Abstract
Reservoir heterogeneity with high permeability zones attributed to channels, fractures, and large pore spaces can cause high water production in hydrocarbon producing wells. This paper investigates the performance of several particle-gel systems for near-wellbore (NWB) formation treatment to prevent or control the water production in mature oil fields. The particle-gel system consists of a polymer/crosslinker as the gel and silica flour as the particles that provide leakoff control. Fluid loss testing was conducted using sands of varying sizes and permeable filter disks, where the sand represents a gravel pack and the disk represents the formation. The filtrate volume was measured to determine the leakoff under different treatment and formation conditions. Effects of particulate concentration, pore space of the permeable filter disk, sand size, and temperature on the leakoff volume and the threshold-pressure, which must be overcome to initiate water flow, were studied. The experimental results reveal that filtrate loss decreases with increasing silica flour concentration and increases with increased pore size of the permeable filter disk, sand particle size, and temperature while the threshold pressure increases with increased silica flour concentration and decreases with increased sand particle size, pore size of the permeable filter disk, and temperature. Practical empirical correlations and charts are developed for fluid loss, pressure initiation for flow, and the critical silica flour concentration which can aid in selection of a suitable particle-gel system for effective NWB formation treatment. A methodology using these correlations and charts is presented for the design of optimal conformance control treatments for effective mitigation of water production in mature oil fields. A field case is also illustrated to demonstrate the importance of the developed empirical correlations in choosing suitable treatment fluids and evaluating the near-wellbore formation treatment under optimum application conditions.
