Simulation of paleotectonic stress field of Silurian Longmaxi shale reservoirs in Wulong area of southeastern Chongqing
-
摘要:
渝东南武隆地区志留系龙马溪组页岩储层发育,构造裂缝是页岩气运移和聚集的主控因素,而古构造应力场控制着构造裂缝的发育,对武隆地区页岩气的勘探开发具有较大影响。本文对武隆地区及周缘发育的节理进行分期配套处理,明确了武隆地区的古构造应力方向,同时通过岩石声发射实验计算得到了古构造应力的大小。在此基础上,利用ANSYS有限元软件建立了武隆地区志留系龙马溪组地层关键构造变形期的地质模型,并通过构造应力场的分析结果明确了该地区关键构造期的构造应力特征,以确定构造应力场数值模拟的边界条件,进而对构造应力场进行数值模拟。研究结果表明:武隆地区受雪峰陆内造山运动的影响,其主要构造变形期为中燕山中期和中燕山晚期,其中燕山中期的最大、最小水平主应力分别为112—194 MPa和60.93—147.99 MPa,中燕山晚期的最大、最小水平主应力分别为75.67—168.32 MPa和31.19—95.56 MPa。模拟结果显示最大水平主应力的高值区大多集中于武隆西向斜核部、断层上盘的局部区域以及断层的拐点和端点处。页岩气有利保存区与断层上盘的距离要远于断层下盘。向斜的核部曲率越大,越易形成“Λ”型裂缝,越有利于页岩气的储集和保存,因此武隆西向斜的页岩气有利保存区优于武隆东向斜。
Abstract:The development of the shale reservoir within the Silurian Longmaxi Formation in the Wulong area of southeastern Chongqing is significantly affected by the superposition of multiple tectonic processes. This has led to intricate structural deformations in the region, making it imperative to analyze the principal controlling elements for shale gas preservation. Given the shale reservoir’s characteristic low porosity and low permeability, tectonic fractures play a pivotal role as the main controlling factor in the migration and accumulation of shale gas. The paleotectonic stress field determines the development of these tectonic fractures, augmenting the reservoir’s storage capacity and enhancing the connectivity among fractures. Consequently, this has a profound impact on the exploration and development of shale gas in the Wulong area. Thus, analyzing the sequence of tectonic evolution, deciphering the direction of the paleotectonic stress field, and quantitatively characterizing the features of the tectonic stress field hold substantial theoretical and practical significance for shale gas exploration and exploitation in this area.
In this research paper, comprehensive field measurements were carried out on the data of conjugate shear joints in the Wulong area and its adjacent periphery. These data were then systematically classified into distinct stages and carefully matched. By leveraging the trend and superposition relationships of fold axes both within the study area and its surrounding regions, the direction of the paleotectonic stress was determined. Through the integration of geochronological data and the outcomes of rock acoustic emission experiments, the tectonic evolution process of the Wulong area was accurately reconstructed. This enabled the determination of the tectonic evolution periods and the corresponding stress magnitudes for each period, while also clarifying the key tectonic deformation period and the fracture distribution traits of the study area. Employing finite element software ANSYS, a three-dimensional geological model was established, specifically focusing on the key tectonic deformation period of the Silurian Longmaxi Formation in the Wulong area. In light of the distribution patterns of rock mechanical parameters in the study area, the mechanical units were appropriately divided, and a corresponding mechanical model was constructed. After multiple rounds of simulation corrections, the optimal boundary stress application conditions for the model were precisely ascertained by analyzing the distinct characteristics of the paleotectonic stress field. Subsequently, numerical simulations of the paleotectonic stress field were executed to elucidate the structural stress characteristics during the key tectonic deformation periods.
The research findings reveal that since the Middle Yanshanian, the Wulong area has mainly experienced two phases of structural stress. These phases are characterized by stress directions in the SE−NW orientation and close to the EW direction, with the tectonic stress manifesting as compressive. During the Middle Yanshanian, under the influence of the progressive expansion of the Xuefeng intracontinental orogenic movement from the SE−NW direction, a series of NE-trending faults and associated folds emerged in the Wulong area and its neighboring areas. These formations coalesced to form the primary structural pattern of the Wulong area, marking the principal structural deformation period. This pattern has since become the dominant tectonic configuration in the region. However, during the early stage of Middle Yanshanian, the stress environment generated by the Xuefeng intracontinental orogeny underwent a transformation in the study area. The stress changed from the SE−NW compressive state to a nearly EW compressive state. This led to the formation of near SN-trending faults and related folds in the area, which superimposed upon the pre-existing structural morphology. In the process, L-shaped and T-shaped fold structures materialized in the study area and its environs. Although the tectonic activity during this late stage of Middle Yanshanian did not succeed in changing the main NE-trending tectonic pattern in the Wulong area.
Regarding the stress magnitudes, in the middle stage of Middle Yanshanian, the maximum horizontal principal stress ranged from 112 MPa to 194 MPa, while the minimum horizontal principal stress ranged from 60.93 MPa to 147.99 MPa. Notably, the high values of the maximum principal stress were concentrated in the core of the western Wulong syncline. In the late stage of Middle Yanshanian, the maximum horizontal principal stress fluctuated from 75.67 MPa to 168.32 MPa, and the minimum horizontal principal stress varied from 31.19 MPa to 95.56 MPa. Significantly, the stress value of the western Wulong syncline surpassed that of the eastern syncline. It is also worth noting that there exists a discernible correlation between the stress distribution characteristics and the burial depth. The stress contours were distributed in a ring-like fashion, with the maximum stress value at the central region progressively diminishing outward. Additionally, the stress gradient of the low-value zone exhibited a close relationship with fault intensity. Specifically, the greater the fault intensity, the steeper the stress gradient of the maximum principal stress. At the endpoints and inflection points of the faults, the high stress regions emerged, where stress concentration occurred. Moreover the stress on the hanging wall of the fault was higher than that on the footwall. As a result, the degree of fracture development on the hanging wall of the fault was more pronounced than that on the footwall. Consequently, the favorable preservation area for shale gas was located farther from the hanging wall of the fault compared to the footwall. Moreover, stress concentration at the endpoints and inflection points of the faults led to the relatively developed structural fractures that were easily interconnected, facilitating the escape of shale gas. Hence, these areas were unfavorable for shale gas preservation. Furthermore, the deformation degree of the western Wulong syncline was more pronounced than that of the eastern Wulong syncline. The greater the deformation degree of the syncline, the larger the curvature of its core, making it more susceptible to the formation of ‘Λ’-type fractures. These fractures were conducive to the storage and preservation of shale gas. Therefore, the favorable preservation area for shale gas in the western Wulong syncline was superior to that in the eastern Wulong syncline. Studying the characteristics of the paleotectonic stress field lays the foundation for exploring the development degree of tectonic fractures and evaluating the effects of deep fracturing, and it is indeed a critical factor influencing high yields.
