IMPORTANT FORMULAE

FIELD UNITS - US IMPERIAL

Nydrostatic Pressure

tll HSP 6,i;: Mud Density $pe) x 0.052 (rb.gar/sqin/tt) x True Vertical Depth 1ri;

Pressure Gradient

l2] Mud or Pressure Gradient @si/ft) : Mud DensitY rppgr x 0.052

i3] Formation Fracture Gradient (psi/rr;:

Maximum Aliowable Mud DensitYoper x 0.052

[4] Influx Gradient gsi/ft):Mud Gradient 1p*vrtl - ((SICP - SmPP) / True Vertieal Influx Height G))

Mud Density

t5l Mud Densif opet: Pressure 6,i; / 0.052 / TVD 1ny

t6] Mud Density tppgl: Pressure Gradient bsi/rt) I 0.052

l7l Kill Mud Density (ppg): SIDPP I 0.052 / TVD ttl + OMD ,oor,

Trwe Vertical Depth

[8] TVD (ft): HSP tpsil / 0.052 / Mud Density 1oorl

t9] TVD (ft): Cosine Deviatioil ldegrees) x Measured Lenglh 1ty

t10l Influx Length in hole (ft) : Pit Gain o6) / Annular Capacity lurvn;

t11l True Vertical Influx Heightlry:Cosine Deviation (degrees) x Influx Length lrty

UNSWSchool of Petroleum EngineeringSvdnev NSW 2052

Document No.NDWCP.QA-FSAPI

Revision No. 6

Date: 27-Jan-2006Formula Sheet API Page I of5

IMPORTANT FORMULAE

FIELD TINiTS - US IMPERIAL

Maximum Allowable Mud Density & Equivalent Circulating Density

Ll2l MAMD (pps) -Leak-off Pressure rpsr / 0.052 / TVD of Shoe 1ri * Test Fluid Density 6o*y

[13] MA.MD (ppe): Total Pressures @ Shoe 1p,iy / 0.052 i TVD of Shoe 1r1

t14] ECD loog;: Annular Friction Loss 1p,iy I A.A52 / TVD rtr + OMD 1oor,

Msximam Allowable Arunular Surface Pressure

[15] MAASP tpsr: (MAMD roo*r- Current Density6oe) x 0.052 x Shoe TVD rnl

Formation Fressure

[16] Formation Pressure (p,i) : HSP 1p"i1+ SIDPP 1p,iy

[17] Formation Pressure (psi) : Pore Pressure Gradieflt lpsi/ft) x TVD 1ty

Y o Ia rn e o C ap a c ity, D isp lac em e nt, O utp u t, V e I o c ity

t18] Volume $br): Capacity Gbvft) x Lenglh 1ny

t19] Pipe or Hole Capacity iurvny: ID2 (inches) I L029.4

t20] Annular Capacity Gbr/ft) : (Hole ID2 1in"r,"*; - Pipe OD21in"n".y) I 1029.4

l2l) Pipe Displacement 6brig;: @ipe OD21;n"r,,".; - Pipe ID2(in"r,"r)) I 1029.4

122] Pump Output &bl/min) : Pump Output@bvstk) x Pump Speed 1,p*;

t23l Annular Veiocity (ff/min): Pump Output gbls/min) / Annular Capacity ouvrl

UNSWSchool of Petroleum EngineeringSvdnev NSW 2052

Document No.NDWCP-QA-FSA.PI

Revision No. 6Date: 27-Jan-2006

Formula Sheet API Page 2 of 5

IMPORTANT FORMULAE

FIELD LNITS - US IMPERIAL

Circulating Fresswres

l24l Initial Circulating Pressure (p.i): Dynamic Pressure Loss 1p,iy + SIDPP tp.i)

t25] Final Circulating Pressure (psi):Dynamic Pressure Loss ip,1 x KMD lppgy / OMD ioory

126] New Pump Pressure (p,i) :Current Pressure lpsi; x (New Rate 1rp-; / Old Rate 1.p*y) '

l27l New Pump Pressure (p.i) :Old Pressuro (psi) x (New Mud DensitY bpel / Old Mud DensitY opel)

Tripping

t28] Length of tubular to pull dry before overbalance is lost 1re :

(Overbalance x (Casing Capacity - Metal Displ")) / (OMD x 0.052 x Metal Displ.)ps. bbl/ft bbl/ft PPC bbffi

1291 Overbalanc€ lpsi): (I{ydrostatic Pressure) - (Formation Fressure): (OMD x 0.052 x TYI)) - (Pore Pressure Gradient x TVD)

ft psi,/ft .ft

t30] Pressure Drop per ft Tripping Dry Fipe (psi/n):(OMD x 0"052 x Metal Dispt.) i (Casing Capacity - Metal Displ.)

ppE bbl/fi bbuft bbuft

[3 1] Fressure Drop per ft Tripping Wet Fipe lpwrt; :

(OMD x 0.052 x Closed End Displ.) i (Casing Capacity * Closed End Displ")pps bbuft bb|fi bbYft

l32l X,evel Drop For FOOI{ Drill Collars (Dry) <ro:(Length of Drill Collars x Metal Displ") / Casing Capacify

ft bbl/ft bbUft

t33] Slug Drop 1re =(Slug Density i OMD x Slug Length in Fipe) - Slug Length in Fipe

ppc ppc ft fI

UNSWSchool of Petroleum EngineeringSvdnev NSW 2052

Document No.NDWCP-QA-FSA"I

Revision No. 6

Date: 27-Jan-2006Formula Sheet API Page 3 of5

IMPORTANT EOBMULAE

FIELD LINITS - US IMPERIAL

t34l Slug Density rppel: OMD x ((Slug Drop/Slug Length in Pipe) + 1)ppC ft Jt

135l Gain in Trip Tank 6br;:((Slug Density / OMD) - 1) * Slug Volume Pumped

ppC ppc bbl

t36] Earite to Raise Dritling Fluid Density snsnnry:(!f* ;3*) x 1500) / (3s"8 - KMo)

Volametric, Migration

l37l PSI PER BBL: Mud Gradient 6svny / Hole Capacity ptvq

t38] Volume to Bleed to Restore BIIP to Formation Pressure lntg:(Increase in Press os,) x Pit Gain tuur,l) / (Formation Press 6,,1 - Increase in Press 6";1 )

t39] Percolation Rate (n/hr):Increase in Drill Pipe Press tusi1hr) / (OMD x 0.052)

Boyle's X'aw

t40] Pressure 6e x Volume 66;: Constant

t4l] New Voiume obr): Constant / New Pressure 6",;

PxV:C

V:C/P

0tker

l42l SICP b.i):((Mud Density - Influx Density) x 0.052 x Influx Height) + SIDPP

l43l Riser Margin tupg):(Choke tine HSF - Seawater EISP) / 0"052 l(TVD * Choke line Length)

T]NSWSchool of Petroleum EngineeringSvdnev NSW 2052

Document No.NDWCP-QA-FSAPI

Revision No. 6

Date: 27-Jan-2006

Formula Sheet API Page 4 of 5