Acta Petrolei Sinica ›› 2018, Vol. 39 ›› Issue (9): 971-979.DOI: 10.7623/syxb201809002

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Quantitative evaluation on overpressure generated from undercompaction and fluid expansion

Liu Tao, Liu Jingdong   

  1. School of Geosciences, China University of Petroleum, Shandong Qingdao 266580, China
  • Received:2018-01-06 Revised:2018-07-21 Online:2018-09-25 Published:2018-09-28

欠压实与流体膨胀成因超压的定量评价

刘桃, 刘景东   

  1. 中国石油大学地球科学与技术学院 山东青岛 266580
  • 通讯作者: 刘景东,男,1984年9月生,2006年获中国石油大学(华东)学士学位,2011年获中国石油大学(华东)博士学位,现为中国石油大学(华东)地球科学与技术学院讲师,主要从事油气地质与勘探方面的教学与科研工作。Email:ljd840911@126.com
  • 作者简介:刘桃,男,1994年3月生,2016年获中国石油大学(华东)学士学位,现为中国石油大学(华东)地球科学与技术学院硕士研究生,主要从事油气地质与勘探方向研究。Email:1115303614@qq.com
  • 基金资助:

    中国石油科技创新基金项目(2017D-5007-0101)、国家自然科学基金项目(No.41702142)和中央高校基本科研业务费专项资金项目(18CX02058A)资助。

Abstract:

Based on rock stress-strain mechanisms and pore structure, this paper studies the logging response characteristics of overpressure generated from undercompaction and fluid expansion, has established the logging evaluation models of different overpressure causes, and quantitatively evaluate overpressure causes in Dongpu depression. The study suggests that under the overpressure induced by undercompaction, storage pores and interconnecting pores in strata with are bigger than those in normal compacted strata. Meanwhile, changes occurred to pore volume and conduction attributes, resulting in the stratum characteristics of high porosity, high AC, low density and low resistivity. However, under the overpressure induced by fluid expansion, only storage pores were enlarged evidently with obvious changes in conduction attributes and few changes in volume attributes, resulting in the stratum characteristics of constant porosity and density, the increased AC and decreased resistivity. Based on the various geology and logging responses caused by different types of overpressure, AC/DEN/R-effective stress model and AC/R-DEN model have been established to quantitatively evaluate the contribution of overpressure respectively induced by undercompaction and fluid expansion. The models are well applied to evaluate the causes of overpressure in Dongpu depression. The results show that in Dongpu depression, the overpressure generated from undercompaction predominates in Es2 and Es3 with the total contribution rate of 53% -92%, while that from fluid expansion (hydrocarbon generation) mainly distributes in Es3 with total contribution rate of 8% -47%. Horizontally, from sag zone, slope zone to central uplift zone, the overpressure contribution rate of fluid expansion (hydrocarbon generation) gradually descends while that of undercompaction ascends.

Key words: overpressure, undercompaction, fluid expansion, quantitative evaluation, Dongpu depression

摘要:

基于岩石应力-应变机理及岩石孔隙结构,研究了欠压实与流体膨胀成因超压的测井响应特征,建立了两种成因超压测井评价模型,并对东濮凹陷超压成因进行了定量评价。研究结果表明:欠压实成因超压下,地层"存储孔"与"连通孔"大于正常压实地层,体积属性、传导属性发生变化,导致地层呈高孔隙度、高声波时差、低密度、低电阻率特征;流体膨胀成因超压下,仅"连通孔"明显扩大,传导属性发生变化,而体积属性变化不大,导致地层孔隙度、密度不变,而声波时差增加、电阻率减小。基于不同成因超压所表现出的各种地质、测井响应差异,建立了声波时差/密度/电阻率-有效应力模型和声波时差/电阻率-密度模型,用于定量评价欠压实与流体膨胀成因超压的贡献大小。模型在东濮凹陷超压成因评价中得到了应用,应用结果显示东濮凹陷沙河街组二段和沙河街组三段超压以欠压实成因为主,总体贡献率为53%~92%,流体膨胀(生烃作用)成因超压主要分布于沙河街组三段,总体贡献率为8%~47%;平面上,由洼陷带、斜坡带至中央隆起带,流体膨胀(生烃作用)成因超压贡献率逐渐降低,欠压实成因超压贡献率逐渐增加。

关键词: 超压, 欠压实作用, 流体膨胀作用, 定量评价, 东濮凹陷

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