-
引言
四川盆地及周缘页岩气分布广泛,储量巨大,近年来已经进入了深层勘探开发阶段。四川盆地及周缘志留系龙马溪组地层发育的黑色页岩,富含有机质,具备良好的生烃能力,是优质的海相烃源岩之一(苏文博等,2007;郭彤楼等,2020)。近年来在武隆向斜部署的钻井均取得了较大的勘探突破,测试日产气量分别可达4.6×104 m3,9.22×104 m3,7.2×104 m3 (张晓明等,2015;云露等,2023)。但武隆地区内不同地区的页岩气产量具有较大的差异,因此开展页岩气富集高产的主控因素分析成为了目前研究的重点。
控制页岩气藏能否形成的主要因素为烃源岩条件和后期构造作用,其中烃源岩条件主要包括烃源岩厚度、有机质含量(total organic carbon,缩写为TOC)、有机质成熟度Ro、有机质类型等。武隆地区志留系龙马溪组页岩均发育于深水陆棚相沉积环境,厚度为32—35 m,TOC在4%—5%之间,Ro为2.6%—2.7%,有机质类型为 Ⅰ 型干酪根,区内烃源岩条件分布差异较小,因此构造作用是影响区内页岩气富集高产的关键性因素(孙玥,2020;何希鹏等,2022)。构造作用对于页岩气藏的改造主要是指古构造应力场决定着构造裂缝的发育程度(聂海宽等,2012;马新华,谢军,2018)。构造裂缝的形成不仅增大了储层的储集空间,也影响了裂缝间的连通性。结合周缘地区页岩气高产井的分布特征可知,地层抬升时间越晚,越有利于页岩气藏的形成(徐政语等,2016;葛勋等,2023)。中生代以来,武隆地区经历了多期的构造活动,区内发生了强烈的挤压变形作用(张海涛等,2018)。多期的构造叠加改造作用使得古构造应力场的分布变得更为复杂。前人对武隆地区的研究多从沉积环境、页岩气地质条件、页岩气藏成因、储层发育特征以及构造对页岩气保存的控制作用等方面开展研究(何利等,2017;何希鹏等,2018;张颖等,2018;何梅朋,2023),或从区域上开展渝东南地区古构造应力场解析以及构造裂缝的分布预测(谢渊等,2012;曾维特,2014;丁文龙等,2016;李萧等,2021;董敏等,2022;张斗中等,2024),但以某一残留向斜为特定研究对象开展的页岩储层古构造应力场研究较少,因而武隆地区构造演化过程的恢复、关键构造变形期的确定以及古构造应力场特征等方面均无较为系统的论述。
鉴于此,本文拟基于武隆及周缘地区的野外实测古应力数据,结合磷灰石裂变径迹等年代学分析测试资料,确定武隆地区龙马溪组地层构造的活动时间,并对武隆及周缘地区的褶皱形态、节理、断裂及滑动特征予以分析。基于此,通过对武隆及周缘地区节理的分期配套处理,解析构造活动期次,确定古构造应力方向;利用岩石声发射实验数据确定古构造应力大小;通过有限元分析软件ANSYS建立三维有限元模型,并结合关键构造期的边界条件进行古构造应力场的数值模拟,解析古构造应力场的展布特征,以期为整个渝东南地区的页岩气勘探和开采难度评价提供指导,为我国南方页岩气的开发提供一定的理论依据。
1. 区域地质概况
武隆地区位于重庆东南部(简称渝东南),构造上位于川东南—湘鄂西褶皱带的过渡带,整体为NE向的宽缓向斜(图1a)。渝东南地区主要经历了加里东期、印支期、燕山期、喜山期等多期构造活动,其中加里东期、印支期和喜山期的构造运动以隆升为主;燕山期的雪峰陆内造山活动对武隆地区的影响最为显著,在此期间该地区形成了褶皱和断裂,且大部分断裂走向为NE。多期构造作用的叠加导致了该地区复杂的构造变形。区内钻井LY1井的测试结果显示,黑色富有机质页岩主要发育于龙马溪组深水陆棚—浅水陆棚相沉积内(何利等,2017;王琳,2020),TOC平均为4.36%,含气量为2.49×103 m3/kg,有机质成熟度Ro为2.54% (张海涛等,2018),测试产量为(4.6—9.2) ×104 m3/d,单井累产超过3 800×104 m3。武隆地区地处川东南常压带,区内压裂后单井产量为(4.6—32.8)×104 m3/d,产量增加明显,这表明常压页岩气勘探取得了重大突破(吴聿元等,2020)。
图 1 武隆地区区域位置图(a) 武隆及邻区地质构造图;(b) 龙马溪组底界构造图;(c) 沿AA′测线的地震解释剖面Figure 1. Regional location map of Wulong area(a) Geological tectonic settings of Wulong and its adjacent areas;(b) Structural map of the bottom boundary of the Longmaxi Formation;(c) Seismic interpretation section along the seismic survey line AA′武隆向斜内的断裂主要沿NNE向和近N-S向展布,以胡家园断层为界,其东、西两侧的向斜分别命名为武隆东、西向斜。受江南隆起的陆内挤压作用,武隆及周缘地区的构造边界主要由齐岳山断层控制(李艺豪,2023)。武隆地区北侧发育NNE向断层,南侧发育大量近N-S向断层,东侧发育近N-S向断层和少量NNE向断层,其中近N-S向断层切割限制了NE向、NNE向断层的进一步扩展(图1b)。区内构造变形以齐岳山断层为界,断层以南以基底冲断作用为主,前寒武系滑脱作用强烈,致使上部盖层强烈抬升,同时寒武系膏盐岩对其上地层也起滑脱作用,致使齐岳山断层上盘发育系列冲断褶皱及相应断夹块,而志留系几乎无滑脱作用;断层以北为断层下盘,构造变形弱。胡家园断层向上冲断至三叠系地层中,断面倾向近SES,倾角较缓,断距较小,与反向派生断层形成冲起褶皱,褶皱西翼地层较缓,东翼地层陡立,剖面可见双层构造。断层上盘整体地层稍缓,形成较宽缓向斜(图1c)。
2. 古构造应力场解析
古构造应力场是指某个地质历史时期的构造应力场,是地质体发生构造形变的直接原因,是油气成藏过程中油气运移与聚集的重要动力。构造应力场的发展演化不仅对油气运移、储层改造有较大影响(张胜利等,2010),还对断裂分布、裂缝型储层发育区的预测有重要意义(刘金华,2009)。
2.1 年代学资料
图2通过两个样品AFT-1和AFT-2给出了武隆地区及周缘磷灰石裂变径迹的热史模拟结果(梅廉夫等,2010;吴航,2019)。样品AFT-1位于齐岳山断层上盘,其热史模拟结果(梅廉夫等,2010)显示该样品在距今105—65 Ma快速降温,距今65—25 Ma缓慢降温,距今25 Ma降温速率突然增大,表明武隆地区地层在距今105 Ma的中燕山晚期达到最大埋深后开始进入快速隆升阶段,在距今65 Ma的晚燕山—早喜山期进入缓慢隆升阶段,在距今25 Ma的喜山期再次迅速抬升,此过程对应于印度板块与亚洲板块的碰撞所导致的四川盆地及周缘地层出现区域隆升的现象(图2)。
样品AFT-2取自方斗山复背斜,其磷灰石裂变的径迹热史模拟结果(吴航,2019)显示:该样品在早-中燕山期(距今150—120 Ma)处于快速升温阶段,在中-晚燕山期(距今120—80 Ma)快速降温,晚燕山期(距今80—20 Ma )处于稳定阶段,距今20 Ma又呈现降温趋势,表明在早-中燕山期(距今120 Ma)方斗山复背斜地区的地层达到最大埋深之后隆升速度开始加快,在晚燕山期(距今80 Ma)前后进入平稳阶段,喜山晚期(距今20 Ma)前后再次迅速抬升至地表。
综上,武隆地区及周缘地层在中燕山期(距今105 Ma)埋深达到最大,此后受雪峰陆内造山运动的影响,地层开始隆升,在晚燕山期(距今70 Ma)地层隆升速度降低,在喜山期(距今25 Ma)地层隆升速度开始加快,这说明武隆地区在燕山期至少经历了两次强烈的构造运动。
2.2 古构造应力方向解析
地层的形变受控于构造应力作用,因此依据褶皱的形态可推断古构造应力的方向特征。下面将对武隆及周缘地区的褶皱形态进行解析,以恢复研究区的构造演化序列。
如图3所示,彭水向斜的轴迹由NE向和SE向轴迹组成,整体展现为“L”形特征,NE向轴迹明显长于SE向轴迹且被SE向褶皱截切,表明NE向褶皱的形成早于SE向褶皱;武隆西向斜的轴迹由NE向和SE向轴迹组成,整体呈“T”形,且NE向轴迹长于SE向;武隆东向斜的轴迹走向为NE向,同样揭示了NE向褶皱的形成早于SE向褶皱;洛龙背斜的轴迹呈“L”形,由两期直立水平褶皱叠加改造而成;白马向斜、老厂坪背斜和焦石坝背斜的褶皱轴迹多呈“T”形,且NE向轴迹均长于SE向轴迹。综上,武隆地区及周缘的背斜和向斜的轴迹走向以NE向褶皱为主,SE向褶皱次之,且NE向褶皱变形早于SE向褶皱,这在一定程度上限制了SE向褶皱的发育。
