Application of fluid inclusion Raman quantitative technique to the study of tight sandstone gas reservoirs: Case study of Jurassic Shaximiao Formation in central Sichuan Basin

  • Teng-qiang WEI , 1 ,
  • Chang-jiang WU 1 ,
  • Ya-hao HUANG , 2 ,
  • Hai-tao HONG 1 ,
  • Xiao-juan WANG 1 ,
  • You-jun TANG 2 ,
  • Ke PAN 1
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  • 1. Exploration and Development Research Institute of PetroChina Southwest Oil & Gasfield Company,Chengdu 610041,China
  • 2. College of Resources and Environment,Yangtze University,Wuhan 430100,China

Received date: 2020-06-23

  Revised date: 2020-11-01

  Online published: 2021-03-10

Supported by

The National Natural Science Foundation of China(41972148)

Highlights

Tight gas exploration is an important part of China's unconventional energy strategy. The multi-stage channel three-dimensional exploration of Jurassic Shaximiao Formation tight gas in Jinqiu Gas Field in central Sichuan Basin has made continuous production breakthroughs. The evolution process analysis of hydrocarbon fluids in tight gas reservoirs is the key to study the accumulation mechanism of tight gas. Taking the sandstone core of Jurassic Shaximiao Formation in Qiulin and Jinhua gas fields in central Sichuan Basin as the research objects, based on petrological observation and in-situ micro-Raman spectroscopy observation, it is found that there are four types of reservoir diagenetic minerals: pure CH4 inclusions, pure CO2 inclusions, mixed CH4-CO2 gas inclusions and N2 rich gas inclusions. The pressure-temperature-time-composition (PVT-x) properties of CH4 and CO2 inclusions are obtained by Raman analysis and thermodynamic model of fluid inclusions. The density of pure CO2 inclusions is calculated by using the distance between Fermi peaks of carbon dioxide, two stages of CO2 fluid accumulation were found: primary CO2 accumulation stage (high density: 0.874-1.020 g/cm3; high homogenization temperature:>210 ℃) and secondary carbon dioxide accumulation period (high density: 0.514-0.715 g/cm3; low homogenization temperature: about 180-200 ℃). CO2 fluids with abnormal high and uniform temperatures speculate that deep hydrothermal fluid activity and emplacement of reservoirs. The paleo-fluid pressure (44.0-58.5 MPa, mean paleo-pressure coefficient of 1.29) calculated by the methane Raman stretching vibration peak provides important evidence to recover the pressure evolution. The hydrocarbon accumulation was in the Late Cretaceous (about 75-65 Ma), close to the early Himalayan uplift period (the deepest stage of stratigraphic burial), and the late organic gas displacement replaced the early inorganic carbon dioxide accumulation. The paleo-pressure recovery of fluid inclusions indicates that the reservoir evolves from weak overpressure to atmospheric pressure, and the weak overpressure indicates that the reservoir has better preservation conditions in the early uplift.

Cite this article

Teng-qiang WEI , Chang-jiang WU , Ya-hao HUANG , Hai-tao HONG , Xiao-juan WANG , You-jun TANG , Ke PAN . Application of fluid inclusion Raman quantitative technique to the study of tight sandstone gas reservoirs: Case study of Jurassic Shaximiao Formation in central Sichuan Basin[J]. Natural Gas Geoscience, 2021 , 32(2) : 164 -173 . DOI: 10.11764/j.issn.1672-1926.2020.11.007

0 引言

致密砂岩气(TSG)作为非常规气藏在世界范围内具有巨大的资源前景1-4,通常是指渗透率小于0.1 μm,孔隙度小于10%的砂岩气藏2。据估计,目前世界致密砂岩气的技术可采储量为(10.5~24)×1012 m3,具有非常规天然气中的最大可采储量。我国大型致密气田主要分布于鄂尔多斯盆地、四川盆地和塔里木盆地,主要位于石炭系、二叠系、三叠系、侏罗系、白垩系和古近系—新近系5。致密气藏具有准连续期聚集,近源高效成藏的地质特征6。致密砂岩的地层压力与天然气的运移、聚集和调整相关,用于评价不同储层保存条件7。流体包裹体拉曼光谱定量分析可以精确恢复油气藏的古压力、古温度和流体组分演化8
拉曼光谱法测定流体包裹体成分的方法可以追溯到20世纪70年代中期9。随着石英毛细管封装固定组分技术的发明,实现对天然流体包裹体的定量分析10-14。通过显微测温学和拉曼光谱观测流体包裹体, 结合热力学模型对流体包裹体特征量化研究(例如组成x和总密度ρ或摩尔体积V), 提供关键约束条件评价P—T捕获条件15-17。拉曼光谱是一种非破坏性技术,能够定性和半定量分析液相、气态和固态,并已广泛应用于流体包裹体分析18。CH4和CO2是盆地中最常见的地质流体系统,应用拉曼峰面积比可计算水相中溶解物或氯浓度19-24,同时拉曼峰偏移原理可定量计算甲烷或二氧化碳单体包裹体压力和密度25-26
本文研究工作以川中金华—秋林地区侏罗系沙溪庙组砂岩中含气流体包裹体为研究对象。应用岩石学观测和激光拉曼显微光谱法(LRM)对不同组分的流体包裹体进行了精细分类。采用显微测温、定量拉曼光谱和热力学建模相结合的方法,测定了含CH4和含CO2流体包裹体(富气相和富水相)的PVT—x性质。该工作对侏罗系致密砂岩气藏成藏时代的获取、盆地异常压力演化具有重要意义,为储层中致密气的富集规律研究提供指导。

