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The Rheology and corrosivity of water‐base drilling fluid under simulated downhole conditions
Author(s) -
Shokoya O. S.,
AlMarhoun M. A.,
Ashiru O. A.
Publication year - 1996
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.19960470603
Subject(s) - drilling fluid , corrosion , rheology , materials science , viscometer , drilling , metallurgy , volumetric flow rate , shear (geology) , composite material , viscosity , petroleum engineering , geology , thermodynamics , physics
The rheological property and corrosion behavior relationship of mild steel type 1018 in a typical drilling fluid used in deep drilling and hot wells was studied. The tests were conducted under conditions that simulate flow, temperature, and pressure encountered during drilling operations. Physical properties that were considered are: shear stress‐shear rate relationship, effective and plastic viscosities, yield strength and gel strength. The properties were determined under high temperature and pressure by using a flow loop, the Baroid roller oven and the FANN‐70 viscometer. The corrosion measurements were carried out by weight loss and electrochemical techniques. The effective and plastic viscosities of the drilling fluid decrease with increase in temperature and increase in time of exposure to downhole conditions. The corrosion rate of 1018 mild steel increase with decrease in pH of the fluid. The corrosion rates are lower at the mildly alkaline pH and higher in the mildly acidic pH range. The drilling fluid generally attacks the grain boundaries of the steel samples. Diffusion was found to be the rate limiting step for the corrosion reactions.