Synthesis And Performances Of Novel Clay Stabilizer

Clay stabilizer is a kind of common oilfield chemicals.when it is not compatible between the clay minerals and the extemal fluid of oil-gas level at oil exploiting operation,clay stabilizers can effectively restrain the clay minerals in formation from hydrating expansion and dispersing migration.But the clay stabilizers of high molecular weight will damage the low-permeability reservoir.Therefore,the development of clay stabilizer of small molecular weight adapted to low permeability reservoir becomes a top priority.A kind of dendritic clay stabilizers of low molecular weight were synthesized for low-permeability reservoir in this paper,while the stabilizing performance and the relationship between structure and performance were studied.Firstly pentaerythritol chloroacetic acid ester was synthesized in this paper,the type of catalyst and cyclohexane was screened.The result shows that it has advantages of poor corrosion,high yield and purity of the product when NaHSO₄·H₂O as catalyst and petroleum ether?60⁹0??as cyclohexane.The optimum reaction conditions of pentaery-thritol chloroacetic acid ester are as follows:the quality of NaHSO₄·H₂O 64.43%,the molar ratio of chloroactic acid to tetramethylolmethane 5.2:1,reaction temperature 80?,reaction time 4 h,the quality of cyclohexane 63.7%.Then the yield reached 92%.The product was characterized by ¹H-NMR and IR.PE-n were synthesized with the homemade chloroacetic acid pentaerythritol ester and triethylamine,dimethyl essien alkyl tertiary amine,dimethyl dodecyl tertiary amine respectively,which is a kind of dendritic ester quaternary ammonium salt clay stabilizer;At the same time,alkyl betaine hydrochloride were synthesized by chloroacetic acid with trimethylamine,triethylamine respectively.The products were characterized by ¹H-NMR and IR.The optimal reaction conditions of PE-3 are as follows:reaction temperature 82?,reaction time 4 hours,the quality of solvent 64.43%,the molar ratio of triethylamine to pentaerythritol chloroacetic acid ester 5.2:1,then the yield reached 96.5%.In the above reaction conditions,the yield of PE-8 and PE-12 can reached 90%using acetone as solvent.According to“SY/T5971-94,clay stabilizing agent injection performance evaluation”,the performance of products including anti-swelling and compatibility was evaluated.The results show that the anti-swelling rate of PE-3 was higher than 90%when the mass concentration was 1%.At the same time,the agent had good anti-swelling durability.After flushing 10 times with water,the anti-swelling rate of the products almost unchanged.The anti-swelling rate of Betaine hydrochloride is not far from KCl while the anti-swelling durability has obviously improved.When PE-3 and Diethyl betaine hydrochloride were at a ratio of 2:1,the anti-swelling rate reached 94.3%.In addition,from the performance evaluation of heat-resistant,formation water compatibility and the recovery rate of cuttings on comprehensive evaluation of stable performance,it proved that the homemade clay stabilizers had the better expansion-prevention effect and broad application prospects.The further study of the structure-function relationship founds that betaine hydrochloride whose chain is short has better stabilizing performance but worse anti-swelling durability compared with PE-n.With the increase of the length of the branched chain,the anti-swelling rate of PE-n decreased.The analyzing the surface tension and contact angle of the products indicates that PE-3 cannot change wettability of the clay.So it is suitable for clay stabilizers.But PE-12 with strong surface activity is unfitable for clay stabilizer.By further analyzing the electron microscopic scanning figure,PE-n has better stabilizing performance because of the dense membranes on the clay formed by its dendritic structure.