西南石油大学学报(自然科学版) ›› 2019, Vol. 41 ›› Issue (1): 68-76.DOI: 10.11885/j.issn.1674-5086.2017.11.15.01

• 地质勘探 • 上一篇    下一篇

柴达木盆地东坪基岩气藏裂缝发育规律研究

李翔1, 刘应如1, 柴小颖2, 龙伟2, 白亚东1   

  1. 1. 中国石油勘探开发研究院西北分院, 甘肃 兰州 730020;
    2. 中国石油青海油田勘探开发研究院, 甘肃 敦煌 736202
  • 收稿日期:2017-11-15 出版日期:2019-02-10 发布日期:2019-02-10
  • 通讯作者: 李翔,E-mail:lixiang1990@petrochina.com.cn
  • 作者简介:李翔,1990年生,男,汉族,甘肃临潭人,工程师,主要从事油气储层预测及综合描述等方面的研究工作。E-mail:lixiang1990@petrochina.com.cn;刘应如,1980年生,男,汉族,四川德阳人,高级工程师,硕士,主要从事油藏描述方面的研究工作。E-mail:liuyr@petrochina.com.cn;柴小颖,1981年生,女,汉族,甘肃兰州人,工程师,硕士,主要从事油气田开发方面的研究。E-mail:chaixyqh@petrochina.com.cn;龙伟,1985年生,男,汉族,陕西汉中人,工程师,硕士,主要从事石油钻井、录井工程、综合地质方面的研究工作。E-mail:longweiyjyqh@petrochina.com.cn;白亚东,1990年生,男,汉族,河南唐河人,硕士,主要从事天然气勘探方面的研究工作。E-mail:baiyd@petrochina.com.cn

Patterns and Comprehensive Predictions of Fracture Development in Bedrock Gas Reservoirs in Dongping, Qaidam Basin

LI Xiang1, LIU Yingru1, CHAI Xiaoying2, LONG Wei2, BAI Yadong1   

  1. 1. Northwest Branch of PetroChina Research Institute of Petroleum Exploration and Development, Lanzhou, Gansu 730020, China;
    2. Research Institute of Exploration and Development, Qinghai Oilfield Ccompany, Petrochina, Dunhuang, Gansu 736202, China
  • Received:2017-11-15 Online:2019-02-10 Published:2019-02-10

摘要: 东坪基岩气藏位于柴达木盆地西北部阿尔金山前东段,是新近发现的中国内陆盆地最大规模基岩古潜山整装气藏。但由于该区基底片麻岩、花岗岩天然裂缝及溶蚀孔洞发育,且成因复杂,非均质性强,单井产量差异大,该气藏的规模上产开发存在较大难度。裂缝是影响基岩储层高产稳产的关键因素,因此,开展该气藏的裂缝发育规律及综合预测研究显得格外重要。为此,在认识其岩性、物性和气藏类型基础上,基于岩芯、薄片以及成像测井等进行了分析统计,明确了东坪基岩以构造缝为主,两类溶蚀裂缝为辅的裂缝系统。通过单井统计结果标定,实现研究区岩性分带,基于叠后振幅方位分解技术实现研究区裂缝平面展布预测。最终结合产能统计分析,通过不同岩性带、不同裂缝类型与产能及改造效果的相对关系,将研究区划分为3个有效裂缝发育区,其中,一个自然产能高效区,两个措施改造潜力区,实现了对研究区储层的综合预测,预测结果与实际产能吻合率均达70%以上,为后续开发调整提供支撑。

关键词: 柴达木盆地, 基岩气藏, 构造缝, 裂缝发育带, 叠后振幅方位分解

Abstract: Located in the front eastern section of the Altyn-Tagh in the northwestern Qaidam Basin, the Dongping bedrock reservoir is the largest complete bedrock buried hill gas reservoir recently discovered in the terrestrial basins of China. Nevertheless, due to natural fractures in gneiss and granite bedrocks and karst caves in the region and their complex formations, the area is highly heterogeneous with significant yield differences between wells. In addition, mass exploitation of a large-scale gas reservoir is relatively difficult. Because fractures are the key factor in allowing high and stable yields of bedrock reservoirs, it is especially important to conduct research on patterns and comprehensive predictions of fracture development in the reservoir of interest. Hence, lithological and physical properties and reserve types of the reservoir were examined, followed by statistical analyses based on core samples, thin sections, and well imaging. We found that the fracture system of the Dongping bedrock reservoir is dominated by tectonic fractures, accompanied by two types of dissolution fractures. The statistics of individual wells were used as standards to divide the study area according to its lithology. The Post-Stack Amplitude Direction Decomposition (PADD) technique was employed to predict the horizontal distribution of fractures in the study area. Finally, the results were integrated and analyzed with yield data. According to the relative relationships between different lithological zones, different fracture types, yields, and transformation effects, the study area was divided into three effective fracture development zones. One is a natural high-yield zone, while the other two are potential areas requiring appropriate transformation measures. Comprehensive predictions of reservoir potential in the study area were performed, and the predicted results matched actual yields at a rate higher than 70%.

Key words: Qaidam Basin, bedrock gas reservoirs, tectonic fractures, fracture development zones, post-stack amplitude direction decomposition

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