Chuong 5a drilling hydraulics hydrostatics

Petroleum Engineering 405 Drilling Engineering * Well Drilling Engineering Drilling Hydraulics Hydrostatics Dr DO QUANG KHANH * Drilling Hydraulics Hydrostatics Hydrostatic Pressure in Liquid Columns[.]

Well Drilling Engineering Drilling Hydraulics - Hydrostatics Dr DO QUANG KHANH Drilling Hydraulics - Hydrostatics  Hydrostatic Pressure in Liquid Columns  Hydrostatic Pressure in Gas Columns  Hydrostatic Pressure in Complex Columns  Forces on Submerged Body  Effective (buoyed) Weight of Submerged Body  Axial Tension in Drill String A = FA/A Read: Applied Drilling Engineering, Ch.4 (Drilling Hydraulics) HW #4 ADE # 4.3, 4.4, 4.5, 4.6 WHY? Drilling Hydraulics Applications  Calculation of subsurface hydrostatic pressures that may tend to burst or collapse well tubulars or fracture exposed formations  Several aspects of blowout prevention  Displacement of cement slurries and resulting stresses in the drillstring Drilling Hydraulics Applications cont’d Bit nozzle size selection for optimum hydraulics Surge or swab pressures due to vertical pipe movement Carrying capacity of drilling fluids Well Control ppore < pmud < pfrac Fig 4-2 The Well Fluid System Forces Acting on a Fluid Element F1 = FWV = specific wt of the fluid pA dp D ) A F2 = ( p  dD F A  D w v F3 = Pressures in a fluid column  At equilibrium, F=0 = F1 + F2 + F3 dp  F 0 pA  ( p  dD D )A  Fw v AD  dp  Fw v dD (p = gh) Incompressible Fluids dp  Fw v dD Integrating, p  Fw v D  p [ p  p when D  ] Incompressible Fluids In field units, Fw v 62   * 144 33  0.433 * 8.33 Fw v  052  1’ x 1’ x 1’ cube 10 Compressible Fluids p = pressure of gas, psia o T = temperature, R V = gas volume, gal  = density, lbm/gal Z = gas deviation factor M = gas molecular wt n = moles of gas m = mass of gas, lbm R = universal gas constant, o = 80.3 psi.gal/lb-mole R 13 Compressible Fluids From Eqs (2) and (4): 052 p M  dp  dD 80.3 Z T  p  p0 Integrating,  Assumptions? dp M  p 1544 Z T [ln p ] p p0 D  D0 dD M D  [D] D 1544 Z T M (D  D ) p p exp [ ] 1544 Z T 14 Example M (D  D ) p p exp [ ] 1544 Z T Column of Methane (M = 16) Pressure at surface = 1,000 psia Z=1, T=140 F (i) What is pressure at 10,000 ft? (ii) What is density at surface? (iii) What is density at 10,000 ft? (iv) What is psurf if p10,000 = 8,000 psia? 15 Fig 4-3 A Complex Liquid Column p 0.052  D  p0 p 0.052  D n p  p  0.052   i ( D i  D i  ) i 1 16 Pa = ? Fig 4-4 Viewing the Well as a Manometer 17 Buoyancy Force = weight of fluid displaced (Archimedes, 250 BC) Figure 4-9 Hydraulic forces acting on a foreign 18 Effective (buoyed) Weight We  W  Fb W - f V W W - f s   We  W    f s    Buoyancy Factor Valid for a solid body or an open-ended pipe! 19 Example For steel,  s  65 lbm / gal immersed in mud, (  f 15 lbm / gal ) the buoyancy factor is:  f   15.0         0.771 s   65.5   A drillstring weighs 100,000 lbs in air Buoyed weight = 100,000 * 0.771 = 77,100 lbs 20