柴达木盆地石圈滩地区铀矿钻探冲洗液研究与应用

Research and application of flushing fluid for uranium deposits drilling in Shiquantan area,Qaidam Basin

柴达木盆地石圈滩地区铀矿资源调查评价钻探中钻遇地层高压异常,0~600 m地层压力系数为1.25~1.4;地层易溶,含盐量最高达1.025%,钻孔资料较少,在钻探过程中经常出现卡钻、塌孔等严重孔内事故。通过对该区地层进行岩性特征分析,根据地层特点进行冲洗液造浆粘土与处理剂优选,提出了一套适用于该区地层的抗盐防塌冲洗液体系,该体系具有良好的抗盐防塌性能,主要表现为:表观粘度38 mPa·s、动切力16.4 Pa、API滤失量4~5mL、泥皮厚度0.3~0.4 mm,薄且致密,护壁效果良好。有效解决了该地区施工盐膏层缩径、塌孔及高压异常条件下冲洗液失稳等难题,平均台月效率从729.76 m提升至1378.78 m,孔径扩大率从130%下降至19.4%,泥浆材料和用水成本从57.91元/m降至38.92元/m,在现场实际应用中取得了良好的经济效益,具有推广应用价值。

During the investigation and evaluation of Uranium deposits in Shiquantan area of Qaidam Basin,the formation pressure anomaly was encountered.The formation pressure coefficient of 0~600m is 1.25~1.4.The formation is easily soluble with a high salt content of up to 1.025%.Accidents such as stuck and collapse usually happened during the drlling process as drilling information about this area is less.In this paper,a set of anti‑salt and anti‑collapse flushing fluid system suitable for the strata in this area is proposed by analyzing the lithological characteristics of the strata in this area,and preferentially selecting the corresponding slurry‑making clay and treatment agent for the flushing fluid.As a result,this systerm has good anti‑salt and anti‑collapse performance,mainly showing as follows:the apparent viscosity 38MPa·s,the dynamic shear force is 16.4Pa,the API filter vector is 4~5mL,the mud skin is thin and dense with the thickness of 0.3~0.4mm which has good wall protection effect.It effectively solved the problems such as shrinkage in salt‑gypsum layers,hole collapse and destabilization of flushing fluid under abnormal conditions of high pressure in this area.As a result,the average monthly efficiency is increased from 729.76m to 1378.78m,the hole expansion rate is reduced from 130%to 19.4%,and the cost of mud material and water is reduced from 57.91RMB/m to 38.92RMB/m.Good economic benefits have been achieved in practical application in the field which make it has the value of popularization and application.