Secondary deposition of iron compounds following acidizing treatments

Journal Article · Mon Sep 01 00:00:00 EDT 1969 · J. Pet. Technol.; (United States)

DOI:https://doi.org/10.2118/2358-PA· OSTI ID:5267884

Smith, C F; Crowe, C W; Nolan, III, T J

Recently there has been increased interest in using chemical additives in acid to prevent secondary precipitation of iron compounds following the acidizing treatment. Acid readily dissolves iron scale in pipe and also attacks iron-containing minerals in the formation under treatment. This dissolved iron will remain in solution in the acid until the acid is spent. As pH of the spent acid begins to rise, the iron loses its solubility and precipitates. The precipitation of ferric hydroxide or other iron-containing compounds can seriously damage the flow channels recently opened by the acid reaction in the formation. Iron is a definite hazard to successful acidizing in some areas, but this does not mean sequestering agents should be routinely used unless there is positive evidence of their need. Like many chemical additives for acid, iron-control agents can be misused and overused with damaging results. Some agents precipitate if the expected downhole sources of iron are not present. In some cases, the iron actually keeps the sequestering agent in solution in spent acid. Thus, the effective use of iron sequestering agents depends upon the chemical conditions existing down hole during acid reaction. (17 refs.)

• Research Organization: Dow Chemical Co.
• OSTI ID: 5267884
• Journal Information: J. Pet. Technol.; (United States), Vol. 21
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
36 MATERIALS SCIENCE
ACIDIZATION
ADDITIVES
OIL WELLS
SCALE CONTROL
COMPLEXES
DEPOSITS
IRON COMPOUNDS
PIPES
PRECIPITATION
WELL COMPLETION
WELL STIMULATION
CONTROL
SEPARATION PROCESSES
STIMULATION
TRANSITION ELEMENT COMPOUNDS
WELLS
020300* - Petroleum- Drilling & Production
360104 - Metals & Alloys- Physical Properties