Abstract
The primary aim of the research project was to develop such chemical systems, which triggered by mixing with water will form the blocking phase. As a novelty, water sensitive homogeneous solutions and water external microemulsions were developed, which are stable until they are diluted with water forming thus stable macroemulsions. Transformation of different metastable systems to stable ones in reservoir space having high water saturation may radically restrict the water flow through their high viscosity and entrapment of the dispersed particles by the pores. As dispersed phases organic silicon compounds, tensides and natural crude oil fractions were tested. The transformation and structure of phases and size of particles were analyzed by photon correlation spectrometry, rheometry, while the flow properties were studied in natural sandstone systems.
The core studies confirmed that all metastable systems reduce the flow of water by 80-90% in water-saturated sandstone. Using chemical-free postflush the flow resistance remains substantial against water in case of silicones; meanwhile the permeability deterioration against oil or gas is negligible. The metastable systems are effective and single step disproportional permeability modifying fluids.
The metastable systems may offer an excellent opportunity for water shutoff in matured oil and gas fields and gas storage facilities. The unique properties of the techniques are that flow resistance may occur only in water saturated reservoir space and in case of technical failure; the flow barrier can be eliminated by oil and gas injection.
