环保型改性生物多肽水基钻井液抑制剂的合成与应用

随着国家对环境保护的日益重视，传统的聚磺钻井液处理剂将慢慢被环保型钻井液处理剂取代。从分子结构设计出发，基于生物多肽明胶进行改性合成了环保型改性生物多肽抑制剂WNGT。明胶改性后在核磁共振图谱的化学位移3.19 ppm和4.12 ppm处出现2个明显的新的特征峰，表明成功制备得到目标产物。线性膨胀实验表明：对比KCl、聚醚胺PEA抑制剂，在相同加量下，WNGT溶液中膨润土的膨胀高度最小，抑制效果最好；WNGT具有优良的抑制黏土水化膨胀性能，2%加量的WNGT，膨润土24 h的膨胀量仅为1.60 mm；与改性前的明胶相比，页岩岩屑滚动回收率达95%以上，相比改性前提高46.05%；膨润土浆中加入2%WNGT后，Zeta电位降至-11.7 mV,WNGT可有效中和黏土负电荷，压缩双电层，降低黏土Zeta电位。在川渝地区开发井沙溪庙砂泥岩井段进行了现场应用，在井浆中加入WNGT后，井浆黏度和切力均有所下降，且能长时间稳住钻井液流变性，保证了在砂泥岩段的顺利钻进，降低了钻井成本。

Synthesis and Application of an Environmentally Friendly Modified Bio-Peptide Shale Inhibitor for Water Based Drilling Fluids

As more and more attentions have been paid to environment protection, the conventional polymer-sulfonate drilling fluid additives are gradually inevitably replaced by environmentally friendly additives. An environmentally friendly modified bio-peptide shale inhibitor, WNGT, has been developed based on molecular structure design of the bio-peptide gelatin. NMR spectrum of the modified gelatin has shown that two distinct new characteristic peaks appeared at the chemical shifts of 3.19 ppm and 4.12 ppm, respectively, indicating that the target product was successfully prepared. Results of the linear expansion test showed that the expansion length of the core tested with WNGT was shorter than two other additives, which were KCl and polyetheramine (PEA), at the same concentration, indicating that WNGT had the best inhibitive capacity in the three shale inhibitors. WNGT has the excellent clay hydration suppressing ability; at a concentration of 2%, the expansion length of the clay core in 24 hours was only 1.60 mm. Percent shale cuttings recovery of the modified gelatin was at least 95%, 46.05% higher than that of the non-modified gelatin. A bentonite slurry treated with 2% WNGT had its Zeta-potential decreased to ?11.7 mV, meaning that WNGT can effectively neutralize the negative charges of the clay, thereby compressing the electric double layer and reducing the Zeta-potential of the clay. This WNGT shale inhibitor has been used on a well located in Chuanyu area, where the well penetrated the Shaximiao sandy shale formation. When the drilling fluid was treated with WNGT, its viscosity and gel strengths were reduced to some extent, and this effect was maintained for a long time, ensuring the successful drilling of the sandy shale formation with the water based polymer drilling fluid and the reducing of drilling cost.