Stability of boreholes drilled through salt formations displaying plastic behavior

Journal Article · Wed Mar 01 04:00:00 EST 1989 · SPE (Society of Petroleum Engineers) Drill. Eng.; (United States)

DOI:https://doi.org/10.2118/15513-PA· OSTI ID:6314719

Infante, E F; Chenevert, M E

This paper presents a mathematical and laboratory analysis that provides solutions to the problem of plastic flow of salt formations into wellbores. The paper predicts how the salt will flow and what type of mud might be used to control such flow for various well conditions. In the mathematical analysis, it is assumed that the incipience of plasticity in the formation is regulated by the level of octahedral shear stress and that the formation is neither permeable nor porous, but homogeneous and isotropic. The stress distribution in the neighborhood of the borehold is studied, and conditions under which this distribution is elastic, elastoplastic, or plastic are determined. Equations are derived that, in terms of two constants of the formation material, yield, and the limit of elasticity. Factors calculated include the radius of the plastic front and the percent of the borehole-diameter shrinkage as a function of mud weight used. This study was prompted by past failures in drilling through the Louann salt formation at depths of 12,500 to 14,000 ft (3810 to 4270 m), a formation that exhibits rapid plastic flow at low mud weights and at temperatures and pressures encountered. The techniques presented were applied to subsequent drilling of this salt section, and the zone was penetrated without the problem of plastic flow.

• Research Organization: Univ. of Minnesota (US); Univ. of Texas (US)
• OSTI ID: 6314719
• Journal Information: SPE (Society of Petroleum Engineers) Drill. Eng.; (United States), Journal Name: SPE (Society of Petroleum Engineers) Drill. Eng.; (United States) Vol. 4:1; ISSN SDENE
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
99 GENERAL AND MISCELLANEOUS
990230 -- Mathematics & Mathematical Models-- (1987-1989)
BOREHOLES
CALCULATION METHODS
CAVITIES
CREEP
DEFORMATION
DISPERSIONS
DRILLING
FLUID FLOW
GEOLOGIC FORMATIONS
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
MIXTURES
PLASTICITY
RESERVOIR PRESSURE
SHEAR
SLURRIES
STABILITY
SUSPENSIONS
WELL DRILLING