Abstract
This paper presents results of laboratory research conducted in the framework of a nano-emulsion technology piloting project for reduction of water production in mature sandstone oilfields offshore. Efforts of a technology developer, an oil and gas exploration and production (E&P) company and a petroleum research institute were put together to develop a fit-for-purpose piloting program. The offshore oilfields selected for the pilot are in the South of Vietnam. A laboratory part of program included list of experiments for testing physical and technological properties of the new product, a nano-emulsion called ESN which stands for Emulsion System with Nanoparticles. This new system is an inverse emulsion, whose nanoparticle augmented physical properties can be easily adapted for control of fluids flow in a wide range of reservoir conditions. A synergy from natural and artificial surfactants chemically intertwined with supercharged silicon dioxide nanoparticles brings to life a whole new scientific concept of the flow-control technologies for petroleum and geosystems industry. The ESN is an environmentally friendly technology used for advanced control of fluids flow subsurface. In this study, an application of ESN is aimed to selectively shut-off water zones within a profile of oil-gas well. The ESN consists of three liquid components: process or sea water, crude oil or diesel and nanoparticle-based surfactant. Implementation of the laboratory part of the piloting program resulted in a ready-for-pilot solution at reasonable cost and time. One of the main tasks of this research was to quantitatively demonstrate effectiveness of the unique features of ESN for selectively blocking water-bearing zones of sandstone reservoirs in Lower Miocene (2950 psi and 91°C) and Late Oligocene (3900 psi and 107°C) hydrocarbon formations. As a basic requirement from the E&P company, ESN had to be stable at said reservoir conditions and compatible with reservoir and process fluids. Besides that, the operator wanted to confirm that ESN is an easy-to-handle flow-control agent in the offshore environment, meaning that it can be prepared with ordinary equipment available at the vessel, all components must be liquids that can be easily mixed at ambient conditions, and properties of the ready-to-use composition do not change during operation. Thus, the laboratory program was executed in three successive stages: 1) ambient condition; 2) high pressure and temperature conditions; and 3) the reservoir conditions. As a result, a stable and reservoir-compatible ESN formulation that met all requirements set by the E&P company was quickly selected. In the series of core floods, it was confirmed that ESN selectively blocks predominantly water-saturated cores, while oil-saturated cores permeability drops slightly with clear tendency to full recovery under crude oil flow.
