New Experiments and Models for Conformance Control Microgels

Water management in mature waterflooded reservoirs is a top priority to push more oil out and control water production. Excess water production through fractures and high permeability thief zones is a growing concern for sweep efficiency and oil production. Gel treatment has been applied widely to plug thief zones and reduce excess water production to improve macroscopic sweep efficiency. Field studies demonstrated that gel treatments can be applied successfully in mature and fractured reservoirs to reduce unwanted fluid production to lower the operating cost causing premature well abandonment. The primary objectives of this work are to conduct laboratory work to understand the transport and propagation of microgel and develop conformance control reservoir simulator to help in screening oil reservoir targets for effective particle gel applications to improve sweep efficiency and reduce the water production. These microgels can be injected as a suspension in water into an injection well. Many experiments were performed to understand the transport mechanism of microgels through porous media and to identify the control variables. The lab data include oil recovery, water cut, resistance factor, residual resistance factor, oil viscosities, gel concentrations, salinity, gel rheology, and gel strength. The success of gel treatment depends on the magnitude of permeability reduction and flow diversion. We have developed correlations for resistance factor, residual resistance factor, and apparent viscosity as a function of gel strength, gel concentration, rock permeability, salinity, and flow rate. The models are validated against lab measurements and implemented into a reservoir simulator called UTGEL. Gel properties such as rheology and adsorption are also investigated. The mechanistic models and numerical tool developed will help to select future conformance control candidates for a given field and to optimize the gel chemistry and treatment