SUBSTANTIATION USE OF INORGANIC WATER SHUTOFF COMPOSITION FOR INCREASING OF DISPLACEMENT EFFICIENCY IN RESERVOIR OF FRACTURED-POROUS TYPE

Abstract

The workis devoted to issuesof development of fractured-porousoil reservoirs. Discrete systems(caverns andfissures) have a significant impact onfiltering in them due to increased filtration characteristics in comparison with the matrix of the rock, so the process of displacing of oil by oil field or injected water is carried out faster. As a result, the water begins to enter the hole through fractures without performing useful work. In these conditions, technical and economic efficiency of development largely determines the timely and proper conduction of operations connected with the restriction of water flow to wells. For water suppression in fractured-porous reservoirs we have designed gell-forming water shut-off composition based on sodium silicate, as the initiator of gelation we used inorganic chromium salt (III). The mechanism of gelation of the composition is following: due to the process of polymerization of silicate anions through the reaction with cations of chromium a three-dimensional atomic chain are formed in the whole volume of the initial composition. The water shut-off composition has a wide range of adjustable time of gelling and strength (due to addition of different amount of cross-linking agent).There is dependences of the strength and time of gelling of water shut-off composition by the temperature that helps to quickly determine the optimal concentration of reagents for specific geological conditions. The effectiveness of the composition is confirmed by results of filtration experiments conducted on samples of natural core with modeling of thermobaric conditions. Proposedwater shut-off composition reduces the water cut of the displaced liquid by 24% and increase the rate of displacement of oil by water in fractured porous reservoir from 0.07 to 0.3.