深部盐矿勘探钻井液研究与应用

Research and Application of Drilling Fluid in Salt Mine Exploration

ZK001井钻遇地层为大段泥岩,部分地层为页岩、含盐泥岩、盐膏层。在泥页岩地层进行大口径全面钻进,钻速较快,固控设备能力有限,引起钻屑中粘土颗粒重复性膨胀、软化及裂解分散,最终可能造成粘土侵,对井内安全造成威胁。深部岩膏层易溶于水,从而导致盐层蠕变、井径扩大、井壁失稳等问题。以ZK001井为例,通过优化钻井液体系及现场施工工艺,解决了地层强造浆、盐层失稳等问题。通过岩石力学测试、阳离子交换容量测试、钻井液体系优选及性能测试,确定了上部地层采用聚合物钻井液体系,下部含盐层取芯钻进转换为饱和盐水钻井液体系。通过选用合适的钻井液密度、粘度、切力量、滤失量、含盐量等指标,可以有效控制上部泥岩井壁稳定、含盐层蠕变、井径扩大的问题。钻进过程中钻井液性能稳定且易于维护,从而保证了钻进工作安全、高效、顺利的进行。

ZK001 well drilling encountered thick layers of mudstone and parts of shale,salt-mudstone and gypsum. The relative large diameter drilling in shale formation often bring repeat clay particles expansive,cracking dispersion and clay invasion,which being a threat to the drilling well,due to fast drilling and inadequate capacity of solids control equipments. And salt creep,hole enlargement and borehole instability might occur in deep gypsum layers,that dissolves easily in water. In ZK001 well,by optimizing drilling fluid system and field technology,the problems,such as strong pulping and salt instability were solved.Through rock mechanics test,cation exchange capacity test,and drilling fluid system optimization and performance test,the authors determined the polymer drilling fluid system in upper formation,and saturated salt water drilling fluid system used in lower saline formation. By choosing suitable drilling fluid density,viscosity,shear strength,filter loss,salt content and other indicators,the problems including borehole stability,salt layer creep and borehole diameter enlargement in upper mudstone have also been brought under control. In the process of drilling,the drilling fluid has stable performance and maintainability,this ensures the drilling work efficient,safety and progressing smoothly.