Successful Application of Foam Frac to Shallow Gas Sands

Abstract

Abstract The purpose of this paper is not to review previous papers and reports on foam fracturing, but rather to relate and review the job procedures and results of foam fracturing treatments in low bottom hole pressure reservoirs in shallow gas sands. pressure reservoirs in shallow gas sands. This paper covers the mechanical hookup, computer programs relating to job design, sand concentrations obtainable, foaming agents and their concentrations, and a system of accurately monitoring foam quality down stream. Conventional equipment can be used to provide up to 2 pounds sand per gallon of provide up to 2 pounds sand per gallon of foam, without viscosifying the water. Also, a differential density measuring system is available for monitoring foam quality as it enters the well. The basic downhole problems solved by this technique are those of fluid retention and formation damage by water-base fluids in these water sensitive and low pressure formations. Introduction Foam fracturing has survived a slow beginning and, because of its present success, has become an established technique for stimulating production from gas wells. The properties and rheology of foam have been discussed by many authors and will not be elaborated on any further. This type treatment has shown to be more effective in gas wells than oil wells. This is largely due to the fact the liquid hydrocarbons have a tendency to break the foam prematurely, and high concentrations of prematurely, and high concentrations of foaming agents tend to cause emulsion problems. Therefore, the two problems cause a "stalemate." In some reservoirs one chemical can be found to foam effectively at low concentrations without causing emulsions, and in some reservoirs small amounts of a demulsifier can be combined with a nonionic foaming agent. Many changes have been made in the treatment design in order to more accurately perform the treatment. perform the treatment.