石油钻采工艺Issue(5)：41-46,6.DOI:10.13639/j.odpt.2014.04.011
钻井液浸泡页岩裂缝宽度的模拟及应用
Simulation and application of shale fracture width immersed in drilling lfuid
摘要
Abstract
In consideration of the fact that, during drilling of horizontal wells with oil-base mud in the pilot area for development of shale gas in our country, down-hole troubles like severe wellbore instability and lost circulation frequently occur, the outcrops of Longmaxi shale in the southeast of Chongqing were taken as experimental objects in order to carry out the tests of shale rock mechani-cal properties before and after immersion in drilling lfuid;based on ifnite element numerical model, a model was built for predicting the dynamic fracture under the condition of single vertical fracture connecting the wellbore, the behaviour of shale fracture width variation after immersion was studied, the method for prediction of dynamic fracture width based on ifnite element was corrected and improved, and the application of fracture width variation simulation was discussed to the protection of leaking reservoirs and control of wellbore instability. The results show that, after immersion in drilling lfuid, the elasticity modulus of shale decreased, the Poisson’s ratio increased and the rock strength reduced signiifcantly;after immersion, the dynamic shale fracture width was more sensite to changes in wellbore pressures;the half-fracture width increment under posite pressure differential of each fracture length and wellbore all increased by about 8%compared with pre-immersion;and the increment of half width increased greatly with the increase of posite pressure differential in the wellbore, and the dynamic fracture width could be up to several millimeter order;the three factors:drilling density, fracture width and bridging grain sizes were closely related. The parameters of dynamic fracture width obtained by the research work are very signiifcant for selecting the LCM materials and grain size grading, controlling proper drilling lfuid density and hence more effectely protecting the reservoir, controlling lost circulation and wellbore instability.关键词
岩石力学/页岩气/钻井液/井漏/裂缝宽度/数值模拟/威201-H1井Key words
rock mechanics/shale gas/drilling lfuid/lost circulation/fracture width/numerical simulation/W201-H1 well分类
能源科技引用本文复制引用
康毅力,皇凡生,游利军,俞杨烽,练章华..钻井液浸泡页岩裂缝宽度的模拟及应用[J].石油钻采工艺,2014,(5):41-46,6.基金项目
973计划课题“深井复杂地层漏失与井壁失稳机理及预测”（编号2010CB226705）资助。 （）
