四川盆地J地区志留系龙马溪组页岩裂缝地震预测与评价

利用三维地震资料进行相干体分析﹑应力场分析﹑P波各向异性分析,对四川盆地J地区龙马溪组优质页岩层段不同规模裂缝的优势发育带进行预测,对比分析表明,对于大型裂缝的预测,相干体分析相对较好;对于中小型裂缝的检测,采用P波各向异性技术的效果相对较好。龙马溪组页岩段底部在构造主体部位上主要发育中小型裂缝,是优质页岩储层的主要分布层段。JY1井区两口水平井的测试结果证实,对龙马溪组优质页岩段开展三维地震裂缝预测是可行的,预测结果可有效地指导该区的页岩气勘探。     

页岩储层构造应力场模拟与裂缝分布预测方法及应用

裂缝是页岩气富集高产的关键因素。页岩储层相对于其他类储层,其塑性相对较强,非构造裂缝比较发育。构造裂缝除了高角度的张性裂缝以外,还发育有较多近水平的层理缝和低角度构造滑脱缝等。针对页岩储集层的特点和裂缝发育特征,从地质成因的角度,明确了页岩储层构造应力场模拟数值模拟与裂缝分布预测的方法,其核心在于建立模拟地区目的层的精确地质模型、力学模型和计算模型。利用页岩的单轴和三轴压缩变形试验和声发射古、今地应力测试结果进行应力场数值模拟,获得研究区构造应力场分布,将应力场模拟果与实际地质资料对比分析,进一步检验校正已建立地质模型的合理性;在此基础上,针对富有机质页岩主要发育张裂缝和剪裂缝的特殊性,分别采用格里菲斯、库伦摩尔破裂准则计算页岩储层张破裂率、剪破裂率,依据张裂缝与剪裂缝所占的比例关系,求取页岩储层的综合破裂率,据此分别定量表征页岩储层中张裂缝、剪裂缝和构造裂缝的发育程度及分布特征;并在全面考虑影响页岩储层裂缝发育程度的综合破裂率、脆性矿物含量、有机碳含量多种主控因素的基础上,进一步提出了页岩“裂缝发育系数”作为最终判别指标,综合定量表征页岩储层裂缝的发育程度和预测裂缝的分布,页岩裂缝发育系数越大,裂缝发育程度则越高。该方法在我国渝东南地区下志留统龙马溪组页岩储层裂缝分布预测中得到了有效应用。此不仅为页岩气甜点优选提供了一种新的技术方法,而且模拟成果对页岩气水平井和压裂改造方案的设计具有重要的参考价值。     

荆门探区五峰组–龙马溪组页岩储层特征及甜点层段评价

为进一步明确荆门探区五峰组—龙马溪组页岩气资源潜力,优选甜点层段,以X井五峰组–龙马溪组一段页岩为主要研究对象,利用干酪根薄片、X衍射、核磁共振、微纳米CT扫描及地化分析等多种测试手段,结合测井解释成果,从岩石学、有机地球化学、矿物组成、孔隙类型及结构、物性及含气性等方面,系统评价五峰组—龙一段各小层储层特征,以优选甜点层段。结果表明:五峰组—龙一段以硅质页岩为主,主要形成于深水陆棚相还原环境,优质页岩段页岩气品质较高,有机地化特征优越;多手段测试孔隙率与渗透率均具有正相关特征,饱和水页岩核磁共振T2谱可分为2类5型,不同类型T2谱所反映的页岩孔径分布特征具有差异性,孤立孔主要存在于小于2 nm的微孔中,占比非常小;基于储层特征评价,优选出龙一$_1^1$—龙一$_1^2$小层为一类储层,五峰组上段和龙一$_1^3$小层为二类储层,龙一$_1^4$小层为三类储层,富碳高硅页岩段的五峰组上段—龙一$_1^3$小层(厚度约17.7 m)为页岩气甜点层段,研究成果可为荆门探区页岩气勘探开发确定水平井的靶体层段提供参考依据。      

