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Drilling Engineering Equations

Browse 266 drilling engineering petroleum engineering equations with variables, units, source references, and calculator links.

Drilling engineering calculators cover hydraulics, mud and cementing, well control, directional drilling, and wellsite pressure checks.

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Drilling EngineeringWell Control

Accumulator Bottles Required for BOP Function Volume

Nbottles=⌈VrequiredVusable,bottle⌉N_{bottles}=\left\lceil\frac{V_{required}}{V_{usable,bottle}}\right\rceil
View formula
Drilling EngineeringWell Control

Accumulator Nitrogen Gas Volume from Boyle Law

VN2=PpreVbottlePsystemV_{N2}=\frac{P_{pre}V_{bottle}}{P_{system}}
View formula
Drilling EngineeringWell Control

Actual Gas Migration Rate from Casing Pressure Increase

RGM=(Pcsg2−Pcsg1)/Δt0.052MWRGM=\frac{(P_{csg2}-P_{csg1})/\Delta t}{0.052MW}
View formula
Drilling EngineeringWell Control

Additional Mud Returned by Slug

Vadd=(WsWm−1)VsV_{add}=\left(\frac{W_s}{W_m}-1\right)V_s
View formula
Drilling EngineeringDrilling Hydraulics

Annular Capacity - bbl/ft

ACbbl=Dh2−Dp21029.4AC_{bbl}=\frac{D_h^2-D_p^2}{1029.4}
View formula
Drilling EngineeringDrilling Hydraulics

Annular Capacity - gal/ft

ACgal=Dh2−Dp224.51AC_{gal}=\frac{D_h^2-D_p^2}{24.51}
View formula
Drilling EngineeringDrilling Hydraulics

Annular Capacity Between Casing and Multiple Strings of Tubing

Ca=Di2−(T12+T22)1029.4C_a=\frac{D_i^2-(T_1^2+T_2^2)}{1029.4}
View formula
Drilling EngineeringMud and Cementing

Annular Cement Volume for Casing Section

Vcem=CannLcemV_{cem}=C_{ann}L_{cem}
View formula
Drilling EngineeringMud and Cementing

Annular Spacer Volume for Casing Job

Vspacer=CannLspacerV_{spacer}=C_{ann}L_{spacer}
View formula
Drilling EngineeringDrilling Hydraulics

Annular Velocity from Pump Output

AV=24.5QDh2−Dp2AV = \frac{24.5Q}{D_h^2 - D_p^2}
View formula
Drilling EngineeringDrilling Hydraulics

Annular Volume Capacity of Pipe

Va=0.7854(Dh2−Do2)L808.5V_a=\frac{0.7854(D_h^2-D_o^2)L}{808.5}
View formula
Drilling EngineeringMud and Cementing

API Water Loss from Seven-and-a-Half Minute Filtrate

V30=2Va−VspV_{30}=2V_a-V_{sp}
View formula
Drilling EngineeringDrilling Hydraulics

Apparent Viscosity from 600 RPM Reading

AV=θ6002AV=\frac{\theta_{600}}{2}
View formula
Drilling EngineeringMud and Cementing

Area Below the Casing Shoe

A=0.7854Dc2A=0.7854D_c^2
View formula
Drilling EngineeringDirectional Drilling

Average Angle Survey Displacements

ΔN=ΔMDsin⁡(I1+I22)cos⁡(A1+A22)\Delta N=\Delta MD\sin\left(\frac{I_1+I_2}{2}\right)\cos\left(\frac{A_1+A_2}{2}\right)
View formula
Drilling EngineeringMud and Cementing

Balanced Cement Plug Length Before Pipe Withdrawal

Lpre=NYCannE+CpipeL_{pre}=\frac{NY}{C_{ann}E+C_{pipe}}
View formula
Drilling EngineeringDirectional Drilling

Balanced Tangential Survey Displacements

ΔN=ΔMD2(sin⁡I1cos⁡A1+sin⁡I2cos⁡A2)\Delta N=\frac{\Delta MD}{2}(\sin I_1\cos A_1+\sin I_2\cos A_2)
View formula
Drilling EngineeringDrilling Hydraulics

Bit Nozzle Impact Force

IF=MWVnQ1930IF=\frac{MWV_nQ}{1930}
View formula
Drilling EngineeringDrilling Hydraulics

Bit Nozzle Jet Velocity

Vn=417.2QN12+N22+N32V_n = \frac{417.2 Q}{N_1^2 + N_2^2 + N_3^2}
View formula
Drilling EngineeringDrilling Hydraulics

Bit Nozzle Pressure Loss

Pb=156.5Q2MW(N12+N22+N32)2P_b = \frac{156.5Q^2MW}{(N_1^2+N_2^2+N_3^2)^2}
View formula
Drilling EngineeringDrilling Operations and Economics

Bit Run Drilling Cost per Foot

CT=B+CR(t+T)FC_T=\frac{B+C_R(t+T)}{F}
View formula
Drilling EngineeringDrilling Hydraulics

Bit-to-Surface Lag Time from Annular Volume

tlag=VAVPO⋅SPMt_{lag}=\frac{V_{AV}}{PO\cdot SPM}
View formula
Drilling EngineeringDirectional Drilling

Borehole Torsion by Cylindrical Helical Method

t=kh(1+2kv2k2)sin⁡(aπ180)cos⁡(aπ180)t=k_h\left(1+\frac{2k_v^2}{k^2}\right)\sin\left(\frac{a\pi}{180}\right)\cos\left(\frac{a\pi}{180}\right)
View formula
Drilling EngineeringDrillstring and Rig Mechanics

Bottomhole Assembly Length for Desired Weight on Bit

L=WbfWdBFL=\frac{W_bf}{W_dBF}
View formula
Drilling EngineeringWell Control

Breakover Point Between Stripping and Snubbing

Lds=Ldc+LbpL_{ds}=L_{dc}+L_{bp}
View formula
Drilling EngineeringWell Control

Brine Fluid Density to Mix for Temperature Correction

ρmix=ρavg+(Tavg−Tsurface)WL\rho_{mix}=\rho_{avg}+(T_{avg}-T_{surface})WL
View formula
Drilling EngineeringDirectional Drilling

Build or Drop Rate from Inclination Change

BUR=(I2−I1)100ΔMDBUR=\frac{(I_2-I_1)100}{\Delta MD}
View formula
Drilling EngineeringDirectional Drilling

Build Rate Component from Dogleg Severity and Toolface

BUR=DLSreqcos⁡(TF)BUR=DLS_{req}\cos(TF)
View formula
Drilling EngineeringDirectional Drilling

Build Section Measured Depth from Build Rate

ΔMD=I2−I1BUR/100\Delta MD=\frac{I_2-I_1}{BUR/100}
View formula
Drilling EngineeringWell Control

Bullhead Pump Speed to Exceed Gas Migration

SPMbh=(RGM/60)CtbgPOSPM_{bh}=\frac{(RGM/60)C_{tbg}}{PO}
View formula
Drilling EngineeringWell Control

