| 莺歌海盆地高温高压盖层封盖能力定量评价 |
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| 引用本文： | 谢玉洪.莺歌海盆地高温高压盖层封盖能力定量评价[J].地球科学,2019,44(8):2579-2589. |
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| 作者姓名： | 谢玉洪 |
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| 作者单位： | 中国海洋石油集团有限公司, 北京 100010 |
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| 基金项目： | 国家科技重大专项“莺琼盆地高温高压天然气富集规律与勘探开发关键技术(三期)2016ZX05024005 |
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| 摘 要： | 莺歌海盆地是我国南海重要的新生代含油气盆地，随着浅层常压层系天然气开发程度的逐渐提高，中深层高温高压层系成为天然气勘探的主要目标，超压背景下盖层封闭的有效性受到广泛关注.近年来，不同学者针对莺歌海盆地盖层进行了大量的研究，但是对高温高压的气藏盖层的封闭机理、破坏条件及其定量评价仍存在一定的问题.通过对莺歌海盆地中深层高温高压层系盖层进行系统的分析，明确盖层的封闭机理为毛细管封闭和水力封闭.利用泥岩盖层排替压力、声波时差及孔隙度之间的关系，对莺歌海盆地区域性盖层的毛细管封闭能力进行预测.莺歌海盆地中深层盖层普遍具有较强的毛细管封闭能力.因此，超压诱发的水力破裂是油气多层位聚集的根本原因，进而提出了盖层水力破裂压力系数定量评价盖层水力破裂风险性.评价结果显示，盖层发生水力破裂与底辟构造活动具有明显的相关性，盖层水力破裂风险由底辟中心向外围逐渐减弱.位于莺歌海盆地斜坡近凹带，且紧邻乐东三大底辟的LD-B区块是油气富集的有利区域.
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| 关 键 词： | 莺歌海盆地 盖层 超压 排替压力 水力破裂 石油地质 |
| 收稿时间： | 2019-01-26 |
Quantitative Evaluation of Sealing Capacity of High Temperature and Pressure Caprocks in Yinggehai Basin |
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| Abstract: | Yinggehai Basin is the important Cenozoic petroliferous basin in China South Sea. With the gradual improvement of the petroleum exploration and development in shallow layers,middle and deep overpressured layers become the main target of the natural gas exploration. Whether the caprocks can effectively seal the oil and gas turns to be a crucial questions for the research. In recent years,different scholars have conducted a lot of researches on the caprocks of Yinggehai Baisn,but there are still some questions in the sealing mechanism,failure conditions and quantitative evaluation of the caprocks in high temperature and pressure. Based on the systematic analysis of the high temperature and pressure caprocks in Yinggehai Basin,it is clear that the sealing mechanism of caprocks is capillary sealing and hydraulic sealing. Using the relationship among displacement pressure,acoustic time and porosity of mudstone to predict the capillary sealing ability of regional caprocks,the results show that the caprocks in Yinggehai Basin have strong capillary sealing ability. Therefore,hydraulic fractures induced by overpressure are the fundamental cause of oil and gas multilayer accumulation,and then propose the cap hydraulic fracturing pressure coefficient to quantitative evaluate the risk of hydraulic fracturing in caprocks. The evaluation results show that there is a significant correlation between the occurrence of hydraulic fracturing in the caprock and the diapir activity,the risk of hydraulic fracturing in caprocks gradually decreases from the diapiric center to the periphery. LD-B block located in the slope near the depression in Yinggehai Basin which is adjacent to the Ledong diapirs,is a favorable area for oil and gas accumulation. |
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