含水条件下湘西北地区牛蹄塘组页岩吸附能力

Adsorption characteristics of moist shale in Niutitang Formation, Northwest Hunan

彭学红 王涛 徐绍轩 王智强1

中国石油新疆油田分公司采油二厂，新疆 克拉玛依 834008 中国石油新疆油田分公司重油开发公司，新疆 克拉玛依 834000

No.2 Oil Production Plant, Xinjiang Oilfield Company, PetroChina, Karamay 834008, China Heavy Oil Development Company, Xinjiang Oilfield Company, PetroChina, Karamay 834000, China

选取湘西北地区页岩开展水蒸气吸附实验，分析影响水蒸气吸附的主控因素，并在此基础上，开展不同含水条件下的页岩甲烷吸附实验，分析水分对甲烷吸附的影响，评价不同含水条件下黏土矿物对页岩整体甲烷吸附的贡献。实验结果表明：高—过成熟阶段的页岩水蒸气吸附特征主要由黏土矿物控制，在低湿度条件下为单层吸附，在高湿度条件下，黏土纳米孔隙发生毛细凝聚；随着水分质量分数的增加，页岩的甲烷吸附能力逐渐下降并趋于稳定。进一步分析表明：在干燥条件下，黏土矿物对2块页岩实验样品的甲烷吸附贡献率可分别达37%和53%，而当水分质量分数达到实际储层情况（3.5%）时，黏土矿物对甲烷吸附能力的贡献率仅分别为12%和13%。因此，干燥条件下的实验将大大高估黏土对甲烷吸附的贡献，影响储量的评估。

In this work, water vapor adsorption experiments were performed on shale samples sourced from Northwest Hunan, then, the main controlling factor were analyzed in detail; subsequently, the moisture-equilibrated samples were used to conduct the methane adsorption experiments to investigate the effect of moisture on methane adsorption and the contribution of clay minerals to shale gas content. The results indicate that water vapor adsorption of shale with over-high maturity are mainly controlled by clay minerals, monolayer absorption occurs under low humidity condition while capillary condensation takes place under higher humidity environment; with the increasing of water content, the methane adsorption capacity of shale samples gradually decreases and then tends to be stabilized. Further analysis shows that: under the dry condition, the contribution of clay minerals to the methane adsorption capacity of two shale samples is 37% and 53%, respectively; however, when water content approaches to the actual reservoir condition(3.5%), the contribution will decline to 12% and 13%. Therefore, the experiments under dry condition mainly overstate the contribution of clay minerals to shale gas content, which will further influence the reserve assessments.

10.6056/dkyqt201803013