Bullheading Formation Fracture Pressure from Gradient

Pfrac=GfracTVDperfP_{frac}=G_{frac}TVD_{perf}
View formula
Drilling EngineeringWell Control

Bullheading Initial Average Fluid Density

ρinit=Ph,init0.052TVDperf\rho_{init}=\frac{P_{h,init}}{0.052TVD_{perf}}
View formula
Drilling EngineeringWell Control

Bullheading Initial Hydrostatic Pressure from Formation Pressure

Ph,init=Pform−SITPP_{h,init}=P_{form}-SITP
View formula
Drilling EngineeringWell Control

Bullheading Maximum Final Surface Pressure

Psurf,final,max=Pfrac−KFW 0.052TVDperfP_{surf,final,max}=P_{frac}-KFW\,0.052TVD_{perf}
View formula
Drilling EngineeringWell Control

Bullheading Maximum Initial Surface Pressure

Psurf,init,max=Pfrac−Ph,initP_{surf,init,max}=P_{frac}-P_{h,init}
View formula
Drilling EngineeringWell Control

Bullheading Volume to Perforations

Vbh=Vlines+Vsurface→EOT+VEOT→top+Vtop→bottomV_{bh}=V_{lines}+V_{surface\to EOT}+V_{EOT\to top}+V_{top\to bottom}
View formula
Drilling EngineeringMud and Cementing

Casing Displacement Volume to Float Collar

Vdisp=CcsgLfcV_{disp}=C_{csg}L_{fc}
View formula
Drilling EngineeringWell Control

Casing Pressure After Subsea Start-Up

Pstart=SICP−PclP_{start}=SICP-P_{cl}
View formula
Drilling EngineeringWell Control

Casing Pressure Increase from Stripping Into Influx

P=H(G−Gi)P=H(G-G_i)
View formula
Drilling EngineeringWell Control

Casing Pressure Increase Rate from Gas Migration

Pinc=RGM MWGP_{inc}=RGM\,MWG
View formula
Drilling EngineeringMud and Cementing

Cement Height in Annulus from Slurry Volume

hann=Vslurry−VcsgCannEh_{ann}=\frac{V_{slurry}-V_{csg}}{C_{ann}E}
View formula
Drilling EngineeringMud and Cementing

Cement Plug Landing Differential Pressure

Pland=Pann−PintP_{land}=P_{ann}-P_{int}
View formula
Drilling EngineeringMud and Cementing

Cement Plug Landing Upward Force

Fup=AcsgPlandF_{up}=A_{csg}P_{land}
View formula
Drilling EngineeringMud and Cementing

Cement Plug Sacks Required for Planned Length

Nplug=LplugChEYN_{plug}=\frac{L_{plug}C_hE}{Y}
View formula
Drilling EngineeringMud and Cementing

Cement Plug Slurry Volume from Sacks

Vslurry=NYV_{slurry}=NY
View formula
Drilling EngineeringMud and Cementing

Cement Remaining in Casing Above Cementing Tool

Vcsg=(Dset−Dtool)CcsgV_{csg}=(D_{set}-D_{tool})C_{csg}
View formula
Drilling EngineeringMud and Cementing

Cement Sacks Required from Slurry Volume

N=VcYN=\frac{V_c}{Y}
View formula
Drilling EngineeringMud and Cementing

Cement Slurry Hydrostatic Pressure at Depth

Ph=GcemDP_h=G_{cem}D
View formula
Drilling EngineeringMud and Cementing

Cement Slurry Pressure Gradient from Density

Gcem=0.05195ρcemG_{cem}=0.05195\rho_{cem}
View formula
Drilling EngineeringMud and Cementing

Cement Slurry Yield from Slurry Volume

Y=Vs7.48Y=\frac{V_s}{7.48}
View formula
Drilling EngineeringMud and Cementing

Centrifuge Mud Processing Evaluation

QU=QM(MW−PO)−QW(PO−PW)PU−POQ_U=\frac{Q_M(MW-P_O)-Q_W(P_O-P_W)}{P_U-P_O}
View formula
Drilling EngineeringWell Control

Closed-Ended Pipe Buoyed Weight with No Fluid Inside

Wbuoyed,closed=Wair−OD2FW24.5W_{buoyed,closed}=W_{air}-\frac{OD^2FW}{24.5}
View formula
Drilling EngineeringDirectional Drilling

Closure Distance and Direction

CD=N2+E2CD=\sqrt{N^2+E^2}
View formula
Drilling EngineeringMud and Cementing

Combined Solubility of Hydrocarbon Gas, CO2, and H2S in a Mud Component

rs,c=fhrsh+fCO2rsCO2+fH2SrsH2Sr_{s,c}=f_hr_{sh}+f_{CO_2}r_{sCO_2}+f_{H_2S}r_{sH_2S}
View formula
Drilling EngineeringWell Control

Constant Bottomhole Pressure Bleed Volume for Rising Gas

Vbleed=ΔPstepCaGV_{bleed}=\frac{\Delta P_{step}C_a}{G}
View formula
Drilling EngineeringDrilling Operations and Economics

Control Drilling Maximum Drilling Rate

MDR=67(MWo−MWi)qDh2MDR=67(MW_o-MW_i)\frac{q}{D_h^2}
View formula
Drilling EngineeringDrillstring and Rig Mechanics

Coring Operation Ton Miles

Tc=2(T4−T3)T_c=2(T_4-T_3)
View formula
Drilling EngineeringDrilling Hydraulics

Critical Flow Rate for Flow Regime Change

Qc=2.448VcDi2Q_c=2.448V_cD_i^2
View formula
Drilling EngineeringDrillstring and Rig Mechanics

Crown Block Capacity

Rc=(H1+S)(n+2)nR_c=\frac{(H_1+S)(n+2)}{n}
View formula
Drilling EngineeringDirectional Drilling

Curvature Radius for a Borehole

R=180C3.1415kR=\frac{180C}{3.1415k}
View formula
Drilling EngineeringDrilling Hydraulics

Cuttings Carrying Capacity Index

CCI=MW AV Keff400000CCI=\frac{MW\,AV\,K_{eff}}{400000}
View formula
Drilling EngineeringDrilling Hydraulics

Cuttings Net Rise Velocity

Vnet=AV−VsV_{net}=AV-V_s
View formula
Drilling EngineeringDrilling Hydraulics

Cuttings Slip Velocity

Vs=0.45PVMWDcut(36800Dcut(DenP/MW−1)(PV/(MWDcut))2+1−1)V_s=0.45\frac{PV}{MWD_{cut}}\left(\sqrt{\frac{36800D_{cut}(DenP/MW-1)}{(PV/(MWD_{cut}))^2}+1}-1\right)
View formula
Drilling EngineeringMud and Cementing

Cuttings Volume Generated per Foot Drilled

Vc=Dh2(1−ϕ)1029.4V_c=\frac{D_h^2(1-\phi)}{1029.4}
View formula
Drilling EngineeringDrilling Operations and Economics

