American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.
This paper was prepared for the Rocky Mountain Regional Meeting of the Society of Petroleum Engineers of AIME, to be held in Billings, Montana, May 15–17, 1974. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is granted upon request to the Editor of the PETROLEUM ENGINEERS JOURNAL is granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made.
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Acid stimulation or clean-up treatments of producing and injection wells are often complicated producing and injection wells are often complicated by hydrocarbons which prevent intimate contact between acid and acid-soluble materials. The use of hydrocarbon solvent-in-acid dispersions to simultaneously dissolve both the hydrocarbon and acid soluble deposits has proved highly effective. This allows one-stage cleanup of hydrocarbon coated formations and avoids costly multi-stage treatments.
The production of oil and gas wells is often seriously hindered by the presence of hydrocarbon and inorganic scale deposits in the tubing, the wellbore, formations and downhole equipment. Only acid soluble inorganic scale will be discussed in this paper. These accumulations of hydrocarbons and inorganic scale cause a gradual decline in production which is often mistaken for the natural production which is often mistaken for the natural decline of a well. These same deposits also lower the injection rates of water injection wells. To obtain full production or injectivity capacity it is often necessary to remove the deposits.
Hydrocarbon removal techniques are numerous and may be divided into three categories:
Mechanical — scrapers and abrasives
Chemical — solvents and surfactants
Thermal — hot oil and heaters
All of these categories have been used commercially. Numerous paraffin inhibitors have also been used to help control the problem. Only the chemical removal techniques will remove an appreciable amount of hydrocarbons from within the rock matrix. Solvent removal differs from surfactant removal in that the solvents dissolve hydrocarbons while surfactants only disperse hydrocarbon deposits.
