Water Plugging Performance of Preformed Particle Gel in Partially Filled Fractures

Preformed particle gel (PPG) treatment has been well-recognized as an efficient method to reduce excessive water production in fractured reservoirs. However, previous research on its plugging efficiency was mainly conducted in open fractures. In this paper, calcite-filled fracture models were designed to comprehensively investigate the water plugging performance of PPG in partially filled fractures which are extremely common in fractured reservoirs. Systematic plugging performance tests have proceeded under various calcite-filling conditions. The results show that the calcite particles can improve the breakthrough and retention of the PPG as well as the plugging efficiency. With increased size and concentration of the calcite particles, the PPG breakthrough pressure gradient increases, and the fracture permeability decreases. When the ratio of average calcite particle diameter to fracture width (R-C) is small (0.15), the fracture permeability is difficult to be further reduced by increasing PPG concentration or PPG size. However, when the R-C increases to 0.21, the plugging performance in fractures filled with more calcite particles or PPG particles, especially the latter, is better than that filled with larger calcite particles. This study provides new insight into the PPG treatment and will contribute to the water control in fractured reservoirs.