D-Exponent from Drilling Parameters

d=log⁡[R/(60N)]log⁡[12Wk/(1000Db)]d=\frac{\log[R/(60N)]}{\log[12W_k/(1000D_b)]}
View formula
Drilling EngineeringDrilling Hydraulics

Depth of a Washout - Method 1

Dw=NsPoCpD_w=\frac{N_sP_o}{C_p}
View formula
Drilling EngineeringDrilling Hydraulics

Depth of a Washout - Method 2

Dw=NsPoCp+CaD_w=\frac{N_sP_o}{C_p+C_a}
View formula
Drilling EngineeringDrilling Operations and Economics

Detailed Drilling Cost per Foot

Cd=Cb+Cto+Cm+(Td+Tt+Tc)(Cr+Cs+Ctr)FTdC_d=\frac{C_b+C_{to}+C_m+(T_d+T_t+T_c)(C_r+C_s+C_{tr})}{FT_d}
View formula
Drilling EngineeringMud and Cementing

Difference in Pressure Gradient Between Cement and Mud

PG=(Wc−Wm)0.052PG = (W_c - W_m)0.052
View formula
Drilling EngineeringMud and Cementing

Differential Hydrostatic Pressure Between Cement Annulus and Mud in Casing

Pd=Pa−PcP_d=P_a-P_c
View formula
Drilling EngineeringMud and Cementing

Dilution Volume to Maintain Circulating Low-Gravity Solids

Vwm=VmFl−FoFl−FaV_{wm}=V_m\frac{F_l-F_o}{F_l-F_a}
View formula
Drilling EngineeringDirectional Drilling

Directional Curvature for a Deviated Well

DC=Δϕ100ΔLDC = \Delta\phi\frac{100}{\Delta L}
View formula
Drilling EngineeringMud and Cementing

Displacement Strokes to Bump Cement Plug

Nstk=VdispPON_{stk}=\frac{V_{disp}}{PO}
View formula
Drilling EngineeringDirectional Drilling

Dogleg Angle - Minimum Curvature Method

β=cos⁡−1[cos⁡I1cos⁡I2+sin⁡I1sin⁡I2cos⁡(A2−A1)]\beta=\cos^{-1}[\cos I_1\cos I_2+\sin I_1\sin I_2\cos(A_2-A_1)]
View formula
Drilling EngineeringDirectional Drilling

Dogleg Severity - Minimum Curvature Method

DLS=βdeg100ΔMDDLS=\frac{\beta_{deg}100}{\Delta MD}
View formula
Drilling EngineeringDrilling Hydraulics

Drill Pipe or Drill Collar Capacity

C=ID21029.4C=\frac{ID^2}{1029.4}
View formula
Drilling EngineeringDrilling Hydraulics

Drill Pipe or Drill Collar Displacement and Weight

Disp=OD2−ID21029.4Disp=\frac{OD^2-ID^2}{1029.4}
View formula
Drilling EngineeringDrilling Hydraulics

Drill String Volume

B=ID21029.4PLB = \frac{ID^2}{1029.4}PL
View formula
Drilling EngineeringDrilling Operations and Economics

Drill-Rate Model Penetration Rate

R=K(Wdb)aWNaNR=K\left(\frac{W}{d_b}\right)^{a_W}N^{a_N}
View formula
Drilling EngineeringDrilling Operations and Economics

Drilled Gas Entry Rate

qgsc=db2RϕSgp310zTq_{gsc}=\frac{d_b^2R\phi S_gp}{310zT}
View formula
Drilling EngineeringDrillstring and Rig Mechanics

Drilling and Connection Ton Miles

TD=3(T2−T1)T_D=3(T_2-T_1)
View formula
Drilling EngineeringMud and Cementing

Drilling Mud Density - Solid Content Analysis of Drilling Muds

ρm=ρwfw+ρlgflg+ρBfB+ρofo\rho_m=\rho_wf_w+\rho_{lg}f_{lg}+\rho_Bf_B+\rho_of_o
View formula
Drilling EngineeringDrillstring and Rig Mechanics

Drillstring Buoyancy Factor from Mud Weight

BF=65.5−MW65.5BF=\frac{65.5-MW}{65.5}
View formula
Drilling EngineeringWell Control

Dry Pipe Pulled Before Fill-Up for Pressure Drop

Ldry=ΔP(Cann+Cdp)0.052MWDdpL_{dry}=\frac{\Delta P(C_{ann}+C_{dp})}{0.052MWD_{dp}}
View formula
Drilling EngineeringDrilling Hydraulics

Duplex Pump Output per Stroke

PO=0.000162S(2Dl2−dr2)PO=0.000162S(2D_l^2-d_r^2)
View formula
Drilling EngineeringDrilling Hydraulics

Duplex Pump Output Rate with Volumetric Efficiency

Qgpm=0.000162S(2Dl2−dr2)EvSPM⋅42Q_{gpm}=0.000162S(2D_l^2-d_r^2)E_vSPM\cdot42
View formula
Drilling EngineeringDrillstring and Rig Mechanics

Effective Drillstring Weight During Drilling

wo=ws(1−ρoρs)w_o=w_s\left(1-\frac{\rho_o}{\rho_s}\right)
View formula
Drilling EngineeringDrillstring and Rig Mechanics

Efficiency of Block and Tackle System

Ebt=FhvtFfvfE_{bt}=\frac{F_hv_t}{F_fv_f}
View formula
Drilling EngineeringDirectional Drilling

EOU Clearance Distance for Wellbore Collision Avoidance

Eclear=CC−(Rref+Roff)E_{clear}=C_C-(R_{ref}+R_{off})
View formula
Drilling EngineeringDrilling Hydraulics

Equivalent Circulating Density

ECD=MW+ΔPa0.052TVDECD = MW + \frac{\Delta P_a}{0.052TVD}
View formula
Drilling EngineeringWell Control

Equivalent Mud Weight from Surface Pressure

EMW=Psurf0.052TVD+MWEMW=\frac{P_{surf}}{0.052TVD}+MW
View formula
Drilling EngineeringMud and Cementing

Filtration Rate for API Fluid Loss Measurement

dVfdt=kAΔPμhmc\frac{dV_f}{dt}=\frac{kA\Delta P}{\mu h_{mc}}
View formula
Drilling EngineeringMud and Cementing

Filtration Volume with Spurt Loss

Vf=Vsp+Vf2−Vf1t2−t1tV_f=V_{sp}+\frac{V_{f2}-V_{f1}}{\sqrt{t_2}-\sqrt{t_1}}\sqrt{t}
View formula
Drilling EngineeringWell Control

Final Circulating Pressure

FCP=SCRPKWMOMWFCP=SCRP\frac{KWM}{OMW}
View formula
Drilling EngineeringWell Control

Formation Integrity Test Pressure

PFIT=(FIT−MW)0.052TVDP_{FIT}=(FIT-MW)0.052TVD
View formula
Drilling EngineeringDrilling Operations and Economics

