Well Composition

A well is the holding mechanism for a series of boreholes. If you were to drill a single hole to 10,000 ft, you would have created a well (to hold the surface information) and a borehole (to hold the information about the subsurface part).

A borehole can be kicked off from another borehole, and this relationship is defined by the link from borehole back to itself. The unique identifier of the parent borehole (tie-in borehole) is stored in the attribute tie_in_borehole.

A well belongs to a field, but a well can also be designated as the discovery well for a field.

The well class contains information about the current status of the well as well as the effective date of this status. It should be noted that this is a denormalization of the status from Well_Status_History and is stored here for the purpose of performance. It also contains the reference data for the well, such as Standard_Pressure, Standard_Temperature, Permanent_Datum_Reference, etc.

A well is identified by a UWI (unique well identifier) and a borehole is identified by a UBHI (unique borehole identifier).

The borehole class holds the information regarding the individual boreholes in a well. It holds the depth information from both the driller and the logger. It also holds the reason and shape of the borehole. The borehole_number is the sequence number of the borehole within the well, i.e., the first borehole in a well would be number 1, the second borehole in a well number 2, and so on.

Both a well and a borehole can have many associated names or labels. Examples of this could be common name or government assigned name. This is implemented in Seabed as either a Well_Alias or a Borehole_Alias. Therefore, if a well had a common name of “East well number 1” then an entry would be made in the Well_Alias table with the Alias_Class of “Common_Name” and Well_Alias of “East well number 1”.

A borehole can also have many Borehole_Sections. A Borehole_Section is the mechanism by which the Seabed database defines the geometry of a borehole. For example, if the first 2,000 ft of a borehole is drilled with a 14-inch bit and then lined with a 12-inch casing, then that would be 1 borehole section. If the borehole is continues with a 10-inch bit and then cased with an 8-inch casing, then that would be a second borehole section.