| The study on clay stabilizing agent can be divided into three periods, from the 1950s to the late 1960s the inorganic salts were mainly used to stabilize clay of the formation. In the 1970s, inorganic multinuclear polymers and cation surfactants were used. And since the 1980s the study and experiments on cationic organic polymer stabilizing clay had been mainly carried out. According to the character of cation polymer, organic polymer for stabilizing clay can be divided into three types: main chain type, that is, the cation lies on the framework of the polymer. Side chain type, that is, the cation lies on the side of the polymer chain. Complicated annulus type, that is, an annulus lies on the framework of polymer and the cation lies on the annulus. The application of clay stabilizing agent as a technical measure to protect oil formation started from the early 1990s in Daqing oil field, And publicized in the late 1990s.The actions of clay stabilizing agent to protect oil formation are to prevent clay particles from hydrating swelling and scattering migration which will block flowing porous canal, which would result in decline in permeability and influence the exploitation of oilfield. In this paper we take the synthesizing technique of clay stabilizing agent as a research object and start from analysis of clay electrical property,reasons of water-sensitiveness of formations and the relationship between clay types and water-sensitiveness. The emphasis is on the synthesis and preparation of the main chain type clay stabilizing agent that is made from epoxy chloropropane . From laboratory experiments we have found the optimum polymerization reaction time,temperature,amount of initiator and monomer molar ratio in the synthesis of PTA clay stabilizing agent. The data we gained from the laboratory experiment indicate that PTA has favorable ability of prohibiting clay hydrating swelling and is an ideal long term-effective clay stabilizing agent. The PTA has been applied on the job site on the basis of laboratory experiments of crude mineral cores. By the end of 2003, the fifth factory extraction of Daqing oil field had treated 717 wells via applying PTA to protect oil formations and raised the productivity of new oil wells effectively, enhanced the recovery of oil formation, improved the exploitative effect of oil field and gained great economic profit. On the basis of application of synthesizing technological study of clay stabilizing agent we have drawn the conclusions as follows:(1)The cation clay stabilizing agent (PTA) is made from epoxy chloropropane and dimethylamine. Its optimum reaction time is 5h,temperture is 65℃, amount of initiator is 1.0% and molar ratio of unit volume is 1.5:1.(2)The PTA has favorably protective behavior for the mineral cores of Xingnan oil field in Daqing. The recovery ratio of debris is greater than 95%, the swelling ratio of clay is less than 3%, the decline ratio to core permeability is less than 10% and it has good persistence comparing with KCl and NH4Cl.(3)By means of actions of its surficial positive charges and intermolecular forces, the PTA can be absorbed on the surface of clay particles to prevent clay mineral from hydrating swelling.(4)The practical application indicates the PTA perforating fluid can improve producing fluid intensity of oil well of 0.9t/d.m, enhance injecting water intensity of water injecting well of 3.31 m~3/d.m.After oil formation protecting measures were adopted ,the skin factor of oil well decreased 0.22 and the completion factor of oil well has been well improved. (5)The effect of using complex formation protecting agent is much better than using clay stabilizing agent alone .The gross and effective net pay thickness ratio of water injecting profile in injection wells has improved 26.0 and 7.3 separately.
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