为进一步解析武隆地区的构造演化过程和古构造应力场特征,对该区及周缘发育的节理进行分期、配套处理,从区域上分析古构造应力场方向的分布规律(钟城等,2018;Tang et al,2018)。通过对节理的分期、配套,对中燕山期以来古构造应力的方向和期次进行恢复。目前最为方便和有效地分析古构造应力方向的方法就是基于诸如节理、擦痕及褶皱等各种地质构造形变痕迹进行反推(李东东,2017)。根据野外观察到的节理面特征、充填情况及交切关系,可以看出NNE向(10°—20°)和SE向(130°—150°)节理面平直,部分节理缝被方解石脉填充,而且由野外露头也可以看出NNE向节理与SE向节理组成了一对平面“X”型共轭剪节理(图4)。
对研究区及周缘进行野外地质调查,实测了336组共轭剪节理的产状,并基于地质构造分析中的赤平极射投影方法对节理数据进行地层复平处理。同期配套的节理与其所受的主应力的方位存在一定的几何关系,即第二主应力σ2的方位平行于一对共轭剪节理交线的中等主应力轴。一般情况下,最大主应力轴第一主应力σ1的方向平行于共轭剪节理的锐角等分线,第三主应力轴最小主应力σ3的方向平行于共轭节理的钝角等分线,具体计算公式如下(顾悦等,1983;Ju et al,2017):
$$ \varphi_2=\arctan\frac{\tan Q_1\cos W_1-\tan Q_2\cos W_2}{\tan Q_2\sin W_2-\tan Q_1\sin W_1}\text{,} $$ (1) $$ {D}_{2}=\arcsin\left|\frac{\sin{Q}_{1}\sin{Q}_{2}\mathrm{s}\mathrm{i}\mathrm{n} ( {W}_{2}-{W}_{1} ) }{\sin\left\{\arccos [ \sin{Q}_{1}\sin{Q}_{2}\mathrm{cos} ( {W}_{2}-{W}_{1} ) +\cos{Q}_{1}\cos{Q}_{2} ] \right\}}\right|\text{,} $$ (2) $$ \varphi_{\mathrm{1\text{,} 3}}=\arctan\frac{\sin Q_1\sin W_1\mp\sin Q_2\sin W_2}{\sin Q_1\cos W_1\mp\sin Q_2\cos W_2}\text{,} $$ (3) $$ {D}_{\mathrm{1\text{,} 3}}=\arcsin\left|\frac{\cos{Q}_{1}\mp \cos{Q}_{2}}{2\cos\left\{\dfrac{180^\circ-\arccos [ \sin{Q}_{1}\sin{Q}_{2}\mathrm{cos} ( {W}_{2}-{W}_{1} ) +\cos{Q}_{1}\cos{Q}_{2} ] }{2}\right\}}\right| \text{,} $$ (4) 式中:Q1和Q2为节理复平后的倾向;W1和W2为节理复平后的倾角;φ1,φ2和φ3为第一、第二、第三主应力方向;D1,D2和D3分别为第一、第二、第三主应力与水平方向的夹角。
利用上述公式恢复各组配套节理的古构造应力方向数据,统计各组节理恢复出的最大主应力方向,进而利用TectonicsFP软件绘制最大主应力方向的玫瑰花图(图3)。统计结果显示,武隆地区自中生代以来主要受到三个方向的构造应力作用,其中:SE向(130°±10°)数据占比最高,在区内广泛分布,该方向应力在区内影响最大;近EW向(100°±10°)数据占比居中,在区内造成的影响次之;NE向(60°±10°)应力数据占比最低,在区内造成的影响最小,在该区的二叠—三叠系地层中NE向节理均有发育,节理面比较粗糙,延伸范围有限。
2.3 古构造应力大小
目前古构造应力大小主要是通过岩石声发射实验(彭瑞等,2015)测定。该方法利用岩石塑性形变的不可逆性以及塑性形变对构造应力的记忆性来对岩石施加应力,当所施加的应力未超过前次加载值时,不会产生声发射,只有当施加应力超过前次加载应力值后,岩石的声发射实验数据曲线才会出现拐点,该点即为凯塞(Kaiser)效应点。通过计算公式可获得凯塞效应点所记录的构造应力大小(薛亚东,高德利,2000;赵奎等,2021;Kaiser,Moss,2022)。这种方法通过岩石声发射实验记录凯塞效应点的数量及其对应的声发射能量大小,而后基于此反演该岩石样品所记录的构造活动期次以及对应期次的构造应力大小。
选取两个样品点K1和K2进行实验,获得的曲线有五个凯塞效应点,表明研究区自三叠系以来主要经历了五期构造应力作用(图5,表1)。结合武隆及周缘地区的年代学资料研究(梅廉夫等,2010;吴航,2019),区内主要构造变形期为中燕山中期,其次为中燕山晚期,因此与其对应的岩石样品所记录的最大构造应力值为中燕山中期的构造应力,第二大构造应力值为中燕山晚期的构造应力。早-中燕山中期构造主要波及齐岳山断层以东,在该区形成了NE向构造带,而及至中燕山晚期,雪峰隆升的前缘扩展受到南川—遵义断层西盘的阻挡作用,研究区内开始发育N-S向以及NW向构造,并叠加于早期NE向构造之上,对早期构造起着叠加改造作用。
表 1 样品K1和K2的岩石声发射实验结果Table 1. Results of rock acoustic emission experiments for the samples K1 and K2样品
编号样品采集
层位早燕山期 中燕山早期 中燕山中期 中燕山晚期 喜山期 σ1/MPa σ3/MPa σ1/MPa σ3/MPa σ1/MPa σ3/MPa σ1/MPa σ3/MPa σ1/MPa σ3/MPa K1 T1j 15.12 7.71 33.53 22.68 150.18 73.14 120.55 40.94 71.70 48.65 K2 T1j 31.16 7.39 50.17 33.06 153.81 141.68 124.30 86.38 109.07 34.65 注:σ1和σ3为最大、最小主应力,T1j为下三叠统嘉陵江组地层。样品测试实验室:成都市成华区东方矿产开发技术研究所;测试者:韦力;测试仪器:美国物理公司生产的AE声发射检测系统。 综合年代学资料(梅廉夫等,2010;吴航,2019)以及地层接触关系可知,武隆向斜的构造变形主要发生于晚侏罗世与白垩纪,即中燕山中期发生强烈的挤压褶皱变形,中燕山晚期则发生构造叠加改造,喜山期则以隆升剥蚀为主。
综上,中燕山中期,武隆地区受到雪峰隆升的前缘扩展作用,该时期的构造应力方向为SE−NW (140°±10°),最大主应力为150.18—153.81 MPa,最小主应力为73.14—141.68 MPa;中燕山晚期,区内构造应力方向改变为近EW向(90°±10°),最大主应力为120.55—124.3 MPa,最小主应力为40.94—86.38 MPa。
2.4 古断裂演化
综合武隆地区及周缘古构造应力场特征的解析对该区内古断裂的演化过程进行分析,可为古构造应力场模拟研究提供详实的资料。武隆地区在早燕山期因受到雪峰陆内造山运动的远程传导作用,区内开始形成了SE−NW向的挤压应力场,但该时期的构造应力相对较小,不足以使研究区内的地层发生构造变形作用;随着时间的推移,区内挤压应力逐渐增大,及至中燕山中期构造应力达到最大,地层开始隆升,并形成了NE−SW向的主体构造格局,相关褶皱和断层也同期生成;在中燕山晚期,区内应力方向改变为近EW向,由于受先存构造形变的制约和古构造应力的影响,近NS向构造变形作用叠加于NE−SW向构造形变之上,产生了构造叠加改造作用,形成了“T”形和“L”形褶皱,但并未影响NE−SW向主体构造格局;晚燕山期至今区内地层以隆升剥蚀为主,构造格局未发生变化,因此中燕山晚期与现今的构造格局差异较小(图6)。
3. 古构造应力场模拟
本节主要通过线性有限元法建立武隆地区的三维地质模型。首先对研究区的地质构造变形、构造样式、断裂特征进行充分研究,以此为基础建立地质模型。利用岩石三轴力学实验获取岩石力学参数后,对地质模型赋予适宜的岩石力学参数,建立力学模型;然后应用有限元进行分析,将一些连续单元离散成有限的节点,再将节点连接起来构成有限的单元;最后对力学模型设置边界条件,运用ANSYS数值模拟软件对龙马溪组地层进行三维模拟,以获得武隆地区中燕山中期、晚期的构造应力分布特征(孙晓庆,2008;Ding et al,2012)。
3.1 地质模型建立
