Time Domain Analysis (TDA)
| MRIL data
can be analyzed independently or in combination with
conventional logs.When MRIL data is processed
independently, it can provide formation porosity and
permeability information, as well as complete
information on fluid types and fluid saturation within
the depth of investigation of the MRIL tool. Time Domain
Analysis (TDA) is an interpretation technique that
utilizes only MRIL data. |
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| Time
Domain Analysis (TDA) operates on the principle that
different fluids have different rates of polorization,
or different T1 relaxation times. The
T1 of both gas and light oil (viscosity less
than 5 cp) is normally much higher than that of water.
TDA is very effective in evaluating gas and light oil
reservoirs. |
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| TDA is
very different from other techniques available because
it uses only MRIL data in the interpretation process; no
conventional data is needed in the processing. |
| » TDA Analysis Features |
| TDA
analysis provides an alternative to the differential
spectrum method for processing dual-Tw echo trains data.
Interpretation is performed in the time domain rather
than in the T2 spectra domain. Key features of TDA
analysis include: |
- Subtraction of the two echo trains from one
another.
- Processing echo differences in the time domain using predicted or measured oil, gas, and water relaxation times and hydrogen-index values
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| » TDA Analysis Benefits |
| TDA
analysis offers the following benefits: |
- Provides accurate formation porosity in gas and
light oil reservoirs.
- Allows complete fluid volume analysis within the depth of investigation of the MRIL tool using only MRIL tool data
- Provides hydrocarbon typing
- Recognizes direct pay
- Improves permeability calculations in light hydrocarbon environment
- Clearly identifies pay zones vs. tight
zones
- Estimates free fluid volume and type in thinly
laminated reservoirs
- Indicates the best possible producing zones in carbonate formation
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| TDA
Analysis was applied to the MRIL tool data above to
obtain these results. Data was acquired using dual wait
time activation. Track 4 contains final total and
effective porosities, BVI and oil volume as well as oil
free water volume. The analysis indicates an oil/water
contact at X283. |
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| Inputs |
MRIL data only from
dual-wait time acquisition which can be acquired using
MRIL-Prime and/or MRIL-WD |
| Outputs |
Volumetric calculation of gas,
oil, and water; Formation Total and Effective Porosity;
Permeability Estimation |
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