Erosion thickness recovery and its significance to hydrocarbon accumulation in northwestern Qaidam Basin
-
摘要: 柴达木盆地西北至一里坪地区面积大、油气资源探明程度低,恢复地层剥蚀厚度对油气资源评价具有重要意义。针对剥蚀厚度恢复的复杂性和恢复结果的不确定性,采用地层趋势延伸法、声波时差法、镜质体反射率法和Easy%Ro最优化法等多种方法相结合,计算了研究区晚期构造运动地层剥蚀厚度,并定量探讨了其对油气成藏的影响。研究区第四系和上新统狮子沟组(N23)普遍遭受剥蚀,局部构造顶部剥蚀量可达1 000 m,上油砂山组(N22)在油泉子等部分构造顶部遭受剥蚀,下油砂山组(N21)仅在盆地周缘被剥蚀。英雄岭构造带、各构造顶部以及阿尔金山前是剥蚀严重的区域,剥蚀量普遍超过500 m;洼陷地带以及研究区东部剥蚀量较小,剥蚀厚度小于500 m,构造活动相对稳定。油气藏和地面油气显示分布与地层剥蚀密切相关,适宜强度的地层剥蚀(300 m<剥蚀量<1 500 m)有利于形成油气藏,而剥蚀厚度超过1 500 m则易造成油气藏的破坏。Abstract: The area from the northwestern Qaidam Basin to Yiliping is large and the exploration degree of proved petroleum reserves is low. It is of great significance for future petroleum resource assessment to recover the thickness of eroded formation. In this paper, several methods including stratigraphic trend extension, interval transit time, vitrinite reflectivity and Easy%Ro optimization were used to calculate the formation erosion thickness during the late tectonic movement in the study area, and its significance for hydrocarbon accumulation was quantitatively discussed. The Quaternary and Pliocene Shizigou Formation (N23) in the study area were generally eroded, with a maximum erosion thickness of about 1 000 m on the top of some local structures. The Upper Youshashan Formation (N22) was eroded on the top of some structures such as Youquanzi, and the Lower Youshashan Formation (N21) was eroded only at the periphery of the basin. The Yingxiongling structural belt, the top of each structure and the Altun foreland are the areas experienced the most serious erosion, generally more than 500 m of thickness. The erosion thickness in the depression and the eastern part of the study area is relatively smaller, usually less than 500 m, and the tectonic activities here are relatively stable. The distribution of petroleum reservoirs and hydrocarbon shows are closely related to the erosion thickness of sedimentary strata. The erosion thickness with appropriate strength (300-1 500 m) is conducive to the formation of oil and gas reservoirs, while an erosion thickness over 1 500 m is easy to cause damage to oil and gas reservoirs.
-
图 2 地层趋势延伸法恢复柴达木盆地西北区地层剥蚀厚度
剖面位置见图 1。
Figure 2. Erosion thickness of northwestern Qaidam Basin recovered by stratigraphic trend extension
表 1 柴达木盆地部分重点井位剥蚀厚度统计
Table 1. Statistics of erosion thickness of some key wells in Qaidam Basin
m 井位 剥蚀地层 地层趋势延伸法 声波时差法 镜质体反射率法 Easy%Ro最优化方法 风3 Q1+2 430 438 450 油6 Q1+2-N22 2 130 4 935 2 200 梁3 Q1+2 413 550 鄂深1 Q1+2-N23 883 934 博1 Q1+2-N23 850 721 落深1 Q1+2-N23 1 217 1 161 1 250 开2 Q1+2-N22 2 286 2 561 风2 Q1+2-N23 1 210 1 129 鸭参3 Q1+2-N23 582 725 677 690 伊深1 Q1+2 478 571 450 表 2 柴达木盆地西北地区部分油气藏剥蚀厚度统计
Table 2. Statistics of erosion thickness of some reservoirs in northwestern Qaidam Basin
油气藏 剥蚀地层 核部剥蚀量/m 储集层 石油储量/104t 天然气储量/108m3 地面油气显示 干柴沟 Q1+2-E32 1 800~2 100 N22-E32 油苗 油墩子 Q1+2-N22 1 500~1 600 N22 油苗 油泉子 Q1+2-N22 1 500~2 100 N22、N21 5 117.0 394 油苗、沥青 英东 Q1+2-N23 600~800 N22、N21 17 193.0 122 无 小梁山 Q1+2 400 N22、N23 3 266.0 52 无 南翼山 Q1+2-N23 1 100~1 600 N22-E32 3 229.4 384 油苗 红沟子 Q1+2-N21 1 200~1 600 N21、N1 1 412.0 油苗 -