前文已基于对武隆地区构造演化的恢复,确定了中燕山中期和中燕山晚期为武隆地区构造变形的关键时期,因此本文对武隆地区古构造应力场的研究主要聚焦于恢复两个关键时期的古构造应力场特征。武隆地区的构造演化特征表明,该区内的主体构造格局在中燕山中期已经形成,虽然中燕山晚期的构造叠加作用产生了较多的断层,但并未对主体构造格局造成显著影响,该格局一直延续至今,所以断裂分布差异是研究区不同时期地质模型的主要区别所在。
3.2 力学模型建立
基于所建立的地质模型,对地质模型单元的岩石力学参数(弹性模量、泊松比)进行赋值,之后将地质模型转变为力学模型后才能进行应力场数值模拟(Camac,Hunt,2009)。对武隆地区钻井LY1,LY2和LY3的目的层岩心样品进行岩石力学三轴实验,获取钻井目的层的岩石力学参数(表2),并利用其对地震数据反演获得的区内岩石力学参数的平面分布进行校正(图7)(王珂等,2014;Li et al,2022)。
表 2 武隆地区多个钻井目的层岩心的岩石力学参数Table 2. Rock mechanical parameters of the target layer cores of several drills in Wulong area样品编号 弹性模量/GPa 泊松比 LY1-1 37.14 0.266 LY1-2 36.70 0.276 LY2-1 31.34 0.292 LY2-2 32.57 0.279 LY3-1 43.22 0.241 LY3-2 43.35 0.232 注:样本测试实验室:成都市成华区东方矿产开发技术研究所;测试者:韦力;测试仪器:美国物理公司生产的TAW-1 000微机电液伺服控制岩石三轴应力试验机。 图7给出了武隆地区志留系龙马溪组的岩石力学参数分布图,可见区内岩石力学参数呈现较大变化。根据岩石力学参数的分布特征,划分出地层力学单元。利用地震反演数据计算各钻井区域纵向上的等效岩石力学参数(王珂等,2013),之后使用加权平均值的方法获取了各力学单元的等效岩石力学参数(表3)(祖克威等,2017)。断裂带区域的岩石力学参数则是按照围岩弹性模量的50%—70%赋值;断裂带区域的泊松比取值则要大于围岩的泊松比0.02—0.1,且断裂展布越复杂,断裂带区域弹性模量赋值越小,泊松比赋值越大;缓冲带区域的岩石力学参数则赋值为区内除断裂带区域外地层的岩石力学参数的均值(孙斌等,2021)。
表 3 中燕山中期和晚期地质模型的岩石力学参数Table 3. The rock mechanical parameters of the geological models in the middle and late stages of the Middle Yanshanian岩石物理参数 弹性模量/GPa 泊松比 力学单元1 43.21 0.23 力学单元2 39.53 0.26 力学单元3 32.51 0.30 力学单元4 28.52 0.32 断层 19.51 0.35 缓冲区 3.62 0.28 确定岩石力学参数之后,赋值到相应的地质模型单元中,并对模型进行网格划分,形成有限元力学模型。本文采用三角形网格单元划分方案对模型进行网格划分,最终中燕山中期模型共划分出3万零252个节点,17万
3178 个单元,中燕山晚期模型共划分出3万2973 个节点,18万6804 个单元(图8)。研究区在中燕山中期形成NE−SW向构造主体,但形成的断裂相对较少;而中燕山晚期所受构造应力小于中燕山中期,但在区内形成的断裂相对较多。因此区内存在中燕山中期和中燕山晚期两个主要的构造变形关键期,两期地层展布形态差异较小,但区内断裂展布特征差异较大,因此两期模型的差异多体现在断裂展布方面。3.3 边界条件
边界条件的设置会受到应力大小、方向和作用方式的影响,而且边界条件设置的合理性对构造应力场数值模拟结果的可靠程度有重大影响,这也是应力场研究的难点(Liu et al,2017)。通过对武隆地区及周缘的古构造应力场分析,得出:武隆地区在中燕山中期受到的应力方向为140°±10°,最大主应力为150.18—153.81 MPa,最小主应力为73.14—152.3 MPa;在中燕山晚期受到的应力方向为90°±10°,最大、最小主应力分别为120.55—141.68 MPa和40.94—119.38 MPa。经过多次应力模拟结果反演,对中燕山中期的地质模型施加的边界条件为:沿138°方向施加154 MPa的最大主应力,沿48°方向施加75 MPa的最小主应力(图9a);中燕山晚期施加的边界条件为:沿95°方向施加138 MPa的最大主应力,沿5°方向施加42 MPa的最小主应力(图9b),并约束边界。模拟结果显示与实际结果的拟合度最高。为了便于施加不同方向的边界构造应力、约束并消除边界效应,在研究区外使用加载边框,使水平构造作用力恰好以正应力的方式施加于边界上(任浩林等,2020)。
3.4 数值模拟结果对比
数值模拟结果与区内岩石声发射实验数据结果的对比显示:中燕山中期和中燕山晚期模拟结果的最大主应力与实测值的吻合度大部分都在97%以上,最大差值为2.45 MPa;最小主应力与实测值的吻合度大部分在95%以上,最大差值为4.07 MPa;差应力的吻合度也基本在95%以上,最大差值为3.32 MPa,在可接受的偏差范围内。综合分析认为,应力差值较小,说明模拟方法可靠(表4)。
表 4 研究区古构造应力场数值模拟结果对比Table 4. Comparison of numerical simulation results of paleotectonic stress field in the study area时期 实测点 最大主应力 最小主应力 差应力 实验结果
/MPa模拟结果
/MPa差值
/MPa实验结果
/MPa模拟结果
/MPa差值
/MPa实验结果
/MPa模拟结果
/MPa差值
/MPa中燕山中期 R1 150.18 152.63 −2.45 73.14 75.71 −2.57 77.04 76.92 0.12 R2 153.81 152.69 1.12 124.30 120.23 4.07 29.51 32.46 −2.95 中燕山晚期 R1 120.55 118.46 2.09 40.94 42.17 −1.23 79.61 76.29 3.32 R2 141.68 139.98 1.70 86.38 83.97 2.41 55.30 56.01 −0.71 3.5 古构造应力场分布规律
3.5.1 中燕山中期
武隆地区五峰—龙马溪组地层中燕山中期页岩的最大水平主应力的模拟结果(图10a)显示,从NE往SW应力值逐渐增大,最大主应力在112—194 MPa之间,应力值的变化范围整体上较大,约为80 MPa。应力整体上与深度具有一定相关性,应力等值线以环状分布,向斜核部区域的应力值最大,向外逐渐减小。应力低值带的应力梯度还与断层强度密切相关,断层强度越大,最大主应力的应力梯度越大,易于在断层末端和转折端形成应力高值区。最大主应力值在173—194 MPa之间,分布在武隆向斜且在研究区的分布面积最广;东北部和西南部区域的应力值较小,为153—163 MPa。
中燕山中期的最小水平主应力的模拟结果(图10b)显示,从SW往NE应力值逐渐增大,中燕山中期五峰—龙马溪组页岩的最小主应力集中分布于NW向,处于60.93—147.99 MPa之间,应力值变化范围较大,约为90 MPa。与最大水平主应力分布的影响因素相同,最小水平主应力也受深度和断层的影响,断层区域为应力低值区,但在断裂末端形成应力高值区。研究区东北部的应力值较大,为126—136 MPa;西南部的应力值较小,为82—104 MPa。
3.5.2 中燕山晚期
中燕山晚期最大水平主应力的模拟结果(图10c)显示:从NE往SW应力值逐渐增大,最大主应力在75.67—168.32 MPa之间;区内北东区域的应力值较低,处于137.05—152.29 MPa之间;应力值整体上变化范围较大,约为90 MPa,且整体上与深度具有一定相关性;应力等值线以环状分布,中心区域应力值最大,向外逐渐减小。应力低值带的应力梯度还与断层强度密切相关,断层强度越大,最大主应力的应力梯度越大,在断层末端和转折端形成应力高值区。最大主应力值在145—168 MPa之间,东北部和西南部的应力值较小,为121—135 MPa。
