Compact and transportable preparation center which can be used for fracturing operations on gas or oil fields, capable of metering out and dissolving two different polymers in the powder form, and including: two pneumatic mechanisms respectively supplying two storage hoppers for two separate polymers; two mechanisms for supplying and metering the polymer originating respectively from the two storage hoppers to a device for dispersing by grinding, also denoted PSU; two series of tanks for hydration and dissolution of the polymers connected to the dispersing and grinding device; two positive displacement vacuum pumps for metering the two solutions each originating from the two series of hydration and dissolution tanks and intended to supply a mixer itself connected to a high-pressure injection pump. Fracturing process employing the preparation center.