1 地质概况

四川盆地位于中国上扬子板块西北部[图1(a)],是以刚性花岗岩为基底的大型复合盆地27-29,晚印支运动后,四川盆地由前陆盆地向陆内坳陷盆地转换,进入侏罗纪“红色盆地”演化阶段,此时川中地区为低缓斜坡带30-31。在此古构造背景下,沙溪庙组发育一套陆源碎屑岩性组合,以红色、灰绿色泥岩为主,夹浅灰色砂岩,属河流—三角洲相沉积,暗色泥岩不发育,自身不具生烃能力。近期在四川盆地川中地区沙溪庙组先后发现了秋林、金华、中台山等含气构造[图1(b)]。沙溪庙组储集空间类型主要为残余原生粒间孔隙与粒内溶孔,储层孔隙度分布在8.0%~15.0%之间,平均孔隙度为11.3%,覆压渗透率分布在0.003 1~0.064 5 μm之间,平均覆压渗透率为0.021 6 μm,属于低孔低渗致密砂岩。通过气源对比分析,沙溪庙组天然气主要来自于上三叠统须家河组和下侏罗统大安寨段、凉高山组烃源岩32。天然气样品分析结果表明,烃类成分以甲烷为主,主要分布在84.89%~97.34%之间, C 2 +的重烃含量主要分布在2.42%~13.53%之间,非烃气体主要包含N2和CO2,总含量为0~1.49%32-33。气藏平面分布表现出显著的源控特征34。气藏类型主要为受河道砂岩分布控制的次生岩性气藏,各气藏测试均不产水。
图1 研究区位置及井位分布

Fig.1 The location of study area and Well distribution

2 样品信息与测试方法

2.1 样品信息

实验岩心样品来自于QL17井和QL18井以及JH9井侏罗系沙溪庙组致密砂岩储层样品(图2),取样深度为1 151.34~2 182.22 m。
图2 四川盆地川中地区三叠系—侏罗系地层综合柱状图

Fig.2 The comprehensive stratigraphic histogram of Triassic-Jurassic strata in central Sichuan area, Sichuan Basin

