| 莺歌海盆地东方区天然气成藏模式及优质天然气勘探策略 |
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| 引用本文： | 徐新德,张迎朝,裴健翔,甘军,李里,熊小峰.莺歌海盆地东方区天然气成藏模式及优质天然气勘探策略[J].地质学报,2014,88(5):956-965. |
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| 作者姓名： | 徐新德 张迎朝 裴健翔 甘军 李里 熊小峰 |
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| 作者单位： | 中海石油（中国）有限公司湛江分公司研究院,中海石油（中国）有限公司湛江分公司勘探开发部,中海石油（中国）有限公司湛江分公司研究院,中海石油（中国）有限公司湛江分公司研究院,中海石油（中国）有限公司湛江分公司研究院,中海石油（中国）有限公司湛江分公司研究院 |
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| 摘 要： | 莺歌海盆地东方区天然气勘探取得重大突破，本文对该区不同气田、不同层段的72个天然气样品，开展了化学组分及其稳定碳同位素分析。研究表明该区天然气存在迥然不同的分布差异：西南区块（XY1-1S/XY13-2构造），浅层天然气中CO2含量高，天然气成熟度总体也较高，而中深层天然气中CO2含量很低，天然气成熟度也相对较低；东北区块（XY1-1/XY13-1构造），浅层天然气中CO2含量总体较低，天然气成熟度也较低，但是中深层天然气中CO2含量总体较高，天然气成熟度也相对较高。根据天然气系列地化特征，结合底辟活动的分析，提出东方区受底辟影响的低能量区和高能量区具有截然不同的天然气充注成藏模式：①西南区块（XY1-1S/XY13-2构造）远离底辟核心区，属低能量活动的底辟波及区，受底辟活动影响程度相对较小，早期低CO2含量、低成熟天然气沿小断裂或裂隙输导体系运移到中深层的黄流组、梅山组聚集成藏。由于底辟能量较低，中深层早期形成的气藏得以完整保存。后期，烃源岩生成的高CO2含量、高成熟天然气沿着底辟活动产生的断层向上运移至莺歌海组浅层聚集成藏。浅层和中深层天然气输导体系可能存在一定差异；②东北区块（XY1-1/XY13-1构造）处于底辟核心区，属高能量活动区，多期强烈的底辟活动形成深大断裂，为天然气的快速运移提供通道，使得早期在黄流组、梅山组中深层聚集的低CO2含量、低成熟天然气遭受破坏，向上发生再次运移至浅层莺歌海组聚集成藏。后期高CO2含量、高成熟天然气主要充注中深层。该模式可以很好地解释莺歌海盆地东方区天然气复杂的分布特征，为莺歌海盆地不同领域，尤其是中深层高温超压领域低CO2的优质天然气勘探提供策略指导。
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| 关 键 词： | 天然气成藏模式 底辟 二氧化碳 优质天然气 东方区 莺歌海盆地 |
| 收稿时间： | 2013/9/22 0:00:00 |
| 修稿时间： | 2014/1/23 0:00:00 |
Gas Accumulating Models and Exploration Strategy for High Quality Natural Gas in Dongfang Area, Yinggehai Basin |
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| Xu Xinde,Zhang Yingzhao,Pei Jinaxiang,Gang Jun,Li Li and Xiong Xiaofeng.Gas Accumulating Models and Exploration Strategy for High Quality Natural Gas in Dongfang Area, Yinggehai Basin[J].Acta Geologica Sinica,2014,88(5):956-965. |
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| Authors: | Xu Xinde Zhang Yingzhao Pei Jinaxiang Gang Jun Li Li and Xiong Xiaofeng |
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| Institution: | CNOOC China Limited, Zhanjiang Branch, Zhanjiang,CNOOC China Limited, Zhanjiang Branch, Zhanjiang,CNOOC China Limited, Zhanjiang Branch, Zhanjiang,CNOOC China Limited, Zhanjiang Branch, Zhanjiang,CNOOC China Limited, Zhanjiang Branch, Zhanjiang |
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| Abstract: | Recently important exploration discovery of natural gas has been obtained in high-temperature and overpressure intervals in Dongfang area, Yinggehai Basin, South China Sea. In this study, chemical component and stable carbon isotopic compositions were analyzed for 72 natural gas samples collected from different gas fields and different production formation, which exhibited widely different distribution characteristics. In southwest region such as XY1-1/XY13-1, natural gas with low CO2 content and low maturity appeared in shallow intervals such as Huangliu Formation and Meishan Formation whilst gas with high CO2 content and high maturity occurred in middle-deep intervals such as Huangliu Formation and Meishan Formation. However, in northeast region such as XY-1S/XY13-2, natural gas just presents reverse distribution characteristics. This kind of distribution is attributed to the effect of diapir action mainly occurred in the XY1-1 region. Based on the geochemical characters of natural gas and evolvement of diapir, two gas accumulating models in low energy area and high energy area are put forward to explain the distinct characteristics occurred in different gas fields. Locating faraway from diapirs, XY1-1S/XY13-2 are rarely influenced by the activity of diapirs. Gas generated by source rock early with low CO2 content and low maturity transports through micro-fractures into middle-deep intervals such as Huangliu Formation and Meishan Formation. Because of the lower energy influenced by the diapirs, gas reservoirs formed early were protected. Subsequently, faults induced by activity of the diapirs led the gas with high CO2 content and high maturity generated in the late stage up to shallow interval such as Yinggehai Formation. There may exist some difference in natural gas conduit system between shallow intervals and middle-deep intervals. On the contrary, XY1-1/XY13-1 are located near to the XY1-1 diaper with high energy, the migration and accumulation of natural gas strongly influenced by intensive activity of the XY1-1 diapir. As a result, gas accumulated early with low CO2 content and low maturity was destroyed and re-migrated up to shallow interval such as Yinggehai Formation and gas generated afterward with high CO2 content and high maturity mainly get into the middle-deep intervals such as Huangliu Formation and Meishan Formation. These two gas accumulating models explain the complicated distribution of the gas in Dongfang area commendably and thus provide strategy guidance for the exploration of high quality natural gas of low CO2 content in Yinggehai Basin. |
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| Keywords: | gas accumulating model diaper carbon dioxide high quality natural gas Dongfang area Yinggehai Basin |
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