摘要
我国油气勘探正向页岩油气领域挺进,富含有机质页岩中普遍发育超压,页岩孔隙压力预测方法的不足制约着页岩油气的研究。分析了生烃增压及欠压实增压的岩石物理响应特征,基于密度与声速数据对生烃增压及欠压实增压的差异化响应,建立了一种利用声速、密度数据分别计算页岩生烃增压量及欠压实增压量,最终实现页岩孔隙压力预测的新方法——声速回弹法。选取生烃条件优越的渤东凹陷作为研究实例,首先利用综合泥岩压实曲线、加载-卸载曲线、声速-密度图解,综合判别了超压的成因,而后利用声速回弹法定量计算了单井欠压实、生烃作用的增压量以及地层孔隙压力,并将其与数值模拟及常规计算方法进行了对比。以LD21-A井为例,页岩超压成因为生烃增压与欠压实复合成因;压力预测结果显示:非烃源岩层段超压由欠压实增压贡献;烃源岩层段超压由生烃增压与欠压实贡献,其中生烃增压量主要分布在5~15 MPa之间(占比约35%~65%),实测压力点生烃增压量为11.09 MPa(占比45%)。新方法可行性较数值模拟更高,与Eaton法相比,不受各层段、区域生烃增压量及欠压实增压量占比不一致的影响。新方法在页岩油气领域及常规油气领域的研究具有重要意义。
[Objective]China′s oil and gas exploration is advancing towards the field of shale oil and gas.Overpressure is commonly developed in organic shale,and the lack of prediction methods for shale pore pressure restricts the research on shale oil and gas.[Methods]This article analyses the physical response characteristics of rock to hydrocarbon generation,pressurization and disequilibrium compaction.Based on density and sound velocity data,the differential responses of hydrocarbon generation pressurization and disequilibrium compaction pressurization were analysed.The hydrocarbon generation pressurization amount is calculated using sound velocity and density,and the disequilibrium compaction is calculated using the density data.Finally,the sound velocity rebound method was established.This article selects the Bodong Depression,which has superior hydrocarbon generation conditions,as a case study.First,comprehensive mudstone compaction curves,loading-unloading curves,and sound velocity-density diagrams are used to comprehensively identify the cause of overpressure.Then,the sound velocity rebound method is used to quantitatively calculate the pressure increase and formation pore pressure of a single well under compaction and hydrocarbon generation,and the results are compared with those of numerical simulations and conventional calculation methods.[Results]Taking the LD21-A well as an example,shale overpressure is caused by a combination of hydrocarbon generation and disequilibrium compaction.The pressure prediction results show that the overpressure of nonsource rock layers is contributed by the disequilibrium compaction.The overpressure of the source rock formation is contributed by hydrocarbon generation and disequilibrium compaction,with hydrocarbon generation pressurization mainly distributed between 5 MPa and 15 MPa(accounting for approximately 35%to 65%),and the measured pressure point hydrocarbon generation pressurization is 11.09 MPa(accounting for 45%).[Conclusion]This new method is vital of importance for the research of both shale and conventional oil and gas fields.
作者
张随随
范昌育
王德英
陈磊
王启明
王震亮
王飞龙
闫昕宇
ZHANG Suisui;FAN Changyu;WANG Deying;CHEN Lei;WANG Qiming;WANG Zhenliang;WANG Feilong;YAN Xinyu(State Key Laboratory of Continental Dynamics,Northwest University,Xi'an 710069,China;Department of Geology,Northwest University,Xi'an 710069,China;CNOOC China Limited,Tianjin Branch,Tianjin 300452,China)
出处
《地质科技通报》
CAS
CSCD
北大核心
2024年第4期27-38,共12页
Bulletin of Geological Science and Technology
基金
中海石油天津分公司项目“渤东凹陷油气成藏动力学与有利勘探方向研究”(CCL2021TJT0NST0338)。
关键词
声速回弹法
生烃增压
欠压实
超压
超压成因
压力预测
页岩孔隙
渤东凹陷
sound velocity rebound method
overpressure generation by hydrocarbon generation
disequilibrium compaction
overpressure
overpressure mechanism
pressure prediction
shale pore
Bodong Depression
作者简介
第一作者:张随随,E-mail:1779510038@qq.com;通信作者:范昌育,E-mail:330413776@qq.com。
