FRACTURING FLUID (GUAR POLYMER GEL) DEGRADATION STUDY BY USING OXIDATIVE AND ENZYME BREAKER

Hydraulic fracturing commonly refered to as fracking is a proven technology
to enhance productivity and maximize recovery in oil and gas wells. Hydraulic
fracturing method is ahnost the same as frac pack but differ in term of treatment
purpose. Frac pack is aim for sand control while hydraulic fracturing is to stimulate
the well. The fracturing fluid used in hydraulic fracturing or frac pack contain a
chemical breakers to reduce the viscosity of the fluid intermingled with the proppant.
Chemical breakers reduce viscosity of the guar, polymer by cleaving the polymer into
small-molecular-weight fragments. The reduction of viscosity will facilitates the
flowback of residual polymer providing rapid recovery of polymer from proppant
pack. Ineffective breakers or misapplication of breakers can result in screenouts or
flowback of viscous fluids both of which 9ail significantly decrease the well
productivity.
Breaker activity of low to medium temperature range oxidative and enzyme
breaker systems was evaluated. ViCon NF an oxidative breaker (Halliburton product)
and GBW 12-CD an enzyme breaker (BJ Services product) were used in this project
with the main objective to study on the degradation pattern of fracturing fluid (guar
polymer gel) as a function of time, temperature and breaker concentration itself. This
paper provides a guideline of how to mix the fracturing fluid, the compositions of the
fracturing fluid, and how to conduct the crosslink and break test. Crosslink test gave
the optimum crosslinker concentration to produce good crosslink gel and the break
test gave the characteristic of the gel during degradation process and also the break
time. Besides relying on the laboratory experiment, information obtained from
research on SPE and US Pattern papers were \)Sed to make a comparison study on
oxidative and enzyme breakers properties.
Degradation pattern observed from the break test showed that reduction in gel
viscosity depends on time, temperature, and breaker concentration. Also, for enzyme
breaker, increasing temperature does not mean more reduction in viscosity.
Observation from experiment also revealed that small concentration of enzyme
breakers provides rapid break compare to oxidative breakers.