Salt free cement-An alternative to collapsed casing in plastic salts

Conference · Sun May 01 04:00:00 EDT 1983 · Soc. Pet. Eng. AIME, Pap.; (United States)

OSTI ID:5397032

Goodwin, K J; Phipps, K

The high incidence (20-25%) of collapsed or doglegged casing in the Williston Basin led to an investigation of cementing systems and practices employed in that area. The vast majority of the collapse problems are occuring across the Charles formation. The Charles contains numerous salt sections over a 600-700 foot gross interval. These salt sections exhibit plastic tendencies when exposed to aqueous drilling fluids; i.e., the salt sections flow. Under plastic conditions, the salt sections flow against the casing before the cement sheath can attain sufficient compressive strength to protect the casing. These salt sections can be seen on conventionally cemented casing strings as 100% bonded sections, in what otherwise appears to be poorly cemented intervals. The plastic salt exhibits a horizontal stress against the casing equivalent to the overburden stress (approximately 1 psi/ft of depth). The use of high concentrations (20-37.2% BWOMW) of salt (NaCl), in cement slurries exhibit a retarding effect on thickening time and the rate of compressive strength development. These excessive development times appear to be contributing to the collapse problems defined. Laboratory investigation of salt dissolution rates in cement slurries, at varying annular velocities, show that salt-free cement slurries can be placed across the salt sections with final salt concentrations of less than 10% (BWOMW), due to salt dissolution. This prompted an investigation involving the possible use of salt-free cement slurries which exhibit controlled thickening times and much faster compressive strength development, across the Charles. To date, the wells that have been cemented in the Williston Basin with the salt-free cement systems have shown no incidence of casing collapse.

• Research Organization: Cand S Consulting,
• OSTI ID: 5397032
• Report Number(s): CONF-8305148-
• Conference Information: Journal Name: Soc. Pet. Eng. AIME, Pap.; (United States) Journal Volume: SPE10885
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020300 -- Petroleum-- Drilling & Production
03 NATURAL GAS
030300* -- Natural Gas-- Drilling
Production
& Processing
ALKALI METAL COMPOUNDS
BUILDING MATERIALS
CAVING
CEMENTING
CEMENTS
CHLORIDES
CHLORINE COMPOUNDS
COMPRESSION STRENGTH
DISPERSIONS
DISSOLUTION
DRILLING FLUIDS
FLOW STRESS
FLUIDS
GEOLOGIC DEPOSITS
HALIDES
HALOGEN COMPOUNDS
MATERIALS
MECHANICAL PROPERTIES
MIXTURES
OPTIMIZATION
SALINITY
SALT DEPOSITS
SLURRIES
SODIUM CHLORIDES
SODIUM COMPOUNDS
STRESS INTENSITY FACTORS
STRESSES
SUSPENSIONS
WELL CASINGS
WELL COMPLETION