砂—泥互层盖层垂向封闭性定量评价  

Quantitative evaluation of vertical sealing of sand-mud interbed caprock

作　　者：高鹏博 吕丁友 黄江波 王改卫 王海学[1,3] Gao Pengbo;Lü Dingyou;Huang Jiangbo;Wang Gaiwei;Wang Haixue(Laboratory of CNPC Fault Controlling Reservoir,Northeast Petroleum University,Daqing 163318,China;Bohai Research Institute of Petroleum,Tianjin Branch,CNOOC,Tianjin 300459,China;Science and Technology Innovation Team in Heilongjiang Province "Fault Deformation,Sealing and Fluid Migration",Daqing 163318,China)

机构地区：[1]东北石油大学CNPC断裂控藏研究室,黑龙江大庆163318 [2]中海石油(中国)有限公司天津分公司,天津300459 [3]黑龙江省科技创新团队“断层变形、封闭性及与流体运移”,黑龙江大庆163318

出　　处：《能源与环保》2021年第11期115-120,共6页CHINA ENERGY AND ENVIRONMENTAL PROTECTION

基　　金：黑龙江省自然科学基金(QC2018041);国家自然科学基金重点联合基金(U1562214)。

摘　　要：断层和裂缝是导致油气垂向调整运移或散失的最主要原因,砂—泥互层层序中油气垂向富集的主控因素是盖层泥地比和垂向封闭能力。以柴达木盆地为例,提出了应用泥地比判定盖层有效性的评价方法。构建了柴达木盆地西缘砂泥互层型盖层有效性定量评价图版。通过柴达木盆地油气纵向分布与盖层泥地比的关系可以看出,当泥地比大于70%时,为有效盖层;当泥地比介于70%~45%时,盖层连通概率明显增加,导致大多数探井出现失利现象;当泥地比小于45%时,基本达到完全连通状态,无法作为盖层封闭油气。大量亚地震断层改变了砂—泥互层盖层的结构,使其形成砂—砂对接渗漏通道,盖层垂向失效,因而建立了应用蒙诺卡罗法定量预测垂向渗漏风险的方法。评价结果表明,上干柴沟组、下油砂山组盖层的渗漏几率较大,风险较高;上油砂山组盖层垂向连通率约为2%,连通性较差,风险较低,这与实际勘探结果具有较好的匹配性。Faults and fractures are the main reasons for the vertical adjustment migration or loss of oil and gas.The main controlling factors for the vertical accumulation of oil and gas in the sandy-mud interbedded sequence are the mud-to-ground ratio and the vertical sealing ability of the cap rock.Taking the Qaidam Basin as an example,this paper put forward an evaluation method of evaluating the effectiveness of cap rock by applying the ratio of mud to ground.A quantitative evaluation chart for the effectiveness of sand and mud interbedded cover beds in the western margin of Qaidam Basin was constructed.According to the relationship between the vertical distribution of oil and gas and the mud-to-ground ratio in Qaidam Basin,it can be seen that when the mud-to-ground ratio is more than 70%,it is an effective cap rock.When the mud-to-ground ratio is between 70%~45%,the probability of cap formation connectivity increases significantly,leading to failure phenomenon in most exploration wells.When the mud-ground ratio is less than 45%,it basically reaches the state of complete connectivity and cannot be used as a cap rock to seal oil and gas.Since a large number of subseismic faults changed the structure of the sand-mud interbed cap rock,resulting in the formation of sand-sand butt leakage channels,and the cap rock failed vertically.Therefore,a Monte Carlo method was established to quantitatively predict the vertical leakage risk.The evaluation results showed that the upper Ganchaigou Formation and the lower Youshashan Formation have higher leakage probability and higher risk.Vertical connectivity rate of the upper Youshashan Formation cap rock is about 2%,with poor connectivity and low risk,which has a good match with the actual exploration results.

关 键 词：盖层有效性 连通性 垂向封闭性 油气保存 

分 类 号：TE111.3[石油与天然气工程—油气勘探]