| Sedimentary Facies and Distribution of Reservoir Rocks from the Feixianguan Formation in the Daxian-Xuanhan Region, NE Sichuan |
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| 作者姓名： | MA Yongsheng MOU Chuanlong GUO Xusheng YU Qian TAN Qinyin |
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| 作者单位： | [1]Southern Branch, SINOPEC, Kunming, Yunnan 650200 [2]Chengdu Institute of Geology and Mineral Resources, Chengdu, Sichuan 610082 |
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| 基金项目： | Thanks are given to Yang Fangwen and Guo Xusheng from the Southern Branch, SIN0PEC for their assistance in this study, especially to Academician Liu Baojun from the Chengdu Institute of Geology and Mineral Resources for his helpful suggestions. |
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| 摘 要： | The Lower Triassic Feixianguan Formation in the Daxian-Xuanhan region, northeastern Sicbuan is interpreted to be a carbonate platform intermediate between the West Hubei-East Cbongqing marine basin and Guangyuan-Wangcang marine basin. Outcrops, well logs and seismic data have disclosed that three sedimentary facies can be identified for the formation： open platform, platform exposed shoal and restricted platform facies. During the early stage of deposition of the Feixianguan Formation, there existed a sedimentary framework all the same as the Late Permian one： open platform in the west, and platform exposed shoal, restricted platform and open platform eastwards. The gradual increase of the shoal area permitted eastward migration of the shoal facies. During the deposition of the third member of the Feixianguan Formation, the study area was invaded by temporary transgressions. Till the deposition of the fourth member of the formation, the study area was prevailed over the unified restricted platform deposits, as indicated by the sedimentary model for the typical carbonate platform shoal deposits. The reservoir rocks in the Feixianguan Formation consist mostly of solution opening dolostone, and the rock types are assembled by oolitic dolostone, residual oolitic dolostone and sucrosic residual oolitic medium- to coarse-grained dolostone. The deep and shallow dual laterologs show relatively high resistivity, clear amplitude differences and time difference saltation of acoustic waves in some intervals. The seismic responses are indicated by low-frequency and highly variable amplitudes and chaotic reflection configurations. The reservoir rocks are characterized by high porosity-high permeability and medium porosity-medium permeability, showing a marked correlation between porosity and permeability. Solution openings are extremely developed in the reservoir rocks, including cast pores, intergranular solution openings, intercrystal pores, intercrystal solution openings, solution openings （caves） and minute fissures. Macropores and coarse pore throats are common. The reservoir rocks are apparently controlled by sedimentary facies in distribution patterns. Vertically, they occur dominantly in the second and first members of the Feixianguan Formation, and laterally in the platform exposed shoals and restricted platforms, where good natural gas potential is expected.
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| 关 键 词： | 四川 碳酸盐 沉积物 岩石 地质构造 |
| 收稿时间： | 2005-05-26 |
| 修稿时间： | 2005-11-16 |
Sedimentary Facies and Distribution of Reservoir Rocks from the Feixianguan Formation in the Daxian-Xuanhan Region, NE Sichuan |
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| Authors: | MA;Yongsheng;MOU;Chuanlong;GUO;Xusheng;YU;Qian;TAN;Qinyin |
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| Abstract: | Abstract The Lower Triassic Feixianguan Formation in the Daxian‐Xuanhan region, northeastern Sichuan is interpreted to be a carbonate platform intermediate between the West Hubei‐East Chongqing marine basin and Guangyuan‐Wangcang marine basin. Outcrops, well logs and seismic data have disclosed that three sedimentary facies can be identified for the formation: open platform, platform exposed shoal and restricted platform facies. During the early stage of deposition of the Feixianguan Formation, there existed a sedimentary framework all the same as the Late Permian one: open platform in the west, and platform exposed shoal, restricted platform and open platform eastwards. The gradual increase of the shoal area permitted eastward migration of the shoal facies. During the deposition of the third member of the Feixianguan Formation, the study area was invaded by temporary transgressions. Till the deposition of the fourth member of the formation, the study area was prevailed over the unified restricted platform deposits, as indicated by the sedimentary model for the typical carbonate platform shoal deposits. The reservoir rocks in the Feixianguan Formation consist mostly of solution opening dolostone, and the rock types are assembled by oolitic dolostone, residual oolitic dolostone and sucrosic residual oolitic medium‐ to coarse‐grained dolostone. The deep and shallow dual laterologs show relatively high resistivity, clear amplitude differences and time difference saltation of acoustic waves in some intervals. The seismic responses are indicated by low‐frequency and highly variable amplitudes and chaotic reflection configurations. The reservoir rocks are characterized by high porosity‐high permeability and medium porosity‐medium permeability, showing a marked correlation between porosity and permeability. Solution openings are extremely developed in the reservoir rocks, including cast pores, intergranular solution openings, intercrystal pores, intercrystal solution openings, solution openings (caves) and minute fissures. Macropores and coarse pore throats are common. The reservoir rocks are apparently controlled by sedimentary facies in distribution patterns. Vertically, they occur dominantly in the second and first members of the Feixianguan Formation, and laterally in the platform exposed shoals and restricted platforms, where good natural gas potential is expected. |
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| Keywords: | Daxian-Xuanhan region Feixianguan Formation carbonate platform exposed shoal physical property distribution of reservoir rocks |
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