## 3 Results
### Rheological Properties with Temperature Response Mechanisms in SFPDF
#### 3.4.3 Discussion of Rheological Properties with Temperature Response Mechanisms  
Based on microscopic analysis and rheological testing of the drilling fluids, Samples 4 and 6 were found to be primarily polysaccharide polymers. In aqueous solution, -OH groups on molecular chains of polysaccharide polymers can adsorb water molecules through hydrogen bonding. This increases the contact and internal resistance to friction between the molecules, giving them greater viscosity. Due to the added inhibitor, NaCl, the -OH group on molecular chain adhered to the -ONa group, and the adsorption of water molecules increased. At the same time, the addition of NaOH readily caused bonds in polysaccharide molecules to rupture, producing oligosaccharides. As the number of oligosaccharides increased, the point of contact between molecules and internal resistance to friction both increased. This made it easier for space truss structures to form, increasing the fluid viscosity and yield stress, and reducing the flow behavior indices. As temperature decreased, molecular kinetic energy decreased between polysaccharides, and the polysaccharide polymer crimps contracted. This reduces the production of the space grid structures, increasing viscosity, and weakening the rheological properties. In Sample 6, XC in water was added to the drilling fluid system. As a result, the polymer became capable of forming a double helix, which rendered the viscosity of the drilling fluid greater than that of the drilling fluid system containing KL (Sample 4).  
PAM has 3 million molecular weight. While this polymer has a linear main chain, its rheological test indicated it has very low viscosity. Analysis of PAM showed a very weak ability to resist degradation by salt; therefore, after the addition of a large amount of NaCl, the carboxylic acid group of the polyacrylamide molecule was blocked, causing the polyacrylamide molecule to take on a curly shape. This destroyed the polyacrylamide bridge and adsorption ability, thus, it was difficult to reach the original property.  
Adding GC to Samples 4-6 modified the rheological properties of the drilling fluid. The apparent viscosity of the three samples with added GC was higher than in the samples without GC, and the rheological properties were undesirable. GC is a polymer, and in the absence of chemical reactions, KL, PAM, and XC are adsorbed through hydrogen bonding and mutual electrostatic forces between the molecules; this allows the formation of longer molecular chains with greater molecular weight in the drilling fluid. As a result, a long molecular chains containing more chain segments can form. To realize the heavy molecular weight of the migrating particles, it is necessary to complete the correct number of chain segments to facilitate synergy. At the same time, the long molecular chains become more seriously entangled, which increases the flow resistance; therefore, the shear viscosity of the polymer  
Figure 6: SEM results of SFPDF containing the GC treatment agent. (**a**) SEM results of the KL polymer drilling fluid; (**b**) SEM results of the PAM polymer drilling fluid; and (**c**) SEM results of the XC polymer drilling fluid.  
increases, the liquidity degrades, and apparent viscosity increases. As the temperature decreases, the energy involved in the molecular kinetics also decreases, and the polymers form tighter curls, slowing down the formation of space grid structures. All of this renders the viscosity higher than under normal temperatures.