Gas Mud Ratio from Drilled Gas

rm=db2RϕSgp310zTqmr_m=\frac{d_b^2R\phi S_gp}{310zTq_m}
View formula
Drilling EngineeringDrilling Operations and Economics

Gas Portion Entry Rate from Rock Removal

qg=qrϕSgq_g=q_r\phi S_g
View formula
Drilling EngineeringMud and Cementing

Gas Solubility in a Mud System

rsm=forso+fwrsw+ferser_{sm}=f_or_{so}+f_wr_{sw}+f_er_{se}
View formula
Drilling EngineeringWell Control

Height Gain from Stripping Into Influx

H=LstrippedCdp+DdpCaH=L_{stripped}\frac{C_{dp}+D_{dp}}{C_a}
View formula
Drilling EngineeringDirectional Drilling

Horizontal Section Inclination from Bed Dip and Thickness

Ih=90∘−dip−sin⁡−1(hresLh)I_h=90^\circ-dip-\sin^{-1}\left(\frac{h_{res}}{L_h}\right)
View formula
Drilling EngineeringDirectional Drilling

Horizontal Wellbore Center-to-Center Separation

Sh=ΔN2+ΔE2S_h=\sqrt{\Delta N^2+\Delta E^2}
View formula
Drilling EngineeringWell Control

Hydraulic Force from Pressure and Diameter

F=PD2(0.7854)F=PD^2(0.7854)
View formula
Drilling EngineeringDrilling Hydraulics

Hydraulic Horsepower at Bit

HHP=PsQ1714HHP = \frac{P_s Q}{1714}
View formula
Drilling EngineeringDrilling Hydraulics

Hydraulic Horsepower per Unit Bit Area

HHPba=QPb1.271714B2HHP_{ba} = \frac{QP_b1.27}{1714B^2}
View formula
Drilling EngineeringMud and Cementing

Hydrocyclone Solids Removal Evaluation

MS=19530SFhcVTMS=19530SF_{hc}\frac{V}{T}
View formula
Drilling EngineeringDrilling Operations and Economics

Hydromechanical Specific Energy

HMSE=WOBAb+120(3.142)NT+1154ηPbQAbROPHMSE=\frac{WOB}{A_b}+\frac{120(3.142)NT+1154\eta P_bQ}{A_bROP}
View formula
Drilling EngineeringWell Control

Hydrostatic Pressure Decrease Due to Gas-Cut Mud

Ploss=MGCVP_{loss}=\frac{MG}{C}V
View formula
Drilling EngineeringWell Control

Hydrostatic Pressure Drop per Foot Pulling Dry Pipe

ΔPdry/ft=0.052MWDdpCann+Cdp\Delta P_{dry/ft}=\frac{0.052MWD_{dp}}{C_{ann}+C_{dp}}
View formula
Drilling EngineeringWell Control

Hydrostatic Pressure Drop per Foot Pulling Wet Pipe

ΔPwet/ft=0.052MWCdp+DdpCann\Delta P_{wet/ft}=0.052MW\frac{C_{dp}+D_{dp}}{C_{ann}}
View formula
Drilling EngineeringWell Control

Hydrostatic Pressure from Mud Weight

HP=0.052MW⋅TVDHP = 0.052 MW \cdot TVD
View formula
Drilling EngineeringWell Control

Hydrostatic Pressure in Annulus Due to Slug

P=VaVs(Ws−Wm)0.052P=V_aV_s(W_s-W_m)0.052
View formula
Drilling EngineeringDrilling Hydraulics

Impact Force per Unit Bit Area

IFa=MWVnQ1.271930B2IF_a = \frac{MWV_nQ1.27}{1930B^2}
View formula
Drilling EngineeringMud and Cementing

Increase Mud Density by Barite

B=1470W2−W135−W2B=1470\frac{W_2-W_1}{35-W_2}
View formula
Drilling EngineeringMud and Cementing

Increase Mud Density by Calcium Carbonate

B=945W2−W122.5−W2B=945\frac{W_2-W_1}{22.5-W_2}
View formula
Drilling EngineeringMud and Cementing

Increase Mud Density by Hematite

B=1680W2−W140−W2B=1680\frac{W_2-W_1}{40-W_2}
View formula
Drilling EngineeringMud and Cementing

Increase Volume by Barite

V=100W2−W135−W2V=100\frac{W_2-W_1}{35-W_2}
View formula
Drilling EngineeringMud and Cementing

Increase Volume by Calcium Carbonate

V=100W2−W122.5−W2V=100\frac{W_2-W_1}{22.5-W_2}
View formula
Drilling EngineeringMud and Cementing

Increase Volume by Hematite

V=100W2−W140−W2V=100\frac{W_2-W_1}{40-W_2}
View formula
Drilling EngineeringWell Control

Initial Circulating Pressure

ICP=SCRP+SIDPPICP=SCRP+SIDPP
View formula
Drilling EngineeringMud and Cementing

Initial Volume Required with Barite

Vi=Vf35−W235−W1V_i=V_f\frac{35-W_2}{35-W_1}
View formula
Drilling EngineeringMud and Cementing

Initial Volume Required with Calcium Carbonate

Vi=Vf22.5−W222.5−W1V_i=V_f\frac{22.5-W_2}{22.5-W_1}
View formula
Drilling EngineeringMud and Cementing

Initial Volume Required with Hematite

Vi=Vf40−W240−W1V_i=V_f\frac{40-W_2}{40-W_1}
View formula
Drilling EngineeringMud and Cementing

Internal Hydrostatic Pressure While Landing Cement Plug

Pint=0.05195(ρcemLshoe+ρdispLdisp)P_{int}=0.05195(\rho_{cem}L_{shoe}+\rho_{disp}L_{disp})
View formula
Drilling EngineeringWell Control

Kick Analysis - Formation Pressure With Well Shut-In

Pfp=SIDPP+MW⋅0.052⋅hP_{fp} = SIDPP + MW\cdot0.052\cdot h
View formula
Drilling EngineeringWell Control

Kick Analysis - Height of Influx

hi=PGACh_i = \frac{PG}{AC}
View formula
Drilling EngineeringWell Control

Kick Analysis - Influx Density

I=MW−SICP−SIDPPhi⋅0.052I = MW - \frac{SICP - SIDPP}{h_i\cdot0.052}
View formula
Drilling EngineeringWell Control

Kick Analysis - Maximum Pit Gain From Gas Kick

MPG=4PVCKWMMPG = 4\sqrt{\frac{PVC}{KWM}}
View formula
Drilling EngineeringWell Control

Kick Analysis - Shut-In Drill Pipe Pressure

SIDPP=Pfp−MW⋅0.052⋅hSIDPP = P_{fp} - MW\cdot0.052\cdot h
View formula
Drilling EngineeringWell Control

Kick Tolerance Bottomhole Gas Volume

KT=min⁡(Vinitial,Vbottom,shoe)KT=\min(V_{initial},V_{bottom,shoe})
View formula
Drilling EngineeringDirectional Drilling

