青海五龙沟矿区泥岩地层冲洗液研究

Drilling fluid for mudstone in Wulonggou Mine of Qinghai Province

摘要:

摘要：青海五龙沟矿区内存在大量泥岩地层，其特点为粘土总含量高，易吸水膨胀，地层微裂隙多，导致钻探过程中易出现钻孔缩径、坍塌以及岩心采取率不足等问题，严重影响了矿体规模及经济价值的评价，研究适用于该区的冲洗液意义重大。本文通过正交试验研发了一套适用于该区泥岩地层钻探的水基冲洗液，该冲洗液配方为：5%膨润土+2%纯碱（Na2CO3）+0.05%高粘聚阴离子纤维素（HV-PAC）+0.4%低粘钠羧甲基纤维素（LV-CMC）+2%磺甲基酚醛树脂（SMP-1）+2.5%无荧光防塌润滑剂（FT-342）+0.4%正电胶（MMH）+1%白油。该冲洗液失水量为4 mL，泥岩在清水中的膨胀率为20.26%，而在冲洗液中降到了3.02%，将泥岩制样放到冲洗液中浸泡24 h，泥岩结构保持完整。该冲洗液滤失量低、抑制性强、配制工艺简单，能很好地适用于五龙沟地区泥岩地层的钻探工作。

Abstract:

There are a large number of mudstone strata in the Wulonggou mining area of Qinghai Province, which are characterized by high total clay content, ease to expand after absorbing water, and many micro-cracks in the strata. In the process of drilling, problems such as hole shrinkage, collapse and insufficient core recovery are easy to occur, which seriously affects the evaluation of the scale and economic value of the ore body. Therefore, it is of great significance to study the drilling fluid suitable for this area. A water-based drilling fluid suitable for mudstone formation has been developed through the orthogonal experiment. The drilling fluid formula was: 5% bentonite + 2% soda ash (Na2CO3) + 0.05% highly viscous polyanionic cellulose (HV-PAC) + 0.4% low viscous sodium carboxymethyl cellulose (LV-CMC) + 2% sulfomethyl phenolic resin (SMP-1) + 2.5% non-fluorescence anti-sloughing lubricant (FT-342) + 0.4% MMH (MMH) + 1% white oil. The drilling fluid had water loss of 4mL, and the expansion rate of mudstone was reduced to 3.02% in the drilling fluid, whereas it is 20.26% in clean water. The mudstone structure remained intact after soaking in the drilling fluid for 24h. The drilling fluid has the advantages of low filtration, strong inhibition and simple preparation process, which can be well applied to drilling of mudstone strata in the Wulonggou area.