| The paper starts with analyzing the action mechanism and the performance requirement of gelling acid and combines with the current research situation of gelling agent at domestic and overseas as well as the molecular design theory of polymer, chooses acrylamide (AM) as the main monomer, and diallyl dimethyl ammonium chloride (DMDAAC) and2-Acrylamide-2-methylpro panesulfonic acid (AMPS) as the modified monomer which contain heat and salt resistance group, and then employs solution polymerization (SP) and inverse emulsion polymerization (IEP) synthesizes two kinds of zwitterions polymer (CHJsp and CHJIEp) which used as the acid gelling agents.Based on the orthogonal experiments, the paper partly discusses the effect of each polymerization’s condition (such as the concentration of initiator, temperature, time, pH of solution and monomer ratio etc.) on intrinsic viscosity of gelling agent CHJsp by means of single factor analysis, thereby optimizes the synthesis conditions is that:the concentration of initiate is0.5%and the mole ratio of potassium peroxydisulfate and sodium hydrogensulfite is1:2, the concentration of monomer is8%and the ratio of monomer is7:1:2, the pH is7at the temperature is40℃under the condition of nitrogen for5hours. For convenience of preparing the acid system and avoiding the purification problem of solution polymerization, the experiment employs inverse emulsion polymerization to synthesize the acid gelling agent CHJIEp, then analysises and chooses oil phase and emulsion system, the paper analyses and discusses the effect of the concentration of emulsifier, monomer and initiator, the ratio of oil and water, the polymerization temperature, time and the ratio of monomer on the intrinsic viscosity of gelling agent CHJIEP by means of single factor analysis, thereby optimizes the polymerization condition is that:the oil phase is5#white oil, the emulsifier is the compound system of Span85and Tween80(the ratio is1:3) and the concentration is3%, the concentration of monomer is40%and the ratio of monomer is7:1:2, the ratio of oil and water is1:3, the concentration of initiate is0.7%and the mole ratio is1:2, the pH is7at the temperature is45℃under the condition of nitrogen for6hours. Furthermore, the chemical structures of these polymers are characterized by FT-IR which shows that the three monomers copolymerized and the products are the target objects.Referring to the People Republic of China petroleum natural gas profession standard SY/T6214-1996"the evaluation method for acid gelling agent", this paper evaluates the performance of acid gelling agent CHJsp and CHJIEp separately which indicate that the synthetic gelling agents have a short dissolve time, especially the CHJIER’s dissolve time is only6mins, and strong ability of thickening,1.0%CHJsp gelling acid’s viscosity is more than96mPa’s while the2.0%CHJIEP gelling acid’s viscosity is84mPa’s. And that the gelling acids have a good rheology performance (heat resistance and shear retardant) and obvious retarding performance, the thermo and shear stability are more than70%. Besides, the gelling agents have a certain salt resistance and a good chemical compatibility with various acid liquors and additives, and the lower surface tension of spent acids is beneficial to flowback. Comparing PAM gelling agents, CHJ has a significantly improved heat resistance and retarding performance, especially in high temperature condition. Even if comparing with other decent acid gelling agents at home and abroad (CT1-6, DSGA and SGA-HT), the CHJ gelling agents also indicates a good performance in thermo stability and retarding performance. |
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