2.2 测试方法

流体包裹体测温采用厚度为300 μm的双面抛光薄片,测试仪器为ZEISS Axio Scope.A1双通道荧光—透射光显微镜联用Linkam-THMSG600冷热台,冷热台经校正后误差为±0.1 ℃。包裹体测温过程中,升温速率控制在0.1~5 ℃/min之间,观察并记录包裹体完全均一和包裹体冰块完全融化时的温度。对气—液两相盐水包裹体进行了均一温度和冰点测定。
高分辨率显微共聚焦激光拉曼光谱仪型号为HORIBA Jobin Yvon S.A.S公司的LabRAM HR800显微激光拉曼光谱仪完成。测试环境温度为20~25 ℃,光源为YAG激光器,波长为532.06 nm,输出功率为350~400 mW,线宽<0.1 nm,激光束在样品表面的功率一般为60~80 mW,光谱仪共焦效果可以达到横向0.1 μm,深度约0.3 μm的空间分辨率测量。仪器波数校正用硅标样的拉曼峰位移为520.70 cm-1,数据单次采集时间一般为10~20 s,叠加20~70 次。
激光拉曼光谱采集对于富气相包裹体采用300光栅,对流体包裹体进行多窗口数据的光谱采集工作(采集范围在0~4 000 cm-1之间),用于定性判断识别均一状态下包裹体的寄主矿物和流体包裹体总组分。然后选取具有0.35 cm-1光谱分辨率的1 800光栅,激光孔径调整为50 μm以便获取到最精确峰位移,在光谱采集中,采用长周期,长累计时间的原则以此获取信噪比最好的拉曼光谱信号。在测试过程中,将氖灯置于电动平台下方,同时采集甲烷和氖灯信号,根据分光器的非线性关系,利用氖灯的激光拉曼光谱标准峰Ne1(标准值v real为2 836.988 8 cm-1)和标准峰Ne2(标准值v real为3 008.127 44 cm-1),对于甲烷包裹体的伸缩振动峰v meas进行校正,精确确定拉曼峰偏移的真实值 (v corr),甲烷包裹体测量拉曼峰偏移校正关系式为:
v c o r r - v r e a l N e 1 v m e a s - v m e a s N e 1 = v r e a l N e 2 - v r e a l N e 1 v m e a s N e 2 - v m e a s N e 1
在室温下,选取1 800光栅,2 900 cm-1光栅中心,进而计算得到甲烷拉曼散射峰的真正峰位移,在玻璃毛细管系统中不同压力条件下测定甲烷拉曼散射峰v 1位移,探讨甲烷拉曼散射峰v 1位移和甲烷包裹体密度、压力的关系。根据实验结果拟合的纯甲烷包裹体甲烷拉曼散射峰位移v d与甲烷包裹体密度ρ的线性关系式(V 0=2 917.58 cm-1):
D =   V d - V 0 = 211.3 ρ 4 - 73.238 ρ 3 + 24.477 ρ 2 - 29.063    2 ρ
通过获取甲烷气包裹体同期盐水包裹体的均一温度(T h),将密度和均一温度的值代入甲烷体系热力学模型方程式(3),可以得到甲烷气包裹体的均一压力(P h)。
Z = P V R T = P r V r T r = 1 + B V r + C V r 2 + D V r 4 +
E V r 5 + F V r 2 β + γ V r 2 e x p   ( - γ V r 2 )
B = a 1 + a 2 T r 2 + a 3 T r 3 C = a 4 + a 5 T r 2 + a 6 T r 3 D = a 7 + a 8 T r 2 + a 9 T r 3 E = a 10 + a 11 T r 2 + a 12 T r 3
F = α T r 3 P r = P P c T r = T T c V r = V V c V c = P T c P c
纯二氧化碳包裹体二氧化碳费米双峰间距Δ(cm-1)与二氧化碳包裹体的密度 ρ线性关系式:
Δ(cm-1)=0.320 027   ρ 2+1.795 706   ρ+102.737 7
式(1)—(4)中:p为压力,0.1 MPa;T为温度,K;R为气体常数,R=0.083 144 67×10-4 MPa·m3/(K·mol);V为摩尔体积,10-3 m3/mol,可由甲烷包裹体的密度ρ及摩尔质量计算;Z为压缩因子; P r T r分别为对比压力、对比温度,其量纲均为1; P c T c分别为临界压力(4.6 MPa)和临界温度(190.4 K),单位与PT相同;a 1=0.087 255 392 8; a 2=-0.752 599 476; a 3=0.375 419 887; a 4=0.010 729 134 2; a 5=0.005 496 263 6;a 6=-0.018 477 280 2;a 7=0.000 318 993 183;a 8=0.000 211 079 375;a 9=0. 000 020 168 280 1;a 10=-0.000 016 560 618 9;a 11=0. 000 119 614 546;a 12=-0.000 108 087 289;α=0.044 826 229 5;β=0.753 97;γ=0. 077 167。
通过获取二氧化碳气包裹体同期盐水包裹体的均一温度(T h),将密度和均一温度的值带入Bakker模型方程,可以得到二氧化碳气包裹体的均一压力(P h)。
利用BasinMod-1D (Version 7.06)软件模拟埋藏—热演化史,该软件综合地层厚度、岩性、绝对年龄、侵蚀厚度和实测钻孔温度等单井数据,并模拟镜质组反射率—深度曲线。镜质组反射率和井眼温度数据来源于中国石油西南油气田公司提供的完井报告。建模过程主要利用实测镜质体反射率和地层温度进行校准。构造沉降史模型依据Airy均衡模型,岩性依据基于剖面附近单井岩屑录井统计,四川盆地在二叠纪古热流值达到最大,随后热流快速降低。侏罗系地层沉积以来热流值相对稳定主要分布在50~62 mW/m2之间。现今平面上热流值从川西南部至川中呈递减趋势。四川盆地在晚白垩世以来广泛抬升剥蚀,盆地周缘剥蚀量较大,川中地区相对较低主体在1.5~3.0 km之间35

3 测试结果

3.1 包裹体特征

含气流体包裹体在石英晶体中的微裂隙和加大边被捕获。室温下包裹体岩石学观察和拉曼特征峰识别可将流体包裹体组合分为4类。包裹体类型I:甲烷单一气相包裹体发现于石英裂隙内,并与水溶液包裹体同期存在,为次生来源成因。此类气包裹体直径在5~11 μm之间。包裹体类型II:室温下为富气相二氧化碳包裹体,包裹体边缘可见液相部分,与水溶液包裹体伴生。通常以簇状分布在石英颗粒内或者线性排列在石英加大边内部。直径在8~11 μm。不同产状的纯二氧化碳包裹体可见原生成因和次生成因,形状为椭圆形到圆形。包裹体类型III:此类包裹体是由气相甲烷和气相二氧化碳组成,直径在7~13 μm之间,常沿着裂隙分布,并存在于加大边中。包裹体类型IV:富氮气包裹体主要为原生成因产状,直径在5~9 μm之间(图3)。
图3 流体包裹体岩相学特征

