PETROLEUM GEOLOGY AND EXPLORATION POTENTIAL OF RUKWA BASIN IN EAST AFRICAN RIFT SYSTEM
-
摘要:
随着东非裂谷西支Albertine盆地勘探获得突破,使该区成为研究和勘探的热点地区。Rukwa盆地作为东非裂谷系中沉积厚度最大的盆地,勘探程度很低。盆地为半地堑结构,位于Tanganyika-Rukwa-Malawi剪切带上,具有走滑拉分的性质。发育二叠系—三叠系Karoo地层、白垩系—古近系Red Sandstone和上新统—更新统Lake Beds三大套地层,沉积地层总厚度最大可达11 km,且横向变化很大。盆地内发育Karoo煤层或黑色页岩和Lake Beds湖相泥岩2套潜在的烃源岩。盆地东南部地层埋深大,具备较好储盖组合条件,断层发育,圈闭和油气运移条件较好,推测为有利勘探区。烃源是盆地勘探最主要的地质风险。
Abstract:Since the breakthrough in oil and gas exploration in the Albertine Basin, the Western Branch of East African Rift System (EARS) has become a hot spot for research and exploration. Among the basins in EARS, the Rukwa Basin is the one with thickest deposits but low exploration degree. It is a pull-apart half graben characterized by strike-slipping, located in the Tanganyika-Rukwa-Malawi transform zone. There are three sedimentary sequences in the basin, i.e. the Permian-Triassic Karoo Super-group, the Cretaceous-Paleogene Red Sandstone group and the Pliocene-Pleistocene Lake Beds respectively. The maximum thickness of total deposits may reach 11 kilometers with great horizontal variation. There are two potential source rocks, the Karoo (coal and black shale) and the Lake Beds (lacustrine mudstone). Good reservoir-seal combination and good hydrocarbon accumulation conditions with well developed fracture system has been found in the southeast, the favorable exploration area of the basin. Source rock is the main geological risk of the exploration in this basin.
-
图 2 Rukwa盆地位置(据文献[6]修改)
Figure 2.
图 3 Rukwa盆地综合柱状图(据文献[1]修改)
Figure 3.
-
[1] IHS Energy Portal Version 2.0. EDIN [EB/OL].https:∥my.ihs.com/Energy/Products
[2] Kreuser T. Rift to drift evolution in Permian-Jurassic basins of East Africa [J]. Geological Society London Special Publications, 1995, 80(1): 297-315. doi: 10.1144/GSL.SP.1995.080.01.14
[3] Morley C K, Nelson R A, Pat ton T L, et al. Transfer zones in the East Africa rift system and their relevance to hydrocarbon exploration in rifts [J]. AAPG, 1990, 74(8):1234-1253. https://pubs.geoscienceworld.org/aapgbull/article-abstract/74/8/1234/38596/transfer-zones-in-the-east-african-rift-system-and
[4] Aanyu K, Koehn D. Influence of pre-existing fabrics on fault kinematics and rift geometry of interacting segments: Analogue models based on the Albertine Rift (Uganda), Western Branch-East African Rift System [J]. Journal of African Earth Sciences, 2011, 59(2/3): 168-184.http://doi.org/10.1016/j.jafrearsci.2010.10.003 http://doi.org/10.1016/j.jafrearsci.2010.10.003
[5] Johnson M R. Stratigraphy of the Karoo super-group in southern Africa: an overview [J]. Journal of African Earth Sciences, 1996, 23(1): 3-15. https://www.sciencedirect.com/science/article/pii/S0899536296000486
[6] Roberts E M. Sedimentology and depositional environments of the Red Sandstone Group, Rukwa Rift Basin, southwestern Tanzania: New insight into Cretaceous and Paleogene terrestrial ecosystems and tectonics in sub-equatorial Africa [J]. Journal of African Earth Sciences, 2010, 57: 179-212. doi: 10.1016/j.jafrearsci.2009.09.002 http://cn.bing.com/academic/profile?id=d8f7089ea4d3c3731719a13094842bf4&encoded=0&v=paper_preview&mkt=zh-cn
[7] Delvaux D. The Karoo to recent rifting in the western branch of the east African Rift System a bibliographical synthesis [M]. Tervuren: Mus. Roy. Afr. Centr., 1991:63-83.
