1.3. Técnicas de reducción de ruido
1.3.2. Autoencoders (AE)
into the spectrum of pore sizes present, which provides information on the irreducible water saturation. Permeability can be estimated from the free-fluid to bound-fluid ratio and the shape of the pore-size distribution. NMR measurement is also useful for fluid identification because it is a hydrogen index measurement, and various fluids have different hydro- gen index values as well as polarization characteristics. NMR data can be processed to yield formation fluid properties such as gas and oil saturation and oil viscosity.
Measurement Specifications
Output Transverse relaxation time (T2) distribution, total porosity, free- and bound-fluid volumes, permeability determined with Schlumberger-Doll Research (SDR) and Timur-Coates equations, capillary bound porosity, small-pore bound porosity, quality control curves and flags
MRF* magnetic resonance fluid station log: Saturation; oil, gas, and water volumes; oil viscosity; water and oil T2 distributions; hydrocarbon-corrected permeability; oil and water log-mean T2 distributions Logging speed Bound-fluid mode: 3,600 ft/h [1,097 m/h]
Short time constant for the polarizing process (T1) environment: 2,400 ft/h [731 m/h] Long T1 environment: 800 ft/h [244 m/h]
Range of measurement Porosity: 0 to 100 V/V Minimum echo spacing: 200 us T2 distribution: 0.3 ms to 3.0 s
Nominal raw signal-to-noise ratio: 32 dB Vertical resolution Stationary: 6-in [15.24-cm] measurement aperture
Depth log (high-resolution mode): 7.5-in [19.05-cm] vertical resolution, three-level stacking Depth log (fast mode): 30-in [76.20-cm] vertical resolution, three-level stacking
Accuracy Total CMR-Plus porosity standard deviation: ±1.0 V/V at 75 degF [24 degC], three-level stacking CMR-Plus free-fluid porosity standard deviation: ±0.5 V/V at 75 degF [24 degC], three-level averaging Depth of investigation Blind zone (2.5% point): 0.50 in [1.27 cm]
Median (50% point): 1.12 in [2.84 cm] Maximum (95% point): 1.50 in [3.81 cm]
Log Quality Control Reference Manual CMR-Plus Combinable Magnetic Resonance Tool 103
Calibration
CMR-Plus tools are calibrated every month.
The calibration setup positions the CMR-Plus tool face up with a cali- bration bottle affixed containing nickel chloride mixed with water in a ratio of 11 g of NiCl to 1 L of water. A Faraday shield is placed over the magnetic section to reduce noise.
All metal objects, including other tools, hand tools, tool stands, and tool end caps, must be removed from the calibration area. The calibration area must be located so that interference from electrical noise (fluo- rescent lights, overhead cranes, and radio towers) is minimized. The CMRPlus tool must not have tools connected below it or any jumper leads that may add noise. The tool should be positioned 3 ft [0.9 m] above the floor to eliminate noise.
Tool quality control
Standard curves
The standard curves of the CMR-Plus tool are listed in Table 1. Mechanical Specifications
Temperature rating 350 degF [177 degC] Pressure rating 20,000 psi [138 MPa]
High-pressure version: 25,000 psi [172 MPa] Borehole size—min. Without integral bow spring: 5.875 in [14.92 cm]
With integral bow spring: 7.875 in [20 cm] Borehole size—max. No limit
Outside diameter Without bow spring: 5.3 in [13.46 cm] With bow spring: 6.6 in [16.76 cm]
Length 15.6 ft [4.75 m]
Weight Without bow spring: 374 lbm [170 kg] With bow spring: 413 lbm [187 kg] Tension 50,000 lbf [222,410 N]
Compression 23,000 lbf [102,310 N]
Table 1. CMR-Plus Standard Curves Output Mnemonic Output Name
BFV_SIG Standard deviation of total bound-fluid porosity CMFF_SIG Standard deviation of free-fluid porosity
CMR_GAIN CMR* system gain
CMR_TEMP CMR temperature
CMRP_MAX CMR porosity (CMRP) using T1/T2 ratio maximum CMRP_MIN CMRP using T1/T2 ratio minimum
DELTA_B0 Difference in the static magnetic field (ΔB0)
FREQ_OP CMR operating frequency
FREQ_WO_ALF Frequency without auto Larmor frequency (ALF) HV_LOADED High voltage when loaded
HV_PEAK_CUR High voltage peak current
NOISE_ENV Noise per echo
NOISE_TOOL Tool hardware noise NOISE_TOOL_WSUM Tool window-sums noise
SPHASE Signal phase
TCMR Total CMR porosity
TCMR_SIG Standard deviation of total CMR porosity
WIN_POR_1 Windows porosity 1
WIN_POR_2 Windows porosity 2
Log Quality Control Reference Manual CMR-Plus Combinable Magnetic Resonance Tool 104
Operation
CMR-Plus data can be acquired versus depth or versus time (stationary measurement).
