Magnetic, Geochemical and Mineralogical Structure and Significance in Complete Space of Oil and Gas Reservoir: Implications for Formation Mechanism of "Chimney Effect
-
摘要: 位于松辽盆地南部某油气田边缘一个油气显示井的磁性测量结果表明, 岩石具有明显的磁性变异结构特征.以磁化率(κ) 为例, 在低缓的背景磁性上主要呈现高强度与中等强度的2类异常: 大于400× 10-5为强磁性, 100× 10-5~ 150× 10-5为中等强度磁性.结合录井资料与地球化学分析解释可知, 强磁性异常主要位于取样间隔的底部干层区, 少数样品位于浅部油气显示层; 中等强度异常主要位于2 70 0m附近的油气显示层.岩石磁性与地球化学成分对应分析表明, 油气显示层岩石的C1和C2成分与磁化率(κ)、饱和磁化强度(Js) 和饱和等温剩余磁化强度(SIRM) 之间呈明显的正相关, 与内禀矫顽力(Hc) 为逆相关, 而干层岩石相关性不明显.矿物成分分析显示, 岩石中主要含铁矿物为磁铁矿、磁赤铁矿、赤铁矿、黄铁矿和菱铁矿.其中磁赤铁矿主要分布在具有中等磁性强度的油气显示层, 而高含量(最高含量达12.5 %) 的磁铁矿主要位于底部干层.磁赤铁矿与赤铁矿、黄铁矿及菱铁矿含量之间相关特征初步表明, 自生磁赤铁矿可能主要来源于原地赤铁矿与黄铁矿.推测油气显示层岩石中磁性偏软的磁赤铁矿属于烃蚀变的产物, 为烃微渗漏效应(或烟筒效应) 的全空间形成机理提供了新证据Abstract: Magnetic measurements of rocks in an oil and gas bearing well located on the margin of an oil and gas field, southern Songliao basin, show that the rocks there are characterized by the conspicuous magnetic anomalous structure. The magnetic susceptibility anomalies (κ), for example, are classified as two categories: the high intensity (κ > 400×10-5) and the moderate intensity (κ : 100×10-5 - 150×10-5) on the low background magnetism. As shown in the interpretation of the logging references and the geochemical analysis, the strong magnetic anomaly is located mainly in the dry layer at the bottom of the sampling interstitial positions. Few samples are located in the oil and gas display layer in the shallow part of the field. The intermediate magnetic anomaly is located in the oil and gas display layer at the depth around 2 700 meters. The correlation between the magnetism and geochemical compositions shows a positive correlation between geochemical compositions C1, C2 and magnetic intensities parameters (i.e. susceptibility κ, saturation magnetization Js and saturation isothermal remnant magnetization SIRM), but a negative correlation between geochemical compositions C1, C2 and intrinsic coercivity in the rocks of the oil and gas bearing layers. However, these correlations are not found in dry layers. The analysis of the iron bearing mineral compositions indicates that the major iron bearing minerals in the rocks are magnetite, maghemite, hematite, pyrite and siderite. In particular, the maghemite distributes mainly in the oil and gas bearing layer with the intermediate magnetic intensity. But the magnetite with the iron contents of 12.5% distributes mainly in the dry layer at the bottom. The correlations in contents between maghemite and hematite and between pyrite and siderite indicate that the authigenous maghemite may have originated largely from the autochthonous hematite and pyrite. It can be inferred that the maghemite, whose magnetic intensity is weak inclined in the rocks of the oil and gas bearing layer, is a product of the hydrocarbon alteration, providing us with some new evidence for the complete space formation mechanism of the hydrocarbon micro percolation effect (or chimney effect).