[8] 许志刚.东非裂谷系西支中南段Karoo地层分布特点与勘探前景[J].吉林地质, 2014, 33(1):14-19. doi: 10.3969/j.issn.1001-26.2014.01.005
[9] Bumby A J, Guiraud R. The geodynamic setting of the Phanerozoic basins of Africa [J]. Journal of African Earth Sciences, 2005, 43: 1-12. http://cn.bing.com/academic/profile?id=6eb686809551b5642f4e79b05461837f&encoded=0&v=paper_preview&mkt=zh-cn
[10] Chorowicz J. The East African Rift System [J]. Journal of African Earth Sciences, 2005, 43(1): 379-410. http://cn.bing.com/academic/profile?id=20a481e6d4989b2a477b61c0c97c3b17&encoded=0&v=paper_preview&mkt=zh-cn
[11] 徐宁, 张杰, 史卜庆, 等.红海盆地石油地质特征及其油气勘探潜力[J].地学前缘, 2014, 21(3): 155-165. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=dxqy201403018
[12] Bosworth W, Huchon P, McClay K. The Red Sea and Gulf of Aden Basins [J]. Journal of African Earth Sciences, 2005, 43: 334-378. doi: 10.1016/j.jafrearsci.2005.07.020
[13] Kim S. Crustal velocity structure of the Rukwa rift in the Western Branch of the East African Rift System [J]. South African Journal of Geology, 2009, 112: 251-260. doi: 10.2113/gssajg.112.3-4.251
[14] Kjennerud T. Short term development of intracontinental rifts, with reference to the late Quaternary of the Rukwa Rift [J]. Marine and Petroleum Geology, 2001, 18: 307-317. doi: 10.1016/S0264-8172(01)00007-1
[15] Delvaux. Late Quaternary tectonic activity and lake level change in the Rukwa Rift Basin [J]. Journal of African Earth Sciences, 1998, 26(3): 397-421. http://cn.bing.com/academic/profile?id=63dea95765dbab29678218de1071ce5d&encoded=0&v=paper_preview&mkt=zh-cn
[16] Damblon F. Identification of a fossil wood specimen in the Red Sandstone Group of southwestern Tanzania: stratigraphical and tectonic implications [J]. Journal of African Earth Sciences, 1998, 26(3): 387-396. http://cn.bing.com/academic/profile?id=d49b71840d44f9f7b5f3844ebd596e4a&encoded=0&v=paper_preview&mkt=zh-cn
[17] Morley C K, Karanja F M, Wescott W A, et al. Geology and geophysics of the western Turkana Basins, Kenya [C]//Morley C K. Geoscience of Rift Systems-Evolution of East Africa: AAPG Study 44. Tulsa: AAPG, 1999: 19-54.
[18] Wescott W A, Krebs W N, Engelhardt D W, et al. New biostratigraphic age dates from the Lake Rukwa rift basin in western Tanzania [J]. American Association of Petroleum Geologists Bulletin, 1991, 75: 1255-1263. http://cn.bing.com/academic/profile?id=ae5cf312263b6f062a83f7ec299160ec&encoded=0&v=paper_preview&mkt=zh-cn
[19] 赵伟, 韩文明, 胡滨.东非裂谷Tanganyika地堑石油地质特征和勘探潜力分析[J].中国地质调查, 2016, 3(1):14-19. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=zgdzdc201601003
[20] Semkiwa. The geology, petrology, palynology and geochemistry of Permian coal basins in Tanzania: 2. Songwe-Kiwira Coalfield [J]. International Journal of Coal Geology, 2003, 55: 157-186. http://cn.bing.com/academic/profile?id=a054bb6ea08d6f07d883bc53f1d9376f&encoded=0&v=paper_preview&mkt=zh-cn
[21] 马君, 刘剑平, 潘校华, 等.东非大陆边缘地质特征及油气勘探前景[J].世界地质, 2008, 27(4): 400-405. doi: 10.3969/j.issn.1004-5589.2008.04.008
[22] 张可宝, 史卜庆, 徐志强, 等.东非地区沉积盆地油气潜力浅析[J].天然气地球科学, 2007, 18(6): 869-874. doi: 10.3969/j.issn.1672-1926.2007.06.018
[23] 赵伟, 韩文明, 胡滨, 等.东非裂谷Albertine盆地石油地质条件和成藏规律[J].四川地质学报, 2016, 36(2):275-279. doi: 10.3969/j.issn.1006-0995.2016.02.023