Information about well logs run in a well. Each record in the table represents a different log of the hole. In the PDMS, well logs are defined as continuous descriptions or measurements of the rocks, bore hole, or drilling history which are related to depths drilled. The logged intervals may extend to the entire interval drilled, or they may represent only portions of the entire hole.
In the PDMS, logs are categorized as either Geophysical Logs or Physical Logs.
The Log Info Subtable contains the following data:
A unique identification number assigned to each log record. Log ID appears in the Log Info Subtable where the number is automatically assigned by Microsoft SQL Server; and in the Strat Picks Subtable where it is used to link each Pick Depth with the specific log that used to determine the depth.
The term Run Number is not standardized in the petroleum industry, however, the most commonly used convention is to assign a sequential number to each time a log is run or rerun for the well. The new logging may occur after additional hole is drilled in the well. Some operators, however, assign a different Run Number each time a new logging tool is run in the hole. Because of this conflicting terminology, the IGS has decided to use whichever Run Number the operator places on the log, although; Caution! this decision was not made until mid-2002, so Run Numbers for some logs entered previously into the PDMS are incorrect.
Run Numbers are assigned to Geophysical Logs, but not to Physical Logs where the Run Number data field is left blank.
As used in the PDMS, well logs (or simply logs) are categorized into one of two Categories:
Trade Name is the name given to a particular Geophysical Log by the company who ran the log. Trade Names are not used in the PDMS for Physical Logs.
The Help Page PDMS Trade Names and Their Associated Log Types
Log Type refers to a group of logs of a similar kind as identified by the IGS.
See Geophysical Logs and Physical Logs for their respective Log Types.
The date a log was reported run on the well log. If the date of the month is unknown, the 1st of the month is used (along with a brief explanatory note in the Log Comments data field). If the date of the year is unknown, January 1st is used (with a note in the Log Comments data field). If the logging date is unknown, the well's Completion Date is used.
Measured depth (in feet) from the Log Datum to the top of the logged interval in a well.
Measured depth (in feet) from the Log Datum to the bottom of the logged interval in a well.
The vertical scale of a well log, normally given in “inches on the log” = “hundreds of feet in the well bore." Geophysical Logs are commonly displayed, one after another, at 2 different scales on the same continuous piece of paper. The large-scale log is used for detailed examination of the log curves, and the small-scale facilitates correlating logs for regional interpretation. In such cases, both Log Scales are listed together as in this example:
"2 inch & 5 inch = 100 feet" means that the same log was presented in both a "2 inch = 100 feet scale" and a "5 inch = 100 feet scale", one after the other, on a continuous piece of paper.
A field in the Log Info Subtable indicating whether a small-scale log (a reduced-scale copy of a full-size log) is filed separately from the full-size log that is contained in the Well Envelope in the paper documents filed at the IGS. Small-scale logs are filed in the IGS Small Log File. The scales of small-scale logs are variable, but 2.5 inch = 100 feet and 1 inch = 100 feet are common. The actual scale for the small-scale log is not entered in the Log Scale data field unless the small-scale log is the only available log for the well.
The reference datum from which the log was measured. There is no industry standard. The Log Datum data field may contain any one of the following values:
Derrick Floor
Ground
Kelly Bushing
Rotary Table
Unknown
Other (with explanation in the Log Comments field)
Height of the Log Datum above ground Elevation. Together they are used to calculate the elevation of Pick SubSea.
Comments related to the log. The Log Comments field is not displayed unless a comment has been entered.
View or download logs in PDF and TIFF file formats. LAS (Log ASCII Standard) format is available for only a very small number of logs.