-
图 2 烃成分随深度变化曲线
a1, a2.顶空气烃成分; b1, b2.吸附烃成分
Fig. 2. Geochemical compositions of samples changing with depth
图 3 含铁矿物含量随深度的变化曲线
a.磁铁矿; b.磁赤铁矿; c.赤铁矿; d.菱铁矿; e.黄铁矿
Fig. 3. Scatter plots of iron-bearing minerals content changing with depth
图 4 磁性参量与烃成分之间的相互关系
a1—a8.全部油气显示层; b1—b8.全部干层
Fig. 4. Scatter plots of relations between magnetic parameters and hydrocarbon compositions
图 5 磁赤铁矿与赤铁矿(a)、菱铁矿(b) 及黄铁矿(c) 含量相互关系
Fig. 5. Relationship of contents between maghemite and hematite (a), siderite (b) and pyrite (c)
表 1 主要代表性层位样品磁性参量的统计值
Table 1. Magnetic parameters of rocks
-
[1] Donovan T J, Forgey R L, Roberts A A. Aeromagnetic detection of diagenetic magnetite over oil fields [J]. American Association of Petroleum Geologists Bulletin, 1979, 63: 245-248. [2] 刘庆生. 微磁方法寻找油气藏的基本原理与应用[M ]. 武汉: 中国地质大学出版社, 1996.LIU Q S. The basic principle and applications of micromagnetic method in oil & gas exploration[M]. Wuhan : China University of Geosciences Press, 1996. [3] Elmore R D, Cranvfor L. Remanence in authigenic magnetite: testing the hydrocarbon-mag netite hypothesis [J]. Journal of Geophysical Research, 1990, 95(B5) : 4539-4549. [4] Foote R S. Use of magnetic field aids oil search[J]. Oil & Gas Journal, 1994, 90 : 137-140. [5] Reynolds R L, Fishman N S, Hudson M R. Sources of aeromagnetic anomalies over Cement oil field (Oklahoma), Simpson oil field (Alasks) and the Wyoming-Idaho-Utah thrust belt[J]. Geophysics, 1991, 56 : 606-617. doi: 10.1190/1.1443077 [6] Saunders D F, Burson K R. Unconventional exploration methods work in East Texas, Alabama Ferry oil field[J]. Oil & Gas Journal, 1989, 13 : 108-110. [7] Saunders D F, Burson K R, Thompson C K. Observed relation of soil magnetic susceptibility and soil gas hydrocarbon analyses to subsurface hydrocarbon accumulation[J]. American Association of Petroleum Geologists Bulletin, 1991, 75: 389-408. [8] Schumacher D. Hydrocarbon-induced alteration of soils and sediments [A]. In: Scumacher D, Abrams M A, eds. Hydrocarbon migration and its near-surface expression [C]. AAPG Memoir, 1996, 66: 71-89. [9] Schumacher D. Surface geochemical exploration for oil and gas: new life for an old technology[J]. The Leaging Edge, 2000, 3: 258-261. [10] Saunders D F, Burson K R, Thompson C K. Model for hydrocarbon microseepage and related near-surface alterations[J]. AAPG, 1999, 83: 170-185. [11] Liu Q S, Cheng T J, Liu S G. Comprehensive evaluation of mechanism of " chimney effect" using principles of magnetism, geochemistry and mineralogy[J]. Chinese Science Bulletin, 1998, 43: 743-748. doi: 10.1007/BF02898951 [12] Liu Q S, Chan L S, Zhang S X, et al. A study of the relationship between authigenic magnetite and hydrocarbon migration in the Mawangmiao oil field, Jianghan basin, Hubei Province, China[J]. Geophysics, 2003 (in press). [13] Cioppa M T, Symons D T A. Timing of hydrocarbon generation and migration : paleomagnetic and rock magnetic analysis of the Devonian Duvernay Formation, Alberta, Canada[J]. Journal of Geochemical Exploration, 2000, 69-70 : 387-390 doi: 10.1016/S0375-6742(00)00031-5 [14] Atekwana E A, Sauck W A, Werkema D D. Investigations of geoelectrical signatures at a hydrocarbon contaminated site[J]. Journal of Applied Geophysics, 2000, 44 : 167-180. doi: 10.1016/S0926-9851(98)00033-0 [15] 刘庆生, 廖乔奇, 曲赞, 等. 非常规综合物化探方法寻找油气藏基础理论研究中的几个问题[J]. 地球科学———中国地质大学学报, 1999, 24 (5): 613-618. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX199906011.htmLIU Q S, LIAO Q J, QU Z, et al. Several issues on basic theory of unconventional comprehensive geophysical and geochemical exploration methods for location of petroleum and gas reservoirs[J]. Earth Science—Journal of China University of Geosciences, 1999, 24(5) : 613-618. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX199906011.htm [16] Burton E A, Machel H G, Jun Q. Thermodynamic constraints on anomalous magnetization in shallow and deep hydrocarbon seepage environments: applications of paleomagnetism to sedimentary geology[J]. SEPM Special Publication, 1993, 49 : 193-207. http://www.researchgate.net/publication/336897841_Thermodynamic_Constraints_on_Anomalous_Magnetization_in_Shallow_and_Deep_Hydrocarbon_Seepage_Environments [17] 刘庆生, 彭信海. 西藏羌塘盆地地表土壤的磁性、地球化学及矿物学特征与烃运移相互关系研究[J]. 地球科学———中国地质大学学报, 1996, 21 (1): 221-226. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX199602022.htmLIU Q S, PENG X H. A research on relationship between soil magnetism, geochemical and mineralogical features and hydrocarbon migration in Qiangtang basin, Xizang[J]. Earth Science—Journal of China University of Geosciences, 1996, 21(1) : 221-226. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX199602022.htm [18] Liu Q S, Liu S G, Qu Z, et al. Magnetic and mineralogical characteristics of hydrocarbon microseepage above oil/gas reservoirs of Tuoku region, northern Tarim basin, China[J]. Science in China (D), 1998, 41 : 121-120 doi: 10.1007/BF02932430 [19] Elmore R D, Engel M H, Crawford L, et al. Evidence for a relationship between hydrocarbon and authigenic magnetite[J]. Nature, 1987, 325: 428-430. doi: 10.1038/325428a0 [20] Liu Q S, Wu Q F, Li H X, et al. Magnetic, geochemical and mineralogical characteristics of soils in Qiangtang basin, Tibet, China: implications for prospective oil and gas lands [J]. Journal of China University of Geosciences, 2001, 12 : 155-159. [21] 王顺金. 矿床矿物学[M]. 武汉: 中国地质大学出版社, 1989.WANG S J. Deposit mineralogy[M]. Wuhan: China University of Geosciences Press, 1989. [22] 多尔特曼НБ. 岩石和矿物的物理性质[M]. 蒋宏耀, 刘腾耀, 卢贤栋, 等译. 北京: 科学出版社, 1985.104.Duoerteman Н Б. Physical proper ties of rocks and minerals[M]. Translated by JIANG H Y, LI U T Y, LU X D, et al. Beijing: Science Press, 1985.104. [23] Yeremin V N, Molostovskiy E A, Pervushova Ye V, et al. Magneticzonation of sedimetary rocks and the spatial distribution of authigenetic iron minerals in hydrocarbon halos[J]. International Geology Reviewer, 1986, 28 : 734-739. doi: 10.1080/00206818609466315 [24] Reynolds R L, Goldhaber M B, Tuttle M L. Sulfidization and magnetization above hydrocarbon reservoirs: applications of paleomagnetism to sedimentary geology[J]. SEPM Special Publication, 1993, 49 : 167-179. [25] Reynolds R L, Tuttle M L, Rice C A, et al. Magnetization and geochemistry of greigite-bearing Cretaceous strata, North Slope basin, Alaska[J]. America Journal of Science, 1994, 294 : 485 -528. [26] Machel H G, Burton E A. Cause and spatial distribution of anomalous magnetization in hydrocarbon seepage environments[J]. American Association of Petroleum Geologists Bulletin, 1991, 75 : 1864 -1874. [27] Thompson R, Oldfeild F. Environmental magnetism[M]. London: Allen & Unwin, 1986.15. [28] Tite M S, Linington R E. Effect of climate on the magnetic susceptibility of soil[J]. Nature, 1975, 256 : 565-566. doi: 10.1038/256565a0 -
下载:
点击查看大图
图(5) / 表(1)
计量
- 文章访问数: 3644
- HTML全文浏览量: 130
- PDF下载量: 7
- 被引次数: 0
