MLchartDataset catalogue

Fast formation

Term · Oil and gas · MLC-T-OAG-004322

A formation whose shear velocity exceeds the compressional velocity of the borehole fluid, so a refracted shear headwave is generated and can be recorded to measure formation shear velocity directly. In a slow formation the shear velocity is lower than the fluid compressional velocity, so no shear headwave forms and shear must be obtained from dipole or other dispersive modes. Most hard rocks, such as carbonates and well-cemented sandstones, are fast formations.

Table 1. Record
IdentifierMLC-T-OAG-004322
FieldOil and gas
SubjectFormation Evaluation
Record as JSON 
{
  "id": "MLC-T-OAG-004322",
  "term": "Fast formation",
  "field": "Oil and gas",
  "definition": "A formation whose shear velocity exceeds the compressional velocity of the borehole fluid, so a refracted shear headwave is generated and can be recorded to measure formation shear velocity directly. In a slow formation the shear velocity is lower than the fluid compressional velocity, so no shear headwave forms and shear must be obtained from dipole or other dispersive modes. Most hard rocks, such as carbonates and well-cemented sandstones, are fast formations.",
  "subject": "Formation Evaluation",
  "url": "https://mlchart.com/terminology/oil-and-gas/fast-formation/"
}

Record 1,479 of 4,469 in Oil and gas terminology (MLC-0103). Request the full dataset.