Relationship between potentiometric surface and abnormally low pressure in the Yanchang Formation, Zhenjing area, Ordos Basin, China

IF 4.2 3区 工程技术 Q2 ENERGY & FUELS
Chao Li , Huixi Lin , Yukai Qi , Likuan Zhang , Lan Yu , Yuhong Lei , Guiqiang Qiu , Liyuan Ma , Hanwen Hu
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Abstract

Abnormally low pressure commonly develops in petroliferous basins. It is closely associated with hydrocarbon distribution and can hinder safe drilling operations. Potentiometric surface is one of the causes of abnormally low pressure, but the relationship between such surface and abnormal pressure has not attracted much research attention. In this paper, a method is proposed for quantifying the potentiometric surface of the tight oil reservoir of the Upper Triassic Yanchang Formation in the Zhenjing area, southern Ordos Basin, China. This method involves screening pressure data that reflect real pore pressure conditions underground and analyzing the formation sealing conditions in the reservoir based on fracture development and the chemical characteristics of the formation water. The relationship between the potentiometric surface and the abnormally low pressure observed in the study area is discussed. The results show that the pressure coefficient of the Yanchang Formation in the Zhenjing area is 0.85–1.02, with an average of 0.93, indicating a state between abnormally low pressure and normal pressure. The Yanchang Formation has complex sealing conditions, with favorable overall sealing and a locally open hydrodynamic environment controlled by sand body connectivity and fault activity. We proposed a method to calculate the potentiometric surface using the measured pressure data with a pressure coefficient close to 1. The potentiometric surface is 1040–1200 m, with a high value in the northwest and a low value in the southeast, and it is 0–350 m below the ground level. The pressure coefficient was calibrated with an average of 1, with the potentiometric surface used as the starting point, indicating that the low pressure coefficient may be caused by the potentiometric surface below the ground level. The results have theoretical implications for the analysis of formation pressure characteristics in areas or basins with comparable geological conditions, and practical implications for the analysis and development of oil and gas.
鄂尔多斯盆地镇井地区延长组电位面与异常低压的关系
异常低压常见于含油气盆地。它与油气分布密切相关,可能会阻碍安全钻井作业。电位面是造成异常低压的原因之一,但电位面与异常低压之间的关系一直没有引起较多的研究。本文提出了鄂尔多斯盆地南部镇井地区上三叠统延长组致密油储层电位面定量方法。该方法包括筛选反映地下真实孔隙压力状况的压力数据,并根据裂缝发育和地层水的化学特征分析储层中的地层密封状况。讨论了研究区异常低压与电位面之间的关系。结果表明:镇井地区延长组压力系数为0.85 ~ 1.02,平均为0.93,处于异常低压与正常压力之间;延长组封闭条件复杂,整体封闭有利,砂体连通性和断裂活动控制着延长组局部开放的水动力环境。提出了一种利用实测压力数据计算电位面,压力系数接近于1的方法。电位面为1040 ~ 1200 m,西北高,东南低,在地面以下0 ~ 350 m。以电位面为起点,标定压力系数平均值为1,说明压力系数低可能是由于低于地面的电位面造成的。研究结果对具有可比地质条件的地区或盆地的地层压力特征分析具有理论意义,对油气分析和开发具有实际意义。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Natural Gas Industry B
Natural Gas Industry B Earth and Planetary Sciences-Geology
CiteScore
5.80
自引率
6.10%
发文量
46
审稿时长
79 days
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