Evaluation of Preformed Particle Gel for Conformance Control Treatment using Static and Dynamic Experiments

PPG with mesh size 40-50 in 100-time diluted sea water, showed the maximum swelling capacity. Presence of 0.8 wt% nno silica in the geAInjection of preformed particle gels (PPG) into fractured reservoirs is one of the most effective methods in reducing unwanted water production and increasing oil recovery. In this research, a sample of PPG has been synthesized by free radical polymerization method, and its performance for the conformance control has been evaluated. The swelling capacity of the synthesized gel has good stability against the desired conditions of temperature, salinity, pH and the presence of carbon dioxide. Also, due to the presence of hydrophilic organic groups, the interactions of oil and formation water lead to an increase in the swelling ratio of gel particles. The plugging performance of synthesized PPG samples in fractures was also investigated by the Hele-Shaw Cell system. The gel network placed in the fracture create a new porous media with far less permeability than the initial fracture. The ability of the gel to maintain the permeability of this formed porous medium depends on the flow rate and salinity of the secondary water injection, as well as the size of the gel particles. Secondary water injection into the fracture after gel placement, forms wormhole-like paths for flow of water through the gel network, and the higher the injected flow rate results in the lower resistance of the gel network against water flow. Gel particles with a matching size ratio (the ratio of the diameter of the swollen gel particles to the width of the fracture) less than 2.9, increase resistance to the water flow with increasing in their size, but the particles with a matching size ratio of 2.9 or higher, reduce the resistance to water flow due to network breakdown. Comparing this value with some of the previously published data, it seems that the critical matching size ratio is independent on gel properties and injection conditions. Finally, the effect of gel treatment in reducing water production and increasing oil recovery has been investigated in the fractured micromodel. The gel particles plugged the fracture and the secondary injected brine was sufficiently diverted towards matrix, so the oil recovery factor from matrix in subsequent water flooding increased by 65%.structure enhanced the stability of the synthesized PPG samples, in the high salinity brines and in the presence of the CO2. Presence of water-soluble fractions of oil, leads to 6 unit increase in the swelling ratio of gel particles due to the hydrophilic nature of these organic groups. The gel network placed in the fracture create a new porous media with far less permeability than the initial fracture. The ability of the gel to maintain the permeability of the formed porous medium depends on the flow rate of the secondary water injection, salinity and the size of the gel particles. Secondary water injection into the fracture after gel placement, opens wormhole-like paths for moving through the gel network, and the higher the injected flow rate, the lower the resistance of the gel network against water flow. Gel particles with a matching size ratio (the ratio of the diameter of the swollen gel particles to the width of the fracture) less than 2.9, increase resistance to the water flow with increasing in their size, but the particles with a matching size ratio of 2.9 or higher, reduce the resistance to water flow due to particle breakdown. This critical matching size ratio is independent of gel properties and injection conditions. The gel network swollen in more salinity has a higher resistance to water flow, while the secondary low salinity water injection, although it reduces the gel strength, but leads to an increase in the resistance of the gels to water flow. In the fractured micromodel test, the oil recovery factor from matrix increased from 29% in the primary fooding to 94% at the end of the secondary flooding.