中燕山晚期最小水平主应力的模拟结果(图10d)显示,研究区西部的应力值较低,从SW到NE应力值逐渐增大,最小主应力在31.19—95.56 MPa之间。应力值变化范围较大,约为60 MPa。最小水平主应力与最大水平主应力分布的影响因素相同,也受深度和断层的影响,断层区域同样为应力低值区,应力高值区集中在断层末端。整个研究区的应力值基本处于79—95 MPa之间;西南区域的应力值较小,处于62—75 MPa之间。
古构造应力场控制着储层岩石的压实强度、构造裂缝发育规律与强度以及断层的封闭性等,这些对油气的运移与聚集均会产生重要影响。深层页岩储层发育有利区为构造应力异常高的低陡构造向斜区。LY1井位于研究区的低陡构造向斜部位,其钻井结果(吴聿元等,2020)显示有较好的油气,说明本文的构造应力场模拟结果可靠。
4. 对页岩气保存的地质意义
武隆地区构造应力场的模拟结果显示该地区逆断层上盘所受的构造应力大于断层下盘,表明断层上盘的形变程度要大于断层下盘,且更易产生构造裂缝。构造裂缝密度越大,裂缝间越易连通,区域内的渗透性越强。然而由于该区域靠近断裂带,极易与断裂带连通,导致页岩气逸散,不利于页岩气保存。因此页岩气富集区与断层上盘的距离大于其与断层下盘的距离。断层的端点、拐点处易产生应力高值区,这使得构造裂缝发育,裂缝间连通性较好,同样不利于页岩气的保存(图11)。
古构造应力场的分布特征显示武隆向斜核部为区内应力高值区,构造应力处于集中且未能释放的状态下,地层中越易产生构造裂缝,因此向斜核部构造裂缝的发育程度要大于向斜两翼,更有利于页岩气的聚集。武隆西向斜两期古构造应力均大于武隆东向斜的古构造应力,进一步验证了武隆西向斜的形变程度要大于武隆东向斜,即武隆西向斜核部的曲率大于武隆东向斜的曲率,两翼地层倾角也大于武隆东向斜。向斜核部的曲率越大,越易在向斜核部形成“Λ”型裂缝,形成有利于页岩气聚集的储集空间,且该裂缝开口向下,页岩气无法产生垂向逸散,有利于页岩气的保存。而地层倾角越大,越容易产生页岩气顺层流动,因此在同一深度范围内,武隆西向斜两翼的页岩气产量要大于武隆东向斜,符合武隆西向斜钻井LY2页岩气产量(9.22×104 m3/日)大于武隆东向斜钻井LY3页岩气产量(7.2×104 m3/日)的实际情况(云露等,2023)。因此武隆西向斜的页岩气富集和保存区优于武隆东向斜,为优先勘探开发区。
5. 讨论与结论
本文基于武隆地区及周缘的地震资料、年代学资料以及节理发育特征,明确了武隆地区的构造变形特征及构造演化过程。在此基础之上,利用ANSYS有限元软件建立了武隆地区志留系龙马溪组关键构造变形期的地质模型,并结合岩石三轴力学实验和岩石声发射实验开展了古构造应力场数值模拟研究,探究了关键构造变形期的古构造应力场分布特征,以及古构造应力场对页岩气保存与富集的影响,主要结论如下:
1) 武隆地区主要受到两期构造应力作用。中燕山中期雪峰陆内造山运动在SE−NW向的递进扩展作用下,在区内形成了NE向主体构造格局;中燕山晚期区内应力场转变为近EW向挤压应力场,在区内形成近SN向构造,并叠加于先存构造变形之上,在区内形成“L”形和“T”形褶皱。
2) 由有限元数值模拟结果可知:中燕山中期最大水平主应力为112—194 MPa,最小水平主应力为60.93—147.99 MPa,最大主应力高值区分布在研究区的中西南部;中燕山晚期最大水平主应力为75.67—168.32 MPa,最小水平主应力为31.19—95.56 MPa,最大主应力高值区多分布于武隆西向斜核部,断层上盘局部区域以及断层拐点、端点处。这与前人在周缘地区的古构造应力场分布特征研究结果(Zhang et al,2022;葛勋等,2023)一致。
3) 综合分析认为,断层上盘的裂缝发育程度要大于断层下盘,且断层端点、拐点处出现的应力集中区域,其构造裂缝发育,易造成页岩气的逸散,不利于页岩气的保存。武隆西向斜的形变程度大于武隆东向斜,向斜变形程度越大,核部曲率越大,越易形成“Λ”型裂缝,有利于页岩气的储集和保存,因此武隆西向斜的页岩气富集区优于武隆东向斜。钻井产量数据也进一步验证了模拟结果的准确性。
本文在力学模型上划分出地质力学单元,该方法提高了模拟结果的准确度。受软件建模的制约,该方法依然存在一定的局限性。随着软件的不断更新,可对模型开展更为精细的划分。
本研究所给出的武隆地区构造演化过程和古构造应力场大小,可为该地区龙马溪组的页岩气开发提供一定的科学支撑。本研究在古构造应力场特征解析的基础上,结合岩石破裂准则,可对区内的裂缝发育特征进行定量表征,对于武隆地区钻井网的部署具有重要意义。
-
图 1 武隆地区区域位置图
(a) 武隆及邻区地质构造图;(b) 龙马溪组底界构造图;(c) 沿AA′测线的地震解释剖面
Figure 1. Regional location map of Wulong area
(a) Geological tectonic settings of Wulong and its adjacent areas;(b) Structural map of the bottom boundary of the Longmaxi Formation;(c) Seismic interpretation section along the seismic survey line AA′
表 1 样品K1和K2的岩石声发射实验结果
Table 1 Results of rock acoustic emission experiments for the samples K1 and K2
样品
编号样品采集
层位早燕山期 中燕山早期 中燕山中期 中燕山晚期 喜山期 σ1/MPa σ3/MPa σ1/MPa σ3/MPa σ1/MPa σ3/MPa σ1/MPa σ3/MPa σ1/MPa σ3/MPa K1 T1j 15.12 7.71 33.53 22.68 150.18 73.14 120.55 40.94 71.70 48.65 K2 T1j 31.16 7.39 50.17 33.06 153.81 141.68 124.30 86.38 109.07 34.65 注:σ1和σ3为最大、最小主应力,T1j为下三叠统嘉陵江组地层。样品测试实验室:成都市成华区东方矿产开发技术研究所;测试者:韦力;测试仪器:美国物理公司生产的AE声发射检测系统。 表 2 武隆地区多个钻井目的层岩心的岩石力学参数
Table 2 Rock mechanical parameters of the target layer cores of several drills in Wulong area
样品编号 弹性模量/GPa 泊松比 LY1-1 37.14 0.266 LY1-2 36.70 0.276 LY2-1 31.34 0.292 LY2-2 32.57 0.279 LY3-1 43.22 0.241 LY3-2 43.35 0.232 注:样本测试实验室:成都市成华区东方矿产开发技术研究所;测试者:韦力;测试仪器:美国物理公司生产的TAW-1 000微机电液伺服控制岩石三轴应力试验机。 表 3 中燕山中期和晚期地质模型的岩石力学参数
Table 3 The rock mechanical parameters of the geological models in the middle and late stages of the Middle Yanshanian
岩石物理参数 弹性模量/GPa 泊松比 力学单元1 43.21 0.23 力学单元2 39.53 0.26 力学单元3 32.51 0.30 力学单元4 28.52 0.32 断层 19.51 0.35 缓冲区 3.62 0.28 表 4 研究区古构造应力场数值模拟结果对比
Table 4 Comparison of numerical simulation results of paleotectonic stress field in the study area
时期 实测点 最大主应力 最小主应力 差应力 实验结果
/MPa模拟结果
/MPa差值
/MPa实验结果
/MPa模拟结果
/MPa差值
/MPa实验结果
/MPa模拟结果
/MPa差值
/MPa中燕山中期 R1 150.18 152.63 −2.45 73.14 75.71 −2.57 77.04 76.92 0.12 R2 153.81 152.69 1.12 124.30 120.23 4.07 29.51 32.46 −2.95 中燕山晚期 R1 120.55 118.46 2.09 40.94 42.17 −1.23 79.61 76.29 3.32 R2 141.68 139.98 1.70 86.38 83.97 2.41 55.30 56.01 −0.71 -
