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INPUT   DATA

♥ EXAMPLE Of Input/Output

Title

Well horizontal length, L		ft
L/Xe	0.25 0.50 0.75 1.00	Xe=drainage X-extent
Xe/Ye	4.00 2.00 1.00 0.50 0.25	Ye=drainage Y-extent
Wellbore radius		ft
Reservoir height		ft
Horizontal permeability		mD
Vertical permeability		mD
Mechanical skin
Reservoir pressure		psi
Bubblepoint pressure		psi
Oil FVF
Oil viscosity		cp

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OUTPUT   VARIABLES   &   GRAPHS

Variables	Values
♦  (qo)max, bbl/d
♦  J, bbl/d/psi
♦  n

IPR For Horizontal Solution Gas-Drive Wells

The relationship between well flow rate and the pressure drawdown (or flowing bottomhole pressure FBHP) is defined as the Inflow performance relationship (IPR). If the FBHP is below the bubblepoint pressure or if inertial effects become significant at high rates, IPR becomes curvilinear rather than linear.

Only a few empirical methods have been proposed to generate IPRs for horizontal wells along the lines of the seminal work of Vogel , notably by Cheng, Kabir and more recently by Retnanto & Economides. The latter appears to be a more coherent method and will be implemented here. Their IPR method is based on estimates of reservoir/well architecture and fluid properties, rather than stabilized flow tests. The shapes of the horizontal well IPRs are similar to Vogel's; the central task is to evaluate the maximum oil flow rate (absolute open flow potential).

Retnanto-Economides's model for the case where the well is in the vertical middle of the reservoir, can be represented by the following series of equations:

where
     q_o = oil flow rate, bbl/day
     q_omax = oil flow rate at FBHP = 0, bbl/day
     p_wf = FBHP = flowing bottom hole pressure, psi
     p_r = reservoir pressure, psi
     p_b = reservoir pressure, psi
     J = productivity index, STB/day/psi
     h = thickness, ft
     n = exponent in IPR equation
     k_h= horizontal permeability, md
    k_v = vertical permeability, md
    s = skin factor, md
    L = length of horizontal well (aligned to x-direction), ft
    X_e = extent of drainage area in x-direction, ft
    Y_e = extent of drainage area in y-direction, ft
    C_H = Shape factor, semi-analytic function of L,X_e,Y_e
    r_e = drainage radius of horizontal well
    r_w = wellbore radius, ft
    B_o = formation volume factor of oil
     μ _o = oil viscosity

Tips

    ◊ Use link EXAMPLE Of Input/Output  to demo data entry expectations and results; you may edit & use it as starting point

BIBLIOGRAPHY

• Retnanto, A. & Economides, M.J.; Inflow performance relationships of horizontal and multibranched wells in a solution-gas-drive reservoir; paper SPE-50659, 1998.
• Economides, M.J., Brand, C.W. & Frick, T.P.; Well configurations in anisotropic reservoirs; SPE Formation Evaluation, Dec. 1996, 257-262.
• Kabir, C.S; Inflow performance of slanted and horizontal wells in solution-gas drive reservoirs; paper SPE-24056, 1992.
• Goode, P.A. & Kuchuk, F.J.; Inflow performance of horizontal wells; SPE Reservoir Engineering, Aug. 1991, 319-323.