非加重改性天然高分子基钻井液体系的流变性

研究非加重改性天然高分子基钻井液处理剂和体系的流变性有益于对其进一步研究和推广应用。实验测定了IND30、NAT20、NFA25加入4％膨润土基浆中配制的悬浮液，在1022s^-1、511s^-1、340．7s^-1、170．3s^-1、10 ．22s^-1、5．11s^-1等6个剪切速率下的剪切力，以及钻井液体系在相同条件下的剪切力，确定了适合的流变方程及流变曲线。结果表明，0．2％以内加量的IND30悬浮液的流动特性接近于宾厄姆模型，塑性粘度和动切力均较基浆增加。0．3％以上加量的IND30悬浮液的流动特性接近于幂律模型，稠度系数高于基浆，流性指数低于基浆；3％以内加量的NAT20悬浮液的流动特性接近于幂律模型，稠度系数低于基浆，流性指数高于基浆；6．0％以内加量的NFA25悬浮液的流动特性接近于宾厄姆模型，塑性粘度较基浆变化不大，动切力下降；依据正交设计的12个配方配制而成的悬浮液的流动特性都接近于幂律模型，稠度系数低于基浆，流性指数高于基浆但接近适宜的范围。

Study on Rheological Properties for Non-weighted Modified-natural-macromolecule Drilling Fluids

Studying on rheological properties of the additives and system of modified-natural-macromolecule drilling fluids will be helpful to the further application and research. The performance of suspending liquid compounded with non-weighted modified-nature-macromolecular additives (IND30, NAT20, NFA25) and 4% bentonite grouting was tested, the tests including shear power on 6 shear rate of 1022/s, 511/s, 340.7/s, 170.3 /s, 10.22 /s and 5.11 /s as well as the shear power of drilling fluid system at the condition as foresaid. The rheological equation and flow curves were found. The flow characteristics of suspending liquid with dosage <0.2% IND30 are similar to Bingham model, and their plastic viscosity and yield point are more than based fluids. The flow characteristics of suspending liquid with dosage >0.3% IND30 are similar to power law model, and consistency index are more than based fluid, liquidity index are less than that of based fluid. The flow characteristics of suspending liquid with addition <3% NAT20 are similar to Power law model, consistency index are less than that of based fluid, and liquidity index are more than that of based fluid. The flow characteristics of suspending liquid with dosage <6% NFA25 are similar to Bingham model, no significantly change the plastic viscosity but decrease yield point. The rheological properties of 12 drilling fluids according to orthorhombic designed formulations are all similar to the Power law model, the consistency index is less than that of based fluid, the flowing index is more than that of based fluid but close on feasible range.