塔里木盆地塔中地区上奥陶统古构造应力场模拟与裂缝分布预测

塔里木盆地塔中地区上奥陶统良里塔格组碳酸盐岩构造裂缝是区内油气显示十分活跃的有效储集空间,其发育和分布主要受古构造应力场的控制。依据塔中地区上奥陶统地震资料的断裂构造解释和钻井、测井裂缝特征分析等成果,在声发射地应力测量、岩石力学参数和单轴抗拉强度测试的基础上,考虑断裂对裂缝形成的影响,采用三维有限元法对塔中地区上奥陶统加里东中期Ⅱ幕裂缝形成期的古构造应力场进行了数值模拟,预测了裂缝的分布。结果表明,裂缝形成期地应力最大主应力有效值为47.9～58.3MPa,平均值为51.97MPa,抗张强度为5.13～6.91MPa,平均值为5.81MPa。有效张应力的高值区是构造裂缝发育的有利地区,主要分布在塔中东部大的断裂带交会处和断裂带的部分区段内,与实际钻井统计的上奥陶统高裂缝线密度和油气井分布区基本吻合,可以为研究区的油气勘探提供新的地质依据。     

四川盆地富顺-永川地区五峰组—龙马溪组应力场模拟及裂缝发育区预测

岩石中构造裂缝主要受控于地层所处的区域构造应力场,地应力对油气的运移、成藏和分布有着重要的作用。通过应用ANSYS有限元数值模拟方法对四川盆地富顺-永川区块的五峰组-龙马溪组进行应力场模拟及分析研究、应用构造曲率法中的三点法对该层段页岩进行张裂缝发育情况预测研究、综合模拟结果与曲率计算数据对目的区域目的层段进行裂缝发育强度综合预测研究,结果表明富顺-永川区块五峰组-龙马溪组应力高值沿背斜走向分布的规律明显,研究区的东部及西南部的背斜应力值较其他区域背斜高;曲率高值沿背斜走向分布的规律明显,研究区东部及西南部背斜曲率值较其他区域背斜高;在现今应力的作用下,研究区背斜处裂缝发育程度较高,向斜处裂缝发育程度较低,研究区东部及西南部背斜裂缝发育程度较其他区域高。      

塔里木盆地塔中地区上奥陶统古构造应力场模拟与裂缝分布预测

塔里木盆地塔中地区上奥陶统良里塔格组碳酸盐岩构造裂缝是区内油气显示十分活跃的有效储集空间,其发育和分布主要受古构造应力场的控制。依据塔中地区上奥陶统地震资料的断裂构造解释和钻井、测井裂缝特征分析等成果,在声发射地应力测量、岩石力学参数和单轴抗拉强度测试的基础上,考虑断裂对裂缝形成的影响,采用三维有限元法对塔中地区上奥陶统加里东中期Ⅱ幕裂缝形成期的古构造应力场进行了数值模拟,预测了裂缝的分布。结果表明,裂缝形成期地应力最大主应力有效值为47.9～58.3MPa,平均值为51.97MPa,抗张强度为5.13～6.91MPa,平均值为5.81MPa。有效张应力的高值区是构造裂缝发育的有利地区,主要分布在塔中东部大的断裂带交会处和断裂带的部分区段内,与实际钻井统计的上奥陶统高裂缝线密度和油气井分布区基本吻合,可以为研究区的油气勘探提供新的地质依据。     

基于MSC MARC的三维构造应力场数值模拟与裂缝预测——以宝浪油田宝北区块为例

MSC MARC的高度非线性有限元分析能力与强大的二次开发接口为复杂三维地质数值模型的建立与三维构造应力模拟与非线性分析提供了有力工具; 并可以通过二次开放子程序建立复杂的岩石本构与破裂准则。本文基于MSC MARC建立了新疆焉耆盆地宝浪油田宝北区块背斜构造三维有限元模型并进行了构造应力模拟分析和裂缝预测。裂缝预测结果与实际动态资料十分吻合。      

川东南地区志留系龙马溪组页岩气有利区评价优选

通过对川东南地区志留系龙马溪组页岩有机质丰度、热成熟度、有机质类型、脆性矿物含量、页岩层厚度、埋藏深度、构造形态等七大地质因素的综合分析,认定该区分布广泛的页岩有机质含量较高,有机质类型较好,热演化程度高,生烃潜力大,具备形成页岩气藏的气源条件。页岩厚度较大,埋深较浅,脆性矿物含量较大,页岩气的保存条件良好,有利于页岩气的压裂与开采。     

Quantitative Prediction of Fracture Distribution of the Longmaxi Formation in the Dingshan Area,China using FEM Numerical Simulation

