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=10.194at(kgf/cm)¡Ö10.2at
1at=1 kgf/cm2=98066.5 Pa =98.0665 kPa=0.0980665 Mpa ´ÖÂÔ¼ÆËãʱ,¿ÉÈÏΪ:
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1MPa=10kgf/cm=10at (Îó²îΪ2%) 1at=100 kPa=0.1 Mpa
1.3.2 British System-----psi
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psi----pounds/inch(pounds per square inch) °õ/Ó¢´ç2
1psi=6.895 kPa¡Ö7 kPa=0.007 Mpa 1000psi¡Ö7 Mpa 5000 psi=35 Mpa
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2£®¾²ÒºÑ¹Á¦/Hydrostatic Pressure 2.1 ¶¨Òå/Definition
¾²ÒºÑ¹Á¦Óɾ²Ö¹ÒºÌåÖØÁ¦²úÉúµÄѹÁ¦¡£ Hydrostatic Pressure is the force exerted
by the weight of static fluid. ¡°hydro¡±------water or liquid ¡°static¡±-------at rest
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2.2 ¹«Ê½ /Formula
Ph= g¦ÑH= 0.00981¦ÑH Mpa
2.3 ×ê¾®ÒºµÄ¾²ÒºÑ¹Á¦/ Hydrostatic Pressure of
Drilling Fluid
ÔÚ×ê¾®×÷ÒµÖÐ, ×ê¾®ÒºµÄ¾²ÒºÑ¹Á¦ÊÇÓɾ®ÖÐ
×ê¾®ÒºÖØÁ¦²úÉúµÄ¡£
Pm= 0.00981¦Ñm H MPa Where:
¦Ñm----×ê¾®ÒºµÄÃܶÈdensity of drilling fluid.
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g/cm(kg/l) H------TVD ´¹Éî m For example:¾ÙÀý
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¦Ñm =1.2 g/cm , H=2000m, ¼ÆËãCalculate: Pm
´ð°¸Answer: Pm=0.00981¦Ñm H
=0.00981*1.2*2000 =23.544(Mpa)
In drilling, hydrostatic pressure is the force
exerted by drilling fluid in the wellbore. When formation pressure is greater than hydrostatic pressure, formation fluid may enter the wellbore. If formation fluid enter the well bore because formation pressure is higher than hydrostatic pressure, a kick has occurred. If prompt action is not taken to control the kick, or kill the well, a
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blowout may occur. To control a well, a proper balance between pressure in the formation and pressure in wellbore must be maintained; Hydrostatic pressure must be equal to or slightly higher than formation pressure.
3. ѹÁ¦ÌݶÈ/pressure gradient 3.1 ¶¨Òå/Definition
µ¥Î»´¹Ö±Éî¶ÈѹÁ¦µÄ±ä»¯Öµ¡£
Pressure gradient is the amount pressure changes with per unit true vertical depth.
TVD&MD: TD
TVD and MD is differ, especially in directionally drilled holes.
TVD is the length of a straight vertical line from the surface to the bottom of the hole. MD or total depth is the length of the well as measured along the actual course of the hole.
3.2 ¹«Ê½/formula
PG??0.00981?(MPa/m)
H
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where:
G-----ѹÁ¦ÌݶÈgradient, Mpa/m P-----ѹÁ¦pressure, Mpa H----´¹ÉîTVD, m
×ê¾®ÒºµÄѹÁ¦Ìݶȣº
Gm = Pm/H=0.00981¦Ñm (Mpa/m) ÀýÈçFor example:
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¦Ñm = 1.24g/cm, H = 3353m. ¼ÆËãcalculate: Gm and Pm
´ð°¸answer: Gm = 0.00981¦Ñm
=0.00981*1.24=0.0122(Mpa/m) Pm = Gm H=0.0122*3353=40.8(Mpa) 3.3 Ó¢ÖƱíʾ·¨/Expression Method of British
System 2
g=0.052ft/s
Pm = 0.052¦Ñm H Where:
Pm ------¾²ÒºÖùѹÁ¦hydrostatic pressure, psi---pounds per square inch.
¦Ñm -------ÃܶÈdensity, ppg----pounds per
gallon.°õ/¼ÓÂØ
H---------TVD, ft¡ªfoot. »»Ëã¹Øϵ/conversion relation:
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1 g/cm= 8.33ppg µË®fresh water
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