Fast-formation arrival

{
  "id": "MLC-T-OAG-001373",
  "term": "Fast-formation arrival",
  "field": "Oil and gas",
  "definition": "A formation signal in cement bond logging that reaches the receiver before the casing arrival, because the formation compressional wave is faster than the steel casing signal, which has a slowness of about 57 microseconds per foot. Dense carbonates such as dolomite and limestone produce it. It appears on the variable density display, and where it shows the cement is usually bonded to both the casing and the formation.",
  "subject": "Formation Evaluation",
  "url": "https://mlchart.com/terminology/oil-and-gas/fast-formation-arrival/"
}