Page 153 - Standard Handbook Petroleum Natural Gas Engineering VOLUME2

122 Reservoir Engineering

hmc Qb SHALE
BOREHOLE

PERMEABLE FORMATION
PERMEABLE FORMATION
'4 SHALE
MUDCAKE
Dominant Orientotion
Dominant Orientotion
of Clay Particles
Particles
of Clay
SHALE
RV
Figure 5-67. Resistivity components on mud cake that develop opposite a
permeable formation.

Average surface temperatures in various oilfield areas are:
Alberta 40°F
California 65°F
Colorado-Northern New Mexico 55°F
Gulf Coast 80°F
Oklahoma 65°F
Permian Basin 65°F
Wyoming 45°F
Figure 5-68 solves this equation graphically [ 1991.
Fluid resistivity at any formation depth can be found using the Arps Equation
if the resistivity at any temperature and formation temperature are known [199]:

T, +6.77
R, = R, (5-93)
T, + 6.77
where & = fluid- resistivity at formation temperature, am
R, = fluid resistivity at some temperature, a-m
T, = formation temperature, "F
T, = temperature R, was measured at, OF
A nomograph that solves this equation graphically is presented in Figure 5-69
[199].
Openhole Logs and lnterpretatlon
SP (Spontaneous Potential). The SP log has 4 basic uses: (1) recognition of
permeable zones, (2) correlation of beds, (3) determination of Rw, and (4)
qualitative indication of shaliness. The SP can only be used in fresh mud and