Formulation of an Emulsified Thermal Acid Blend for SAGD Applications in Eastern Alberta

摘要

Conventional emulsified acids composed of a strong mineral acid and an aromatic solvent, such as xylene, are commonlyused to stimulate both water injection and production wells. When this system is properly applied, it is effective in dissolvingorganic and inorganic deposits, and in stripping off layered scales that may be deposited onto the inner surface of the tubing.Until recently, application of this system has been restricted to conventional reservoirs: however, with proper compatibilityand corrosion testing, the emulsified acid system can be used to successfully stimulate thermal heavy oil reservoirs. Thermalheavy oil wells often exhibit significant calcite scaling on the long horizontal slotted liner, as well as an emulsion of low APIoil dispersed in an aqueous mixture. Previous treatments using 1% HCl acid or 5% Acetic have addressed the issue withscaling. However, the issue with the heavy oil emulsion remained unresolved. By using a high temperature emulsifiedorganic acid, both calcite scale and heavy organic deposits can be removed along the length of the slotted liner. 5% or 10%acetic acid emulsified in a 4:1 ratio with a modified wax and asphaltene solvent blend, in conjunction with a liquid organicacid corrosion inhibitor and an emulsifying surfactant, have proven to be an effective treatment in the remediation of scalesand build up of organic deposits. Also, the blend is designed to maintain sufficient corrosion protection despite the hightemperature environments that are characteristic of thermal heavy oil wells. This paper details the acid compatibility testingprocedure, corrosion testing, and subsequent analysis that were required to formulate this specialized acid blend.