(a)石英裂隙内发育的不混溶甲烷体系包裹体群,透射光;(b)石英加大边内部次生二氧化碳气包裹体,透射光;(c)孤立状分布的原生二氧化碳气包裹体以及沿裂隙分布的次生甲烷气包裹体,透射光;(d)石英加大边内部的次生二氧化碳和甲烷混合气包裹体,透射光;(e)石英颗粒内部的原生二氧化碳气包裹体,透射光;(f)石英愈合裂隙内发育的次生甲烷和二氧化碳混合气包裹体,透射光;(g)石英微裂隙内次生甲烷和二氧化碳气包裹体,透射光;(h)石英加大边内部纯二氧化碳气包裹体和穿过石英颗粒以及石英加大边的纯甲烷气包裹体,透射光;(i)晚期次生混合气包裹体群(FIA3)切穿早期次生混合气包裹体群(FIA4)

Fig.3 Petrographic characteristics of fluid inclusions

对于上述4种气体包裹体共存的含水包裹体进行了均一温度显微观测,流体包裹体的盐度(wt.% NaCl equivalent,下同)是根据最终冰点温度计算获得(T m, ice)。对流体包裹体的显微温度测量数据和计算参数进行了总结,并在图4中进行了图形化说明。甲烷气包裹体(类型I)伴生盐水包裹体均一温度范围在100~170 ℃之间,分布主峰位于120~130 ℃之间。纯二氧化碳包裹体(类型II)可以分为2期,原生二氧化碳包裹体伴生盐水包裹体的均一温度范围为180.0~230.0 ℃,分布的主峰位于210~230 ℃之间。甲烷和二氧化碳混合气包裹体(类型III)伴生盐水包裹体的均一温度范围为190.0~200.0 ℃。氮气包裹体伴生盐水包裹体的均一温度范围为200.0~210.0 ℃。水溶液包裹体与纯CH4包裹体的融冰温度在-10.1~-13.8 ℃之间,盐度范围为14.0%~17.6%。水溶液包裹体与纯CO2包裹体的融冰温度在-4.9~-1.7 ℃之间变化,计算盐度范围为0.92~2.30%。
图4 秋林—金华地区侏罗系沙溪庙组流体包裹体均一温度与盐度直方图

Fig. 4 Histogram of homogenization temperature and salinity of fluid inclusions of Jurassic Shaximiao Formation in Qiulin-Jinhua area

3.2 拉曼光谱定量分析

石英矿物中CO2和CH4气包裹体的压力和密度可以用定量拉曼分析来测量,图5A—A″展示了纯CH4流体包裹体的典型拉曼光谱,它们是在均一状态下采集的拉曼光谱。表1列出了根据甲烷的C—H伸缩振动峰(v 1)获得的13个纯CH4包裹体(I型包裹体)的数据。总体而言,石英矿物中次生纯CH4流体包裹体的密度范围为0.195~0.237 g/cm3(平均值为0.222 g/cm3)。表2为9个纯CO2包裹体(II类包裹体)的数据汇总,采用拉曼光谱利用二氧化碳费米双峰间距进行了均匀状态下的分析,获取二氧化碳PVTx性质。纯CO2包裹体可分为2类:原生CO2包裹体密度为0.874~1.020 g/cm3(平均值为0.941 g/cm3);次生CO2包裹体密度为0.514~0.715 g/cm3(平均值为0.651 g/cm3)。利用显微热力学模型36-37结合共生盐水包裹体的密度和均一温度计算均一压力。
图5 典型流体包裹体拉曼光谱

(a)纯甲烷包裹体拉曼光谱(300光栅和1 800光栅)以及氖灯拉曼光谱图;(b)纯二氧化碳包裹体拉曼光谱(300光栅和1800光栅)以及氖灯拉曼光谱图;(c)甲烷和二氧化碳混合气包裹体拉曼光谱图;(d)富氮气包裹体拉曼光谱图

Fig.5 Raman spectra of typical fluid inclusions

表1 纯甲烷包裹体拉曼定量参数汇总

Table 1 Summary of Raman quantitative parameters of pure CH4 inclusion

序号 井名 深度/m v true /cm 密度/(g/cm³) 同期盐水包裹体均一温度/oC 捕获压力/MPa 压力系数
1 QL-17 2 166.8 2 911.95 0.230 130.0 56.9 1.32
2 QL-17 2 166.8 2 912.30 0.210 128.0 49.1 1.14
3 QL-17 2 168.2 2 911.91 0.229 121.5 54.5 1.43
4 QL-17 2 168.2 2 911.98 0.225 122.5 53.3 1.38
5 QL-17 2 182.2 2 911.85 0.232 127.0 57.0 1.36
6 QL-17 2 182.2 2 912.60 0.195 127.0 44.0 1.05
7 QL-18 2 093.1 2 911.75 0.237 125.0 58.5 1.43
8 QL-18 2 093.1 2 912.06 0.220 125.0 52.0 1.27
9 QL-18 2 087.1 2 912.03 0.220 127.0 52.4 1.25
10 QL-18 2 087.1 2 912.10 0.219 124.0 51.4 1.25
11 JH-9 2 212.9 2 912.38 0.210 120.0 47.5 1.25
12 JH-9 2 212.9 2 911.82 0.230 126.4 56.1 1.34
13 JH-9 2 212.9 2 911.86 0.230 126.4 56.1 1.34
表2 纯二氧化碳包裹体拉曼定量参数汇总