[1] 薛志文, 屈争辉, 成捷, 等. 二连盆地吉尔嘎朗图凹陷剥蚀量恢复及其对油气藏的影响[J]. 高校地质学报, 2019, 25(5): 714-721. https://www.cnki.com.cn/Article/CJFDTOTAL-GXDX201905008.htmXUE Zhiwen, QU Zhenghui, CHENG Jie, et al. Denudation restoration in the Jiergalangtu Sag of the Erlian Basin and its significance to hydrocarbon accumulation[J]. Geological Journal of China Universities, 2019, 25(5): 714-721. https://www.cnki.com.cn/Article/CJFDTOTAL-GXDX201905008.htm [2] 刘景彦, 林畅松, 肖建新, 等. 东海西湖凹陷第三系主要不整合面的特征、剥蚀量的分布及其意义[J]. 现代地质, 1999, 13(4): 432-438. https://www.cnki.com.cn/Article/CJFDTOTAL-XDDZ199904012.htmLIU Jingyan, LIN Changsong, XIAO Jianxin, et al. Characteristics and erosions of the major tertiary unconformities and their significance to petroleum exploration in the Xihu Trough, the East China Sea[J]. Geoscience, 1999, 13(4): 432-438. https://www.cnki.com.cn/Article/CJFDTOTAL-XDDZ199904012.htm [3] 赵桂萍. 鄂尔多斯盆地杭锦旗地区上古生界烃源岩热演化特征模拟研究[J]. 石油实验地质, 2016, 38(5): 641-646. doi: 10.11781/sysydz201605641ZHAO Guiping. Thermal evolution modeling of Neopaleozoic source rocks in Hangjinqi region, Ordos Basin[J]. Petroleum Geology & Experiment, 2016, 38(5): 641-646. doi: 10.11781/sysydz201605641 [4] 郭泽清, 马寅生, 易士威, 等. 柴西地区古近系—新近系含气系统模拟及勘探方向[J]. 天然气地球科学, 2017, 28(1): 82-92. https://www.cnki.com.cn/Article/CJFDTOTAL-TDKX201701009.htmGUO Zeqing, MA Yinsheng, YI Shiwei, et al. Simulation and exploration direction of Paleogene-Neogene gas system in the western Qaidam Basin[J]. Natural Gas Geoscience, 2017, 28(1): 82-92. https://www.cnki.com.cn/Article/CJFDTOTAL-TDKX201701009.htm [5] 黄成刚, 常海燕, 崔俊, 等. 柴达木盆地西部地区渐新世沉积特征与油气成藏模式[J]. 石油学报, 2017, 38(11): 1230-1243. https://www.cnki.com.cn/Article/CJFDTOTAL-SYXB201711002.htmHUANG Chenggang, CHANG Haiyan, CUI Jun, et al. Oligocene sedimentary characteristics and hydrocarbon accumulation model in the western Qaidam Basin[J]. Acta Petrolei Sinica, 2017, 38(11): 1230-1243. https://www.cnki.com.cn/Article/CJFDTOTAL-SYXB201711002.htm [6] 付锁堂. 柴达木盆地油气勘探潜在领域[J]. 中国石油勘探, 2016, 21(5): 1-10. https://www.cnki.com.cn/Article/CJFDTOTAL-KTSY201605001.htmFU Suotang. Potential oil and gas exploration areas in Qaidam Basin[J]. China Petroleum Exploration, 2016, 21(5): 1-10. https://www.cnki.com.cn/Article/CJFDTOTAL-KTSY201605001.htm [7] 钟建华, 郭泽清, 杨树锋, 等. 柴达木盆地茫崖坳陷古近系—新近系Ro分布特征及地质意义[J]. 地质学报, 2004, 78(3): 407-415. https://www.cnki.com.cn/Article/CJFDTOTAL-DZXE200403013.htmZHONG Jianhua, GUO Zeqing, YANG Shufeng, et al. Vertical distribution of the Tertiary vitrinite reflectivity (Ro) and its geological significance in the western Qaidam Basin[J]. Acta Geologica Sinica, 2004, 78(3): 407-415. https://www.cnki.com.cn/Article/CJFDTOTAL-DZXE200403013.htm [8] 郭泽清, 刘卫红, 李本竞, 等. 柴达木盆地西部埋藏史分析与油气关系类型[J]. 地球学报, 2005, 26(5): 465-471. https://www.cnki.com.cn/Article/CJFDTOTAL-DQXB200505012.htmGUO Zeqing, LIU Weihong, LI Benjing, et al. An analysis of the burial history of western Qaidam Basin in relation to oil-gas accumulation[J]. Acta Geoscientica Sinica, 2005, 26(5): 465-471. https://www.cnki.com.cn/Article/CJFDTOTAL-DQXB200505012.htm [9] 曹海防. 