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| |+ {{table number|4}}Resolution and application of porosity and lithology devices | | |+ {{table number|4}}Resolution and application of porosity and lithology devices |
| |- | | |- |
− | ! Tool | + | ! Tool || Vertical Resolution || Radius of Investigation || Applications || Limitations |
− | ! Vertical Resolution
| |
− | ! Radius of Investigation
| |
− | ! Applications
| |
− | ! Limitations
| |
| |- | | |- |
− | | Compensated density | + | | Compensated density || 18 in. || 8 in. || Estimate porosity || Pad contact device |
− | | 18 in. | |
− | | 8 in. | |
− | | Estimate porosity | |
− | | Pad contact device | |
| |- | | |- |
− | | Compensated neutron | + | | Compensated neutron || 2 ft || 10 in. || Estimate porosity and identify presence of gas || Needs environmental corrections; sensitive to standoff from wall |
− | | 2 ft | |
− | | 10 in. | |
− | | Estimate porosity and identify presence of gas | |
− | | Needs environmental corrections; sensitive to standoff from wall | |
| |- | | |- |
− | | Sonic | + | | IPL* (Integrated Porosity Lithology) || 1 ft || -- || Estimate porosity and identify presence of gas, thin bed evaluation, shalt sand evaluation || Needs environmental corrections; sensitive to standoff from wall |
− | | 2 ft | |
− | | Typically 6 in. | |
− | | Measure compressional velocity and estimate porosity | |
− | | Sensitive to compressibility | |
| |- | | |- |
− | | FWS (monopole) | + | | Sonic || 2 ft || Typically 6 in. || Measure compressional velocity and estimate porosity || Sensitive to compressibility |
− | | 4 ft | |
− | | Typically 6 in. | |
− | | Measure compressional and shear velocities and estimate porosity | |
− | | Cannot measure shear velocity when shear velocity > mud velocity | |
| |- | | |- |
− | | Dipole sonic | + | | FWS (monopole) || 4 ft || Typically 6 in. || Measure compressional and shear velocities and estimate porosity || Cannot measure shear velocity when shear velocity > mud velocity |
− | | 4 ft | |
− | | Typically 12 in. | |
− | | Measure shear velocity | |
− | | —
| |
| |- | | |- |
− | | Photoelectrical effect (Pe) | + | | Dipole sonic || 4 ft || Typically 12 in. || Measure shear velocity || — |
− | | 2 in. | + | |- |
− | | 2 in. | + | | CMR* (Combinable Magnetic Resonance) || 6 in. || 1 in. || Porosity, pore size distribution, permeability || Minimum 6.5 in. wellbore |
− | | Identify lithology and correlation | + | |- |
− | | Does not work in barite mud and pad contact tool | + | | Photoelectrical effect (Pe) || 2 in. || 2 in. || Identify lithology and correlation || Does not work in barite mud and pad contact tool |
| |} | | |} |
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