Table 2 Summary of Raman quantitative parameters of pure CO2 inclusion

序号 井名 深度/m 费米双峰间距/cm-1 密度/(g/cm³) 同期盐水包裹体均一温度/oC 捕获压力/MPa
1 QL-17 2 168.2 103.48 0.514 193.0 41.3
2 QL-17 2 168.2 104.35 0.921 188.5 114.8
3 QL-17 2 182.2 103.91 0.701 201.3 68.4
4 QL-17 2 182.2 104.35 0.921 203.5 122.9
5 QL-18 2 093.1 103.85 0.673 189.1 60.1
6 QL-18 2 093.1 103.94 0.715 189.1 66.8
7 QL-18 2 087.1 104.26 0.874 223.3 117.5
8 QL-18 2 087.1 104.44 0.970 245 165.9
9 QL-18 2 087.1 104.53 1.020 245 191.1
不同气液比的流体包裹体线性排列在一组包裹体体系中,表明纯CH4/CO2和含水的盐水包裹体是不混相体系捕获。因此,均一温度和压力与捕获状态相一致。基于拉曼光谱与相关热力学模型的结合36-37,可以得到富水、富气相包裹体的组成和密度。

3.3 盆地模拟

根据现今的沉积厚度和孔隙—深度关系模拟确定热史和埋藏史,采用Falvey (1981)的消除压实系数校正。BasinMod软件的默认值为压实系数对应的初始孔隙度和岩性(页岩/泥岩、砂岩、粉砂岩和灰岩)。各地层单元的层序资料来源于西南油气田公司勘研院。侵蚀厚度、构造沉降、生烃、古埋藏深度和古热流数据3438基于BasinMod 1D软件的瞬态热流模型,可以利用岩石单元的热导率来计算当今的热流。模型的反射率和温度与实测数据具有良好的相关性。QL-17埋藏史和热史重建表明,在约165 Ma和地层温度85 ℃下,烃源岩进入生油窗(早期成熟阶段)。在145 Ma左右,地层成熟度R O达到0.7%。在85 Ma(晚白垩纪)时,热成熟度R O达到1.3%,这与生油阶段的结束一致。喜马期构造运动造成了地层隆起和侵蚀(图6)。
图6 流体包裹体古压力恢复投图

Fig. 6 Paleo-pressure recovery diagram of fluid inclusions

4 讨论

4.1 储层流体演化

通过岩相学观察和激光拉曼原位定性分析,发现石英中含有大量的原生和次生含CO2流体包裹体。高密度原生二氧化碳包裹体(0.874~1.020 g/cm3),均一温度通常大于210 ℃捕获于成岩过程早期。而低密度(0.514~0.715 g/cm3)、低均一温度(约180~200 ℃)的次生CO2包裹体则属于次生流体充注形成捕获于成岩作用之后。利用投点法可以估算油气聚集时间39。甲烷气包裹体共生的水溶液包裹体均一温度范围特征表明,致密砂岩中的烃类气体是一期成藏(约67 Ma),油气成藏时间晚于CO2充注时间。CO2气包裹体均一温度远高于地温梯度,间接反映了热液活动进入储层。致密砂岩储层的流体组成变化从早期的CO2聚集到晚期的甲烷聚集过程,不同比例CH4和CO2气包裹体混合证明了甲烷驱替CO2的过程,形成目前的侏罗纪沙溪庙组气藏,天然气主要由甲烷组成并含有少量非烃类气体(二氧化碳和氮气)。
致密砂岩储层的流体组成变化从早期的来自深部地层CO2聚集到晚期的来自须家河组甲烷聚集过程,表明从深部地层断至沙溪庙组气藏的断层是流体运移的主要通道,是油气成藏关键因素之一,对勘探具有重要指导意义。