The CMR-Plus tool is commonly run in autotuning mode, which allows the operating frequency to automatically adjust to changes in the static
magnetic field B0. When the CMR-Plus tool is run in manual mode, the
tool must be retuned if one or both of the following conditions apply: • the difference between the operating and central search
frequencies exceeds 15 kHz
• ΔB0 exceeds 0.1 mT [1 gauss] during logging.
Planning CMRPlus jobs involves many variables depending on hole conditions, formation, and type of fluids, among other factors. To help job planning, it is recommended to run the CMR Advisor to select the best suitable pulse sequence.
The CMR-Plus tool must be run eccentered using a minimum of two bow springs, inline eccentralizers, or powered caliper devices above and below the sonde. Skid contact with the formation is essential. Precise repeatability specifications are not available because of the variety of possible logging speeds, pulse sequences, and environmental factors such as temperature, salinity, and rugosity.
Format
The format in Fig. 1 is used mainly as a quality control. • Depth track
– If the Insufficient Wait-Time Flag is on, this may indicate that the polarization time is insufficient. This does not necessarily mean that the computed results are incorrect, but that the standard deviation is high. Consult your Schlumberger represen- tative when this flag is displayed.
– An increase in the No Update Count is caused by logging too fast or by telemetry problems.
• Track 1
– The three window porosities should be similar and free of spikes. – The difference between Windows 2 and 3 should be less than 3 V/V.
• Track 2
– CMR_GAIN should read close to 0.8–1.0 for low-temperature fresh-mud wells and close to 0.3–0.5 in hot wells with conductive mud. It may drop further in zones of washouts.
– DELTA_B0 and CMR_TEMP should decrease slowly while logging up.
– FREQ_OP should slightly increase while logging up (at about 0.8 kHz/degC).
– With autotuning, the area indicated as ALF Frequency Correction should be small; the maximum acceptable difference between the FREQ_WO_ALF and FREQ_OP should not be more than 50–60 kHz.
– SPHASE should remain relatively constant through porous regions.
• Track 3
– ΔB0 should be zero if a Larmor frequency search task (LFST)
was conducted before the log is started. A rapidly varying Δ B0
suggests the presence of debris, which may affect data quality. – Standard deviations of total porosity, free-fluid porosity, and
bound-fluid porosity all vary proportionally with temperature and inversely with the amount of stacking, but should remain below 3 V/V.
– If noise is a problem, the software flags the data yellow where the noise curve is above 3 V/V, and then red if it exceeds 6 V/V. Examine the echo to find out if the noise source is the tool con- figuration (indicated where noise pattern does not change with depth) or from the environment.
• Track 4
– The CMRP_MAX and CMRP_MIN curves trigger the Insufficient Wait-Time Flag in the depth track.
– If the regulated HV_LOADED curve drops below 240 V, data is flagged red to indicate that the transmitter is not receiving enough power.
– The HV_PEAK_CUR increases when there is an increase in load- ing on the antenna (e.g., in zones of washouts).
Log Quality Control Reference Manual CMR-Plus Combinable Magnetic Resonance Tool 105 Number of Components: 30 Downhole Stacking: 3 Uphole Stacking: 1 First Echo Used: No
Multiple T2 Cutoffs(msec): (0.3 1 3 10 33 100 300 1000 3000) Sample Int.(in): 7.5 Req Log Speed (f/h): 2700
CMR System Gain (CMR_ GAIN)
(−−−−
0 1
Standard Deviation of Free Fluid Porosity (CMFF_SIG)
(V/V) 0 1 0 CMRP − T1T2min (CMRP_ T1T2R_MIN) (V/V) 0 4 0 Delta B0 (DELTA_B0) (MTES) −0.5 0.5
Operating Frequency (FREQ_ OP)
(KHZ)
2100 2300
Frequency without ALF (FREQ_WO_ALF) (KHZ) 2100 2300 Gamma Ray (GR) (GAPI) 0 150
HILT Caliper (HCAL) (IN) 16 6
High Voltage When Loaded (HV_LOADED)
(V) 27
0 2
2 0
High Voltage Peak Current (HV_PEAK_CUR)
