Evaluation of New Techniques of Acidizing in Western Canada

During the period from 1960 to 1968, stimulation with acid has gainedprominence through the development and introduction of new acidizing techniquesin Western Canada. The benefits derived from these innovations are many andvaried. When put to proper use, these new acidizing techniques can producesubstantial returns on dollars invested in stimulation and may in certain casesmake the difference between a well being a commercial or noncommercial producer. Many new products and ideas havebeen tried, but only a limited number have gained a permanent place in thestimulation field. Acidizing with mixtures of acid and alcohol has beenaccepted because of better post-treatment cleanup of the formation. Use of thegases, nitrogen and carbon dioxide, in conjunction with acid treatments to givedeep acid penetration and fast cleanup with savings in rig costs has provedsuccessful. Treatments with high-strength hydrochloric acid provide a veryeconomical means to get deep acid penetration. Additional benefits are inherent in the use of each of these acidizingmodifications. Basic treatment costs are certainly a consideration whenchoosing a treatment, however they should not be emphasized to a degree whereobvious benefits are lost. Combining treatment technology, laboratoryevaluations, and well and reservoir information with past history, whenavailable, is an essential ingredient for good treatment design. INTRODUCTION THE USE OF AUXILIARY AIDS with acid treatments has steadily increased withthe expansion of this service. Many products and techniques have enjoyed ashort period of success in this field, only to be replaced as technicaladvances are made. Acetic acid is an example of a product that was used on manytreatments over a period of several years. This acid offers low corrosion rates and very slow reaction rates, but itscost is high when the reactive power of acetic acid is compared to HCI. Atpresent, it is being used on very few jobs. This does not mean that operatorshave gone back to using straight 15% HCI in place of acetic acid. The morelogical explanation appears to be that other auxiliary products have gainedincreased usage. The products briefly reviewed in this paper have gamed apermanent place in acidizing and their usage appears to be increasing. Athorough knowledge of available products for acidizing will assist operators inmaking the proper choice of treating solution for a particular well and candefinitely improve the return on dollars invested for this service.