4.2 储层孔隙异常压力

流体包裹体捕获温度和压力记录了侏罗系致密砂岩的圈闭条件。根据石英矿物的古埋藏深度与流体包裹体的捕获压力的综合研究,可以确定沙溪庙组接近最大古埋藏时期存在异常超压状态。甲烷包裹体的捕获压力区间为44.0~58.5 MPa(表1),计算压力系数范围为1.05~1.43(平均为1.29,图7),而现今地层压力梯度(DST随钻压力梯度)约为1.16,表明喜马拉雅隆升早期储层处于最大埋藏条件下的中低超压状态,气藏成藏初期具有较好的保存条件,油气充注程度高。川中地区沙溪庙组现今气藏不同砂组实测压力系数差异较大,范围为0.4~1.16,平均约为0.7,为常压—中低压气藏,是由于后期受到喜马拉雅期强烈构造运动的破坏,气藏储层孔隙压力由初期中低超压降低到现今常压、低压状态。保存条件较好的常压、中低超压气藏是下一步勘探的重点,而中低压、低压气藏不是油气充注不充分,而是后期调整泄压的结果,结合适当的钻采和储层改造工艺技术,仍然具有较好勘探潜力。
图7 川中地区侏罗系沙溪庙组油气成藏史

Fig. 7 Hydrocarbon accumulation history of Jurassic Shaximiao Formation in central Sichuan Basin

5 结论

通过在石英颗粒中观察到的多种组分古流体为研究压力—温度—时间—组成提供了信息(PVT—x)。根据我们的研究结果,可以得出以下结论:
(1)纯CO2包裹体组合可分为2个阶段:原生包裹体包裹在石英颗粒内部(高密度:0.874~1.020 g/cm3; 高均一温度:>210 ℃),次生成因CO2包裹体包裹在石英微裂隙或加大边中(低密度:0.514~0.715 g/cm3; 低均一温度: 约180~200 ℃)。与CO2气包裹体伴生的水溶液包裹体均一温度远高于地温梯度,推测存在深部热液活动。纯甲烷包裹体序列组合仅观察到一期充注,属于次生成因(密度:0.195~0.237 g/cm3)。将投点法与埋藏史模型相结合,可以有效地计算出气藏相对形成时间。甲烷气包裹体伴生水溶液包裹体的最大均一温度区间(120.0~130.0 ℃)表明在接近最大埋藏深度的晚白垩世成藏(约67 Ma)。CH4气成藏晚于CO2气成藏,成为天然气储层的主要贡献。不同比例的CH4—CO2混合包裹体表明了有机与无机流体相互驱替的动态演化过程。
(2)含CH4流体包裹体的定量拉曼分析可用于确定古压力。致密气储层流体孔隙压力范围为44.0~58.5 MPa,古压力系数范围为1.05~1.43,平均压力梯度为1.29,与现今地层压力梯度(约1.16)相比,喜马拉雅期储层处于最大埋藏条件下的中低超压状态,受到喜山期强烈构造运动的破坏,气藏储层孔隙压力降低到常压状态,超压响应代表了油气成藏保存条件较好。
1
杨华, 付金华, 刘新社, 等. 鄂尔多斯盆地上古生界致密气成藏条件与勘探开发[J]. 石油勘探与开发, 2012,39(3):295-303.

YANG H, FU J H, LIU X S, et al. Accumulation conditions and exploration and development of tight gas in the Upper Paleozoic of the Ordos Basin[J]. Petroleum Exploration and Development, 2012, 39(3):295-303.

2
邹才能,朱如凯,吴松涛,等.常规与非常规油气聚集类型、特征、机理与展望——以中国致密气为例[C].北京:中国石油地质年会,2011.

ZOU C N, ZHU R K, WU S T, et al. Types, Characteristics, Mechanism and Prospect of Conventional and Unconventional Oil and Gas Accumulation-A Case Study of China's Dense Oil and Gas[C]. Beijing:China Petroleum Geology Annual Conference, 2011.

3
戴金星, 倪云燕, 吴小奇. 中国致密砂岩气及在勘探开发上的重要意义[J]. 石油勘探与开发, 2012,39(3):257-264.

DAI J X, NI Y Y, WU X Q. Tight sandstone gas in China and its significance in exploration and development[J]. Petroleum Exploration and Development,2012,39(3):257-264.

4
OLSON J E, LAUBACH S E, LANDER R H. Natural fracture characterization in tight gas sandstones: Integrating mechanics and diagenesis[J]. AAPG Bulletin, 2009,93(11):1535-1549.

5
赵正望, 李楠, 刘敏, 等. 四川盆地须家河组致密气藏天然气富集高产成因[J]. 天然气勘探与开发, 2019,42(2):39-47.

ZHAO Z W, LI N, LIU M, et al. Origin of gas accumulation and high yield in tight gas reservoirs of Xujiahe Formation, Sichuan Basin[J]. Natural Gas Exploration and Development, 2019,42(2):39-47.

6
孙龙德, 邹才能, 贾爱林, 等. 中国致密油气发展特征与方向[J]. 石油勘探与开发, 2019,46(6):1015-1026.

SUN L D, ZOU C N, JIA A L, et al. Development characteristics and orientation of tight oil and gas in China[J]. Petroleum Exploration and Development, 2019,46(6):1015-1026.

