Page 154 - Standard Handbook Petroleum Natural Gas Engineering VOLUME2

Formation Evaluation 143
Temperature Gradient Conversions: loF/10O ft = 1.823'C/100 rn
loC/l0O rn = 0.5486°F/100 ft
Annual Mean
S@ce Temperature Temperature, "C

EXAMPLE Bottom hole temperature, BHT, is 200°F at 11,000 R (Point A).
Temperature at 8,000 ft is 167°F (Point 8).

Figure 5-68. Chart for estimating formation temperature [199].

is run with several resistivity tools. The curve is presented in Track 1 and is
scaled in millivolts (mV).
The SP log is a record of the naturally occurring electrical currents created
in the borehole. These currents or circuits usually occur at bed boundaries and
are created by the interaction between fresh drilling mud and salty formation
water. The curve represents the potential difference between a stationary
electrode on the surface (ground) and a moving electrode in the borehole.
Theory. The total potential (E,) can be separated into two components: the
electrochemical ( Ec) and the electrokinetic (4). The electrokinetic component
is generally very small and is often ignored. It is created when an electrolyte (mud