丁文龙,曾维特,王濡岳,久凯,王哲,孙雅雄,王兴华. 2016. 页岩储层构造应力场模拟与裂缝分布预测方法及应用[J]. 地学前缘,23(2):63–74. Ding W L,Zeng W T,Wang R Y,Jiu K,Wang Z,Sun Y X,Wang X H. 2016. Method and application of tectonic stress field simulation and fracture distribution prediction in shale reservoir[J]. Earth Science Frontiers,23(2):63–74 (in Chinese).
董敏,郭伟,张林炎,吴中海,马立成,董会,冯兴强,杨跃辉. 2022. 川南泸州地区五峰组—龙马溪组古构造应力场及裂缝特征[J]. 岩性油气藏,34(1):43–51. Dong M,Guo W,Zhang L Y,Wu Z H,Ma L C,Dong H,Feng X Q,Yang Y H. 2022. Characteristics of paleotectonic stress field and fractures of Wufeng-Longmaxi formations in Luzhou area,southern Sichuan Basin[J]. Lithologic Reservoirs,34(1):43–51 (in Chinese).
葛勋,汤济广,赵培荣,唐永,许启鲁. 2023. 渝东南彭水地区页岩储层构造应力场模拟解析[J]. 西南石油大学学报(自然科学版),45(5):27–42. Ge X,Tang J G,Zhao P R,Tang Y,Xu Q L. 2023. Simulation and analysis of tectonic stress field of shale reservoir in Pengshui area,southeast Chongqing[J]. Journal of Southwest Petroleum University (Science &Technology Edition),45(5):27–42 (in Chinese).
顾悦,陈世桢,贾小瑛,张竹如. 1983. 关于节理裂隙面产状随地层复平变化的一种简捷计算方法[J]. 贵州工学院学报,(3):24–28. Gu Y,Chen S Z,Jia X Y,Zhang Z R. 1983. A simple method for calculating the occurrence of joint fracture surface with the change of strata releveling[J]. Journal of Guizhou Institute of Technology,
(3):24–28 (in Chinese). 郭彤楼,何希鹏,曾萍,高玉巧,张培先,何贵松. 2020. 复杂构造区页岩气藏地质特征与效益开发建议:以四川盆地及其周缘五峰组—龙马溪组为例[J]. 石油学报,41(12):1490–1500. Guo T L,He X P,Zeng P,Gao Y Q,Zhang P X,He G S. 2020. Geological characteristics and beneficial development scheme of shale gas reservoirs in complex tectonic regions:A case study of Wufeng-Longmaxi Formations in Sichuan Basin and its periphery[J]. Acta Petrolei Sinica,41(12):1490–1500 (in Chinese).
何利,宋春彦,谭钦银,程锦翔,王瑞华,杨贵来. 2017. 川东南武隆地区五峰组—龙马溪组页岩气形成条件及富集区分析[J]. 海相油气地质,22(3):47–56. He L,Song C Y,Tan Q Y,Cheng J X,Wang R H,Yang G L. 2017. Accumulation conditions and enrichment zones of shale gas in Wufeng-Longmaxi Formation in Wulong area of southeast Sichuan Basin[J]. Marine Origin Petroleum Geology,22(3):47–56 (in Chinese).
何梅朋. 2023. 武隆地区五峰组—龙马溪组优质浅层常压页岩储层发育特征及含气性影响因素[J]. 非常规油气,10(3):64–73. He M P. 2023. Development characteristics and gas-bearing factors of high-quality shallow ordinary-pressure shale reservoirs in Wufeng-Longmaxi Formation in Wulong area[J]. Unconventional Oil &Gas,10(3):64–73 (in Chinese).
何希鹏,何贵松,高玉巧,张培先,卢双舫,万静雅. 2018. 渝东南盆缘转换带常压页岩气地质特征及富集高产规律[J]. 天然气工业,38(12):1–14. He X P,He G S,Gao Y Q,Zhang P X,Lu S F,Wan J Y. 2018. Geological characteristics and enrichment laws of normal-pressure shale gas in the basin margin transition zone of SE Chongqing[J]. Natural Gas Industry,38(12):1–14 (in Chinese).
何希鹏,高玉巧,马军,张培先,何贵松,周頔娜,刘娜娜,孙斌. 2022. 重庆市武隆区黄莺乡五峰组—龙马溪组剖面沉积特征及地质意义[J]. 油气藏评价与开发,12(1):95–106. He X P,Gao Y Q,Ma J,Zhang P X,He G S,Zhou D N,Liu N N,Sun B. 2022. Sedimentary characteristics and geological significance of outcrop in Wufeng-Longmaxi Formation,Huangying Town,Wulong District,Chongqing[J]. Petroleum Reservoir Evaluation and Development,12(1):95–106 (in Chinese).
李东东. 2017. 武陵山区中新生代古构造应力场分析[D]. 北京:中国地质大学(北京):33−34. Li D D. 2017. Analysis of the Characteristics of Paleotectonic Stress in Area of Wuling Mount[D]. Beijing:China University of Geosciences (Beijing):33−34 (in Chinese).
李萧,吴礼明,王丙贤,胡秋媛,董大伟. 2021. 渝东南地区龙马溪组构造应力场数值模拟及裂缝有利区预测[J]. 地质科技通报,40(6):24–31. Li X,Wu L M,Wang B X,Hu Q Y,Dong D W. 2021. Numerical simulation of tectonic stress field and prediction of fracture target in the Longmaxi Formation,southeastern Chongqing[J]. Bulletin of Geological Science and Technology,40(6):24–31 (in Chinese).