7
贾承造, 郑民, 张永峰. 中国非常规油气资源与勘探开发前景[J]. 石油勘探与开发, 2012,39(2):129-136.

JIA C Z, ZHENG M, ZHANG Y F. Unconventional oil and gas resources and exploration and development prospects in China[J].Petroleum Exploration and Development,2012,39(2):129-136.

8
BONDAR E, KOEL M. Application of supercritical fluid extraction to organic geochemical studies of oil shales[J]. Fuel, 1998,77(3):211-213.

9
ZOZULYA A A, DIDDAMS S A, CLEMENT T S. Investigations of nonlinear femtosecond pulse propagation with the inclusion of Raman,shock,and third-order phase effects[J]. Phy-sical Review A, 1998,58(4):3303-3310.

10
LU W, CHOU I, BURRUSS R C, et al. A unified equation for calculating methane vapor pressures in the CH4-H2O system with measured Raman shifts[J]. Geochimica et Cosmochimica Acta, 2007,71(16):3969-3978.

11
SEITZ J C, PASTERIS J D, CHOU I M. Raman spectroscopic characterization of gas mixtures; I, Quantitative composition and pressure determination of CH4, N2 and their mixtures[J]. American Journal of Science, 1993,293(4):297-321.

12
HUANG Y, TARANTOLA A, WANG W, et al. Charge history of CO2 in Lishui Sag, East China Sea Basin: Evidence from quantitative Raman analysis of CO2-bearing fluid inclusions[J]. Marine and Petroleum Geology, 2018,98:50-65.

13
WANG X, CHOU I M, HU W, et al. Raman spectroscopic measurements of CO2 density: Experimental c alibration with high-pressure optical cell (HPOC) and fused silica capillary capsule (FSCC) with application to fluid inclusion observations[J]. Geochimica et Cosmochimica Acta, 2011,75(14):4080-4093.

14
DUBESSY J, LHOMME T, BOIRON M, et al. Determination of chlorinity in aqueous fluids using raman spectroscopy of the stretching band of water at room temperature: Application to fluid inclusions[J]. Applied Spectroscopy, 2002,56(1):99-106.

15
DUBESSY J, POTY B, RAMBOZ C. Advances in C-O-H-N-S fluid geochemistry based on micro-Raman spectrometric analysis of fluid inclusions (English Title: Advances in C-O-H-N-S fluid geochemistry based on micro-Raman spectrometric analysis of fluid inclusions)[J]. European Journal of Mineralogy, 1989,1(4):517-534.

16
BURKE E A J. Raman microspectrometry of fluid inclusions[J]. Lithos, 2001,55(1):139-158.

17
GARCIA-BAONZA V, RULL F, DUBESSY J. Raman spectroscopy of gases, water and other geological fluids[J]. European Mineralogical Union Notes in Mineralogy, 2012,12(1):279-320.

18
FREZZOTTI M L, TECCE F, CASAGLI A. Raman spectroscopy for fluid inclusion analysis[J]. Journal of Geochemical Exploration, 2012,112(1):1-20.

19
GUILLAUME D, TEINTURIER S, DUBESSY J, et al. Calibration of methane analysis by Raman spectroscopy in H2O-NaCl-CH4 fluid inclusions[J]. Chemical Geology, 2003,194(1-3):41-49.

20
PIRONON J, GRIMMER J O W, TEINTURIER S, et al. Dissolved methane in water: Temperature effect on Ramanquantification in fluid inclusions[J]. Journal of Geochemical Exploration, 2003,78-79:111-115.

21
AZBEJ T, SEVERS M J, RUSK B G, et al. In-situ quantitative analysis of individual H2O-CO2 fluid inclusions by laser Raman spectroscopy[J]. Chemical Geology, 2007,237(3):255-263.

22
BAUMGARTNER M, BAKKER R J. Raman spectroscopy of pure H2O and NaCl-H2O containing synthetic fluid inclusions in quartz: A study of polarization effects[J]. Mineralogy and Petrology, 2009,95(1-2):1-15.

23
CAUMON M, DUBESSY J, ROBERT P, et al. Fused-silica capillary capsules (FSCCs) as reference synthetic aqueous fluid inclusions to determine chlorinity by Raman spectroscopy[J]. European Journal of Mineralogy, 2013,25(5):755-763.

24
CAUMON M, TARANTOLA A, MOSSER-RUCK R. Raman spectra of water in fluid inclusions: I. Effect of host mineral birefringence on salinity measurement: Effect of mineral birefringence on salinity measured by Raman spectroscopy[J]. Journal of Raman Spectroscopy, 2015,46(10):969-976.

25
FABRE D, THIÉRY M M, VU H, et al. Raman spectra of solid CH4 under pressure. I. Phase transition between phases II and III[J]. Journal of Chemical Physics, 1979,71(7):3081-3088.

