Preformed Particle Gel Propagation Through Super-K Permeability Sand and Its Resistance to Water Flow During Conformance Control

Abstract

Abstract Excess water production has long been considered a major problem leading to the life-shortening of oil and gas wells and operational problems. High-permeability streaks, fractures, conduits, and fracture-like features can expedite an undesirable water channeling and early water breakthrough during water flooding. Preformed particle gel (PPG) is one of the commercial gels invented exclusively to plug such features to reduce excess water production, improve sweep efficiency, and increase oil production. This paper reports the results of laboratory experiments that studied the PPG's injection and placement mechanism through Super-K permeability cores to reduce unwanted water production and increase oil recovery. Extensive experiments were conducted to examine the effect of the sand permeability, PPG size, concentration, and water salinity on the PPG injection process, passing criteria, and plugging efficiency to water flow. A two foot sand pack model with four pressure taps was designed to monitor PPG transport and plugging performance. The results showed that the PPG propagated deep into the sand pack. PPG's in-depth permeability reduction to the core was dependent on the PPG size, strength, concentration, and sand permeability. Fully swollen gel particles had better injectivity than partially swollen particles with a larger diameter size; particle strength was more dominant in influencing particle movement than was particle size. The injection pressure increased as the PPG concentration, water salinity, and gel particle size increased. A large injection pore volume was required for the PPGs to be produced at effluent when both the water salinity and particle size were increased and when the PPGs concentration decreased. PPG transport through Super-K permeability sand exhibited three patterns of injection processes based on both the threshold pressure and the injection pressure measurements across the sand pack cores: low gel particle retention and pass; high gel particle retention and pass; and high gel particle retention, breaking, and pass. After the PPG injection process was completed, cycles of saline water were injected into the sand pack to test the PPG's resistance to water flow. The PPG's blocking efficiency to water flow increased as the PPG strength, size, and concentration increased. The PPG placement mechanism, such as washout, was also found to considerably affect the water injection flow processes. The results of this laboratory experiment will aid in the selection of future conformance control candidates and also optimize the particle gel treatment design for large-scale field projects.