钻井液与完井液2016，Vol.33Issue(6)：33-39,7.DOI:10.3696/j.issn.1001-5620.2016.06.006
华北古近系及潜山内幕地层井壁稳定性研究
Borehole Stability in Drilling the Paleogene System and Inner Buried Hill in Huabei Oilfield
摘要
Abstract
The lithology of the Paleogene system in the Huabei oilfield is mainly sandstone and mudstone,intercalated occasionally with basalt and coal bed.Different formation pressure systems have been found in this oilfieid.Time required for coping with troubles during drilling accounted for 73.62％ of the total time required for coping with troubles encountered in the whole process of drilling operation.The destabilization mechanism of the micro-fractured Paleogene system has been studied from mineral analysis,rock mechanics,formation stress measuring to mechanism of borehole wall destabilization.Large variations of cohesion (6-25 MPa) and angle of internal friction (26°-45°) of formation rocks and high formation stress cause micro fractures along the weak planes in rocks,resulting in borehole collapse and lost circulation.Abundant clays cause the formation to hydrate and swell,and after long time of soaking in water,network of fractures result.When pressure of mud column is greater than the collapse pressure of formation,the widths of the fractures increase exponentially,resulting in borehole wall sloughing.To stabilize borehole wall,Polyetherarnine and a nano plugging agent were introduced into KCl drilling fluid.Polyetheramine inhibit osmotic hydration of clay through ether bonds and hydrogen bonds,and the unique action of amino group.This technology has been used in several wells such as Yangtan-1,Wen'an-101x and Antan-lx which penetrated the Paleogene system,no downhole troubles have occurred.The well Yangtan-1 successfully penetrated the long section shale formation which experienced severe borehole wall collapse in adjacent wells.The average hole enlargement of the well Yangtan-1 was only 1.8％,and the maximum hole enlargement,14.82％.The well Antan-lx had maximum mud density of 1.50 g/cm3,0.19 g/cm3 less than the mud density used in adjacent wells.Furthermore,excessive mud density is disadvantageous to borehole wall stabilization.It is suggested that the mud density should only be 15％ higher than the equivalent density of collapse pressure,provided that there is no well control risk.关键词
井壁稳定/潜山地层/力学稳定/强抑制强封堵钻井液/钻井液性能/润滑性Key words
Destabilization of borehole wall/Borehole wall collapse/Mechanism of borehole wall destabilization/Oil and gas exploration分类
能源科技引用本文复制引用
王东明,陈勉,罗玉财,于建涛,徐明磊,虞海法,杨恺..华北古近系及潜山内幕地层井壁稳定性研究[J].钻井液与完井液,2016,33(6):33-39,7.基金项目
中国石油天然气股份有限公司重大科技专项“华北油田上产稳产800吨关键技术研究与应用”(2014E-35). （2014E-35）
