莺歌海盆地地层压力演化特征及其与天然气运聚成藏的关系

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。     

琼东南盆地超压系统泄压带: 可能的天然气聚集场所

泄压带是超压系统内部流体向外运移的通道和有利的油气聚集场所, 对水溶相天然气析离成藏更有着重要意义.本文综合应用速度谱、测井、钻井和地层测试等资料预测了琼东南盆地超压系统的分布, 将其划分为3种结构类型; 结合粘土分析等资料识别出了4种类型的泄压带, 并讨论了泄压带的分布与可能的天然气聚集区带.琼东南盆地中央坳陷带整体发育一个超压系统, 其分布格局主要受陆坡带的形成和莺歌海盆地超压传递的影响, 陆坡区的超压明显强于非陆坡区, 西部的超压整体强于东部并在浅部呈现自西向东传递的趋势.泄压带内的天然气成藏主要取决于压力、温度和溶解气量, 需满足溶解气量足够多和溶解度变化量足够大, 相对而言, Ⅱ型泄压带成藏条件最优, 既有断裂沟通深部水溶气和浅部储层, 又有温压条件的显著变化, 因而流体运移最活跃.Ⅲ型泄压带次之, 但分布最广, 该类型最有利部位分布在陵水低凸起和宝岛凹陷北坡.      

Development of Overpressure in the Tertiary Damintun Depression, Liaohe Basin, Northern China

The Damintun depression is one of the four depressions in the Liaohe basin in northern China, and is a rift basin developed in the Paleogene. This paper discusses in detail the characteristics of pressure and fluid potential of the Damintun depression based on a synthesis of the data from boreholes, well tests and seismic surveys. Data from sonic logs, well tests and seismic velocity measurements are used to study the pressure characteristics of the areas. From the sonic log data, shales can be characterized as normally pressured, slightly overpressured or highly overpressured; from the well test data, the pressure-depth gradient in oil-producing intervals implies hydrostatic pressure in general. Most seismic profiles in the Damintun depression are of sufficiently high quality for seismic velocities to be measured. The fluid pressures, excess pressures and pressure coefficients in 47 representative seismic profiles are predicted using formula calculation methods, and further transformed to fluid potenti     

准噶尔盆地腹部盆1井西凹陷超压研究

准噶尔盆地腹部盆1井西凹陷存在明显的深部超压系统(4400m以下)。通过对超压段地质、钻井、地球物理特征的研究发现,超压段多为砂、泥岩互层,泥岩段大多几米到十几米厚,孔隙度在8%以下,已经过充分的压实,进入超压段,泥浆密度大幅增加,远大于1.2g/cm~3,砂岩、泥岩段同时具有高声波时差和低电阻率特征,井旁地震速度具有异常低值特征,超压顶面形态不规则,穿层分布,并且宏观上往往在一定的深度范围内。经过分析,欠压实以及煤层不是超压带低速的原因,烃类生成尤其是天然气生成对现今超压贡献最大。     

Characteristics of overpressure distribution and its implication for hydrocarbon exploration in the Qiongdongnan Basin

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.     

Mudstone compaction and its influence on overpressure generation, elucidated by a 3D case study in the North Sea

Mudstones are one of the least permeable rocks in most sedimentary sequences. Accordingly they can act as seals for fluid flow leading to abnormal overpressures. Nevertheless, mudstone compaction and related permeability and porosity decrease are not adequately described in current basin modelling software, because only mechanical compaction is taken into account. In reality, however, clay minerals undergo severe chemical diagenesis which certainly influences petrophysical properties and compaction. In this context a mathematical approach which has been originally developed in soil mechanics has been adapted to basin modelling. The underlying mathematical equations are carefully explained in the text. In the basic equation the compression coefficient is a function of void ratio and effective stress. Using these equations, overpressure can be predicted by using petroleum systems modelling techniques. This is shown for a real 3D case study in the North Sea, in which strong overpressure occurs. A compaction model for mudstones that depends strongly on the clay content of the individual stratigraphic units is used for the calibration of porosities in the 3D case study. In addition, a chemical compaction model that reduces porosities by using a kinetic reaction is used for the deeper part of the basin where mechanical compaction processes are less important. The pressure generation process depends strongly on permeability and compressibility of the porous medium. Therefore, the use of mudstone compaction and permeability models is sufficient to produce pore overpressures. In the case studied, abnormal overpressures are generated during burial together with the petroleum generation process. The mechanical and chemical compaction mechanisms ensure that the pressures are preserved in the deeper part of the basin.     

