准噶尔南缘膏泥岩地层井壁失稳机理

发布时间：2018-03-02 22:08

本文选题：准噶尔盆地　切入点：黏土矿物　出处：《科学技术与工程》2017年28期 　论文类型：期刊论文

【摘要】：准噶尔盆地南缘山前安集海河组和紫泥泉子组地层钻井过程中易发生遇阻、卡钻、井漏等井下复杂事故。为研究这两组地层井壁失稳的原因,从岩心的黏土矿物组分、微观结构、力学性能、分散膨胀性能的角度,同时结合典型井的测井等数据,研究地层的坍塌压力和破裂压力的当量密度,综合分析井壁失稳机理。研究认为:安集海河组和紫泥泉子组地层均具有黏土含量高(30%)、伊/蒙混层含量高(57%)且混层比高(55%)的特点,电镜扫描显示岩心表面含有大量伊/蒙混结构,因此,钻井液滤液依靠压差和毛细管作用侵入地层是造成地层非均匀水化膨胀是地层失稳的主要原因;岩屑的回收率和膨胀率结果可见地层具有高分散高膨胀的特点,极易造成井壁坍塌及钻井液性能恶化;岩心实验显示岩心抗压强度较低,经水基钻井液浸泡后破碎或者产生裂纹,油基钻井液浸泡抗压强度下降,说明岩心本身的抗压强度低也是地层不稳定的本质原因;另外,地层孔隙压力高,钻井液安全密度窗口窄,钻井液密度控制不当也是导致地层失稳(漏失和坍塌)的重要原因。
[Abstract]:In order to study the reasons for the instability of formation wall in the south margin of Junggar Basin, the formation of Anjihaihe formation and Ziniequanzi formation in the southern margin of Junggar Basin are prone to some complicated downhole accidents, such as blocking, drilling, well leakage, etc. In order to study the clay mineral components in the core, The angle of microstructure, mechanical property, dispersive expansion performance, and combining with the logging data of typical wells, the equivalent density of collapse pressure and fracture pressure of formation is studied. The mechanism of wellbore instability is analyzed synthetically. It is considered that both the formation of the Anji Haihe formation and the Zinequanzi formation have the characteristics of high clay content (30%), high content of Yi / Mongolian layer (57%), and high mixing layer ratio (55%). Scanning electron microscope (SEM) shows that there are a large number of Iran / monolayer structures on the core surface. Therefore, the drilling fluid filtrate invades the formation by pressure difference and capillary action, which is the main cause of formation instability caused by heterogeneous hydration expansion. The results of recovery rate and expansion rate of cuttings show that the formation is characterized by high dispersion and high expansion, which can easily cause wall collapse and deterioration of drilling fluid performance, and core experiments show that core compressive strength is low, After being soaked in water-based drilling fluid, the fracturing or cracking occurs, and the immersion compressive strength of oil-base drilling fluid decreases, which indicates that the low compressive strength of the core itself is also the essential cause of formation instability. In addition, the formation pore pressure is high. The narrow window of drilling fluid safety density and improper control of drilling fluid density are also the important causes of formation instability (leakage and collapse).
【作者单位】：中国石油天然气股份有限公司新疆油田公司工程技术研究院;长江大学石油工程学院油气钻采工程湖北省重点实验室;
【基金】：中国石油新疆油田公司项目(XJYT-gcjsyjy-2016-JS-223)资助
【分类号】：TE28

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