Study On A New Type Of Temperature And Salt Resistant Selective Plugging Agent

A large amount of produced water in oil production process has become a sevre problem.Oil well water plugging prove to be the inevitable course to improvethe production efficiency of the oil field.However,as for the high temperature and high salinity reservoir,the ordinary polymer water shutoff system is not good to fulfill its requirement,there are some problems in the process of water plugging,such as a short gelling time,poor thermal stability and a short effective time.Many temperature and salt and water blocking systems designed in domestic and foreign reserch can not be widely used because of the high cost,environmental protection,poor stability and other shortcomings.In order to solve these problems,a new plugging agent system has been developed in this paper.this plugging agent has the advantages of low cost,resistance of high temperature and high salinity,and the crosslinking agent polyethyleneimine in its system is environmental.The main content of this paper and several achievements made are as follows:(1)Based on the theory of chemical synthesis,initiation mechanism and crosslinking mechanism,the modification of acrylamide was proposed,and the anti-temperature and salt-resistant groups were introduced,and the comonomer suitable for the plugging agent system was selected.Two kinds of initiator and two kinds of crosslinking agents was picked out for the next preparation of research.(2)Through a large number of laboratory indoor synthesis experiments and preliminary screening evaluation,it was confirmed that the main components of the plugging agent system were acrylamide,t-butyl acrylate and 2-acrylamide-2-methylpropanesulfonic acid Meta-polymers were screened to optimize the initiator,crosslinker and oxygen scavenger and stabilizer in the plugging agent system and to determine the optimum concentration of each component.(3)The new temperature-resistant and salt-tolerant water-blocking agent was evaluated in this paper.The effects of temperature and salinity on the gelation properties were studied.The time of gel formation of the plugging agent becomes shorter with the increase of temperature,and the gelation time is 10 hours at 100 ?,and the formation time of the plugging agent is prolonged with the increase of the degree of mineralization.High salinity reduces gel strength.In general,the water shutoff agent system maintained a high strength at 100 ? in a high salinity salt of 13 × 104 and had a thermal stability time of more than 90 days.(4)An indoor core flow experiment was conducted.The viscosity retention rate of this water blocking agent is over 80%and it has a good shear resistance.The resistance coefficient of the water shutoff agent is 1.04,so its injection property is good.For cores of different permeability,high temperature water shutoffers have a good plugging effect,the matrix core blocking rate reaches 99.5%or more;with the increase of the water shut-off injection volume PV,the blocking rate of water shutoff agent on the core decreased,but the range of this reduce is small,not more than 1%,water-blocking agent has good scour resistance.