井壁稳定性分析在煤层气勘探开发中的应用  

Application of wellbore stability analysis in CBM exploration and development

作　　者：林龙生[1] 王文文[1] LIN Long-sheng;WANG Wen-wen(Oilfield Technology Department,China Oilfield Services Limited,Langfang 065201,China)

机构地区：[1]中海油田服务股份有限公司油田技术事业部,河北廊坊065201

出　　处：《煤炭科技》2021年第5期117-121,共5页Coal Science & Technology Magazine

摘　　要：煤层气属于一种清洁能源,随着煤层气储层勘探和开发的进一步发展,出现的问题越来越多。煤层钻井除了煤层损害、完井较难等问题以外,井壁失稳是最需要关注的问题,那么能够准确评价井眼稳定性的方法就非常关键。通过测井曲线计算岩石力学参数,包括单轴抗压强度、杨氏模量、泊松比、内摩擦角、内聚力等。将测井资料计算的岩石力学参数作为输入参数,在三轴应力下对岩样进行了岩石力学参数的动、静态同步测试,并对动静态弹性参数进行了线性回归,计算出地层三压力剖面及安全泥浆密度范围,为煤层钻探提供帮助,从而真正达到安全高效生产。研究地区位于沁水盆地南部,通过对井壁稳定性的模型进行分析结果表明,3号和5号煤层附近实际使用的钻井泥浆比重比较接近计算的最小安全泥浆比重,泥浆安全窗口较小,容易出现井漏风险,说明在煤层段所使用的泥浆比重偏小。通过模型分析可知,X1井需要提高泥浆比重,以控制钻井过程中的井壁稳定性。Coalbed methane is a kind of clean energy.With the further development of coalbed methane reservoir exploration and development,there are more and more problems.In addition to the problems of coal seam damage and difficult completion in coal seam drilling,wellbore instability is the most important problem to be concerned,so the method to accurately evaluate borehole stability is very critical.Rock mechanics parameters,including uniaxial compressive strength,Young′s modulus,Poisson′s ratio,internal friction angle and cohesion,are calculated by logging curves.Taking the rock mechanics parameters calculated by logging data as input parameters,the dynamic and static synchronous tests of rock mechanics parameters are carried out on rock samples under triaxial stress,and the dynamic and static elastic parameters are linearly regressed to calculate the three pressure profile and safe mud density range of the formation,so as to provide help for coal seam drilling,so as to truly achieve safe and efficient production.The study area is located in the south of Qinshui Basin.Through the analysis of wellbore stability model,the results show that the proportion of drilling mud actually used near the No.3 and No.5 coal seams is close to the minimum safety mud proportion calculated,and the mud safety window is small,which is prone to the risk of lost circulation,indicating that the proportion of mud used in the coal seam section is small.Through the model analysis,it can be seen that X1 well needs to increase the mud gravity to control the wellbore stability during drilling.

关 键 词：煤层 井壁稳定性 应力 岩石力学 泥浆窗口 

分 类 号：P618.13[天文地球—矿床学]