Island • Guyed Tower • Tension Leg Platform • Spar Platform

  7. Pile-founded steel jacket platform Cost increases rapidly with depth Bending moments Natural Frequency Mud Line

  8. ~100 sec nat.frequency (waves ~ 6-10 sec) Pivot at bottom (problem) Buoyed tower concept of 1970

  9. 1983 1,000 ft of water FAIRLEAD 200 TON CLUMP WEIGHTS Principal features of the Lena guyed tower

  10. High ice forces Weak soild Shallow water ~1,000 ft dia. Arctic drilling structure - Ice Island

  11. Spar Platform in Transit

  12. Spar Platform Installed

  13. Rule 36 - TRC • Protection of the General Public from the Effects of H2S • Applicable if H2S Concentration > 100 ppm • Operator must determine the H2S Concentration • and the Potential Flow Rate Point of Escape Radius of Exposure

  14. H2S • Determination of Radius of Exposure • The 100 ppm radius of exposure (in ft) R100= dist. from source where H2S conc. = 100 ppm Q = source strength = open flow potential, SCFD

  15. H2S • Determination of Radius of Exposure • The 500 ppm radius of exposure (in ft) R500= dist. from source where H2S conc. = 500 ppm Q = source strength = open flow potential, SCFD • These are the Pasquill - Gifford Equations

  16. Example A well that is about to be drilled is estimated to have an open flow potential of 5 million SCFD. Based on other wells in the field it is estimated that the H2S mole fraction in the gas mixture will be 0.1. Calculate the radius of exposure to H2S concentrations of 500 ppm and 100 ppm.

  17. Example = 2,250 ft

  18. Example = 4,924 ft ppm 500 100 R500 R100

  19. To Determine Q Use open flow potential Where insufficient data exist for calculating R100 (100 ppm radius): Assume R100= 3,000 ft

  20. Storage Tanks for Production • If H2S conc. > 500 ppm (i) Post warning sign within 50’ of facility (ii) Fencing is required in populated area

  21. Storage Tanks for Production • In general, If R500 > 50 ft: (i) Post warning signs on access roads (ii) Post marker signs at public crossing e.g. Poison Gas and Caution in Black and Yellow colors

  22. Need Contingency Plan if: (i) R100 > 50 ft • and includes public area other than public road 100 ppm can cause throat irritation in < 1 hr (ii) or R500 > 50 ft • and includes public road 500 ppm can cause unconsciousness in < 2 min death in ~1/2 hr (iii) or R100 > 3,000 ft {600 ppm can cause death after a few minutes}

  23. Must provide for action of alerting and protecting the public following accidental release of a potentially hazardous volume of H2S. Plan must include (names and) phone numbers of people to be notified…e.g. Supervisor Hospital and Fire Dept./ Sheriff or Police District Railroad Commission etc. Local Residents The Contingency Plan

  24. Drilling Provision: If we also need to: (i) Maintain protective breathing equipment at the well site (ii) Install and maintain automatic H2S detection and alarm equipment (iii) Provide means for flaring the gas

  25. Drilling Provision (iv) Provide remote control of BOP and choke equipment - at safe distance (v)DST of H2S zones only during daylight (vi) Notify railroad commission prior to performing such DST etc.

  26. Provide training for personnel • Submit certificate of compliance (with all the rules) • 30 days prior to commencement of drilling or WO • Certificate must be approved before commencing activities

  27. Altered conditions may require submittal of amended certificate Certificates are non-transferable Completion reports for new wells must include the H2S conc. of the gas if in excess of 100 ppm

  28. What is Buoyancy? Buoyancy is the net effect of all the pressure forces acting on a submerged body. The buoyancy force is equal to the weight of fluid displaced. For example, a one-cubic-ft rock submerged in a tank containing water would experience a buoyancy force equal to the weight of 1 cu. ft of water, i.e., 62.4 lbf.

  29. The End

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