深部盐矿勘探钻井液研究与应用

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。

Research and Application of Drilling Fluid in Salt Mine Exploration

The formation of ZK001 well is a large section of mudstone, and the local formation is a salt mudstone and a salt gypsum layer. Shale formation has strong water sensitivity, which is easy to cause the drilling fluid clay contamination, borehole instability, bit balling and other issues; The deep salt mudstone and salt bed have strong characteristics of water-soluble and creep property, easily lead to the expansion of well diameter and core corrosion. In this paper, taking well ZK001, for example, it has solved the problems such as formation strong mud making, instability of salt bed and borehole diameter enlargement by optimizing drilling fluid system and on-site construction process. With the help of the rock mechanics test, mineral identification, cation exchange capacity test, drilling fluid system optimization and performance testing ,it was determined to use polymer drilling fluid system in the upper formation ,and translate it into saturated salt water drilling fluid system before deep salt coring drilling. Selecting proper drilling fluid performance parameter in field work could effectively prevent the slurry making in upper mudstone formations and avoid creep and borehole diameter enlargement in salt bed formations. The performance of drilling fluid is stable and easy to be maintained, which ensures the safety and high efficiency of drilling, which provides a reliable guarantee for the successful completion of the coring task.