摘要
构造抬升作用不仅会降低地层压力,还会造成孔隙回弹引起地层物理属性的变化,基于此的欠压实识别和欠压实超压恢复会造成较大的误差。为准确判断和计算构造抬升区的欠压实超压,首先分析构造抬升造成的泥岩测井曲线变化,然后结合回弹系数,提出利用加载—卸载曲线计算欠压实超压量的方法,并利用该方法对鄂尔多斯盆地延长组7段欠压实超压进行了恢复。结果表明:孔隙回弹改变了正常压实段结束时的测井曲线特征,导致声波时差和密度减小,电阻率和中子孔隙度增大;通过对比加载—卸载曲线法与地层压力模拟和等效深度法的计算结果,发现不考虑孔隙回弹的常规欠压实超压计算方法计算结果偏大,在构造抬升区并不适用。在构造抬升区,需要识别综合泥岩压实曲线上声波时差和密度突然减小,电阻率和中子孔隙度突然增大的曲线特征,才能识别欠压实发育层段,而利用加载—卸载曲线能更加准确地恢复抬升区的欠压实超压,为构造抬升区压力的演化及油气成藏和预测提供更有效的研究基础。
Tectonic uplift will not only reduce the formation pressure but also cause pore rebound which leads to changes in the physical properties of the formation.There are several errors without considering the pore rebound when the conventional methods are used to identify the disequilibrium compaction and calculating the overpressure.In order to accurately identify the disequilibrium compaction and calculate the disequilibrium compaction overpressure of the tectonic uplift area,this article introduces the impact of tectonic uplift on logging data firstly;then,a method to calculate disequilibrium compaction overpressure by combining pore rebound experiments and loading/unloading equations is introduced;finally,taking Yanchang Formation in Xiasiwan area of Ordos Basin as an example,the loading-unloading curve method was used to restore the disequilibrium compaction overpressure in Chang 7 Member of the Yanchang Formation.The results show that the logging curve characteristics at the end of the normal compaction section change by the pore rebound,that is,acoustic time difference and the density decrease,resistivity and neutron porosity increase;By comparing the calculation results of loading-unloading curve method,formation pressure simulation and equivalent depth method,it is found that the conventional calculation results of disequilibrium compaction without considering pore rebound are too large in the tectonic uplift area,which is not applicable in the tectonic uplifting area.Research shows that it needs to identify the logging curve characteristics that acoustic time,density decreases,and the resistivity,neutron porosity increases to identify the disequilibrium compaction,using the method of loading-unloading curve can restore the disequilibrium compaction overpressure in the uplift area more accurately,which provides a more effective research basis for pressure evolution,hydrocarbon accumulation and prediction in tectonically uplifted areas.
作者
韩晓洁
范昌育
高潮
张丽霞
尹锦涛
王成达
王宁
HAN Xiaojie;FAN Changyu;GAO Chao;ZHANG Lixia;YIN Jintao;WANG Chengda;WANG Ning(State Key Laboratory of Continental Dynamics,Department of Geology,Northwest University,Xi'an 710069,China;Shaanxi Key Laboratory of Lacustrine Shale Gas Accumulation and Exploitation,Xi'an 710075,China;Research Institute of Shanxi Yanchang Petroleum(Group)Co.,Ltd,Xi’an 710075,China)
出处
《天然气地球科学》
CAS
CSCD
北大核心
2023年第7期1163-1172,共10页
Natural Gas Geoscience
基金
陕西省陆相页岩气成藏与开发重点实验室(筹)开放课题“泥岩异常低压对页岩气富集的控制作用——以鄂尔多斯盆地典型陆相页岩为例”(编号:YJSYZX18SKF0002)资助.
关键词
欠压实超压
构造抬升
超压预测
超压计算
孔隙回弹
鄂尔多斯盆地
Undercompaction overpressure
Tectonic uplift
Overpressure prediction
Overpressure calculation
Pore rebound
Ordos Basin
