选择性絮凝剂在页岩气废弃油基钻井液中的应用

Application of Selective Flocculant in Shale Gas Waste Oil-based Drilling Fluid

川渝地区页岩气地层油基钻井液钻井过程中产生的岩屑离心液低密度固相含量高,粘度大,难以重复利用且处理费用高。针对上述问题,本文首先介绍了页岩气油基钻井液中低密度固相的特点、使用的油基钻井液絮凝剂和絮凝机理以及岩屑废弃离心液中的现场处理工艺,实验研究了油基钻井液絮凝剂与现场钻井液的配伍性,最后分析了油基钻井液絮凝剂的作用效果以及絮凝后离心液的回收处理方法。室内评价表明油基钻井液絮凝剂与现场钻井液配伍性良好,可以降低油基钻井液的粘度,改善其流变性。现场试验表明油基钻井液絮凝剂可以大幅度降低废弃离心液的低密度固相含量,处理后低密度固相含量与现场油基钻井液的低密度固相含量相当;且絮凝处理后的离心液按20%的加量加入到油基钻井液中对油基钻井液的性能影响很小。本文证明了油基钻井液絮凝剂可以提高油基钻井液的重复利用率,降低废弃物的数量。

The centrifugal fluid of drilling cuttings,produced during the drilling process using oil-based drilling fluids in shale gas formations in the Sichuan-Chongqing area,has a high low-density solid content and high viscosity,which is difficult to reuse and the processing costs is high.Aiming at the above problems,this paper first introduced the characteristics of the low-density solid of oil-based drilling fluids,the oil-based flocculant used in this paper and flocculation mechanism.Then,the on-site treatment process of the waste centrifugal fluid was also introduced.The compatibility of oil-based flocculant and field drilling fluid was experimentally studied.Finally,the performance of oil-based flocculation and the recovery method of centrifugal fluid after flocculation were analyzed.The laboratory evaluation shows that the oil-based d flocculant had a good compatibility with the field drilling fluid,which could reduce the viscosity of the oil-based drilling fluid and improve the rheology of oil based drilling fluid.Field test shows that the oil-based flocculant could greatly reduce the low-density solid content of the waste centrifugal fluid.The low-density solid content after treatment was equivalent to that of the on-site oil-based drilling fluid.The centrifugal fluid after the flocculation treatment had little effect on the performance of the oil-based drilling fluid when the usage was 20%.This paper proved that oil-based flocculants can increase the reuse rate of oil-based drilling fluids and reduce the amount of waste.