柴达木盆地西部第三系油气成藏条件与富集规律研究[D]. 广州: 中国科学院研究生院(广州地球化学研究所), 2007.CAO Haifang. A study on formation conditions and accumulation regularity of Teriary reservoirs in the western Qaidam[D]. Guangzhou: Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 2007. [10] SUN Ping, GUO Zeqing, HE Wenyuan, et al. Restoration of eroded thickness of the Neogene strata in the western Qaidam Basin and its significance for oil and gas occurrence[J]. Acta Geologica Sinica (English Edition), 2017, 91(4): 1352-1362. doi: 10.1111/1755-6724.13366 [11] CHEN Xuanhua, GEHRELS G, YIN An, et al. Geochemical and Nd-Sr-Pb-O isotopic constrains on Permo-Triassic magmatism in eastern Qaidam Basin, northern Qinghai-Tibetan plateau: implications for the evolution of the Paleo-Tethys[J]. Journal of Asian Earth Sciences, 2015, 114: 674-692. doi: 10.1016/j.jseaes.2014.11.013 [12] GUO Pei, LIU Chiyang, GIBERT L, et al. How to find high-quality petroleum source rocks in saline lacustrine basins: a case study from the Cenozoic Qaidam Basin, NW China[J]. Marine and Petroleum Geology, 2020, 111: 603-623. doi: 10.1016/j.marpetgeo.2019.08.050 [13] 王亮. 柴达木盆地新生代不整合的发现对阿尔金断裂研究的启示[D]. 杭州: 浙江大学, 2009.WANG Liang. The study revelation of the Altyn Tagh fault basing on the discovery of the unconformity in the Qaidam Basin[D]. Hangzhou: Zhejiang University, 2009. [14] 吴颜雄, 薛建勤, 冯云发, 等. 柴西地区新构造运动特征及其对成藏影响[J]. 石油实验地质, 2013, 35(3): 243-248. doi: 10.11781/sysydz201303243WU Yanxiong, XUE Jianqin, FENG Yunfa, et al. Neotectonic movement feature and its controlling effect on accumulation in western Qaidam Basin[J]. Petroleum Geology & Experiment, 2013, 35(3): 243-248. doi: 10.11781/sysydz201303243 [15] 付锁堂, 袁剑英, 汪立群, 等. 柴达木盆地油气地质成藏条件研究[M]. 北京: 科学出版社, 2014.FU Suotang, YUAN Jianying, WANG Liqun, et al. Study on the geological conditions of hydrocarbon accumulation in Qaidam Basin[M]. Beijing: Science Press, 2014. [16] 吴涛, 吴采西, 戚艳平, 等. 准噶尔盆地地层剥蚀厚度定量恢复方法研究与应用: 以克拉玛依油田八区二叠系下乌尔禾组为例[J]. 古地理学报, 2015, 17(1): 81-90. https://www.cnki.com.cn/Article/CJFDTOTAL-GDLX201501009.htmWU Tao, WU Caixi, QI Yanping, et al. Quantitative resumption method of stratum denudation thickness and its application in Junggar Basin: a case study on the Permian Lower Urho Formation in block 8 of Karamay Oilfield[J]. Journal of Palaeogeography, 2015, 17(1): 81-90. https://www.cnki.com.cn/Article/CJFDTOTAL-GDLX201501009.htm [17] 孔金平. 地震厚度趋势法在乐乡关地垒剥蚀量恢复中的应用[J]. 江汉石油职工大学学报, 2016, 29(4): 18-20. https://www.cnki.com.cn/Article/CJFDTOTAL-JSZD201604008.htmKONG Jinping. Application of seismic thickness trend method in recovery of horst denudation quantity in Lexiangguan[J]. Journal of Jianghan Petroleum University of Staff and Workers, 2016, 29(4): 18-20. https://www.cnki.com.cn/Article/CJFDTOTAL-JSZD201604008.htm [18] DOW W G. Kerogen studies and geological interpretations[J]. Journal of Geochemical Exploration, 1977, 7: 79-99. [19] 佟彦明, 宋立军, 曾少军, 等. 利用镜质体反射率恢复地层剥蚀厚度的新方法[J]. 