Kickoff Point from Target TVD and Build Sections

KOP=TVDtarget−ΔTVDbuild1−ΔTVDtangent−ΔTVDbuild2KOP=TVD_{target}-\Delta TVD_{build1}-\Delta TVD_{tangent}-\Delta TVD_{build2}
View formula
Drilling EngineeringWell Control

Kill Weight Mud Determination - Moore Equation

KWM=SIDPP0.052TVD+OMWKWM=\frac{SIDPP}{0.052TVD}+OMW
View formula
Drilling EngineeringMud and Cementing

Lateral Load Imposed on a Casing Centralizer

FL,+=mWLsin⁡θ+2Tsin⁡δF_{L,+}=mWL\sin\theta+2T\sin\delta
View formula
Drilling EngineeringMud and Cementing

Lateral Load Imposed on a Casing Centralizer with a Dogleg

FL,+=mWLsin⁡θ+2Tsin⁡δF_{L,+}=mWL\sin\theta+2T\sin\delta
View formula
Drilling EngineeringMud and Cementing

Lead Cement Sacks Required in Annulus

Nf=hcACEY1N_f=\frac{h_cACE}{Y_1}
View formula
Drilling EngineeringWell Control

Level Drop After Pumping a Slug

Ldrop=(Ws/Wm−1)VsCdpL_{drop}=\frac{(W_s/W_m-1)V_s}{C_{dp}}
View formula
Drilling EngineeringDrilling Hydraulics

Linear Annular Capacity of Pipe

Co=0.7854(Dh2−Do2)808.5C_o=\frac{0.7854(D_h^2-D_o^2)}{808.5}
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Drilling EngineeringDrilling Hydraulics

Linear Pipe Capacity

Ci=0.7854Di2808.5C_i=\frac{0.7854D_i^2}{808.5}
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Drilling EngineeringMud and Cementing

Load to Break Cement Bond

F=0.969ScdHF=0.969S_cdH
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Drilling EngineeringWell Control

Maximum Allowable Annular Surface Pressure from Shoe EMW

MAASP=(MWmax−MW)0.052TVDshoeMAASP=(MW_{max}-MW)0.052TVD_{shoe}
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Drilling EngineeringWell Control

Maximum Allowable Mud Weight From Leak-Off Pressure

MWmax=MW+Pl0.052TVDMW_{max} = MW + \frac{P_l}{0.052TVD}
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Drilling EngineeringWell Control

Maximum Allowable Surface Pressure Governed by Casing Burst

MASP=PbcS−(Wu−Wo)0.052HMASP = P_{bc}S - (W_u - W_o)0.052H
View formula
Drilling EngineeringDrilling Hydraulics

Maximum Drilling Rate for Larger Holes

MDR=67(MWo−MWi)qcDh2MDR = \frac{67(MW_o - MW_i)q_c}{D_h^2}
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Drilling EngineeringDrillstring and Rig Mechanics

Maximum Equivalent Derrick Load

Fde=(n+4n)FhF_{de}=\left(\frac{n+4}{n}\right)F_h
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Drilling EngineeringDrillstring and Rig Mechanics

Maximum Length of Drillpipe for a Specific Bottomhole Assembly

Lm=[(Tf)−MOP−Wb]BFWdL_m=\frac{[(Tf)-MOP-W_b]BF}{W_d}
View formula
Drilling EngineeringMud and Cementing

Maximum Recommended Low-Gravity Solids

LGS=200[SF100−0.3125(MW8.33−1)]LGS=200\left[\frac{SF}{100}-0.3125\left(\frac{MW}{8.33}-1\right)\right]
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Drilling EngineeringMud and Cementing

Maximum Recommended Solids Fraction in Drilling Fluid

SF=2.917MW−14.17SF=2.917MW-14.17
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Drilling EngineeringDirectional Drilling

Maximum Slanted Well Length in Reservoir Thickness

L=hcos⁡(απ/180)L=\frac{h}{\cos(\alpha\pi/180)}
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Drilling EngineeringWell Control

Maximum Surface Pressure From Gas Kick in Water-Based Mud

MSP=0.2PVKWMCMSP=0.2\sqrt{\frac{PVKWM}{C}}
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Drilling EngineeringDrillstring and Rig Mechanics

Maximum Weight on Bit

WOB=LdWdBFcos⁡(απ/180)SFWOB=\frac{L_dW_dBF\cos(\alpha\pi/180)}{SF}
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Drilling EngineeringDrilling Operations and Economics

Mechanical Specific Energy

MSE=WOBAb+120πNTAbROPMSE=\frac{WOB}{A_b}+\frac{120\pi NT}{A_bROP}
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Drilling EngineeringDirectional Drilling

Minimum Allowable Separation Distance from Separation Factor

MASD=SFmin(Rref+Roff)MASD=SF_{min}(R_{ref}+R_{off})
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Drilling EngineeringDirectional Drilling

Minimum Curvature Ratio Factor

RF=2βtan⁡(β2)RF=\frac{2}{\beta}\tan\left(\frac{\beta}{2}\right)
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Drilling EngineeringDirectional Drilling

Minimum Curvature Survey Displacements

ΔN=ΔMD2(sin⁡I1cos⁡A1+sin⁡I2cos⁡A2)RF\Delta N=\frac{\Delta MD}{2}(\sin I_1\cos A_1+\sin I_2\cos A_2)RF
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Drilling EngineeringWell Control

Minimum Surface Pressure Before Stripping

Pmin=WcLstandDc2(0.7854)P_{min}=\frac{W_cL_{stand}}{D_c^2(0.7854)}
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Drilling EngineeringWell Control

Mud Pressure Gradient from Mud Weight

MWG=0.052MWMWG=0.052MW
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Drilling EngineeringMud and Cementing

Mud Volume Required to Spot Balanced Cement Plug

Vspot=(Dpipe−Lplug)Cpipe−VspacerV_{spot}=(D_{pipe}-L_{plug})C_{pipe}-V_{spacer}
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Drilling EngineeringMud and Cementing

Mud Weight Increase Required to Balance Pressure

Wm=FA(0.052)LcW_m=\frac{F}{A(0.052)L_c}
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Drilling EngineeringMud and Cementing

Mud Weight Reduction by Dilution

Vr=VmW1−W2W2−DwV_r = V_m\frac{W_1 - W_2}{W_2 - D_w}
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Drilling EngineeringWell Control

New MAASP After Kill Mud Weight

MAASPkill=(MWmax−KMW)0.052TVDshoeMAASP_{kill}=(MW_{max}-KMW)0.052TVD_{shoe}
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Drilling EngineeringDrilling Hydraulics

New Pump Circulating Pressure

Pc=Pp(qnqo)2P_c=P_p\left(\frac{q_n}{q_o}\right)^2
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Drilling EngineeringDrilling Hydraulics

New Pump Circulating Pressure - Square Law

Pnew=Pcurrent(NnewNold)2P_{new}=P_{current}\left(\frac{N_{new}}{N_{old}}\right)^2
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Drilling EngineeringDrilling Hydraulics