北部湾盆地涠西南凹陷超压系统与油气运移

利用地震层速度、声波测井及各种录井资料研究北部湾盆地涠西南凹陷超压系统及油气运移 ,用以指导下一步油气勘探。研究发现主要生烃层段流沙港组二段泥岩的欠压实是形成异常高压的主要原因 ,异常压力主要分布于凹陷中心地区。最大压力封闭点及油的成熟门限深度可以区分异常高压层的作用 ,在生油门限以下的异常压力带中的快速压实段 ,是油气初次运移最有利的层段。研究发现本区存在两种油气运移方式 ,即向泥岩下方运移和侧向运移 ,最后指出勘探油气的有利地区     

Effect of Overpressure on Rock Frame and Its Implications for Overpressure Evolution

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.     

Prediction of Shale Gas Pressure based on Multi-channel Seismic Inversion in Fuling

The accurate prediction of formation pressure is important in oil/gas exploration and development. However, the achievement of this goal remains challenging, due to insufficient logging data and the low predictive data accuracy from seismic data. In this work, a case study was carried out in the Baima area of Wulong, in order to develop a workflow for accurately predicting shale gas formation pressure. The multi-channel stack method was first used, as well as the inversion of single-channel seismic data, to construct velocity and density models of the formation. Combined with the existing well-logging data, the velocity and density models of the whole well section were established. The shale gas formation pressure was then estimated using the Eaton method. The results show that the multi-channel seismic stacking method has a higher accuracy than the inversion of the formation velocity obtained by the single-channel seismic method. The discrepancies between our predicted formation pressure and the actual formation pressure measurement are within an acceptable range, indicating that our workflow is effective.     

与温度全相关的有效骨架压力模型及其在库车坳陷的应用

鉴于世界上极大多数盆地模拟系统的超压史尚未达到实用水平,本文基于力平衡方程、质量守恒法则及达西定律,完整地推导出了与温度全相关的有效骨架压力史的数学模型,使之适用于盆地模拟。通过塔里木盆地库车坳陷的实际模拟,尤其是克拉2井和依南2井超压史的现今值接近于实测数据,即平均相对误差绝对值分别约为3%和5%,证明该有效骨架压力模型具有较高的精度,既能使超压数值模拟避免通过岩石力学实验来测试有效骨架压力,又能达到实用水平。库车坳陷的实例指出:1)在有效骨架压力计算中所用的孔隙流体的密度和黏度与温度相关是必要的,否则超压计算结果会远离实测压力数据。这也恰好与盆地模拟中这两个参数原本与温度相关一致了;2)影响超压的最敏感参数是渗透率,将实测压力数据作为约束条件,在容许的范围内对Kozeny-Carman渗透率公式中的Sa(骨架的颗粒比面)进行校准,这是获得正确的超压史之关键;3)剥蚀事件对地史、热史乃至超压史的模拟结果的影响。     

沾化凹陷渤南洼陷沙四段～孔店组的热史及超压演化

利用EASR%Ro模型,计算了渤南洼陷沙四段～孔店组(Es4-Ek)的古地温和古地温梯度的演变值。古地温的演变与盆地的构造演化关系密切,抬升剥蚀期地层温度下降,沉降期地层温度升高,地史过程中地温梯度的变化呈逐渐降低的趋势。采用盆地模拟技术,恢复且再现了渤南洼陷Es4-Ek地史期的超压演化过程。此过程与该区构造演化和有机质生烃增压作用紧密相关,沉积和剥蚀速率及地层地史期的孔渗性决定了早期超压幅度的高低,而后期构造运动的改造及有机质的生烃作用,决定了现今压力系数的大小。压力在漫长的发展演化过程中,经历了超压积累～破裂泄压～超压再积累～再破裂泄压的反复过程,说明盆地的压力场是一个动态发展的过程,其间伴随着高压流体的幕式排放。     

