The plugging performance of preformed particle gel to water flow through large opening void space conduits

Preformed particle gels (PPGs) is a diverting agent that is used to solve the conformance problem in low permeability rich oil zones. It is injected to reduce thief zone permeability and then divert displacing fluid into poorly swept zones. However, PPG propagation and plugging mechanisms through heterogeneous void space conduits (VSC) still remain unpredictable and sporadic. This study examined the effect of gel strength and conduit heterogeneity on PPG plugging performance to water flow. Tubes with different internal diameters were used to emulate different sizes of VSCs. Two conduit models were designed, including (1) a uniform conduit diameter model and (2) a non-uniform conduit diameter model. Gel particles decreased uniformly the permeability across the conduit, and their plugging performance to water flow decreased when gel strength decreased. Gel particle injection pressure increased substantially when the conduit became heterogeneous. Some gel particles accumulated at the choke point and some passed through. This propagation mechanism caused a significant rise in PPG resistance to water flow. In contrast to the uniform conduit diameter experiment results, gel plugging performance to water flow improved when the gel strength within non-uniform conduit model reduced. The increase in plugging performance was caused by conduit diameter heterogeneity and increasing gel particle sizes. This paper demonstrates important impact elements of gel propagation and water flow for different opening conduit situations.