Horizontal Gas Well — Joshi C

Joshi deliverability with PVT Z-factor, viscosity interpolation and skin

Input

Horizontal well, reservoir and PVT inputs

Horizontal Permeability, kh		mD
Vertical / Horizontal Permeability, kv/kh		dimensionless
Reservoir Thickness, h		m
Horizontal Length, L		m
Drainage Radius, re		m
Wellbore Radius, rw		m
Development Horizontal Skin, S		dimensionless
Reservoir Pressure, Pr		psig
Reference Pwf		psig
Deliverability exponent, n		dimensionless
Reservoir Temperature		°F

PVT input: Copy the whole 3-column PVT table from Excel and paste it directly into the PVT grid. You do not need to enter each cell individually. Order: Pressure (psig) → Z-factor → Gas Viscosity (cP).

Row	Pressure (psig)	Z-factor	Gas Viscosity (cP)
1	200	0.9798	0.016
2	500	0.9542	0.0163
3	800	0.9318	0.0168
4	1100	0.9127	0.0173
5	1400	0.8973	0.018
6	1700	0.8857	0.0189
7	2000	0.878	0.0199
8	2052.7	0.8771	0.0201
9	2300	0.8752	0.0211
10	2800	0.8791	0.0232
11	3400	0.8952	0.026
12	4000	0.9206	0.0288
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Live Result

LIVE

Results update automatically as you change an input or PVT row.

Result	Value	Unit / Remark
Beta	—	sqrt(kh/kv)
Joshi a	—	m
Joshi Resistance, DJ	—	dimensionless
Total Resistance, DJ + Skin	—	dimensionless
Z at Pr	—	interpolated
Viscosity at Pr	—	cP, interpolated
Z at Pwf	—	interpolated
Viscosity at Pwf	—	cP, interpolated
m(Pr)	—	psia²/cP
m(Pwf) reference	—	psia²/cP
Δm = m(Pr) − m(Pwf)	—	psia²/cP
q at Reference Pwf	—	MMscf/d
Pressure Deliverability Term, X	—	psia^(2n)
C — Reference Pwf	—	MMscf/d / psia^(2n)
C — Reference Pwf	—	Mscf/d / psia^(2n)

Skin treatment: D_total = D_Joshi + S. Skin is added as an additional resistance.

q = kh × h(ft) × Δm / [1422 × T_R × (D_Joshi + S)]

C = q / {[(Pr + 14.7)² − (Pwf + 14.7)²]ⁿ}

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Remarks

This calculator uses the Joshi horizontal-well geometry with an additional development-well skin.

Gas Z-factor and viscosity are taken from the editable PVT table and linearly interpolated at Pr and Pwf.

Delta pseudopressure uses the same PVT-anchor trapezoidal integration and linear interpolation method as the Excel workbook. The displayed m(Pr), m(Pwf) and Δm are rounded to 2 decimals; full precision is retained internally for q and C.

The PVT grid accepts a complete Excel table by direct paste. Header rows, blank rows and comma-formatted numbers are handled automatically.