New Pump Circulating Pressure with Friction Exponent

Pnew=Pcurrent(QnewQold)nP_{new}=P_{current}\left(\frac{Q_{new}}{Q_{old}}\right)^n
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Drilling EngineeringWell Control

New Pump Pressure with Mud Weight Change

Pnew=PcurrentMWnewMWoldP_{new}=P_{current}\frac{MW_{new}}{MW_{old}}
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Drilling EngineeringDrilling Hydraulics

Nozzle Area from Three Jet Sizes

Na=N12+N22+N321303.8N_a=\frac{N_1^2+N_2^2+N_3^2}{1303.8}
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Drilling EngineeringDrilling Hydraulics

Open-Ended Displacement Volume of Pipe

Vo=0.7854(Do2−Di2)L808.5V_o=\frac{0.7854(D_o^2-D_i^2)L}{808.5}
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Drilling EngineeringWell Control

Open-Ended Pipe Buoyed Weight

Wbuoyed,open=WairBFW_{buoyed,open}=W_{air}BF
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Drilling EngineeringMud and Cementing

Optimal Solids Removal Efficiency

ηrs=1−1−Vs1−Vs+Vc/Vs\eta_{rs}=1-\frac{1-V_s}{1-V_s+V_c/V_s}
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Drilling EngineeringDrilling Hydraulics

Overall Diesel-to-Mud-Pump Efficiency

ηo=ηeηlηmηv\eta_o=\eta_e\eta_l\eta_m\eta_v
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Drilling EngineeringDrilling Hydraulics

Overall Power System Efficiency

Ei=PQiE_i=\frac{P}{Q_i}
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Drilling EngineeringDrilling Hydraulics

Percentage Pressure Loss at Bit

Ppsib=100PbPsP_{psib} = \frac{100P_b}{P_s}
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Drilling EngineeringDrilling Hydraulics

Plastic Viscosity from 600 and 300 RPM Readings

PV=θ600−θ300PV=\theta_{600}-\theta_{300}
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Drilling EngineeringWell Control

Pore Pressure Gradient - Rehm and McClendon

gp=0.398log⁡10(dcn−dco)+0.86g_p=0.398\log_{10}(d_{cn}-d_{co})+0.86
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Drilling EngineeringWell Control

Pore Pressure Gradient - Zamora

gp=gndcndcog_p=g_n\frac{d_{cn}}{d_{co}}
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Drilling EngineeringDrilling Hydraulics

Power Law Consistency Index from 300 RPM Reading

Keff=5111−nθ300K_{eff}=511^{1-n}\theta_{300}
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Drilling EngineeringDrilling Hydraulics

Power Law Flow Behavior Index from Rheometer Readings

n=3.322log⁡10(θ600θ300)n=3.322\log_{10}\left(\frac{\theta_{600}}{\theta_{300}}\right)
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Drilling EngineeringWell Control

Pressure by Each Barrel of Mud in Casing

Pbbl=1029.4⋅0.052MWDh2−Dp2P_{bbl}=1029.4\cdot0.052\frac{MW}{D_h^2-D_p^2}
View formula
Drilling EngineeringMud and Cementing

Pressure Required to Overcome Mud Gel Strength in Annulus

Pm=yL300(Dh−Dp)P_m = \frac{yL}{300(D_h - D_p)}
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Drilling EngineeringMud and Cementing

Pressure Required to Overcome Mud Gel Strength Inside Drill String

Pm=yL300dP_m=\frac{yL}{300d}
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Drilling EngineeringDirectional Drilling

Projected Turn Rate from Azimuth Change

TR=(A2−A1)sin⁡(I1+I22)100ΔMDTR=\frac{(A_2-A_1)\sin\left(\frac{I_1+I_2}{2}\right)100}{\Delta MD}
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Drilling EngineeringDrilling Hydraulics

Pump Input Power from Fuel Consumption Rate

Pi=QfH2545P_i=\frac{Q_fH}{2545}
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Drilling EngineeringDrilling Hydraulics

Pump Pressure Exponent from Two Pump Tests

n=ln⁡(P1/P2)ln⁡(Q1/Q2)n=\frac{\ln(P_1/P_2)}{\ln(Q_1/Q_2)}
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Drilling EngineeringDrilling Hydraulics

Pump Pressure from Bit Drop and Friction Losses

Pp=ΔPbit+PdP_p=\Delta P_{bit}+P_d
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Drilling EngineeringMud and Cementing

Radial Force Related to Axial Load in Cementing Slips

Wr=1−μtan⁡αμ+tan⁡αFW_r=\frac{1-\mu\tan\alpha}{\mu+\tan\alpha}F
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Drilling EngineeringDirectional Drilling

Radius of Curvature from Dogleg Severity

Rc=180πDLS100R_c=\frac{180}{\pi DLS}100
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Drilling EngineeringDirectional Drilling

Radius-of-Curvature Build Section Departure

ΔDEP=180ΔMD(cos⁡I1−cos⁡I2)π(I2−I1)\Delta DEP=\frac{180\Delta MD(\cos I_1-\cos I_2)}{\pi(I_2-I_1)}
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Drilling EngineeringDirectional Drilling

Radius-of-Curvature Build Section TVD Gain

ΔTVD=180ΔMD(sin⁡I2−sin⁡I1)π(I2−I1)\Delta TVD=\frac{180\Delta MD(\sin I_2-\sin I_1)}{\pi(I_2-I_1)}
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Drilling EngineeringWell Control

Rectangular Tank Capacity per Foot

Crect,ft=LW(0.178)C_{rect,ft}=LW(0.178)
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Drilling EngineeringWell Control

Rectangular Tank Capacity per Inch

Crect,in=LW(0.0148)C_{rect,in}=LW(0.0148)
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Drilling EngineeringWell Control

Rectangular Tank Volume

Vtank=LWH5.615V_{tank}=\frac{LWH}{5.615}
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Drilling EngineeringDirectional Drilling

Required Dogleg Severity from Build and Turn Components

DLSreq=BUR2+TR2DLS_{req}=\sqrt{BUR^2+TR^2}
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Drilling EngineeringMud and Cementing

Resulting Force After Casing Cementing Job

Fres=Fdown−FupF_{res}=F_{down}-F_{up}
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Drilling EngineeringWell Control

Riser Hydrostatic Loss on Disconnect

ΔPriser=0.052MW(WD+AG)−0.052SW WD\Delta P_{riser}=0.052MW(WD+AG)-0.052SW\,WD
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Drilling EngineeringWell Control

Riser Margin from Hydrostatic Loss

RM=ΔPriser0.052(TVD−WD−AG)RM=\frac{\Delta P_{riser}}{0.052(TVD-WD-AG)}
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Drilling EngineeringDrilling Operations and Economics

Rock Removal Rate from Bit Diameter and ROP

qr=db2R11000q_r=\frac{d_b^2R}{11000}
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Drilling EngineeringDrilling Operations and Economics

Rotary-Speed Drill-Rate Model Penetration Rate

R=K′NaNR=K'N^{a_N}
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Drilling EngineeringDrilling Operations and Economics

