Composition Technique Of Polyacrylamide Used In Zirconium Gelling Fracturing Fluid Of Coalbed Methane

The polyacrylamide (PAM) can be used in zirconium gelling fracturing fluid of coal-bedmethane. But there are many requirements of its molecular weight, the number anddistribution of－COO－in its molecular chain. The synthesis craft of the right PAM can becontrolled by two temperatures. With using the acrylamide as synthesis monomer and the(NH4)2S2O8as the initiator, the polyacrylamide was prepared by the method of the waterysolution radical polymerization. The chain structure of the polyacrylamide can be controled.The effects of kinds of initiator, reaction temperature, the adding temperature of initiator,monomer concentration, reaction time, initiator amount, on the parameters of PAM wereinvestigated. Those parameters were characterized by molecular weight, degree of hydrolysisof PAM the and so on. Moreover, the relationship between the evaluating effect of PAM andsynthesis conditions is discussed by orthogonal experiment. The feasibility that the samplecan be used as the base fluid of fracturing fluid of coal-bed methane was characterized bycross-linking capability between polyacrylamide and zirconium species. The results showedthat the polyacrylamide can be synthesized by using ammonium persulfate as initiator andbeing controlled by two temperatures. Also the cross-linking capability between the productand zirconium species is good. The main factor to affect the molecular weight andcross-linking capability of the polyacrylamide was amount of (NH4)2S2O8. And degree ofhydrolysis of PAM was mainly affected by the reaction temperature.In order to study the reason that why Zr4+can be crosslinked with polymer in lowtemperature and the unflowable system is formed. According to the kinetics of gelationreaction, in order to control the time of cross-linking and the strenth of zirconium gel, thefactors influencing on the reaction including the structure and type, molecular weight,concentration, degree of hydrolysis of PAM, crosslinking ratio, concentration of H+areresearched. At the same time, the characteristic of Zr4+in the water was analyzed and thecrosslingking mechanisim which is the crosslinking of the multinuclear olation complex-ionof Zr4+with the carboxyl of PAM was proved.With using the evaluation criterion of the fracturing fluid of coal-bed methane, thecharacteristic of the zirconium gelling fracturing fluid had been investigated with optimal synthesis PAM as base fluid. The results showed that zirconium gelling fracturing fluid in lowtemperature has high capability of resistance to be sheared, good capability of sand-carryingand width generation and low fluid loss coefficient. zirconium gel can be broke in2hourswith redox system as gel breaker. The viscosity of the fluid was less than5mPa·s. There wasno residua after being broke. Zirconium gel can be easily made and use less additive and basefluid. It can be used as fracturing fluid of coal-bed methane.