李艺豪. 2023. 川东—川鄂渝黔地块武隆地区地质构造与大型滑坡响应关系研究[D]. 北京:中国地质科学院:49−50. Li Y H. 2023. Study on the Relationship Between Geological Structure and Large Landslide in Wulong Area of the Eastern Sichuan Block-ChuanEYuQian Block[D]. Beijing:Chinese Academy of Geological Sciences:49−50 (in Chinese).
刘金华. 2009. 油气储层裂缝形成、分布及有效性研究[D]. 青岛:中国石油大学(华东):88−89. Liu J H. 2009. Study on the Formation,Distribution and Effectiveness of Reservoir Fractures With Oil and Gas[D]. Qingdao:China University of Petroleum (East China):88−89 (in Chinese).
马新华,谢军. 2018. 川南地区页岩气勘探开发进展及发展前景[J]. 石油勘探与开发,45(1):161–169. Ma X H,Xie J. 2018. The progress and prospects of shale gas exploration and exploitation in southern Sichuan Basin,NW China[J]. Petroleum Exploration and Development,45(1):161–169 (in Chinese).
梅廉夫,刘昭茜,汤济广,沈传波,凡元芳. 2010. 湘鄂西—川东中生代陆内递进扩展变形:来自裂变径迹和平衡剖面的证据[J]. 地球科学:中国地质大学学报,35(2):161–174. Mei L F,Liu Z Q,Tang J G,Shen C B,Fan Y F. 2010. Mesozoic intra-continental progressive deformation in western Hunan-Hubei-eastern Sichuan Provinces of China:Evidence from apatite fission track and balanced cross-section[J]. Earth Science:Journal of China University of Geosciences,35(2):161–174 (in Chinese).
聂海宽,包书景,高波,边瑞康,张培先,武晓玲,叶欣,陈新军. 2012. 四川盆地及其周缘下古生界页岩气保存条件研究[J]. 地学前缘,19(3):280–294. Nie H K,Bao S J,Gao B,Bian R K,Zhang P X,Wu X L,Ye X,Chen X J. 2012. A study of shale gas preservation conditions for the Lower Paleozoic in Sichuan Basin and its periphery[J]. Earth Science Frontiers,19(3):280–294 (in Chinese).
彭瑞,孟祥瑞,赵光明,董春亮,左超. 2015. 不同岩性岩石声发射地应力测试及其应用[J]. 中南大学学报(自然科学版),46(9):3377–3384. Peng R,Meng X R,Zhao G M,Dong C L,Zuo C. 2015. Acoustic emission insitu stress testing of different lithology rock and its application[J]. Journal of Central South University (Science and Technology),46(9):3377–3384 (in Chinese).
任浩林,刘成林,刘文平,杨熙雅,李文研. 2020. 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[J]. 地质力学学报,26(1):74–83. Ren H L,Liu C L,Liu W P,Yang X Y,Li W Y. 2020. Stress field simulation and fracture development prediction of the Wufeng Formation-Longmaxi Formation in the Fushun-Yongchuan block,Sichuan Basin[J]. Journal of Geomechanics,26(1):74–83 (in Chinese).
苏文博,李志明,Ettensohn F R,Johnson M E,Huff W D,王巍,马超,李录,张磊,赵慧静. 2007. 华南五峰组—龙马溪组黑色岩系时空展布的主控因素及其启示[J]. 地球科学:中国地质大学学报,32(6):819–827 Su W B,Li Z M,Ettensohn F R,Johnson M E,Huff W D,Wang W,Ma C,Li L,Zhang L,Zhao H J. 2007. Distribution of black shale in the Wufeng-Longmaxi Formations (Ordovician-Silurian),South China:Major controlling factors and implications[J]. Earth Science:Journal of China University of Geosciences,32(6):819–827 (in Chinese).
孙斌,鞠玮,杨敏芳,杨兆彪,刘洪林,王胜宇. 2021. 滇东北地区煤储层现今地应力分布特征及渗透性预测[J]. 中国煤炭地质,33(4):44–50. Sun B,Ju W,Yang M F,Yang Z B,Liu H L,Wang S Y. 2021. Distribution of present-day in-situ stresses and permeability prediction within coal reservoirs of northeastern Yunnan region[J]. Coal Geology of China,33(4):44–50 (in Chinese).
孙晓庆. 2008. 古构造应力场有限元数值模拟的应用及展望[J]. 断块油气田,15(3):31–33. Sun X Q. 2008. Present situation and prospect of application for finite element numerical simulation of paleotectonic stress fields[J]. Fault-Block Oil and Gas Fields,15(3):31–33 (in Chinese).
孙玥. 2020. 四川盆地龙马溪组页岩气富集的控制因素及评价[D]. 北京:中国石油大学(北京):45−46. Sun Y. 2020. Comparative Analysis and Periphery of Shale Gas Enrichment and Depletion Factors in the Wufeng-Longmaxi Formation in the Sichuan Basin[D]. Beijing:China University of Petroleum (Beijing):45−46 (in Chinese).
王珂,戴俊生,冯阵东,解艳雪,樊阳,王媛,赵力彬. 2013. 砂泥岩间互地层等效岩石力学参数计算模型及其应用[J]. 地质力学学报,19(2):143–151. Wang K,Dai J S,Feng Z D,Xie Y X,Pan Y,Wang Y,Zhao L B. 2013. Calculation model of equivalent rock mechanical parameters of sand-mud interbed and its application[J]. Journal of Geomechanics,19(2):143–151 (in Chinese).
王珂,戴俊生,冯建伟,王俊鹏,李青. 2014. 塔里木盆地克深前陆冲断带储层岩石力学参数研究[J]. 中国石油大学学报(自然科学版),38(5):25–33. Wang K,Dai J S,Feng J W,Wang J P,Li Q. 2014. Research on reservoir rock mechanical parameters of Keshen foreland thrust belt in Tarim Basin[J]. Journal of China University of Petroleum (Edition of Natural Science),38(5):25–33 (in Chinese).
王琳. 2020. 渝东南地区重点层系页岩气富集条件及可采资源[D]. 北京:中国地质大学(北京):63−64. Wang L. 2020. Enrichment Conditions and Recoverable Resources of Shale Gas of the Focus Layers in Southeast Chongqing[D]. Beijing:China University of Geosciences (Beijing):63−64 (in Chinese).
吴航. 2019. 川东地区中-新生代构造隆升过程研究[D]. 北京:中国石油大学(北京):126−127. Wu H. 2019. Meso-Cenozoic Tectonic Uplift Process of the Eastern Sichuan Basin[D]. Beijing:China University of Petroleum (Beijing):126−127 (in Chinese).
吴聿元,张培先,何希鹏,高玉巧,何贵松,孙斌,万静雅,高全芳,周頔娜. 2020. 渝东南地区五峰组—龙马溪组页岩岩石相及与页岩气富集关系[J]. 海相油气地质,25(4):335–343. Wu Y Y,Zhang P X,He X P,Gao Y Q,He G S,Sun B,Wan J Y,Gao Q F,Zhou D N. 2020. Lithofacies and shale gas enrichment of Wufeng Formation-Longmaxi Formation in southeastern Chongqing[J]. Marine Oil and Gas Geology,25(4):335–343 (in Chinese).
谢渊,丘东洲,王剑,汪正江,刘建清,余谦,李嵘,杨平,李旭兵. 2012. 雪峰山西侧盆山过渡带震旦系—下古生界油气远景区预测与评价[J]. 地质通报,31(11):1769–1780. Xie Y,Qiu D Z,Wang J,Wang Z J,Liu J Q,Yu Q,Li R,Yang P,Li X B. 2012. Prediction and evaluation of the Sinian-Lower Paleozoic oil-gas prospective areas in the basin-mountain transitional region on the western side of the Xuefeng Mountain[J]. Geological Bulletin of China,31(11):1769–1780 (in Chinese).
