Research and Successful Field Application of Nanosilica System for Gas Shutoff in Horizontal Well

Abstract

Abstract Innovative and cost-effective gas shutoff technologies are required to improve the oil recovery and avoid the problems associated with the unwanted gas production. A novel strong and stable material with controlled gelation time was developed to isolate gas production zones over a wide range of parameters including the temperature, pressure, injectivity duration, and flow rate. This paper details the nanosilica for gas shutoff from laboratory development to successful field treatment. The nanosilica technology is composed of modified nanosilica and an activator which is used to trigger the viscosity of the system. The gelation time and gel strength of the nanosilica in presence of different concentrations of the activator have been investigated. In addition, the impact of the temperature on the gelation time was examined. The gas shutoff field treatment was designed to prevent the gas production from horizontal oil well based on the results obtained in the laboratory at comparable conditions. Laboratory results revealed that the two-component system namely the modified nanosilica and the activator exhibits low viscosity i.e. 6 cp prior to the exposure to high temperature. Once the temperature is increased to certain values, the viscosity of the mixture will increase depending on the concentration of the activator such that the start point of colloid-gelling ranged from a few minutes to several hours at a given temperature. Thus, this fluid system can be placed as a single phase, low-viscosity solution into the targeted formation zones and subsequently gelled inside the formation resulting in complete plugging. For the job design, production logging tools were run on the E-coil string to detect the gas source and measure the bottomhole temperature required for the formulation of gas shutoff nanosilica, and also to measure the injection pressure to monitor the injectivity. The objective of this job is to isolate the 980 ft. of stand-alone screens. Results unveiled the great potential of nanosilica as a gas-shutoff approach to mitigate gas intrusion with a sustainable 65% gas reduction compared to pre-treatment results. The new trend of using eco-friendly and nanoscale particles in gas control applications is a breakthrough in the oil industry. Laboratory results and field data revealed that the nanosilica for gas shutoff was effective over a wide range of parameters including the temperature, pressure and permeability.