Introduction to Well Cementing

20 minutes read

Quantities and Units of Measurement

Certain fundamental physical quantities – along with the units of measurement that describe them—are integral to cement job planning and execution. This section summarizes these quantities and relates them to key concepts in well engineering.

The units of measurement used throughout this discussion of cementing are traditional oilfield units. Oilfield units originated from field practices in the U.S., although they are commonly used today throughout the world. Many operating areas use the SI (metric) system of units in well engineering.

It is also common in some areas to use a combination of oilfield and SI units. A drilling report, for example, might indicate that a 12 1/4 inch hole was drilled to a depth of 1000 meters.

Table 1 lists the physical quantities most commonly used in cementing, along with the units of measurement.

Table 1: Common Units of Measurement used in Cementing
Quantity	Typical Oilfield Unit(s)	SI (Metric Units)	Common Conversions
Length $(L)$	foot $(ft)$ inch $(in)$	meter $(m)$	$1\, ft = 12\, in$ $1\, ft = 0.3048\, m$ $1\, m = 39.37\, in$
Area $(L^2)$	square foot $(ft^2)$ square inch $(in^2)$	square meter $(m^2)$	$1\, ft^2 = 144\, in^2$ $1\, ft^2 = 0.09290304 \, m^2$
Volume $(L^3)$	gallon (gal –U.S.) cubic foot $(ft^3)$ or barrel $(bbl)$	cubic meter $(m^3)$	$7.48\, gal = 1\, ft^3$ $42\, gal = 1\, bbl$ $5.615\, ft^3 = 1\, bbl$ $1\, bbl = 0.1589873\, m^3$ $1\, ft^3 = 0.02831685\, m^3$
Mass $(M)$	Pound-mass $(lb_m)$	kilogram $(kg)$	$1\, lb_m = 0.45359237\, kg$ $1\, kg = 2.2046\, lb_m$
Density $(\tfrac{M}{L^3})$	Pounds per gallon ( $\tfrac{lb_m}{gal}$ or $ppg$ ) Pounds per cubic foot ( $\tfrac{lb_m}{ft^3}$ or $pcf$ )	kilogram/cubic meter $(\tfrac{kg}{m^3})$	$1\, pcf = 16.01846\, \tfrac{kg}{m^3}$ $1\, ppg = 119.8264\, \tfrac{kg}{m^3}$ $1\, ppg = 7.48\, pcf$
Speed $(\tfrac{L}{t})$	Feet per second ( $\tfrac{ft}{s}$ ) Feet per minute ( $\tfrac{ft}{min}$ )	meters/second $(\tfrac{m}{s})$	$1\, \tfrac{ft}{s} = 0.3048\, \tfrac{m}{s}$ $1\, \tfrac{ft}{min} = 0.00508\, \tfrac{m}{s}$
Force $(\tfrac{ML}{t^2})$	Pound-force ( $lb_f$ )	Newton $(N)$	$1\, lb_f = 4.448\, N$
Pressure $(\tfrac{M}{Lt^2})$	Pounds per square inch ( $psi$ )	Kilopascal $(kPa)$	$1\, psi = 6.894757\, kPa$
Temperature	degrees Fahrenheit ( $^{\circ}F$ )	$^{\circ}C$ = degrees Celsius	$^{\circ}C =\tfrac{(^{\circ}F -32 )}{1.8}$