古地理学报, 2005, 7(3): 417-424. https://www.cnki.com.cn/Article/CJFDTOTAL-GDLX200503015.htmTONG Yanming, SONG Lijun, ZENG Shaojun, et al. A new method by vitrinite reflectance to estimate thickness of eroded strata[J]. Journal of Palaeogeography, 2005, 7(3): 417-424. https://www.cnki.com.cn/Article/CJFDTOTAL-GDLX200503015.htm [20] MAGARA K. Thickness of removed sedimentary rocks, paleopore pressure, and paleotemperature, southwestern part of Western Canada Basin[J]. AAPG Bulletin, 1976, 60(4): 554-565. [21] 刘玉瑞. 声波时差法计算地层剥蚀量问题的斧正[J]. 复杂油气藏, 2015, 8(2): 1-6. https://www.cnki.com.cn/Article/CJFDTOTAL-FZYQ201502002.htmLIU Yurui. Correction of erosion thickness of strata calculated by acoustic time difference[J]. Complex Hydrocarbon Reservoirs, 2015, 8(2): 1-6. https://www.cnki.com.cn/Article/CJFDTOTAL-FZYQ201502002.htm [22] 赵军, 曹强, 付宪弟, 等. 基于米兰科维奇天文旋回恢复地层剥蚀厚度: 以松辽盆地X油田青山口组为例[J]. 石油实验地质, 2018, 40(2): 260-267. doi: 10.11781/sysydz201802260ZHAO Jun, CAO Qiang, FU Xiandi, et al. Recovery of denuded strata thickness based on Milankovitch Astronomical Cycles: a case study of Qingshankou Formation in X Oilfield, Songliao Basin[J]. Petroleum Geology & Experiment, 2018, 40(2): 260-267. doi: 10.11781/sysydz201802260 [23] BURNHAM A K, SWEENEY J J. A chemical kinetic model of vitrinite maturation and reflectance[J]. Geochimica et Cosmochimica Acta, 1989, 53(10): 2649-2657. [24] 邱楠生, 顾先觉, 丁丽华, 等. 柴达木盆地西部新生代的构造—热演化研究[J]. 地质科学, 2000, 35(4): 456-464. https://www.cnki.com.cn/Article/CJFDTOTAL-DZKX200004008.htmQIU Nansheng, GU Xianjue, DING Lihua, et al. Tectono-thermal evolution of western Qaidam Basin, Northwest China[J]. Scientia Geologica Sinica, 2000, 35(4): 456-464. https://www.cnki.com.cn/Article/CJFDTOTAL-DZKX200004008.htm [25] 莫午零, 郑亚东, 张文涛, 等. 柴达木盆地油泉子储油构造分析[J]. 石油与天然气地质, 2007, 28(3): 324-328. https://www.cnki.com.cn/Article/CJFDTOTAL-SYYT200703004.htmMO Wuling, ZHANG Yadong, ZHANG Wentao, et al. Analysis of the Youquanzi oil-bearing structure in Qaidam Basin[J]. Oil & Gas Geology, 2007, 28(3): 324-328. https://www.cnki.com.cn/Article/CJFDTOTAL-SYYT200703004.htm [26] ZHANG Wei, JIAN Xing, FU Ling, et al. Reservoir characterization and hydrocarbon accumulation in late Cenozoic lacustrine mixed carbonate-siliciclastic fine-grained deposits of the northwestern Qaidam Basin, NW China[J]. Marine and Petroleum Geology, 2018, 98: 675-686. [27] 刘成林, 平英奇, 郭泽清, 等. 柴达木盆地西北古近系—新近系异常高压形成机制分析[J]. 地学前缘, 2019, 26(3): 211-219. https://www.cnki.com.cn/Article/CJFDTOTAL-DXQY201903030.htmLIU Chenglin, PING Yingqi, GUO Zeqing, et al. Genetic mechanism of overpressure in the Paleogene and Neogene in the northwestern Qaidam Basin[J]. Earth Science Frontiers, 2019, 26(3): 211-219. https://www.cnki.com.cn/Article/CJFDTOTAL-DXQY201903030.htm [28] 房媛, 汤达祯, 许浩, 等. 南翼山油田浅层低压油气藏形成机理[J]. 特种油气藏, 2014, 21(5): 24-28. https://www.cnki.com.cn/Article/CJFDTOTAL-TZCZ201405006.htmFANG Yuan, TANG Dazhen, XU Hao, et al. Formation mechanism of shallow reservoirs with low pressure in Nanyishan oilfield[J]. Special Oil & Gas Reservoirs, 2014, 21(5): 24-28. https://www.cnki.com.cn/Article/CJFDTOTAL-TZCZ201405006.htm