(MA) 1000
0 0
Noise per Echo (NOISE_ ENV[0])
(V/V) 0
1 . 0
Tool Hardware Noise (NOISE_ TOOL[0])
(V/V) 0
1 . 0
Tool WSUM Noise (NOISE_ TOOL_WSUM[0]) (V/V) 0 1 . 0 (NO_ UPDATE_ COUNT) (−−−− 0 10
Signal Phase (SPHASE[0]) (DEG) −180 180 Tension (TENS) (LBF) 0 0 0 0 2
Standard Deviation of Total CMR Porosity (TCMR_SIG) (V/V) 0 1 . 0 Total CMR Porosity (TCMR) (V/V) 0.4 0 Tuning Mode (TUNING_ MODE) (−−−− −1 3 Window Porosity 1 (CMR_ RAW_PHI[0]) (V/V) 0 4 . 0 Window Porosity 2 (CMR_ RAW_PHI[1]) (V/V) 0 4 . 0 Window Porosity 3 (CMR_ RAW_PHI[2]) (V/V) 0 4 . 0
ALF Frequency Correction Delta B0 Caution
HV Loaded Below Limit CMRP max to min Caution Moderate Noise
Noise Out of Tolerance
Window Porosity 2 to 3
Insuff. WT Flag
PIP SUMMARY Time Mark Every 60 S
CMR DEPTH LOG REPORT PARAMETER SUMMARY
Tool Type: CMR−Plus Cart. Number: X Sonde Number: X
Kit Number: X DHC Version : 16.4 DSP Version : 13 SP Version : 2062001
Mode: Sandstone Depth Log − B Mode LFST Freq(khz) : 2213 LFST Temp(degc) : 40.39
Log Direction: Up Polarization Correction: On EPM: No
Despiking: Off High Res: Off KBFV: Off DMRP: Off
Echo Spacing(us): (200)
Polarization Times(sec) for: T1=1s: (2.X) T1=3s: (2.X ) T1=5s: (2.X )
Number of Echoes: (1200)
Repetition: (1) Duty Cycle (highest): 0.0351
Regularization: Auto
T2 Min(msec): 0.3 T2 Max(msec): 3000 T2 Cutoff(msec): 33 T1/T2: 2
Number of Components: 30 Downhole Stacking: 3 Uphole Stacking: 1 First Echo Used: No
Multiple T2 Cutoffs(msec): (0.3 1 3 10 33 100 300 1000 3000)
Standard Deviation of Total Bound Fluid Porosity (BFV_
SIG) (V/V) 0 1 . 0 Cable Speed (CS) (F/HR) 3000 0 CMR Temperature (CMR_ TEMP) (DEGF) 160 0 6 (−−−− 0 10.1 (V/V) 0 CMRP − T1T2max (CMRP_ T1T2R_MAX) (V/V) 0.4 0 (V/V) 0.4 0 Bad Hole Flag g XX50
Response in known conditions
• Clean waterbearing formations: CMRPlus porosity is comparable with neutron and density porosities in clean water-bearing sand- stones and carbonates.
• Shaly formations: CMRPlus porosity is a total porosity measure- ment and is lower than neutron porosity and slightly higher than density porosity in shaly formations (depending on the quantity and type of clay).
• Shale: CMRPlus porosity reads much lower than neutron porosity but higher than density porosity (depending on the type of clay in the shales), and free-fluid porosity is typically 0% porosity.
• Gas zones: CMRPlus porosity is much lower than density porosity and usually slightly lower than neutron porosity (the CMR-Plus response depends on invasion and the hydrogen index of the gas). • Heavy oil zones: CMRPlus porosity does not include the volume of
very heavy oil (or bitumen), so it is much lower than neutron and density porosities when heavy oil is present.
• Washouts: CMRPlus porosity spikes high in washouts and intervals where the skid is not in good contact with the formation.
• Mudcake: CMRPlus readings are usually unreliable where mudcake thickness exceeds 0.5 in [1.3 cm].
*Mark of Schlumberger
Copyright © 2009 Schlumberger. All rights reserved. 09-FE-0167
Log Quality Control Reference Manual Sonic Scanner Acoustic Scanning Platform 107
Overview
The Sonic Scanner* acoustic scanning platform provides a 3D rep- resentation of the formations surrounding the borehole by scanning both orthogonally and radially. Acoustic technology is used to acquire borehole-compensated (BHC) monopole with long and short spacings, cross-dipole, and cement bond quality measurements. In addition to making axial and azimuthal measurements, the tool radially measures the formation for both near-wellbore and far-field slowness. The typical depths of investigation are 2 to 3 times the borehole diameter. The wide frequency spectrum used by the Sonic Scanner tool cap- tures data at a high signal-to-noise ratio, regardless of the formation slowness. The combination of a long axial array and multiple transmit- ter-receiver spacings enables the measurement of a radial monopole profile across the near-wellbore altered zone.