Abstract: The effect of various chemical or biological agents in well treatment fluids can be delayed by sequestering the agents in the discontinuous phase of an emulsion for a period of time, before the emulsion is destabilized by exposure to at least one of: (1) a change in temperature, (2) a change in pH, (3) a change in salinity, (4) a change in alcohol concentration, (5) a change in stabilizing surfactant concentration, (6) a change in organic ion concentration, (7) a change in destabilizing surfactant concentration, (8) a change in surfactant adsorbent material concentration, (9) an ultrasonic pulse, and (10) an electrical field. Upon exposure to the emulsion destabilizing condition, the agent sequestered in the discontinuous phase of the emulsion is released into the continuous phase of the fluid composition, where it can have its intended effect.

Abstract: The crosslinking of galactomannan gum fracturing fluids by borate ion is delayed for high temperature applications by completing boron in a basic solution with an organic polyol. Low pumping friction pressures are achieved by the delay in the crosslinking with the boron being available at high temperatures to add high temperature stability to the fracturing fluid at temperatures ranging upto about 300.degree. F.