Nitrogen and carbon dioxide have proved to be very effective production tools. In many fracturing and acidizing jobs, the use of one of these inert gases along with the stimulation fluid has improved the efficiency of the treatment, and sometimes made the treatment possible.
A review of case histories of many jobs using nitrogen and carbon dioxide as completion aids shows clearly the value of this technique as it is presently being used.
Before nitrogen and carbon dioxide could be put to use by the oil industry, it was necessary to develop special equipment that could move and handle them in the field. Now that this has been done, research efforts are being directed toward finding out more about the effects of these gases under simulated reservoir conditions so that present treating techniques can be improved even further.
As early as January, 1938, portable well-service equipment was available for supplying limited quantities of low-pressure (100 psi) gas to aid in well-stimulation treatments.
Although the use of compressed gas increased the efficiency of acid stimulation treatments, use of the portable compressors limited this application to low-pressure wells where a low-rate treatment or a low gas-to-acid ratio was sufficient to help in return of the spent-acid solutions. High-pressure wells could be treated by this method only when a source of high-pressure gas was close to the well being treated. The weight and cost of a portable high-pressure, high-volume gas compressor for general field service made such a unit impractical.