26
ZHANG J, QIAO S, LU W, et al. An equation for determining methane densities in fluid inclusions with Raman shifts[J]. Journal of Geochemical Exploration, 2016,171:20-28.

27
李晓清, 汪泽成. 四川盆地古隆起特征及天然气的控制作用[J]. 石油与天然气地质, 2001,22(4):347-351.

LI X Q, WANG Z C. Characteristics of paleo-uplift in Sichuan Basin and controlling effect of natural gas[J]. Oil & Gas Geology, 2001,22(4):347-351.

28
王庭斌. 天然气与石油成藏条件差异及中国气田成藏模式[J]. 天然气地球科学, 2003,14(2):4-11.

WANG T B. The difference of gas and oil accumulation conditions and the gas accumulation model in China[J]. Natural Gas Geoscience, 2003,14 (2):4-11.

29
王平, 刘少峰, 郑洪波, 等. 四川盆地东部弧形构造控制的地形和水系发育[J]. 第四纪研究, 2013,33(3):461-470.

WANG P, LIU S F, ZHENG H B, et al. Topography and drainage system development controlled by arc-shaped structures in the eastern Sichuan Basin[J]. Quaternary Research, 2013,33(3):461-470.

30
唐大海, 陈洪斌, 谢继容, 等. 四川盆地西部侏罗系沙溪庙组气藏成藏条件[J]. 天然气勘探与开发, 2005,28(3):14-19.

TANG D H, CHEN H B, XIE J R, et al. Accumulation conditions of Jurassic Shaximiao Formation gas reservoir in western Sichuan Basin[J]. Natural Gas Exploration and Development,2005,28(3):14-19.

31
蒋裕强, 漆麟, 邓海波, 等. 四川盆地侏罗系油气成藏条件及勘探潜力[J]. 天然气工业, 2010,30(3):22-26.

JIANG Y Q, QI L, DENG H B, et al. Accumulation conditions and exploration potential of Jurassic oil and gas in Sichuan Basin[J]. Natural Gas Industry, 2010,30(3):22-26.

33
肖富森, 马廷虎. 川东北五宝场构造沙溪庙组气藏勘探开发认识[J]. 天然气工业, 2007,27(5):4-7.

XIAO F S, MA T H. Exploration and development of gas reservoir in Shaximiao Formation of Wubaochang structure in northeast Sichuan[J]. Natural Gas Industry, 2007,27(5):4-7.

32
肖富森, 黄东, 张本健, 等. 四川盆地侏罗系沙溪庙组天然气地球化学特征及地质意义[J]. 石油学报, 2019,40(5):568-576, 586.

XIAO F S, HUANG D, ZHANG B J, et al. Geochemical characteristics and geological significance of natural gas in Jurassic Shaximiao Formation, Sichuan Basin[J]. Acta Petrolei Sinica. 2019,40(5):568-576, 586.

34
林小云, 魏民生, 丰勇, 等. 四川盆地川西坳陷东坡沙溪庙组油气成藏关键时刻研究[J]. 石油实验地质, 2017,39(1):50-57.

LIN X Y, WEI M S, FENG Y, et al. Study on the key moments of hydrocarbon accumulation in Shaximiao Formation in the Dongpo of west Sichuan Depression, Sichuan Basin[J].Petroleum Geology and Experiment. 2017,39(1):50-57.

35
刘树根, 孙玮, 李智武, 等. 四川盆地晚白垩世以来的构造隆升作用与天然气成藏[J]. 天然气地球科学, 2008, 19(3):294-300.

LIU S G, SUN W, LI Z W, et al. Tectonic uplift and gas accumulation since Late Cretaceous in Sichuan Basin[J]. Natural Gas Geoscience,2008, 19(3):294-300.

36
PENG D Y, ROBINSON D B. Two and three phase equilibrium calculations for systems containing water[J]. Canadian Journal of Chemical Engineering, 1976,54(6):595-599.

37
DUAN Z, MAO S. A thermodynamic model for calculating methane solubility, density and gas phase composition of methane-bearing aqueous fluids from 273 to 523K and from 1 to 2000 bar[J]. Geochimica et Cosmochimica Acta, 2006,70(13):3369-3386.

38
张小菊, 伏美燕, 邓虎成, 等. 川西东斜坡地区沙溪庙组致密砂岩储层断-砂配置关系对天然气富集的控制作用[J]. 矿物岩石, 2020,40(3):107-119.

ZHANG X J, FU M Y, DENG H C, et al. The controlling effect of fault-sand allocation relationship on gas enrichment in tight sandstone reservoirs of Shaximiao Formation in the slope area of the southwestern Sichuan Basin[J]. Journal of Mineralogy and Petrology, 2020,40(3):107-119.

39
OSBORNE M, HASZELDINE S. Evidence for resetting of fluid inclusion temperatures from quartz cements in oilfields[J]. Marine & Petroleum Geology, 1993,12(3):271-278.

Outlines

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