Fracture prediction is a technical issue in the field of petroleum exploration and production worldwide. Although there are many approaches to predict the distribution of cracks underground, these approaches have some limitations. To resolve these issues, we ascertained the relation between numerical simulations of tectonic stress and the predicted distribution of fractures from the perspective of geologic genesis, based on the characteristics of the shale reservoir in the Longmaxi Formation in Dingshan; the features of fracture development in this reservoir were considered. 3D finite element method (FEM) was applied in combination with rock mechanical parameters derived from the acoustic emissions. The paleotectonic stress field of the crack formation period was simulated for the Longmaxi Formation in the Dingshan area. The splitting factor in the study area was calculated based on the rock breaking criterion. The coefficient of fracture development was selected as the quantitative prediction classification criteria for the cracks. The results show that a higher coefficient of fracture development indicates a greater degree of fracture development. On the basis of the fracture development coefficient classification, a favorable area was identified for the development of fracture prediction in the study area. The prediction results indicat     

湖北宜昌志留系龙马溪组几丁虫及其年代和生物复苏意义

调查分析了位于湖北省宜昌市分乡的一口志留系钻孔,在龙马溪组下段至上段下部的进尺约100 m的岩芯中采取了313件样品进行几丁虫分离,其中165件炭质泥岩和泥岩样品中共发现保存完整的早志留世几丁虫化石917枚。自下而上识别出Belonechitina?postrobusta,Conochitina alargada,Armoricochitina sp.和Conochitina emmastensis生物带。几丁虫生物带的组合特征和时代意义,及其与全球其它地区同期几丁虫对比,暗示几丁虫Conochitina alargada的始限位置与笔石Monograptus triangularis的始限位置接近,可以作为埃隆期底界界线划分的生物化石参考标志之一。志留纪龙马溪组几丁虫多样性最早发生在鲁丹期末期,在埃隆期晚期出现丰度和分异度的明显升高。微量元素组成的环境意义研究显示龙马溪组下段下部黑色页岩与下段上部深灰色页岩和上段下部黄绿色页岩形成于氧化环境,龙马溪组下段下部黑色页岩中几丁虫属种稀少不是环境所致,而是奥陶纪生物大绝灭之后志留纪几丁虫生物复苏之前几丁虫生物残存复苏阶段的产物,暗示奥陶纪大绝灭之后志留纪几丁虫生物复苏开始于鲁丹期晚期,并在埃隆期中-晚期发生辐射。     

Simulation of Paleotectonic Stress Fields and Distribution Prediction of Tectonic Fractures at the Hudi Coal Mine, Qinshui Basin

Study on tectonic fractures based on the inversion of tectonic stress fields is an effective method. In this study, a geological model was set up based on geological data from the Hudi Coal Mine, Qinshui Basin, a mechanical model was established under the condition of rock mechanics and geostress, and the finite element method was used to simulate the paleotectonic stress field. Based on the Griffith and Mohr-Coulomb criterion, the distribution of tectonic fractures in the Shanxi Formation during the Indosinian, Yanshanian, and Himalayan period can be predicted with the index of comprehensive rupture rate. The results show that the acting force of the Pacific Plate and the India Plate to the North China Plate formed the direction of principal stress is N-S, NW-SE, and NE-SW, respectively, in different periods in the study area. Changes in the direction and strength of the acting force led to the regional gradients of tectonic stress magnitude, which resulted in an asymmetrical distribution state of the stress conditions in different periods. It is suggested that the low-stress areas are mainly located in the fault zones and extend along the direction of the fault zones. Furthermore, the high-stress areas are located in the junction of fold belts and the binding site of multiple folds. The development of tectonic fractures was affected by the distribution of stress intensity and the tectonic position of folds and faults, which resulted in some developed areas with level Ⅰ and Ⅱ. There are obvious differences in the development of tectonic fractures in the fold and fault zones and the anticline and syncline structure at the same fold zones. The tectonic fractures of the Shanxi Formation during the Himalayan period are more developed than those during the Indosinian and Yanshanian period due to the superposition of the late tectonic movement to the early tectonic movement and the differences in the magnitude and direction of stress intensity.     

