Proc. IODP, 327, Methods

Table T1. IODP depth scale terminology, Expedition 327. (See table notes.)


Depth scale	Acronym	Origin	Method description	Submethod	Unit	Previous name*	Previous unit*
Drillers depth scale:
Drilling depth below rig floor	DRF	Drill floor	Add lengths of all drill string components deployed beneath rig floor from bit to point on rig floor where length of deployed portion of last string is measured	Describe how drill string component length and length deployed at rig floor are measured	m	Depth	mbrf
Drilling depth below seafloor	DSF	Seafloor	Subtract distance between rig floor and sea level from an estimate of seafloor depth at DRF scale using one of the submethods	Specify submethod used:	m	Depth	mbsf
				A. Tag seafloor
				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 core top and add to core top DSF scale using one of the submethods	Specify submethod used:	m	Depth	mbsf
				A. Let overlap if long
				B. Scale if long
				C. Other
Core composite depth below seafloor	CCSF	Seafloor	Align cores from one hole or multiple adjacent holes using one of the submethods to create a newly constructed depth scale	Specify submethod used:	m	Depth	mcd
				A. Append if long
				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 rig floor	Describe how wireline length deployed at rig floor is measured	m	Depth	mbrf
Wireline log depth below seafloor	WSF	Seafloor	Subtract distance between rig floor and sea level from an estimate of seafloor depth at WRF scale using one of the submethods	Specify submethod used:	m	Depth	mbsf
				A. Seafloor signal
				B. Drilling depth
				C. Inherit depth
				D. Other
Wireline log speed-corrected depth below seafloor	WSSF	Seafloor	Correct for irregular motion of tool during logging using accelerometer data; use for high-resolution logs such as FMS	Describe measurement method if applicable	m	Depth	mbsf
Wireline log matched depth below seafloor	WMSF	Seafloor	Pick log data from one run as reference and map other run data using several tie points	Describe reference log and number/type of tie points used	m	Depth	mbsf

Notes: * = ODP depth scale conventions. Drillers depth scale is based on length of drill pipe lowered below drill floor. Core depth scale is based on actual length of core recovered and drillers depth and can vary with time as core expands or contracts. Thus, 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 wireline length between downhole tool and shipboard winch. FMS = Formation MicroScanner. See IODP Depth Scales Terminology at www.iodp.org/program-policies/.

Close | Next | Top of page