Why Log? • Fluid contact detection and movement (material balance) • Other water/gas movement • Injection frontal advance • Water salinity
Special Applications • • • •
Old wells Gravel-pack monitoring Channeling behind casing In-situ petrophysical properties
Formation Evaluation Logs for cased hole formation evaluation – Gamma ray – NGS log – Neutron log – Sonic log – Thermal decay time log – Gamma ray spectrometry tool
NEAR & FAR COUNTS
SIGMA GR RATIO
TDT ANALYSIS
Completion Evaluation Production logging applications – Well performance – Well problems – Well testing – Single and multi phase flow – Flow anomalies
Completion Evaluation • Evaluating completion efficiency • Detecting mechanical problems, breakthrough, coning • Providing guidance for workovers, enhanced recovery projects • Evaluating stimulation treatment effectiveness • Monitoring and profiling of production and injection
Completion Evaluation • Detecting thief zones, channeled cement • Single layer and multiple layer well test evaluation • Determining reservoir characteristics • Identifying reservoir boundaries for field development
Completion Evaluation Production logging tools – Spinner flow meters – Radioactive tracer tools – Fluid density tools – Nuclear fluid density tools – Temperature tools – Noise tools
Gamma Ray 0
9000
2
API Caliper Inches
CAL
Pressure
500 7 0
4000 PSIA 4200 Temperature Density Total Flow BPD 28000 0.2 °F g/cm3 245 0 1.2 240
W at e V r sl f = op G 3 as ft / e = m 0. in 04 sl und o 3 V pe er rp f = pr s/ = 12 0 es (f t /m ft/ .04 su in m 0 re ) in rp s/ (ft /m in )
10
lop
6
slo
2
f
s p i r ps 25 7 4. 0.0 in 1 at pe = ft/m s 0 Ga slo = 5 Vf V
W
at e
r
4
t / (f
/m
) in
Spinner speed, rps rev/sec
p ps = e= 3.5 0. ft/ 040 m in rps /( f t/m
e=
0. 0 5r
8
Ide al s
Spinner speed, rps rev/sec
in
)
10
8
6
4
2
0
0 0
40
80
120
160
200
240
Fluid velocity, ft/minute
(A) Continuous flowmeter (small diameter)
280
320
0
40
80
120
160
200
240
280
Fluid velocity, ft/minute
(B) Fullbore continuous flowmeter
Electrical connection
Upper bearing Magnet Pickup coil
Spinner
Lower bearing
Schematic of Schlumberger/Sondex type continuous flowmeter spinner
Peco type spinner flowmeter
Spinner
Basket Basket flowmeter opened in production well
CCL Electronic cartridge
Comumicatation CCL cartridge Electronic cartridge
Spinner section
Flowmeter Water-cut meter
Packer spring
Densimeter
Packer spring Packer tube
Packer bag
Packer bag Pump Filter
Fluid entrance port
Pump Filter
Well Sketch
Continuous Flowmeter, rps 0
20
40
Temperature 40°C
60°C
80°C
“F”
“E”
“D”
“C”
“B”
“A”
Flowmeter Flowmeter after before treatment treatment 11.000 B/D 23.000 B/D
Shut in one day Shut in three days During injection
Review of Flowmeter Types •
Continuous – In-situ calibration (takes time but arguably more valid than a chart as it takes actual tool characteristics into account) – Medium to high flowrates. Poor sensitivity to low rates, especially in multi-phase flow – Interpretation becomes difficult in multi-phase flow, especially in inclined pipe
•
Stationary – Point measurements – Lab-derived response chart – Low to medium flow rates. (pressure differential across the sealing element induces leaks and eventually moves the tool) – Converging effect tends to homogenize fluid mixture in relatively narrow tool body - better interpretation in multiphase flow.
Completion Evaluation • Radioactive Tracer Tools – Can be placed into the following two categories: Ê Gamma ray tools without downhole ejectors for releasing radioactive material Ê Gamma ray tools with downhole ejectors and multiple gamma ray detectors
Background
First detector 10.5 seconds
Second detector
6 seconds
Formation GR Cable speed CCL
Temperature GR Lower GR Upper
Tracker ejection ∆ Depth
Flow rate, B/D
4900 Presumed path of annulus water
A
5000
B C D E F G H I
Near detector 51.5”
Ejector
1000
CCL
500
Far detector 59.0”
4000
0
5100
Completion Evaluation • Fluid Density Tools – Gradiomanometer tool – Pressure-temperature tool – Nuclear fluid density tool
Completion Evaluation • Temperature Tools – Detection of gas production via the cooling effect of expanding gas – Qualitative evaluation of fluid flow indicated by departures from the geothermal gradient – Temperature information for PVT equations – Evaluation of fracture treatments – Evaluation of mechanical integrity of a completion
Completion Evaluation • Noise Tools – Two types of noise logs Ê Single frequency Ê Multiple frequency
Cement Evaluation • • • •
Cement bond log (CBL) Variable density log (VDL) Compensated cement bond log Cement evaluation tools (CET)
Cement Evaluation • The cement bond log (CBL) – The CBL, later combined with the VDL waveform, has been for many years the primary way to evaluate cement quality. The principle of measurement is to record the transit time and attenuation of an acoustic wave after propagation through the borehole fluid and casing wall.
Cement Evaluation • Compensated Cement Bond Tool – A newer generation tool that is lighter and more flexible for use in deviated holes. The principle of the measurement consists of recording two sets of receiver amplitudes and computing their ratio. This ratio is then used to compute attenuation.
Cement Evaluation • Cement Evaluation Tool – This tool evaluates the quality of the cementation in eight directions with very fine vertical resolution.
