Oil and gas wells produce crude oils containing substantial amounts of asphaltenic and/or paraffinic hydrocarbons that accumulate on the walls, casing, tubing, etc. of wells and drilling equipment. In addition, deposits of acid-soluble material, such as calcium carbonate or clays, clog the wells and related equipment and slow down production. These deposits can become coated with the asphaltenic and/or paraffinic hydrocarbons. Accordingly, effective clean up requires a solvent that will strip off the hydrocarbons and thereby allow the deposits to break loose and move out of the well. Various techniques have been employed for the removal of deposits including the use of a mutual solvent in combination with an aqueous acidic solution. The mutual solvent is used to remove the asphaltenic and/or paraffinic hydrocarbons while the acid solution removes the acid soluble material. For example, a process wherein a mixture of an octanol and a lower alcohol is used with, ahead of or behind aqueous acid solutions to acidize oil wells is taught by U.S. Pat. No. 3,819,520. The alcohols taught by this patent, however, are not very good at dissolving or stripping asphaltenic hydrocarbons.
A solvent system for use in oil and gas wells which readily strips or dissolves asphaltenes is described by U.S. Pat. No. 5,152,907. The solvent system comprises a hydrocarbon solvent, a substantially water-soluble alcohol, and a substantially oil-soluble alcohol. However, due to growing health and safety concerns there remains a need for a system that readily dissolves or strips paraffins and asphaltenes and which avoids the use of hydrocarbons. The present invention answers this need.