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The Qiongdongnan Basin is a strongly overpressured basin with the maximum pressure coefficient over 2.2. Two types of vertical overpressure configuration can be identified by electronic logs and mud pressure, based on the calibration with the test pressure. The first is a double overpressure configuration, in which the middle low overpressure zone divides the entire overpressure zone into two zones. The double overpressure configuration lies primarily in the western part of the basin. The second is a single overpressure configuration, in which overpressure increases with depth. The single overpressure configuration lies primarily in the eastern part of the basin. Distribution maps of the overpressure top and overpressure horizons show three important characteristics: (1) The distribution of the pressure coefficient is not uniform. There are many low overpressure zones against a background of high overpressure. (2) The pressure coefficient in the western area is greater than in the eastern area. The maximum pressure coefficient in the western area is greater than 2.2. (3) There is a low overpressure interval between the high overpressure zones in the western area. Based on the overpressure distribution, some important implications for hydrocarbon exploration can be drawn. In the Qiongdongnan Basin, it has been shown that normal pressure zones are favorable for hydrocarbon accumulation, and strongly overpressured zones (pressure coefficient greater than 1.8) are unfavorable for hydrocarbon accumulation. Accordingly, the NW low overpressure belt around wells R, Q and S should be beneficial for hydrocarbon accumulations, and should be considered as the next exploration play in the Qiongdongnan Basin. Theoretical hydrofracture calculation and interpretation of the sand injectites indicate the presence of widespread hydrofractures in the basin. Comparison between the sealing capacities of the double overpressure and single overpressure configurations shows that the former is superior for hydrocarbon accumulation and preservation. Because of the strong sealing capacity provided by the displacement pressure and pore pressure difference between the seal rock and reservoir in the double overpressure configuration zone, hydrocarbons barely penetrate the seal rock in the middle low overpressure zone. Therefore, the exploration interval should be within and below the middle low overpressure zone in the western basin. 相似文献
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沉积盆地超压普遍发育,形成机制多样,其演化过程对油气运聚成藏具有重要的影响作用。综合试油、测井资料并结合有效应力特征,分析了黄河口凹陷超压的成因机制,表明东营组超压形成受欠压实和生烃作用的共同影响,沙河街组超压成因以生烃作用为主。压力史演化数值模拟证实,构造活动控制的断层开启和砂岩夹层共同作用造成的超压释放是部分区域实测地层压力接近于常压的原因。超压发育与演化特征控制了黄河口凹陷现今不同类型油藏的垂向分布：在现今超压比较发育、未受断裂活动影响且压力释放作用不明显的区域,以寻找古近系原生油气藏为主;而在断裂沟通古近系与新近系的区域则有利于新近系次生油气藏的形成与勘探。 相似文献
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在黏土矿物转化的化学动力学模型中,大多数模型只考虑了温度、时间和流体介质的影响。然而,最近的一些研究表明,超压抑制黏土矿物的转化。考虑到超压对黏土矿物转化的抑制作用,建立了超压背景下黏土矿物转化的化学动力学模型,并用最优化方法确定了超压抑制因子,从而使伊/蒙混层中蒙皂石层质量分数模拟值与实测值的误差达到最小。为检验其合理性,将该模型分别应用于一个新生代盆地和一个中生代盆地。模拟结果表明:在超压地层中伊/蒙混层中蒙皂石层质量分数的模拟值与实测值吻合较好,在压力系数为1.2～1.7的地层中,超压对伊/蒙混层中蒙皂石层质量分数的抑制可达15%～20%。 相似文献
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目前准噶尔盆地腹部地区超压演化过程仅提供了相对时间、概念、定性的认识,并未达到定量化。本文以东道海子北凹陷为例,基于流体包裹体、单井一维和剖面二维烃源岩成熟生烃史模拟技术,采用生烃增压模型定量化评价了侏罗纪八道湾组顶部和底部烃源岩的生烃增压演化过程。研究结果表明侏罗纪八道湾组为东道海子北凹陷主力烃源岩,具有幕式排烃的特点。八道湾组底部烃源岩经历了3 次超压增加和两次超压释放的过程,顶部烃源岩经历了两次超压增加和一次超压释放的过程。八道湾底部烃源岩3 次超压增加的时间分别为距今170～70 Ma、55～23 Ma、10～0 Ma,对应最大压力系数均为2.0,最大剩余流体压力50 MPa,两次超压释放的时间分别为70～55 Ma、23～10 Ma;八道湾组顶部烃源岩两次超压增加的时间分别为130～40 Ma、23～0 Ma,对应流体最大压力系数最大亦可达2.0 左右,最大剩余流体压力44 MPa,超压释放的时间为40～23 Ma。 相似文献
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Prediction of Overpressure Contributed Mainly by Structural Compression Using Impedance Inversion in Kuqa Depression, Tarim Basin 总被引：1，自引：1，他引：1