徐政语,梁兴,王维旭,张介辉,王希有,舒红林,黄程,王高成,鲁慧丽,刘臣,张朝,李庆飞,徐鹤. 2016. 上扬子区页岩气甜点分布控制因素探讨:以上奥陶统五峰组—下志留统龙马溪组为例[J]. 天然气工业,36(9):35–43. Xu Z Y,Liang X,Wang W X,Zhang J H,Wang X Y,Shu H L,Huang C,Wang G C,Lu H L,Liu C,Zhang C,Li Q F,Xu H. 2016. Controlling factors for shale gas sweet spots distribution in the Upper Yangtze region:A case study of the Upper Ordovician Wufeng Fm−Lower Silurian Longmaxi Fm,Sichuan Basin[J]. Natural Gas Industry,36(9):35–43 (in Chinese).
薛亚东,高德利. 2000. 声发射地应力测量中凯塞点的确定[J]. 石油大学学报(自然科学版),24(5):1–3. Xue Y D,Gao D L. 2000. Determination of Kaiser point in measurement of geo-stress with acoustic emission[J]. Journal of the University of Petroleum,China,24(5):1–3 (in Chinese).
云露,高玉巧,高全芳. 2023. 渝东南地区常压页岩气勘探开发进展及下步攻关方向[J]. 石油实验地质,45(6):1078–1088. Yun L,Gao Y Q,Gao Q F. 2023. Progress and research direction of normal-pressure shale gas exploration and development in southeastern Chongqing[J]. Petroleum Geology &Experiment,45(6):1078–1088 (in Chinese).
曾维特. 2014. 渝东南地区下古生界页岩储层裂缝发育特征与分布预测研究[D]. 北京:中国地质大学(北京):37−38. Zeng W T. 2014. The Characteristics and Distribution Prediction of Fractures in Lower Paleozoic Shale,Southeast of Chongqing Area[D]. Beijing:China University of Geosciences (Beijing):37−38 (in Chinese).
张斗中,陈孔全,汤济广,庹秀松,马帅. 2024. 鄂西荆门地区志留系龙马溪组古构造应力场研究及裂缝预测[J]. 地球学报,45(2):217–231. Zhang D Z,Chen K Q,Tang J G,Tuo X S,Ma S. 2024. Paleotectonic stress field and fracture prediction of Silurian Longmaxi Formation in Jingmen area,western Hubei[J]. Acta Geoscientica Sinica,45(2):217–231 (in Chinese).
张海涛,张颖,何希鹏,高玉巧,张培先. 2018. 渝东南武隆地区构造作用对页岩气形成与保存的影响[J]. 中国石油勘探,23(5):47–56. Zhang H T,Zhang Y,He X P,Gao Y Q,Zhang P X. 2018. The effect of tectonism on shale gas formation and preservation in Wulong area,southeastern Chongqing[J]. China Petroleum Exploration,23(5):47–56 (in Chinese).
张胜利. 2010. 构造应力场模拟:有限元理论、方法和研究进展[J]. 西北地震学报,32(4):405–410. Zhang S L. 2010. Modeling of tectonic stress field:The theory,method and related research progress of the finite element method[J]. Northwestern Seismological Journal,32(4):405–410 (in Chinese).
张晓明,石万忠,徐清海,王任,徐壮,王健,王超,袁琪. 2015. 四川盆地焦石坝地区页岩气储层特征及控制因素[J]. 石油学报,36(8):926–939. Zhang X M,Shi W Z,Xu Q H,Wang R,Xu Z,Wang J,Wang C,Yuan Q. 2015. Reservoir characteristics and controlling factors of shale gas in Jiaoshiba area,Sichuan Basin[J]. Acta Petrolei Sinica,36(8):926–939 (in Chinese).
张颖,张海涛,何希鹏,高玉巧,张培先. 2018. 渝东南武隆地区龙马溪组页岩孔裂隙特征研究[J]. 西南石油大学学报(自然科学版),40(4):29–39. Zhang Y,Zhang H T,He X P,Gao Y Q,Zhang P X. 2018. Shale pore characteristics of Longmaxi Formation in Wulong area,southeastern Chongqing[J]. Journal of Southwest Petroleum University (Science &Technology Edition),40(4):29–39 (in Chinese).
赵奎,项威斌,曾鹏,杨道学,伍文凯,龚囱,杨贤达. 2021. 岩石声发射Kaiser效应研究现状及展望[J]. 金属矿山,(1):94–105. Zhao K,Xiang W B,Zeng P,Yang D X,Wu W K,Gong C,Yang X D. 2021. Research status and prospect of Kaiser effect in rock acoustic emission[J]. Metal Mine,(1):94−105 (in Chinese).
钟城,秦启荣,魏志红,李虎,邓毅,何威. 2018. 酒店垭—桑木场构造须家河组节理发育特征与应力场解析[J]. 现代地质,32(2):279–288. Zhong C,Qin Q R,Wei Z H,Li H,Deng Y,He W. 2018. Characteristics and tectonic stress field of joints in Xujiahe Formation of Jiudianya-Sangmuchang structure[J]. Geoscience, 32 (2):279−288 (in Chinese).
祖克威,曾大乾,程秀申,卓色强,李松峰. 2017. 普光地区嘉二段构造裂缝形成机理及预测[J]. 新疆石油地质,38(4):407–413. Zu K W,Zeng D Q,Cheng X S,Zhuo S Q,Li S F. 2017. Forming mechanism and prediction of structural fractures in the second member of Jialingjiang Formation in Puguang area[J]. Xinjiang Petroleum Geology,38(4):407–413 (in Chinese).
Camac B A,Hunt S P. 2009. Predicting the regional distribution of fracture networks using the distinct element numerical method[J]. AAPG Bulletin,93(11):1571–1583. doi: 10.1306/07230909040
Ding W L,Fan T L,Yu B S,Huang X B,Liu C. 2012. Ordovician carbonate reservoir fracture characteristics and fracture distribution forecasting in the Tazhong area of Tarim Basin,Northwest China[J]. J Petrol Sci Eng, 86 − 87 (3):62–70.
Ju W,Wang J L,Fang H H,Gong Y P,Zhang S J. 2017. Paleostress reconstructions and stress regimes in the Nanchuan region of Sichuan Basin,South China:Implications for hydrocarbon exploration[J]. Geosci J, 21 (4):553–564.
Kaiser P K,Moss A. 2022. Deformation-based support design for highly stressed ground with a focus on rockburst damage mitigation[J]. J Rock Mech Geotech Eng,14(1):50–66.
Li J J,Qin Q R,Li H,Zhao S X. 2022. Paleotectonic stress field modeling and fracture prediction of the Longmaxi Formation in the N216 well block,southern Sichuan basin,China[J]. Arab J Geosci,15(4):347.
Liu J S,Ding W L,Wang R Y,Yin S,Yang H M,Gu Y. 2017. Simulation of paleotectonic stress fields and quantitative prediction of multi-period fractures in shale reservoirs:A case study of the Niutitang Formation in the Lower Cambrian in the Cen’gong block,South China[J]. Mar Petrol Geol,84:289–310.
Tang Y,Yang F,Lü Q Q,Tang W J,Wang H K. 2018. Analysis of the tectonic stress field of SE Sichuan and its impact on the preservation of shale gas in Lower Silurian Longmaxi Formation of the Dingshan region,China[J]. J Geol Soc India,92(1):92–100. doi: 10.1007/s12594-018-0957-z
Zhang D Z,Tang J G,Chen K Q,Wang K M,Zhang P X,He G S,Tuo X S. 2022. Simulation of tectonic stress field and prediction of tectonic fracture distribution in Longmaxi Formation in Lintanchang area of eastern Sichuan Basin[J]. Front Earth Sci,10:1024748.