Formation Preconditioning With CO_2 To Improve Sandstone Acidizing

摘要

Acidizing oil wells in sandstone formations often causes a variety of problems, ranging from unwanted stimulation of water and inadequate productivity improvement to upsetting of surface separation facilities. A simple but effective change in the procedure for conducting such treatments can remedy these problems. That change involves displacing the oil from the zone to be acidized with a miscible gas, typically CO_2. Such displacement, often called preconditioning the formation, prevents interaction between the acid, its byproducts, and the resident oil. Early results with this treatment indicate less stimulation of water, reduced emulsion separation problems at the surface, and a greatly improved productivity response.