环保型高效页岩抑制剂聚赖氨酸的制备与评价

为了解决泥页岩地层钻井过程中井壁失稳的难题，研制出一种兼具强抑制性和优良环保性的水基钻井液页岩抑制剂--聚赖氨酸，并对其性能进行了评价。评价过程及结果如下：①借助红外光谱、核磁共振、电感耦合等离子质谱、热重分析等方法对其进行了化学表征；②通过线性膨胀实验、泥页岩热滚回收实验和膨润土造浆实验等手段，系统地评价了该抑制剂对泥页岩的抑制性能；③抗温性能和pH 值适应性评价结果表明，温度在180 ℃以内、pH 值在7 ～ 10 范围内该抑制剂均能发挥良好的抑制作用；④生物降解试验结果表明，该抑制剂易于降解，环保性能优异。结论认为，聚赖氨酸具有优异抑制性能的原因在于其能够有效地中和泥页岩中膨润土表面负电荷，将表面Zeta 电位降低至接近零点，而又不会造成电性反转，从而最大限度地压缩扩散双电层，使泥页岩不易分散；并且其抑制作用优于KCl、小阳离子、Ultrahib 等目前常用的几种抑制剂。

Preparation and evaluation on polylysine: An environmentally-friendly efficient shale inhibitor

Polylysine was developed to solve the problem of borehole wall instability during shale drilling. It is a type of environmentallyfriendly water-based drilling fluid shale inhibitor with a high inhibition performance. In this paper, polylysine was evaluated on its shaleinhibition performance. First, it was chemically characterized by means of FT-IR, NMR, ICP-MS and TGA. Second, its shale inhibitionperformance was systematically evaluated via linear swelling tests, shale hot aging recovery tests and bentonite grout preparation tests.Third, its heat resistance and pH adaptability were evaluated. It is shown that polylysine is outstanding in shale inhibition capacities inthe conditions with temperature below 180 ℃ and pH in the range of 7-10. And fourth, biodegradation tests were performed. It is indicatedthat polylysine is an environmentally friendly shale inhibitor that can be easily biodegraded. Research results show that the reason forthe predominant inhibition capacity of the polylysine is that it can neutralize negative charges on the surfaces of bentonite and reduce thesurface Zeta potential to near zero. And besides, no electric reverse is induced, so diffuse electric double layers can be compressed to themaximum extent. Therefore, shale diffusion does not easily happen. To sum up, the polylysine is superior to several commonly used shaleinhibitors (e.g. KCl, NW-1 and Ultrahib) in terms of inhibition capacity.