Abstract
Stimulation of sandstone formations is a challenging task, which involves several chemicals and physical interactions of
the acid with the formation. Some of these reactions may result in formation damage. Mud acid has been successfully
used to stimulate sandstone reservoirs for a number of years. It is a mixture of hydrofluoric (HF) and hydrochloric (HCl)
acids designed to dissolve clays and siliceous fines accumulated in the near-wellbore region. Matrix acidizing may also
be used to increase formation permeability in undamaged wells. The change may be up to 50% to 100% with the mud
acid.
For any acidizing process, the selection of acid (Formulation and Concentration) and the design (Pre-flush, Main
Acid, After-flush) is very important. Different researchers are using different combinations of acids with different
concentrations to get the best results for acidization. Mainly the common practice is combination of Hydrochloric Acid –
Hydrofluoric with Concentration (3% HF – 12% HCl).
This paper presents the results of a laboratory investigation of Orthophosphoric acid instead of hydrochloric acid in
one combination and the second combination is Fluoboric and formic acid and the third one is formic and hydrofluoric
acid. The results are compared with the mud acid and the results calculated are porosity, permeability, and FESEM
Analysis and Strength tests. All of these new combinations shows that these have the potential to be used as acidizing
acids on sandstone formations.
Citation
ID:
169788
Ref Key:
zaman2013journalperformance