| 吉木萨尔凹陷二叠系超压成因及分布预测 |
| 投稿时间：2023-10-04 修订日期：2023-10-26 点此下载全文 |
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| 中文摘要:准噶尔盆地吉木萨尔凹陷二叠系普遍发育异常高压,被认为是影响钻井工程高效安全和油气成藏动力条件评价的关键因素。但其成因机制目前缺乏研究,目的层埋藏较深,现有超压计算方法精度不高,超压分布特征也不够明确。本文基于钻井、测井和测试资料对研究区目的层现今实测地层压力进行分析,结合泥岩压实特征、源岩有机地球化学特征以及现今构造背景探讨了超压成因机制,同时利用岩石静力平衡原理改进了压力预测模型,以成因为导向,形成适用于研究区的压力预测方法,并对研究区进行了压力分布预测。研究表明,(1)吉木萨尔凹陷二叠系局部发育高幅超压,其中芦草沟组压力系数最高可达1.8；(2)研究区二叠系超压成因主要为非均衡压实和生烃增压两种机制,另外还可能存在水热增压机制；(3)现有压力预测模型假设过强且精度较低,本文基于岩石静力平衡方程原理,引入颗粒应力参数,消除特察模型缺陷,构建新的压力计算模型,新模型压力预测精度明显高于传统方法；(4)异常高压主要发育在凹陷西部深洼区及中西部斜坡带,压力系数高值区主要位于J36井区,高幅超压受到生烃凹陷控制。上述成果及认识对吉木萨尔凹陷二叠系钻探和油气勘探评价有比较重要的指导意义。 |
| 中文关键词:吉木萨尔凹陷 二叠系 超压成因 非均衡压实 生烃增压 压力预测 颗粒应力 |
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| Mechanism of generation and Prediction of distribution for Overpressure within Permian in Jimusar Depression, Junggar Basin |
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| Abstract:Abnormal pore pressure,developed in Permian all over the Jimusar depression, eastern Junggar Basin, is recognized as the key factor affecting the safety and efficiency in a drilling process and evaluation of the dynamic conditions of hydrocarbon accumulation. However, overpressure origins are still not studied systematically, the accuracy of traditional overpressure calculation methods is not high enough due to its deep burial and distribution law is barely clear. In this study, current measured pore pressure feature of the target layer is analyzed based on drilling, logging and formation testing data, combined with compaction characteristics of mudstone, organic geochemical characteristics and the present tectonic settings, and then mechanisms of overpressure generation are discussed. Further, based on the static equilibrium principle of formation, pore pressure prediction model is improved theoretically. At the same time, new method suitable for study area is formed considering generation mechanism of overpressure, and pressure distribution in study area is predicted. The results show that (1) High amplitude overpressure is generally developed in the Permian of Jimusar depression, and the pressure coefficient of Formation Lucaogou is up to 1.8; (2) The overpressure of Permian in the study area is mainly caused by disequilibrium compaction and hydrocarbon-generating supercharging, and hydrothermal mechanism may also exist; (3) The traditional pressure prediction models have extremely strict assumptions and low accuracy. In this paper, based on the principle of static equilibrium equation, grain stress parameters are introduced to eliminate the defects of Terzaghi model, and a new pressure calculation model is proposed, whose accuracy is significantly improved; (4) The overpressure is mainly developed in the western deep sag and the central-western slope zone, the high-pressure coefficient is mainly located in the J36 well area, which controlled by the hydrocarbon-generating depression. The above results and understandings have important guiding significance for Permian drilling and evaluation of hydrocarbon exploration in Jimusar depression. |
| keywords:Jimusar Depression Permian mechanism of overpressure generation disequilibrium compaction hydrocarbon-generating supercharging pore pressure prediction grain stress |
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