支撑剂单颗粒沉降速率与线性胶压裂液黏弹性关系

通过线性胶压裂液中的单颗粒支撑剂静态沉降实验,研究黏弹性对支撑剂沉降速率的影响,并尝试用线性胶压裂液内部结构的表征解释所得结论。结果表明,支撑剂单颗粒沉降速率都随着黏弹性模量的增大而减小。对于羟丙基瓜尔胶HPG和纤维素FAG-500线性胶,以黏性为主,耐高温聚合物XST239线性胶黏性和弹性相当,此3种液体悬砂能力是黏性和弹性综合作用的结果,所以与复模量G*拟合相关系数最高,拟合结果分别为lgu=-1.6928 lgG*+0.2468、lgu=-0.9214 lgG*-0.1824、lgu=-0.8307 lgG*-0.2132。低浓度速溶黄原胶XCD溶液以弹性为主,支撑剂沉降速率由弹性模量决定,lgu=-2.0426 lgG'-0.1286,场发射冷冻扫描电镜FE-SEM表征分析表明,XCD液体内部为蜂窝结构,XST239液体内部是非常密集的片层结构,HPG和FAG-500液体内部为疏松的片层结构。

Study on Relationship between Sedimentation Rate of Single Proppant Particle and Viscoelasticity of Linear Colloid Fracturing Fluid

The effect of viscoelasticity of thickening agent solution on the sedimentation rate of proppant particles was studied through static sedimentation test of a single proppant particle in the solution of thickening agent used in linear colloid fracturing fluids.Effort was made to explain the study results using characterization of the internal structure of the linear colloid fracturing fluid.It is understood that the sedimentation rate of a single proppant particle decreases with increase in viscoelastic modulus.Some linear colloids, such as hydroxypropyl guar gum(HPG) and FAG-500, a cellulose, appear to be more viscous, while XST239, a high temperature polymer, has viscosity that is equivalent to its elasticity.The sand suspension capacity of these three thickening agents is a mixture of the function of the viscosity and the elasticity of these agents, and thus has the maximum fitting correlation coefficient with the complex modulus G*.The fitting results are:lgu=-1.6928 lgG*+0.2468, lgu=-0.9214 lgG*-0.1824, lgu=-1.6928 lgG*+0.2468, lgu=-0.8307 lgG*-0.2132.Low concentration XCD solution is more of an elastic solution, and the sedimentation rate of proppant particles is determined by the elastic modulus of the solution:lgu=-2.0426 lgG'-0.1286.Characterization by FE-SEM shows that XCD solution has honeycomb structures inside it, and XST239 solution has dense lamellar structures in it, while in HPG and FAG-500 solutions, there are loose lamellar structures.