ShiWanzhong ChenHonghan ZhangXiming ChenHuichao 《中国地质大学学报(英文版)》2004,15(3):341-348
The origin and distribution of formation overpressure have effect not only on hydrocarbon migration and accumulation, but also on technique of drilling well. The study and prediction of overpressure are very important in basin analysis. At present, overpressure is mostly predicted by stack velocity.The process in calculating inter-velocity from stack velocity is very complex and inevitably leads to errors. Especially, this method is not available in the case that structural compression contribution to overpressure occurred. This paper introduces a new method, impedance inversion, to predict overpressure,and the principle is discussed. This method is used to predict the overpressure in Kuqa depression, Tarim basin and as a result, the absolute errors are less than 0.1, and relative errors are less than 5％ for predicted fluid pressure coefficients to the drill stem test (DST) measurements. It suggests that this method can be widely used to predict overpressure in foreland basins. 相似文献
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Overpressure is a hot topic in the study of sedimentary basins. It is important in generation,maturation migration,and accumulation of hydrocarbon,but the effects of overpressure on rock frame have not been investigated. In this study,experiments were carried out to study the effects of overpressure on rock frame structures using five core samples from the Junggar basin,Northwest China. The deformations and velocities for the samples were measured at different effective pressures related to non-equilibrium compaction and fluid expansion overpressure mechanisms. The results show that the effect of overpressure on rock frames gradually increases when the effective pressure drops down to a certain value (called critical pressure). Moreover,non-equilibrium compaction mechanism has more effects on rock frames than fluid expansion mechanism under the same effective pressure. Furthermore to study rock frame structural changes,we use Kuster and Toks?z's expressions to simulate the effective aspect ratios of inclusions α (penny shapes) for different effective pressures. The results show that the α decreases dramatically when the effective pressure decreases from the critical pressure. Changes of α can be interpreted as responses to the rock frame changes when grains conform one another by rotating and self-adjusting. However,different mechanisms of overpressure have different effects on rock frames. The rock frame can be affected more easily by overpressure in shallow regions generated by non-equilibrium compaction mechanism. Once this kind of rock frames are preserved after overpressure releases to a normal hydrostatic pressure,they can be identified by their specific rock frame characters. This method provides a new way to study overpressure release and fluid migration and accumulation. 相似文献
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异常地层压力预测是油气勘探和钻井工程关注的热点问题。对于勘探程度低、探井稀少的地区,压力分布特征的不明确制约油气勘探进展和钻井高效实施,因此,地层压力预测精度有待提高。在地层孔隙静力平衡原理的指导下,以准噶尔盆地腹部实际地质资料和压力测试数据为基础,建立了基于颗粒应力的地层压力预测模型。研究表明,(1)经典压力预测模型存在缺陷,特察模型并非静力平衡方程,有效应力不是骨架真正承担的力;(2)采用孔隙型介质颗粒应力参数建立了孔隙静力平衡方程,通过研究区深层侏罗系已钻井超压预测对比,发现基于颗粒应力的压力预测方法精度有所提高;(3)压力预测模型仅考虑了内动力因素即沉积增压,超压成因补偿不可忽视。研究区发现准南构造挤压应力向盆地内部传递,形成了规律性分布的超压分量,附加地应力的补偿是提高超压预测精度的有效途径。 相似文献
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钻井资料显示莺歌海盆地现今存在超压,纵向上由浅至深可划分为常压带、过渡带和超压带。利用测井声波时差和地震速度资料,按等效深度法计算了莺歌海盆地大量排气期(1.9 Ma)和现今超压值,并恢复了单井超压的演化。结果表明,地层超压平面上是以乐东区为中心向北向东递减的,临高隆起带和莺东斜坡带大部分为常压,单井上超压演化是逐渐增大的。这一结果与不同地区地质历史上沉降中心和沉积环境密切相关。莺歌海盆地超压的存在使天然气在剩余压力的作用下垂向运移。天然气藏均分布在乐东和东方地区黄流组顶底压差大、莺歌海组盖层超压封闭能力强的地区。靠近底辟区、且同时满足上述2个条件的储层更有利于天然气成藏。 相似文献