Chemical Remediation of Excessive Water Production

Abstract

Abstract Excessive water production in oil wells diminishes their operational lifespan and presents notable technical and economic problems, including corrosion, less oil production, and scaling. These challenges are addressed with chemical techniques such as polymer-gel treatments and nano-silica which isolate water pathways within rock formations. These systems form gels upon contact with water but disperse when exposed to oil. The primary objective of this work is to develop polymer and nano-silica gels and compare their performance at reservoir conditions. In this paper, we conduct a comparative study of two systems used to remedy the wells with excessive water production. Rheology and visual inspection are employed to assess the gels and gelation time formed by both systems. Various formulations of emulsified polymer-crosslinker and nano-silica systems, are inspected through rheology and tested in core flooding experiments. The better emulsifier is selected and added before the polymer, to help in diverting the mechanism to the water zone. The emulsifier tends to form emulsion and raise the viscosity of the oil zone. Then the pH of the system rose followed by the addition of polymer and crosslinker. In the nano-silica system, the breakers and activators are assessed to get the efficient system used in the study. Improved systems are proposed and tested alongside oil to explore breaking mechanisms. Then, core flooding experiments were conducted at 94 °C, 2000 psi confining, and 400 psi back pressure to evaluate the efficiency of the old and improved systems. The visual and viscosity experiments identified the optimal concentrations of copolymer and nano-silica, tested both with and without oil, and suggested a better replacement. Based on the rheology results, appropriate concentrations of the activator and breaker were recommended for each temperature level to be used in core flooding evaluations. In these experiments, the selected concentrations significantly reduced water production across all types of core plugs tested. Following treatment, the emulsifier polymer crosslinker and nano-silica have a specific range of maintained structural integrity under varying temperatures and pressure differentials. The proposed system combination effectively inhibited water flow in different types of core samples by gelling the water zones and filling fractures and pores that directed water flow. Both proposed systems impede water flow while forming emulsions with oil, which allow the passage of oil. However, the long-term integrity needs to be assessed to have a better view of the system, besides the cost of the two materials. This study emphasizes the viability of different innovative systems as a practical chemical solution to manage excessive water production in oil wells with significant pore openings.