川西南盐津地区志留系龙马溪组页岩地球化学特征及地质意义*

In order to find out the element geochemical characteristics of Silurian Longmaxi Formation shale in Yanjin area,southwestern Sichuan Basin,as well as the material source and structural background of shale formation,the petromineralogy and geochemistry of 19 shale samples from Niuzhai section of Yanjin area were tested and analyzed. Combined with the previous research results and adjacent areas,the rare earth elements were mainly applied to discuss the sedimentary environment, the accumulation rate,material source and tectonic setting of the Longmaxi Formation shale in the study area. The results show that the mineral composition of the Longmaxi Formation in Niuzhai section of Yanjin is mainly quartz,carbonate minerals and clay minerals. The mineral triangle diagram shows that the Longmaxi Formation shale is mainly a combination of clay shale and mixed shale. The normalized partition pattern of rare earth elements is characterized by Ce deficit and weak Eu enrichment. The δCe values,Ni/Co and V/Cr values of the samples indicate that the paleo-water depth increases suddenly in the early stage and becomes shallow gradually in the later stage. Oxygen content gradually changes from anoxic reduction state in the early stage to weak oxidation state in the later stage. La_N/Yb_N values show that the shale deposition rate increases firstly and then decreases under the influence of sea level and terrigenous debris input. Provenance analysis shows that the source rocks area are mainly felsic igneous rocks and intermediate-acid geological bodies of granitoids. The La-Th-Sc diagram and tectonic setting characteristics show that the main tectonic setting of the source rocks is passive continental margin. Combined with previous studies and tectonic setting,it is inferred that the main source of the Longmaxi Formation shale is formed in the Passive continental margin of hypoxia,and the provenance is mainly from the Kang-Dian ancient land to the west of the study area,followed by the Central Guizhou uplift.     

塔里木盆地大北气田构造应力场解析与数值模拟

构造应力场研究对于塔里木盆地大北气田的开发具有重要理论与现实意义。通过区域断裂与背斜长轴走向、钻井诱导缝走向与井壁坍塌方位分别确定了古、今构造应力场的方向,采用测井资料计算了古、今构造应力场的大小。在此基础上,利用ANSYS有限元分析软件建立了大北气田主体气藏区大北102区块和大北201区块的地质模型,并通过测井资料计算及动静态转换确定岩石力学参数,利用构造应力场解析结果确定边界条件,进行了大北气田古今构造应力场的数值模拟,分析了构造应力场的分布规律以及构造应力场与构造裂缝和产能的关系。结果表明:大北气田古、今水平最大主应力方向分别约NNW336°和NWW305°,应力大小分别具有σHσhσv和σHσvσh的特征,分别属于Ⅱ类和Ⅲ类地应力;主应力和主差应力在平面上表现为背斜高部位为低值、翼部为高值,纵向上随深度增加而增大;构造裂缝的走向受控于水平最大古构造应力方向,与现今水平最大主应力方向近似平行或呈小角度相交,构造裂缝可沿走向继续延伸,开度也不会因构造挤压作用大幅降低,有效性可得到很好的保存,气藏区构造裂缝发育程度与主差应力的大小呈正相关关系;背斜高点是构造应力的低值区,油气在应力势差和浮力的共同驱动下聚集成藏,其中主差应力较大的井点构造裂缝较发育,无阻流量较高,因此在背斜高点主差应力较大的区域部署井位,有较大概率获得天然气的高产。     

塔中地区构造应力场数值模拟研究

构造应力场研究对于油气运聚分析及储层特征描述具有重要的理论和实际意义。本文根据塔中隆起断裂特征及其演化史,结合钻井资料,选择中下奥陶统碳酸盐岩为主要研究对象,应用大型有限元分析软件ANSYS,在处理断层问题时运用非连续的接触算法,模拟了中奥陶世末、中泥盆世末、三叠纪末、新近纪末的构造应力场,研究了该区不同时期的古应力分布特征。研究表明,最大主压应力受东部车尔臣-星星峡走滑断裂影响显著,在隆起区沿断裂带呈条带状低值分布,在不同时期塔中Ⅰ号断裂带无一例外地位于最大主压应力的最低区,反映了塔中断裂带尤其是塔中Ⅰ号断裂带是油气运移的有利指向区。最小主压应力沿断裂带呈条带状高值分布,在断裂的上盘、断裂走向发生变化和断裂的倾末端是张应力高值区,为张裂缝发育的重要构造部位。最小主压应力和最大剪应力受车尔臣-星星峡走滑断裂的影响明显减弱。     

鄂尔多斯煤盆地西缘古构造应力场演化分析

通过野外节理、断层等构造形变的观测分析,恢复了鄂尔多斯盆地西缘古构造应力场分布特征。自中生代以来,研究区南、北段古构造应力场在不同时期均有所不同:印支期,北段最大主压应力方向为NW-SE向,南段为NE—SW向;燕山期,北段最大主压应力方向为NWW-SEE向,南段为NEE-SWW向;喜马拉雅期,北段主要受拉张应力,方向为NNW-SSE向;南段最大主压应力方向为NNE-SSW向。据研究区所处特殊的大地构造位置以及地球动力学背景,分析了研究区构造应力场演化的主控因素。     

湖南扬子地区志留系龙马溪组页岩气成藏条件及前景评价

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