摘要
油基钻井液可有效降低施工成本,缩短钻井周期,在大斜度定向井、水平井及各种复杂地层钻探施工中应用广泛。然而,油基钻井液侵入会改变井周地层的岩石物理性质,给储层流体识别、测井精细评价带来极大挑战。为明确油基钻井液侵入对核磁共振(nuclear magnetic resonance,NMR)测井响应的影响,选取新疆准噶尔盆地南缘超深井致密砂砾岩储层岩心,围绕岩石物性、钻井液成分、油水比、流体性质、钻井液侵入时间、温度6个方面分别开展油基钻井液成分、油基钻井液驱替和油基钻井液渗吸3组岩石物理实验,并分析实验过程中核磁共振T 2谱变化特征。结果表明:油基钻井液中的基液组分既能在正向压差作用下侵入井周地层,也可通过浮力和毛管力的作用渗吸进入地层。当地层含水/油时,油基钻井液基液侵入会引起微小孔隙T 2谱(<10 ms)横向弛豫时间和谱峰值减小,谱峰逐渐左移;而中孔隙T 2谱峰(>100 ms)右移且面积增大;上述T 2谱变化速率受到地层渗透率、侵入时间和温度影响明显,钻井液类型、油水比等因素影响有限。
For the lower cost and shorter drilling cycle,oil-based mud is widely used in drilling highly deviated directional wells,horizontal wells,and various complex formations.However,oil-based mud invades the formation,changes the physical properties of the formation around the well,and brings great challenges to fluid identification and reservoir evaluation.In order to figure out the influence of oil-based mud invasion on nuclear magnetic resonance(NMR)logging response,the cores of tight sandstone and conglomerate reservoirs in ultra-deep wells in the southern margin of Junggar Basin,Xinjiang were selected,and three groups of petrophysical experiments were carried out,including composition of oil-based mud,oil-based mud displacement,and oil-based mud imbibition,and the variation characteristics of nuclear magnetic resonance T 2 spectrum during the experiment were analyzed simultaneously.The results indicated that the base fluid components in the oil-based mud can not only invade the formation around the well under positive differential pressure but also infiltrate into the formation through buoyancy and capillary force.When the formation contains water/oil,the invasion of base fluid will cause the transverse relaxation time and spectral peak of micropore T 2 spectrum(<10 ms)to decrease,and the spectral peak will gradually shift to the left.The T 2 spectrum peak(>100 ms)of mesopores moves to the right and the area increases.The above T 2 spectrum change rate is mainly affected by formation permeability,invasion time and temperature,but limited by mud type,oil-water ratio,and other factors.
作者
张浩
倪利平
罗刚
王雪亮
王亮
ZHANG Hao;NI Li-ping;LUO Gang;WANG Xue-liang;WANG Liang(Exploration Division of Xinjiang Oilfield Company,PetroChina,Karamay 834000,China;Xinjiang Branch of CNPC Logging Co.,Ltd.,Karamay 834000,China;College of Energy,Chengdu University of Technology,Chengdu 610059,China)
出处
《科学技术与工程》
北大核心
2023年第12期5013-5021,共9页
Science Technology and Engineering
基金
国家自然科学基金联合基金(U2003102)
四川省自然科学基金面上项目(2023NSFSC0260)
中国石油天然气集团公司重大科技专项(2020T-007-002)。
关键词
油基钻井液
地层侵入
核磁共振(NMR)
测井响应
oil-based drilling fluid
formation invasion
nuclear magnetic resonance(NMR)
logging response