Rotating Horsepower from Torque and Speed

RHP=TN5252RHP=\frac{TN}{5252}
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Drilling EngineeringDrillstring and Rig Mechanics

Round Trip Ton Miles

RTTM=WpD(Lp+D)+2D(2Wb+Wc)5280⋅2000RT_{TM}=\frac{W_pD(L_p+D)+2D(2W_b+W_c)}{5280\cdot2000}
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Drilling EngineeringDrillstring and Rig Mechanics

Setting Casing Ton Miles

Tc=0.5[WpD(Lcs+D)+DWb]5280⋅2000T_c=\frac{0.5\left[W_pD(L_{cs}+D)+DW_b\right]}{5280\cdot2000}
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Drilling EngineeringDrillstring and Rig Mechanics

Short Trip Ton Miles

TST=T6−T5T_{ST}=T_6-T_5
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Drilling EngineeringWell Control

Shut-In Pressure Increase from Gas Migration Time

ΔP=RGM MWG Δt\Delta P=RGM\,MWG\,\Delta t
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Drilling EngineeringDirectional Drilling

Sliding Percentage from Required and Motor Dogleg Severity

Sslide=DLSreqDLSmotor100S_{slide}=\frac{DLS_{req}}{DLS_{motor}}100
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Drilling EngineeringMud and Cementing

Slurry Density for Cementing Calculations

σs=94+Wa+8.33QwVs\sigma_s=\frac{94+W_a+8.33Q_w}{V_s}
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Drilling EngineeringMud and Cementing

Solid Content Ratio of Drilling Mud

fsm=fschmcAVmf_{sm}=\frac{f_{sc}h_{mc}A}{V_m}
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Drilling EngineeringMud and Cementing

Solids Analysis for High-Salt Content Muds

SW=(5.88×10−8CCl1.2+1)PvwSW=(5.88\times10^{-8}C_{Cl}^{1.2}+1)P_{vw}
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Drilling EngineeringMud and Cementing

Solids Buildup in Mud System

Vsb=Vh(1−ηs)V_{sb}=V_h(1-\eta_s)
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Drilling EngineeringMud and Cementing

Solids Control Efficiency

ηsce=VrVdVh\eta_{sce}=V_r\frac{V_d}{V_h}
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Drilling EngineeringMud and Cementing

Spacer Contact Time from Turbulent-Flow Volume

tcontact=Vtf5.616qdispt_{contact}=\frac{V_{tf}}{5.616q_{disp}}
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Drilling EngineeringMud and Cementing

Spacer Volume Behind Slurry to Balance Cement Plug

Vs=CaEVaCpV_s=\frac{C_a}{E}V_aC_p
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Drilling EngineeringMud and Cementing

Specific Gravity of Cuttings by Mud Balance

SGc=12−0.12WrSG_c=\frac{1}{2-0.12W_r}
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Drilling EngineeringWell Control

Specific Gravity to Fluid Weight

FW=8.33SGFW=8.33SG
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Drilling EngineeringWell Control

Stored Hydraulic Fluid Volume in Accumulator Bottle

Vfluid=Vbottle−PpreVbottlePsystemV_{fluid}=V_{bottle}-\frac{P_{pre}V_{bottle}}{P_{system}}
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Drilling EngineeringDrillstring and Rig Mechanics

Stretch Force from Elastic Elongation

F=AE(La−LbLb)F=AE\left(\frac{L_a-L_b}{L_b}\right)
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Drilling EngineeringDrilling Hydraulics

Strokes per Minute Required for Target Annular Velocity

SPM=AV ACqoSPM=\frac{AV\,AC}{q_o}
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Drilling EngineeringDrillstring and Rig Mechanics

Stuck Pipe Free Point from Pipe Stretch - Method 1

hf=SfpcPFh_f=\frac{Sfpc}{PF}
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Drilling EngineeringDrillstring and Rig Mechanics

Stuck Pipe Free Point from Pipe Stretch - Method 2

hf=735294eWdpPdh_f=\frac{735294eW_{dp}}{P_d}
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Drilling EngineeringWell Control

Subsea Choke Line Pressure Loss

CLPL=0.000061MWLQ1.86ID4.86CLPL=\frac{0.000061MWLQ^{1.86}}{ID^{4.86}}
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Drilling EngineeringWell Control

Subsea Choke Line Pressure Loss Adjusted for Mud Weight

CLPL=WnCLPLoWoCLPL=\frac{W_n CLPL_o}{W_o}
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Drilling EngineeringWell Control

Subsea Choke Line Velocity

V=24.5QID2V=24.5\frac{Q}{ID^2}
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Drilling EngineeringWell Control

Subsea Maximum Allowable Mud Weight from Leakoff Test

Wmax=Plo0.052H+WuW_{max}=\frac{P_{lo}}{0.052H}+W_u
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Drilling EngineeringWell Control

Subsea Stack Casing Burst Pressure

CBP=YPc−HP+HPswCBP=YP_c-HP+HP_{sw}
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Drilling EngineeringWell Control

Surface Pressure During Drill Stem Test

P=0.052h(EMW−SG⋅8.33)P = 0.052h(EMW - SG\cdot8.33)
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Drilling EngineeringWell Control

Surface Test Pressure Required to Frac the Formation

PST=FGD−0.052ρmDP_{ST}=FGD-0.052\rho_mD
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Drilling EngineeringWell Control

Surface-to-Bit Strokes for Wait and Weight Schedule

Sbit=CdpTDPOS_{bit}=\frac{C_{dp}TD}{PO}
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Drilling EngineeringMud and Cementing

Tail Cement Sacks Required in Annulus

Na=htACEY2N_a=\frac{h_tACE}{Y_2}
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Drilling EngineeringMud and Cementing

Tail Cement Sacks Required in Casing

Nc=hfcCY2N_c=\frac{h_{fc}C}{Y_2}
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Drilling EngineeringDirectional Drilling

Tangential Survey Displacements

ΔN=ΔMDsin⁡I2cos⁡A2\Delta N=\Delta MD\sin I_2\cos A_2
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Drilling EngineeringDirectional Drilling

Target TVD Increase from Bed Dip and Departure

ΔTVDtarget=DEPtan⁡(dip)\Delta TVD_{target}=DEP\tan(dip)
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Drilling EngineeringDirectional Drilling

Three-Dimensional Wellbore Center-to-Center Separation

S3D=ΔN2+ΔE2+ΔTVD2S_{3D}=\sqrt{\Delta N^2+\Delta E^2+\Delta TVD^2}
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Drilling EngineeringWell Control

Time to MAASP During Gas Migration

tlimit=MAASP−SICPcurrentRGM MWGt_{limit}=\frac{MAASP-SICP_{current}}{RGM\,MWG}
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Drilling EngineeringDirectional Drilling

Toolface Angle from Build and Turn Components

TF=atan2⁡(TR,BUR)TF=\operatorname{atan2}(TR,BUR)
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Drilling EngineeringMud and Cementing

