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

摘要:

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4~5 mL、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。

Abstract:

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.