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PRODUCTION LOGGING MEASUREMENTS AND
ANALYSIS


I . Introduction


Production logging encompasses a number of cased hole logging measurements

usually run in completed injection or production wells to evaluate the performance of the

well itself or of the reservoir. Although the most common application of production

logging is to obtain the well flow profile, a measure of the distribution of fluid flow into

or out of the wellbore, there are numerous other applications, such as detecting channels

or leaks. In .this article, the primary production logging measurements and interpretation

procedures will be reviewed; the application of production logging to well and reservoir

behavior diagnosis is treated in Chapter 14.

The chapter is organized according to the logging environment or logging

objective. First, the use of temperature, radioactive tracer, and spinner flowmeter logs for

measuring flow profiles in single-phase flow is described. Then, the more difficult

application of logging in multiphase flow is treated, introducing the basket flowmeter,

density, and capacitance logs that are used in this environment. Finally, production

logging techniques for completion evaluation are considered. For a more complete

treatment of the logging methods presented here, the reader is referred to Hill [1990].


II. Production Logging Measurements in Single-Phase Flow

2.1 Temperature Logging


The temperature log is probably the simplest, most accurate, and most widely

applicable production log. A temperature log is a measurement of the temperature in the

well as a function of depth -a typical temperature log from a gas production well is shown

in Figure 1 [Atlas Wireline Services, 1982.]

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Fig. 1 Typical temperature log displays


Notice that two curves are displayed, with one being the temperature versus depth
(usually called the gradient curve) and the other being the derivative of temperature with
depth (the differential curve). The differential curve is recorded to accentuate changes in
temperature behavior. Often, temperature logs will be run both with the well flowing and
with the well shut-in, since a shut-in period will sometimes result in larger temperature
anomalies at injection or production intervals.

The temperature in a well depends on many factors, including the temperature of
the surrounding formations, the wellbore flow conditions, the heat transfer characteristics
of the completion, and fluid movements near the wellbore. The natural temperature
distribution in the earth is called the geothermal temperature profile. Because of the heat
transfer from the earth’s interior to the atmosphere, the temperature in the earth’s crust
increases with depth, leading to a geothermal temperature profile such as that shown in
Figure 2 [Connolly, 1965] from a region in Canada.

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Using this value of us, qg, qo, and qT are calculated with Eqs. 30 through 32; the results

are shown in Table 7.



Table 7

Curtis Method Interpretation Results (Example 5)



station qT qg qo qo

(ft3/d) (ft3/d) (ft3/d) (b/d)

1 21200 10000 11200 2000

2 15500 11800 3700 700

3 11500 7800 3700 650

4 5700 1700 4000 700

5 0 0 0 0





The flow profiles obtained are plotted in Fig. 18. The profile is presented as a plot

of total flow rate and a plot of oil flow rate, with the difference between these values

being the gas flow rate. A few points about these results are worth noting. First, at station

5, the flowmeter reads 0 rps and the density tool shows a density higher than the oil

density. These results show this to be the rathole region, indicating no oil or gas is

flowing at this depth.

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Fig. 18 Example 5 two-phase log interpreted flow profile

Comparing the results obtained with the Nicolas-Witterholt correlation with those
obtained with the Curtis method, qualitatively they are similar, with both showing the
majority of the oil production coming from Zones A and D. Both show the primary gas
production from Zones B and C. However, notice that with the Curtis method, Zones B
and C are interpreted to produce essentially no oil, while with the Nicolas-Witterholt
interpretation, over 400 b/d of oil is found to be produced by these zones. Unfortunately,
it is not possible to know which is more correct, as both methods are empirical
correlations of complex two-phase flow phenomena.


IV. Completion Evaluation with Production Logs


Production logs are often used to inspect the well completion. Locating tubing,
casing, or packer leaks, detecting channels behind pipe, and evaluating the condition of
the cement are all common applications. In this section, we will review methods for
locating channels or leaks followed by a discussion of cement evaluation.


Channel and Leak Detection

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Wells in Chayvo Field, Sakhalin, Russia – New Conveyance and Flow Profiling

Approach,” SPE 103589 presented at the SPE Russian Oil and Gas Technical Conference

and Exhibition, Moscow, Russia, Oct. 3-6, 2006.



Froelich, B., Pittman, D., and Seeman, B.: “Cement Evaluation Tool: A New Approach

to Cement Evaluation,” JPT (Aug. 1982) p. 1835-1841.



Interpretive Methods for Production Well Logs, 2nd Edition, Atlas Wireline Services,

Western Atlas Inc., Houston (1982).



Jackson, R. R., Ayan, C., and Wakefield, J.: “Flow Diagnosis and Production Evaluation

in High Flowrate Oil-Water Producers Using Optical-Fibre Holdup Sensors,” SPE 71727

presented at the SPE ATCE, New Orleans, LA., Sept. 30 – Oct. 3, 2001.



Kessler, Calvin and Frisch, Gary: “New Fullbore Logging Sensor Improves the

Evaluation of Production in Deviated and Horizontal Wells,” SPE 29815 presented at the

1995 Middle East Oil Technical Conference and Exhibition, Bahrain, March 11-14, 1995.



Mas, C., Walterhouse, B., Van Vliet, J. P. M., and Rahman, H. A.: “Evaluations of Sub

Horizontal Well Performance with Optical and Electrical Probes,” SPE 72150 presented

at the SPE Asia Pacific Improved Recovery Conference, Kuala Lumpur, Malaysia, Oct.

8-9, 2001.



Morris, C., Sabbagh, L., Wydrinski, R., Hupp, J., Van Kuijk, R., and Froelich, B.:

“Application of Enhanced Ultrasonic Measurements for Cement and Casing Evaluation,”

SPE 105648 presented at the SPE/IADC Drilling Conference, Amsterdam, The

Netherlands, Feb. 20-22, 2007.



Sask, D., Hundt, C. D., Slade, J. M., and Daly, P.: “Production and Video Logging in

Horizontal Low-Permeability Gas Wells,” SPE 108084 presented at the SPE Rocky

Mountain Oil and Gas Technology Symposium, Denver, CO., April 16-18, 2007.



Theron, B., Vuhoang, D., Rezgui, F., Catala, G., McKeon, D., and Silipigno, L.:

“Improved Determination of Gas Holdup Using Optical Fibre Sensors,” presented at the

SPWLA Annual Symposium, Dallas, Texas, June 4-7, 2000. SPWLA (cited in SPE

71727).

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