From the previous articles, Equivalent Circulating Density (ECD) in ppg, you may want to know how to determine annular pressure loss in order to calculate Equivalent Circulating Density (ECD) in ppg.
So use the following formula to calculate annular pressure loss. This formula will roughly give you idea about how much annular pressure loss you will encounter. For this 2021 update, we’ve added the formula in both oilfield and metric unit.
Oilfield Unit
P= [(1.4327 × 10-7) × MW × L × V2] ÷ (Dh – Dp)
P = annular pressure losses, psi
MW = mud weight in ppg
L = length of annular in ft
V = annular velocity in ft/min
Dh = hole or casing ID in inch
Dp = drill pipe or drill collar OD in inch
Example:
Mud weight = 13.0 ppg
Length = 8000 ft
Circulation rate = 320 gpm
Hole size = 6.5 in.
Drill pipe OD = 4.0 in.
Determine annular velocity, ft/mm: v = (24.5 x 320) ÷ (6.52 – 4.02)
v = 299 ft/min
Determine annular pressure losses, psi: P = [(1.4327 × 10-7) × 13.0 × 8000 × 2992] ÷ (6.5 – 4.0)
P = 531.65 psi
Metric Unit
P= [(7.39 × 10-6) × MW × L × V2] ÷ (Dh – Dp)
P = annular pressure losses, KPa
MW = mud weight in kg/m³
L = length of annular in m
V = annular velocity in m/min
Dh = hole or casing ID in mm
Dp = drill pipe or drill collar OD in mm
Example:
Mud weight = 1,560 kg/m³
Length = 2,400 m
Circulation rate = 1,200 l/m
Hole size = 165 mm
Drill pipe OD = 100 mm
Determine annular velocity, ft/mm: v = (1,000 × 1,200) ÷ (π × (1652 – 1002) ÷ 4)
v = 88.7 m/min
Determine annular pressure losses, psi: P = [(7.39 × 10-6) × 1560 × 2400 × 88.72] ÷ (165 – 100)
P = 3,349 KPa
PS, This is the estimation for annular pressure. For more accurate, you may need to consult to a drilling fluid company to perform simulation since they have advanced software that can account for many parameters ie cutting loading, mud rheology, etc.
Download the spreadsheet from the link below.
Ref books:
Lapeyrouse, N.J., 2002. Formulas and calculations for drilling, production and workover, Boston: Gulf Professional publishing.
Bourgoyne, A.J.T., Chenevert , M.E. & Millheim, K.K., 1986. SPE Textbook Series, Volume 2: Applied Drilling Engineering, Society of Petroleum Engineers.
Mitchell, R.F., Miska, S. & Aadny, B.S., 2011. Fundamentals of drilling engineering, Richardson, TX: Society of Petroleum Engineers.
