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INPUT   DATA

♥ EXAMPLE Of Input/Output

Title

Reservoir pressure		psi
Flowing bottomhole press.		psi
Oil flow rate		BOPD
Slant angle		°

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OUTPUT   VARIABLES   &   GRAPHS

Open flow oil rate	bbl/day
♦  (qo)max, Cheng
♦  (qo)max, Vogel

IPR For Slanted 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.

A number of empirical methods have been proposed to generate IPRs along the lines of the seminal work of Vogel on the subject. These methods usually require a least one stabilized flow test (so-called single-point test) in which flow rate, FBHP and average reservoir pressure are measured. These 3 attributes uniquely define the IPRs coresponding to that reservoir pressure.

Cheng's Model applies to the cases where the well penetrates the producing interval at an angle. The angle ranges from zero (vertical well) to 90 degrees (horizontal well). The model is a semi-analytical one, wherein the coefficients of the polynomial equations vary with the inclination angle. For example, the correlations for the 30 and 75 degrees scenarios are respectively:

[q_o/q_omax]_30° = 0.9959 - 0.1254[p_wf/p_r] - 0.8682[p_wf/p_r]²
[q_o/q_omax]_75° = 0.9915 + 0.1002[p_wf/p_r] - 1.0829[p_wf/p_r]²

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
     θ = slant or deviation angle, degrees

Tips

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

BIBLIOGRAPHY

• Cheng, A.M.; Inflow performance relationships for solution-gas-drive slanted/horizontal wells; paper SPE-20782, 1990.
• Kabir, C.S; Inflow performance of slanted and horizontal wells in solution-gas drive reservoirs; paper SPE-24056, 1992.
• Vogel, J.V.; Inflow performance relationships for solution-gas drive wells; JPT, Jan. 1968, 83-92.