天然气充注导致储层增压的定量研究

超压对于油气勘探具有重要的意义。以天然气为载体的压力传递是储层超压的重要成因机制。由于地层水和原油对于天然气的溶解性和压缩性存在明显差异,造成了含水地层和油层在天然气充注过程中具有不同压力演化路径。本研究模拟计算不同原始孔隙流体的地层在受到甲烷充注时的压力演化,建立了甲烷充注量与超压的定量关系,进而探讨天然气充注增压的影响因素。结果表明：天然气充注在一定条件下可以造成地层压力的增大;不同原始孔隙流体的储层压力演化路径不同。原始孔隙流体为天然气的地层最先出现超压,但增压缓慢;含水层比含油层增压迅速,更易形成超压;同等封闭条件下,浅部地层比深部地层更易形成超压,高温盆地比低温盆地更易形成超压。     

阳霞凹陷超压成因及与油气成藏关系

地层超压的形成和分布不仅与油气的运聚成藏有关, 而且还直接影响油气钻井工程.因此, 超压的研究和预测成为当今含油气盆地研究中的重要内容.阳霞凹陷属于库车坳陷的一个次级构造单元, 钻井揭示凹陷内有超压发育.笔者应用测井资料、测试资料和地震资料分析了阳霞凹陷内超压的成因以及超压与油气成藏的关系, 得出以下认识: (1) 在阳霞凹陷内, 上第三系吉迪克组膏泥岩中的超压是以欠压实成因为主控因素, 下第三系和白垩系中的超压是以构造成因为主控因素, 形成了上下两套成因机制并不完全相同的超压系统. (2) 从构造演化时间上来看, 巴西盖组与巴什基奇克组的超压形成时间最晚在上新世的库车组时期, 早于油气大规模运移时期(库车晚期—第四纪西域期).由于缺少断层的疏导, 积聚的超压无法通过断层释放, 阻挡了后期油气在巴西盖组与巴什基奇克组中聚集成藏, 使得库1井所钻遇的圈闭成藏规模不足.      

Performance evaluation of HWRF model during post monsoon tropical cyclone Nilofar

An accurate tropical cyclone track and intensity forecast is very important for disaster management. Specialized numerical prediction models have been recently used to provide high-resolution temporal and special forecasts. Hurricane Weather Research and Forecast (HWRF) model is one of the emerging numerical models for tropical cyclone forecasting. This study evaluates the performance of HWRF model during the post monsoon tropical cyclone Nilofar on the north Indian Ocean basin. The evaluation uses the best track data provided by the Indian Meteorological Department (IMD) and the Joint Typhoon Warning Centre (JTWC). Cyclone track, central pressure, and wind speed are covered on this evaluation. Generally, HWRF was able to predict the Nilofar track with track error less than 230 km within the first 66 h of forecast time span. HWRF predicted more intense tropical cyclone. It predicted the lowest central pressure to be 922 hPa while it reached 950 hPa according to IMD and 937 hPa according to JTWC. Wind forecast was better as it predicted maximum wind speed of 122 kt while it reached 110 and 115 kt according to IMD and JTWC, respectively.     

超压背景下黏土矿物转化的优化模型

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%。     

四川盆地川西坳陷高异常地层压力分布特征

本文通过分析川西坳陷２０多个含气构造的主要地层压力资料，对川坳陷高异常地层压力的分布特征有了一定的认识。认为川西高异常地层压力在纵向层位上主要分布于侏罗系和上三叠统，压力分段明显，相同的力段在不同的构造既不等时也不等深；在平面上高异常地层压力分布广泛，超高压区刚分布于川西北地区，并形成两个超高压中心，整个高异常地层压力的分布虽然总体上基本一致，但在不同层位，不同时期也存在着差异。     