Top of Cement Depth from Annular Cement Height

Dtoc=Dset−hannD_{toc}=D_{set}-h_{ann}
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Drilling EngineeringDrilling Hydraulics

Total Circulation Strokes from Drillstring and Annular Volume

S=VDS+VAVOS=\frac{V_{DS}+V_{AV}}{O}
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Drilling EngineeringWell Control

Total Mud Returned by Slug

Vreturn=WsWmVsV_{return}=\frac{W_s}{W_m}V_s
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Drilling EngineeringMud and Cementing

Total Required Mixing Water for Cement Job

Vw=NQwV_w=NQ_w
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Drilling EngineeringMud and Cementing

Total Solids Generated While Drilling

Wcg=350ChL(1−ϕ)SGcW_{cg}=350C_hL(1-\phi)SG_c
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Drilling EngineeringMud and Cementing

Total Tail Cement Sacks Required

Nt=Na+NcN_t=N_a+N_c
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Drilling EngineeringWell Control

Total Usable Fluid Volume from Accumulator Bank

Vtotal=NbottlesVusable,bottleV_{total}=N_{bottles}V_{usable,bottle}
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Drilling EngineeringMud and Cementing

Total Water Requirement per Sack of Cement

Qw=Qc+QaQ_w=Q_c+Q_a
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Drilling EngineeringDrillstring and Rig Mechanics

Traveling Block Speed from Fast Line Speed

vtb=vfnv_{tb}=\frac{v_f}{n}
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Drilling EngineeringWell Control

Trip Margin from Yield Point and Annular Clearance

TM=YP11.7(Dh−Dp)TM=\frac{YP}{11.7(D_h-D_p)}
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Drilling EngineeringDrilling Hydraulics

Triplex Pump Output per Stroke

PO=0.000243Dl2LsPO=0.000243D_l^2L_s
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Drilling EngineeringDrilling Hydraulics

Triplex Pump Output Rate with Volumetric Efficiency

Qgpm=0.000243Dl2LsEvSPM⋅42Q_{gpm}=0.000243D_l^2L_sE_vSPM\cdot42
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Drilling EngineeringDrilling Hydraulics

Tubular and Open-Hole Capacity

Cbbl=Di21029.4C_{bbl}=\frac{D_i^2}{1029.4}
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Drilling EngineeringWell Control

Tubular Buoyed Weight with Different Internal and Annular Fluids

Wbuoyed,diff=Wair+ID2FWtbg24.5−OD2FWann24.5W_{buoyed,diff}=W_{air}+\frac{ID^2FW_{tbg}}{24.5}-\frac{OD^2FW_{ann}}{24.5}
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Drilling EngineeringDirectional Drilling

Turn Rate Component from Dogleg Severity and Toolface

TR=DLSreqsin⁡(TF)TR=DLS_{req}\sin(TF)
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Drilling EngineeringMud and Cementing

Upward Force at the Bottom of the Casing Shoe

Fu=AΔPF_u=A\Delta P
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Drilling EngineeringWell Control

Usable Fluid Volume per Surface Accumulator Bottle

Vusable=Vfluid,operating−Vfluid,minV_{usable}=V_{fluid,operating}-V_{fluid,min}
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Drilling EngineeringDrilling Hydraulics

Velocity of Fluid in Annulus

va=Q2.448(Do2−Dp2)v_a = \frac{Q}{2.448(D_o^2-D_p^2)}
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Drilling EngineeringDirectional Drilling

Vertical Curvature for Deviated Wells

VC=(Ib−Ia)100ΔLVC = (I_b - I_a)\frac{100}{\Delta L}
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Drilling EngineeringWell Control

Vertical Cylindrical Tank Capacity per Foot

Ccyl,ft=D27.148C_{cyl,ft}=\frac{D^2}{7.148}
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Drilling EngineeringWell Control

Vertical Cylindrical Tank Volume

Vcyl=Ccyl,ftHV_{cyl}=C_{cyl,ft}H
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Drilling EngineeringMud and Cementing

Volume of Liquid Oil plus Water Required to Prepare a Desired Volume of Mud

SV=35−W235−W1DVSV=\frac{35-W_2}{35-W_1}DV
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Drilling EngineeringMud and Cementing

Volume of Slurry per Sack of Cement

Vs=94Sc8.33+WaSa8.33+QwV_s=\frac{94}{S_c8.33}+\frac{W_a}{S_a8.33}+Q_w
View formula
Drilling EngineeringWell Control

Volumetric Mud Bleed from Allowed Pressure Rise

Vbleed=ΔPallowFp/bblV_{bleed}=\frac{\Delta P_{allow}}{F_{p/bbl}}
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Drilling EngineeringWell Control

Wait and Weight Drill Pipe Pressure at Schedule Strokes

Pdp=ICP−(ICP−FCP)SschedSbitP_{dp}=ICP-\frac{(ICP-FCP)S_{sched}}{S_{bit}}
View formula
Drilling EngineeringWell Control

Wait and Weight Pressure Drop over Stroke Interval

ΔPinterval=(ICP−FCP)SintervalSbit\Delta P_{interval}=\frac{(ICP-FCP)S_{interval}}{S_{bit}}
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Drilling EngineeringWell Control

Wait and Weight Pressure Drop per Stroke

ΔPstk=ICP−FCPSbit\Delta P_{stk}=\frac{ICP-FCP}{S_{bit}}
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Drilling EngineeringMud and Cementing

Weight of Additive per Sack of Cement

Wa=PaWcW_a=P_aW_c
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Drilling EngineeringDirectional Drilling

Wellbore Separation Factor from EOU Radii

SF=CCRref+RoffSF=\frac{C_C}{R_{ref}+R_{off}}
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Drilling EngineeringDirectional Drilling

Wellbore Separation Ratio to Minimum Allowable Distance

RMASD=CCMASDR_{MASD}=\frac{C_C}{MASD}
View formula
Drilling EngineeringWell Control

Wet Pipe Pulled Before Fill-Up for Pressure Drop

Lwet=ΔP Cann0.052MW(Cdp+Ddp)L_{wet}=\frac{\Delta P\,C_{ann}}{0.052MW(C_{dp}+D_{dp})}
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Drilling EngineeringWell Control

Workover Buoyancy Factor from Fluid Weight

BF=65.4−FW65.4BF=\frac{65.4-FW}{65.4}
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Drilling EngineeringWell Control

Workover Kill Fluid Weight from Bottomhole Pressure

KFW=BHP0.052TVDKFW=\frac{BHP}{0.052TVD}
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Drilling EngineeringWell Control

Workover Kill Fluid Weight from Shut-In Tubing Pressure

KFW=SITP0.052TVDperf+OFWKFW=\frac{SITP}{0.052TVD_{perf}}+OFW
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Drilling EngineeringMud and Cementing

Yield of Clays as Drilling Fluids

Eclay=1MclayE_{clay}=\frac{1}{M_{clay}}
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Drilling EngineeringDrilling Hydraulics

Yield Point from 600 and 300 RPM Readings

YP=2θ300−θ600YP=2\theta_{300}-\theta_{600}
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