Formation and Development of Abnormal Low Pressure in the Yanchang Formation of the Central-Eastern Ordos Basin and its Influencing Factors  

作　　者：HE Lijuan YU Qiang REN Zhanli LI Rongxi LEI Xianghe SUN Xianyao YANG Qike WANG Tianzi YUAN Ruize 

机构地区：[1]School of Earth Science and Resources,Chang'an University,Xi'an 710054,China [2]Key Laboratory of Western China Mineral Resources and Geological Engineering,Ministry of Education,Chang'an University,Xi'an 710054,China [3]State Key Laboratory of Continental Dynamics,Northwest University,Xi'an 710069,China [4]Kela Mining Oil and Gas Management Area,Tarim Oilfield,Kuerle,Xinjiang 841000,China [5]State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum(Beijing),Beijing 102249,China

出　　处：《Acta Geologica Sinica(English Edition)》2025年第2期582-597,共16页地质学报(英文版)

基　　金：funded by the Major Project of the Changqing Oilfield‘Research on the Tectonic,Sedimentary,Mechanism and New Exploration of the Mesoproterozoic Changcheng System in the Ordos Basin’(ZDZX2021);the National Natural Science Foundation of China(42241204,42073054);the Fundamental Research Funds for the Central Universities,CHD(300102272205,300102272207).

摘　　要：The present-day pressure pattern is the ultimate result of the evolution of paleo-pressure,so understanding the variation of stress throughout geological history is of great significance for oil and gas accumulation.In this study,the fission track method was used to reconstruct the cooling history of sandstone samples from the Yanchang Fm.in the central-eastern Ordos Basin and the cause of the low-pressure anomaly in the Yanchang Fm.was analyzed.The max.burial depth pressure was reconstructed and the pressure evolution of the formation in the Futan 1 well was simulated,using Petromod 1D.The fission track data and Petromod 1D simulation results indicate that the Yanchang Fm.reached its max.burial depth and experienced a high paleo-pressure of 30.92 MPa at around 100 Ma.Since the Late Cretaceous,the formation pressure evolution in the study area can be divided into two stages.From 100 to 20 Ma,the formation slowly uplifted,with the pressure gradually decreasing.Since the Miocene(about 20 Ma),the pressure rapidly decreased to the current pressure of approximately 6.92 MPa.Based on the above research results,the influence of pore rebound and temperature decrease on formation pressure was quantitatively calculated.The results show that during the first stage,the pressure reduction caused by pore rebound and cooling was 3.86 MPa and 3.49 MPa,respectively,with a decrease of about 12.48%and 11.28%.During the second stage,the pressure reduction caused by pore rebound and cooling was 6.32 MPa and 9.60 MPa,respectively,with a decrease of about 20.43%and 31.04%.The formation of low pressure in the Yanchang Fm.in the central and eastern basin is mainly controlled by pore rebound and temperature reduction,caused by erosion after stratigraphic uplift.The decrease in temperature plays a decisive role in determining the formation process of the low-pressure oil reservoir.

关 键 词：low-pressure oil reservoir fission track THERMOCHRONOLOGY paleo-geothermal uplift cooling history 

分 类 号：P618.13[天文地球—矿床学]