储气砂中浅层气溢出过程数值模拟研究

基于A.Nermoen的物理实验,文章进行了浅层气溢出过程数值模拟,区别于以往常用的欧拉-欧拉方法,文章采用了基于欧拉-拉格朗日方法的新型的离散粒子模拟方法MP-PIC（multiphase particle-in-cell）模型。揭示超压气体释放的机制,以及浅层气溢出过程中速度、压力的变化情况和变化规律。模拟得到的颗粒流化现象以及气泡的产生、运动和溢出现象与试验现象相一致,数模计算结果与实验资料两者相关度为0.94,相关性较好。临界流化速度和压力与土层的高度呈正相关,临界流化压力与实验结果较为接近,但由于马格努斯力（magnus）等作用力未考虑,导致临界流化速度相比于实验偏低。该模型方法能处理任意尺寸分布的颗粒,适用庞大的颗粒量,紧密耦合气固间相互作用,适用性好,准确性高,为数值模拟提供了便利。     

准噶尔盆地阜康凹陷侏罗系超压成因、垂向传导及油气成藏

沉积盆地中超压广受关注,但对超压传导规律认识的不足制约了高压领域的油气勘探.以准噶尔盆地阜康凹陷侏罗系为例,通过超压类型地质综合判识、关键超压表征参数的理论计算及流体包裹体压力恢复,首次认识到了垂向传导对于储集层超压的重要贡献,结合压力垂向传导机制及过程,探讨了油气藏的运聚及泄露意义.研究结果表明,侏罗系超压由4类超压环境中7种致压因素引起,经历2期大规模压力跨层垂向传导,储集层段发育以垂向传导为主因的复合超压,形成3类不同动力特征的油气藏.压力垂向传导是储集层超压的主要成因机制,断-盖的力学性质、差应力及流体压力等3类因素控制压力垂向传导,传导背景下,形成3类与传导作用有关的油气藏:受断层垂向传导控制的超压油藏、受连通砂体侧向传导控制的超压油藏以及超压界面上的常压油藏,上述3类油气藏的运聚及泄露特征差异较大.      

准噶尔盆地西北部地层压力演化与油气成藏有利动力条件研究

准噶尔盆地西北部发育异常高压,异常高压是油气垂向运移的重要动力条件,目前已经在超压带上发现大量高压油气藏。为了揭示现今地层压力特征,恢复成藏期古压力演化特征。利用测井方法和2D盆地模拟技术,得到超压的分布和演化特征,并讨论了超压对油气运移的影响。结果表明,研究区单井地层压力结构可以分为三类;由古至今,各地层超压逐渐变大,超压由浅部地层向深部地层逐渐变大;各时期平面上超压分布呈规律性变化,整体上是由西北部向东南部逐渐增大;超压的分布和演化成为油气垂向运移有利动力条件,对研究区高压油气藏的形成具有重要的意义。     

辽东湾地区辽中北洼超压的发育演化 及油气幕式成藏

基于地层测试数据,利用声波时差的等效深度法以及数值模拟方法对辽中北洼地区超压的分布和演化进行了研究。结果表明本区超压普遍发育,储层超压主要发育于古近系及潜山,最大压力系数193;东二下亚段及以下地层泥岩段中普遍发育欠压实,计算压力系数可达到19以上。不均衡压实和生烃作用是泥岩层超压发育的主要成因,它源传导型是储层超压发育的主要机制。沙河街组沉积以来,烃源岩中超压开始发育并逐渐增加,东营组沉积末期达到高峰,随后开始泄放降低,明下段沉积期开始,超压再次积累增大直至现今。JZ20 2凝析气田的储层流体包裹体及温压方面的证据、油气成熟度和烃源岩生烃史方面的证据以及原油物性方面的证据表明其油气成藏为晚期幕式快速充注成藏。同时研究区断裂发育少,活动性弱,油气沿断层垂向运移受限,充注期主力烃源岩发育强超压,产生水力破裂微裂缝成为油气幕式排放的通道,同时为油气长距离的侧向运移提供了充足的动力,属于超压主导型油气晚期幕式快速成藏。