延长气田钻井井径扩大率影响因素分析

Analysis of Influencing Factors of well Diameter Expansion Rate in Yanchang Gas Field

延长气田位于鄂尔多斯盆地伊陕斜坡,钻井过程中井壁失稳引起的井壁坍塌经常造成井下复杂情况。为了降低井下复杂工况发生概率,分别从现场实测数据及理论计算方面进行了分析计算,结果表明:石千峰组石盒子组地层岩石本身微裂缝发育脆性大是造成井壁坍塌地质因素,井壁长时间浸泡及泥浆性能不达标是造成井壁坍塌的工程因素;允许井壁适当坍塌,适当降低钻井液密度可以起到保护储层的目的。

Yanchang gas field is located in the Yishan slope of Ordos Basin.The borehole collapse caused by borehole instability often results in complex downhole conditions.In order to reduce the probability of complex working conditions,the analysis and calculation are carried out from the field measured data and theoretical calculation.The results show that the geological factors of shaft wall collapse are the brittle development of micro fractures in Shihezi Formation of Shiqianfeng Formation,and the engineering factors of shaft wall collapse are the long-time immersion of shaft wall and the substandard mud performance;the proper collapse and suitability of shaft wall are allowed When the density of drilling fluid is reduced,the reservoir can be protected.