单元生死功能数值法在井壁稳定中的应用  

APPLICATION OF THE NUMERICAL METHOD BY ELEMENT BIRTH AND DEATH FUNCTION IN THE WELLBORE STABILITY

作　　者：孙清华[1] 邓金根[1] 李玉梅[1] 谭春飞[1] 李军[1] 杨恒林 

机构地区：[1]中国石油大学石油天然气工程学院,北京102249 [2]中国石油集团钻井工程技术研究院,北京100195

出　　处：《大庆石油地质与开发》2013年第6期170-174,共5页Petroleum Geology & Oilfield Development in Daqing

基　　金：国家科技重大专项“煤层气钻井工程技术及装备研制——煤层气储层保护与井壁稳定技术研究”(2011ZX05036);国家科技重大专项课题“复杂结构井优化设计与控制关键技术”(2011ZX05009-005);国家“973”重大专项“深井复杂地层安全高效钻井基础研究——深井复杂地层钻井压力系统模型与规律”(2010CB226704)

摘　　要：为了减少煤储层伤害以及最大程度地提高煤层气水平井单井产量，开展了煤层气欠平衡钻井技术的现场应用研究。以沁水盆地3#煤层水平井为例，建立了煤层水平井井壁稳定分析的三维弹塑性有限元模型，运用ANSYS有限元程序中单元生死功能，诊断井周破坏单元并通过对破坏单元的杀死和激活功能，有效地实现了井筒开挖的非连续动态过程，得到了不同钻井液密度下井壁破坏半径长轴、破坏区角度和井径扩大率。单元生死功能数值法对煤层井壁稳定分析准确有效，可进一步推广应用。In order to reduce the coal reservoir damage and improve the production of individual horizontal CBM well to the greatest extent, the field application researches on CBM underbalanced drilling technology are carried out. Taking No. 3 coal seam horizontal well in Qinshui Basin as an example, 3D elastoplastic FEM （finite element method） model is established for the analysis of the wellbore stability of the coal-bed well, the element birth and death function in the program of ANSYS finite element is first used to diagnose the damaged elements near the well- bore, and furthermore by means of the functions of killing and activating these failed elements, the discontinuous dynamic process of the wellbore excavation is effectively realized, and morover, the major axis of the damaged well- bore radius, angle of failure zones and wellbore enlarged rate under the conditions of different drilling fluid densities are obtained. The numerical method is accurate and effective for the analysis of the wellbore stability of coal beds, so it can be further generalized and applied.

关 键 词：煤层气 井壁稳定 弹塑性 ANSYS 单元生死 

分 类 号：TE243[石油与天然气工程—油气井工程]