** Table T1.** IODP depth scale terminology. (See table notes.)

Depth scale name |
Acronym | Origin | Method description | Submethod | Unit |
Previous name |
Previous unit |
---|---|---|---|---|---|---|---|

Drillers depth scale | |||||||

Drilling depth below rig floor |
DRF | Drill floor | Add the lengths of all drill string components deployed beneath the rig floor, from bit to the point on the rig floor where the length of the deployed portion of the last string is measured. | Describe submethod of measuring drill string component length and length deployed at rig floor | m | Depth | mbrf |

Drilling depth below seafloor |
DSF | Seafloor | Subtract the distance between rig floor and sea level from an estimate of seafloor depth at the drilling depth below rig floor scale using one of the submethods | A. Tag seafloor | m | Depth | mbsf |

B. Mudline core | |||||||

C. Visual control | |||||||

D. Inherit depth | |||||||

E. Other | |||||||

Core depth scale | |||||||

Core depth below seafloor |
CSF | Seafloor | Measure core sample or measurement offset below the core top and add it to the core top’s drilling depth below seafloor; apply one of the submethods. | A. Let overlap if long | m | Depth | mbsf |

B. Scale if long | |||||||

C. Other | |||||||

Core composite depth | CCSF | Seafloor | Align cores from one hole or multiple adjacent holes based on one of the submethods. The result is a newly constructed depth scale. | A. Append if long | m | Depth | mcd |

B. Scale by factor | |||||||

C. Correlate features | |||||||

D. Splice | |||||||

E. Other | |||||||

Wireline depth scale | |||||||

Wireline log depth below rig floor |
WRF | Drill floor | Measure length of wireline extended beneath the rig floor. | Describe submethod | m | Depth | mbrf |

Wireline log depth below seafloor |
WSF | Seafloor | Subtract the distance between rig floor and sea level from an estimate of seafloor depth at the wireline depth below rig floor scale using one of three submethods | A. seafloor signal | m | Depth | mbsf |

B. Drilling depth | |||||||

C. Inherit depth | |||||||

D. Other | |||||||

Wireline log speed-corrected depth below seafloor | WSSF | Seafloor | Correction for irregular motion of the tool during logging using accelerometer data; used for high-resolution logs such as microresistivity (FMS). | Describe submethod if applicable | m | Depth | mbsf |

Wireline log matched depth below seafloor |
WMSF | Seafloor | Pick log data from one run as a reference and map other run data using several tie points. | Describe reference log and number/type of tie points used | m | Depth | mbsf |

Notes: Drillers depth scale is based on length of drill pipe lowered below the drill floor. Core depth scale is based on the actual length of core recovered and drillers depth, which can vary with time as core expands or contracts. Core depth is technically not a depth but can be used to derive a depth by cumulating all core lengths. Wireline depth scale is based on the wireline length between the downhole tool and shipboard winch. FMS = Formation MicroScanner. See IODP Depth Scale Terminology at www.iodp.org/program-policies.

Close | Next | Top of page