神木区块水平井钻井提速与钻井液优化研究

RESEARCH ON IMPROVING HORIZONTAL WELL ROP AND DRILLING FLUID OPTIMIZATION IN SHENMU BLOCK

神木区块上部延长组由于地层压实作用小,渗透性强、可钻性极好、泥岩段吸水膨胀快,常出现全井段缩径;刘家沟组和石千峰组地层可钻性极差且造浆性极强,常出现钻头泥包;为了满足斜井段正常施工,钻井液相对密度达到一定程度时导致刘家沟底界发生压差渗透性漏失;进入山西组出现大段的煤层,常出现煤层垮塌;在水平段施工期间,由于部分砂岩储层发育较好,渗透性极强,孔斜度较大,常导致渗透性漏失,这些情况的出现,严重制约着钻井提速,不仅增长了钻井周期,还严重影响着钻井井身质量、钻井速度、钻井成本和施工风险。为此,结合神木区块低成本开发实际,进行该区块的钻井液优化设计,制定了具体的措施,形成了该区块提速的钻井液技术,在钻井中得到推广应用,取得了较好的应用效果,为该区块低成本开发提供了技术支持。

Because of weak compaction,high permeability,wonderful drillability as well as strong mudstone expansibility with water,the hole diameter reduction of whole well section often occur on upper Yanchang formation of Shenmu area.Bit balling often appear due to poor drillability and fortissimo mud making ability in the Liujiagou formation and Shiqianfeng formation.For achieving successful drilling on well deviation section,the differential pressure permeability loss happened on the bottom of Liujiagou formation when relative density of drilling fluid is to a certain degree.The thick coal layer is existence in Shanxi formation,it often results in collapse of coal.During the horizontal section operation,parts of the sandstone reservoir with high permeability and large porosity led to permeable loss.For these problems,the drilling speed was seriously restricted,the drilling period was prolonged,the well bore quality was affected and drilling costing was increased.So combining the fact of development with low cost in Shenmu block,the drilling fluid was optimized and the corresponding drilling measures were worked out,and a new drilling fluid technology suited for improving ROP in Shenmu block was formed.The technology was used successfully in Shenmu block,and good results were got.