New Technology for Improving Water Flooding Efficiency by Adjusting Advantage Channels

Underground cross-linking profile control and water shutoff and deep fluid flow to chemical agent system are usually composed of main agent, cross-linking agent and additives. The cost of cross-linking agent and additives generally accounts for 30–50% of the total cost of the system. Many inorganic salt ions are widely used as cross-linking agent or additives. In this paper, using Ca2+ and Mg2+ scale forming ion source in CaCl2 water type oilfield high salinity formation water (as water injection) as crosslinking agent, cross-linking of original inorganic microgel is carried out to reduce the cost of steering agent. The formation of nano microscale inorganic microgel with density similar to that of environmental water source can be formed by cross-linking of the steering agent with scale forming ions in formation water. The microgel can be dispersed or suspended in water, and gradually adsorbed on the rock skeleton of the dominant channel such as hole or crack to form a micro gel coating in order to narrow the flow dominant channel and form resistance to flow. The passage of plugging does not die, achieving the purpose of adjusting the dominant channel, expanding the volume and improving the efficiency of water flooding. At the same time, the particle size of the micro gel can prevent it from entering the low permeability matrix to contaminate the oil layer. The diversion agent has the characteristics of rapid dissolution, temperature resistance, salt resistance, environmental protection, long-term effectiveness and no construction risk. Field tests of deep profile control and flooding have been carried out in reservoirs with different temperature and salinity at home and abroad. After profile control diversion in test blocks or well groups, the effect of improving water flooding is good. The average increase of water injection pressure is 2–3 MPa, and the effective rate of increasing oil production and precipitation in oil wells is more than 80%, and the validity period is less than one year up.