水基钻井液用低增黏提切剂的合成与性能评价

为了实现在调控钻井液黏度的情况下获得良好的携岩能力，以丙烯酰胺（AM）、2-丙烯酰胺基-2-甲基丙磺酸（AMPS）、二甲基二烯丙基氯化铵（DMDAAC）、甲基丙烯酰氧乙基-N，N-二甲基丙磺酸（DMAPS）和十六烷基疏水单体（C16-D）为原料，采用自由基聚合法，制备了一种新型的两性疏水缔合聚合物（PAADDC）。采用傅里叶变换红外光谱（FTIR）和核磁共振（1H NMR）表征了PAADDC的分子结构，采用静态光散射（SLS）测定了聚合物的分子量，并对其流变性能进行了评价。结果表明，100℃老化16 h，加量为0.2% PAADDC的钻井液的表观黏度、塑性黏度、动切力和动塑比分别为18.5 mPa·s，11.5 mPa·s，7.0 Pa和0.61 Pa/mPa·s，抗温可达160℃。与常规增黏剂相比，PAADDC具有良好的热稳定性和更佳的抑黏增切效果。在60～180℃热老化实验中，动塑比值随PAADDC用量的增加而降低。环境扫描电镜（ESEM）和原子力显微镜（AFM）的观察表明，PAADDC在溶液中形成了连续的三维网状结构，这是其剪切强度显著提高的主要原因。

Synthesis and Evaluation of a Low Viscosity Gelling Agent for Water Base Drilling Fluids

A new zwitterionic hydrophobically associating polymer PAADDC has been synthesized by radical polymerization using monomers such as acrylamide (AM), 2-acrylamido-2-methylpropane sulfonic acid (AMPS), dimethyl diallyl ammonium chloride (DMDAAC), 3-dimethyl (methacryloyloxyethyl) ammonium propane sulfonate (DMAPS) and a cetyl monomer (C16-D). PAADDC was developed for improving the cuttings carrying capacity of water base drilling fluids at controlled viscosity. The PAADDC synthesized was characterized by FT-IR and 1HNMR, and its molecular weight was determined by static light scattering (SLS) method. Drilling fluids treated with 0.2% PAADDC, after aging 16 h at 100℃, had properties as follows:AV=18.5 mPa·s, PV=11.5 mPa·s, YP=7 Pa and YP/PV=0.61 Pa/mPa·s. This drilling fluid was resistant to high temperatures to 160℃. Compared with other filter loss reducers, PAADDC has better thermal stability and better suspending performance at controlled viscosity. In aging test at 60-180℃, the YP/PV ratio of the drilling fluid was decreasing with increase in the concentration of PAADDC. ESEM and AFM examination of the molecular behavior of PAADDC showed that in solution PAADDC forms a continuous 3D network structure, which is taken as the main factor of obviously increasing the shearing strength of the drilling fluids.