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本文从PAM水溶液在多孔介质中流动时的流变学特征出发,提出了超高分子量的PAM水溶液具有较低的γ值,可能是理想的渗透型压裂液。但是,超高分子量PAM难于合成和易于机械降解,使其不能在实际中得到应用。而化学剂交联的PAM水溶胶由于分子中存在着部分交联桥键,又容易制备,是实际上可以使用的理想的渗透型压裂液。然而,PAM化学交联产物并非全是溶胶,总是含有凝胶,并随着凝胶合量的增高,不仅改变其流变特征,而且也改变压裂液的渗透性能,使之向非渗透型过渡。因此,对PAM压交联产物中溶胶和凝胶含量的测定及分配理论的讨论,对制取优良的PAM压裂液是十分重要的。 本文自行设计了一个自动落球粘度计,用之测定交联过程中的凝胶点qc。并用萃取法测定溶胶分数和S凝胶分数G。然后对qc、S和G进行理论处理,得到了溶胶和凝胶分配方程式的简化式。进而用该简化式对起始线型PAM的分子量特征与交联产物中溶胶分数S的关系进行讨论,从而对正确选择起始线型PAM以获得优良的渗透型压裂液给予理论指导。
In this paper, based on the rheological characteristics of PAM aqueous solution flowing in porous media, it is proposed that the ultra-high molecular weight PAM aqueous solution has a low γ value and may be an ideal osmotic fracturing fluid. However, ultra-high molecular weight PAM is difficult to synthesize and easy to mechanical degradation, so that it can not be applied in practice. The chemical cross-linked PAM hydrosols due to the existence of a part of the cross-linked crosslinks in the molecule, but also easy to prepare, and can actually be used as an ideal osmotic fracturing fluid. However, the chemical crosslinked PAM products are not all sol-gel and always contain gels. With the increase of gel content, not only the rheological characteristics but also the permeability of the fracturing fluid are changed, Transition Therefore, the discussion on the determination of the content of sol and gel in PAM cross-linked products and the theory of distribution are very important for the preparation of excellent PAM fracturing fluid. In this paper, an automatic falling ball viscometer was designed and used to determine the gel point qc in the crosslinking process. The sol fraction and S gel fraction G were determined by the extraction method. Then the theoretical treatment of qc, S and G, sol and gel distribution equations simplified. Furthermore, the relationship between the molecular weight of the starting linear PAM and the sol fraction S in the crosslinked product was discussed by using the simplified formula, which provided theoretical guidance for correctly selecting the initial linear PAM to obtain the excellent infiltration fracturing fluid.