The phenomenon of free fall during primary cementing
For many years the oil industry has been performing primary cementing jobs perhaps without a complete understanding of the actual flow behavior of the fluids in the well during the cementing operation. It is well known that in many jobs the well ''goes on a vacuum'', ''U tubes'' or ''free-falls'' while the heavy fluids (cement slurries, spacers) are being pumped down the casing. When this occurs, one loses control of the job rates since the column of fluids in the casing free-falls at rates different than the pump rates at the surface. During the first stages of free-fall, the free-falling column of fluids accelerates and the free-fall rate is larger than the surface pump rate. This early acceleration causes a ''partially empty'' or ''discontinuous'' zone or gap to form between the free-falling column of fluids and the wellhead. It is possible that this initial acceleration is not detrimental to the cement-mud displacement process, unless the job was designed to be pumped under plug flow and the accelerated rates take it out of the plug flow regime.
- Research Organization:
- Amoco Production Co.
- OSTI ID:
- 6395164
- Report Number(s):
- CONF-8409104-
- Journal Information:
- Soc. Pet. Eng. AIME, Pap.; (United States), Vol. SPE13045; Conference: 59. annual Society of Petroleum Engineers of AIME technical conference, Houston, TX, USA, 16 Sep 1984
- Country of Publication:
- United States
- Language:
- English
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