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Reservoir Engineering Calculators

Use 34 in-depth reservoir engineering petroleum engineering calculators with formulas, units, default calculations, source references, assumptions, and...

Reservoir engineering calculators cover volumetrics, Darcy flow, material balance, pressure transient analysis, reserves, recovery, and well performance.

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Reservoir EngineeringWell Performance

Joshi Horizontal Well Productivity Index

Jh=0.00708khhμoBo[ln⁡Rh+βhLln⁡(βh2rw)+s]J_h=\frac{0.00708k_hh}{\mu_oB_o\left[\ln R_h+\frac{\beta h}{L}\ln\left(\frac{\beta h}{2r_w}\right)+s\right]}
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Reservoir EngineeringMaterial Balance and Production

Gas Produced by Gas Expansion

Gp=43560Ahϕ(1−Swi)(1Bgi−1Bg)G_p=43560Ah\phi(1-S_{wi})\left(\frac{1}{B_{gi}}-\frac{1}{B_g}\right)
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Reservoir EngineeringMaterial Balance

Water Influx Constant for van Everdingen-Hurst Aquifer

B=1.119ϕctre2hfB=1.119\phi c_tr_e^2hf
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Reservoir EngineeringMaterial Balance

van Everdingen-Hurst Single-Step Water Influx

We=BΔpWeDW_e=B\Delta p W_{eD}
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Reservoir EngineeringFluid Flow in Porous Media

Darcy's Law for Linear Single-Phase Flow

q=0.001127kAΔPμLq = \frac{0.001127 k A \Delta P}{\mu L}
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Reservoir EngineeringPVT and Rock-Fluid Properties

API Gravity

API=141.5SGo−131.5API = \frac{141.5}{SG_o} - 131.5
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Reservoir EngineeringPermeability and Flow

Brooks-Corey Nonwetting Relative Permeability

krn=(1−Se)2[1−Se1+2/λ]k_{rn}=(1-S_e)^2\left[1-S_e^{1+2/\lambda}\right]
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Reservoir EngineeringPermeability and Flow

Buckley-Leverett Breakthrough Pore Volumes

tD,bt=(dfwdSw)shock−1t_{D,bt} = \left(\frac{df_w}{dS_w}\right)_{shock}^{-1}
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Reservoir EngineeringPVT and Rock-Fluid Properties

Capillary Number

Nc=μw⋅V⋅0.304886400⋅σowN_c = \frac{\mu_w \cdot V \cdot 0.3048}{86400 \cdot \sigma_{ow}}
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Reservoir EngineeringPVT and Rock-Fluid Properties

Characteristic Time for Linear Diffusion in Reservoirs

τ=Cu(Φ⋅βf+βr)⋅μ⋅l2k\tau = C_u \frac{(\Phi \cdot \beta_f + \beta_r) \cdot \mu \cdot l^2}{k}
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Reservoir EngineeringWell Performance

Craft and Hawkins Vertical Well Critical Coning Rate

qo=0.007078koh(pws−pwf)μoBoln⁡(re/rw)PRq_o=\frac{0.007078k_oh(p_{ws}-p_{wf})}{\mu_oB_o\ln(r_e/r_w)}PR
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Reservoir EngineeringMaterial Balance and Production

Cumulative Gas Production – Tarner’s Method

Gp=N⋅[(Rsi−Rs)−Boi−BoBg]−Np⋅(BoBg−Rs)Gp = N \cdot \left[ (Rsi - Rs) - \frac{Boi - Bo}{Bg} \right] - Np \cdot \left( \frac{Bo}{Bg} - Rs \right)
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Reservoir EngineeringPVT and Rock-Fluid Properties

Cumulative Oil Production – Undersaturated Oil Reservoirs

Np=N⋅ce⋅(BoiBo)⋅ΔPNp = N \cdot c_e \cdot \left( \frac{B_{oi}}{B_o} \right) \cdot \Delta P
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Reservoir EngineeringFluid Flow in Porous Media

Darcy-Forchheimer Superficial Velocity

v=2Gμ/k+(μ/k)2+4βρGv=\frac{2G}{\mu/k+\sqrt{(\mu/k)^2+4\beta\rho G}}
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Reservoir EngineeringPressure Transient Analysis

Dimensionless Pressure for Linear Flow Constant Rate General Case

pD=kA(pi−p)141.2qBμp_D=\frac{k\sqrt{A}(p_i-p)}{141.2qB\mu}
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Reservoir EngineeringReserves and Recovery

Duong Oil Production Rate

q(t)=q1x−meaFF=x1−m−11−mF∣m=1=ln⁡xx=t1 day\begin{aligned}q(t)&=q_1x^{-m}e^{aF}\\F&=\frac{x^{1-m}-1}{1-m}\\F|_{m=1}&=\ln x\\x&=\frac{t}{1\,\mathrm{day}}\end{aligned}
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Reservoir EngineeringPressure Transient Analysis

Fracture Conductivity During Bilinear Flow

FC=[44.1QμBmbfh(ϕμctk)0.25]2F_C=\left[\frac{44.1 Q \mu B}{m_{bf} h (\phi \mu c_t k)^{0.25}}\right]^2
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Reservoir EngineeringPVT Properties

Gas Expansion Factor from Formation Volume Factor

Eg=35.37PzTE_g = 35.37 \frac{P}{zT}
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Reservoir EngineeringPVT Properties

Gas Formation Volume Factor

Bg=0.02827zTPB_g = 0.02827 \frac{zT}{P}
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Reservoir EngineeringReserves and Recovery

Logistic Growth Cumulative Oil Production

Np(t)=Ktnt1/2 n+tnN_p(t)=\frac{Kt^n}{t_{1/2}^{\,n}+t^n}
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Reservoir EngineeringReserves and Recovery

Logistic Growth Oil Production Rate

q(t)=Knt1/2 ntn−1(t1/2 n+tn)2q(t)=\frac{Knt_{1/2}^{\,n}t^{n-1}}{(t_{1/2}^{\,n}+t^n)^2}
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Reservoir EngineeringReserves and Recovery

Modified Hyperbolic Decline Rate

q(t)=qi(1+bDith)−1/b×e−Dt(t−th)th=min⁡(t,ts)ts=Di−DtbDiDt\begin{aligned}q(t)&=q_i(1+bD_it_h)^{-1/b}\\&\quad\times e^{-D_t(t-t_h)}\\t_h&=\min(t,t_s)\\t_s&=\frac{D_i-D_t}{bD_iD_t}\end{aligned}
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Reservoir EngineeringReservoir Volumetrics

Original Gas in Place - Volumetric Method

G=43560Ahϕ(1−Swi)BgiG = \frac{43560 A h \phi (1 - S_{wi})}{B_{gi}}
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Reservoir EngineeringMaterial Balance and Production

Original Oil in Place from General Oil Material Balance

N=F−WeEo+mEg+EfwN = \frac{F-W_e}{E_o+mE_g+E_{fw}}
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Power-Law Exponential Decline RatePseudosteady-State Dimensionless Pressure Drop for Horizontal WellRadial Pressure Distribution in Single-Phase Liquid FlowRadius of InvestigationSkin Factor from Pressure Transient Semilog AnalysisSteady-State Radial Liquid Flow RateStretched Exponential Decline RateTight Gas Pore Volume from Squared-Pressure Declinevan Genuchten Nonwetting Relative Permeabilityvan Genuchten-Mualem Wetting Relative Permeability