| 蜀南地区龙马溪组页岩气工业建产区游离气和孔隙度下限讨论 |
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| 引用本文： | 饶权,康永尚,黄毅,赵群,王红岩.蜀南地区龙马溪组页岩气工业建产区游离气和孔隙度下限讨论[J].现代地质,2021,35(4):1054-1064. |
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| 作者姓名： | 饶权 康永尚 黄毅 赵群 王红岩 |
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| 作者单位： | 1.中国石油大学(北京) 地球科学学院,北京 1022492.中国石油大学(北京) 油气资源与探测国家重点实验室,北京 1022493.中国石油集团测井有限公司 西南分公司,重庆 4000214.中国石油勘探开发研究院,北京 100083 |
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| 基金项目： | 国家科技重大专项(2017ZX05035004-003);国家科技重大专项(2017ZX05035003-003) |
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| 摘 要： | 游离气作为页岩气重要赋存形式之一,决定了页岩气的开发潜力及经济效益。以蜀南地区龙马溪组页岩为例,结合X-射线衍射、岩石有机碳、储层物性、测井解释及生产测试等资料,对比分析了四川盆地及周缘页岩游离气含量与测试日产气量的关系,初步提出了工业建产区页岩游离气含量下限,并从烃源、储集及保存等方面对页岩游离气含量主控因素进行了系统研究,在此基础上探讨了工业建产区页岩孔隙度下限。结果表明:页岩游离气含量大于2.5 m3/t时,更易获得工业气流;蜀南地区龙马溪组页岩游离气含量与TOC、孔隙度、硅质矿物含量、地层压力系数、裂缝发育整体呈一定正相关,而与含水饱和度、碳酸盐矿物含量具有一定负相关;裂缝发育、含水饱和度以及硅质矿物、碳酸盐矿物等能通过关联孔隙度而间接影响游离气含量,均不作为页岩游离气含量主控因素,页岩游离气含量主控因素为TOC、孔隙度及地层压力系数;利用容积法对不同孔隙度下页岩游离气含量进行了蒙特卡罗模拟计算,发现当页岩孔隙度大于4%时,游离气含量大于下限值2.5 m3/t的概率超过50%,建议以4%作为工业建产区选择的孔隙度下限,以此控制页岩气开发的地质风险。页岩储层含气量评价建议以游离气评价为中心,重点从TOC、孔隙度、地层压力系数等3个方面开展系统评价。
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| 关 键 词： | 页岩气 龙马溪组 游离气 主控因素 TOC 孔隙度 地层压力系数 |
| 收稿时间： | 2020-05-05 |
| 修稿时间： | 2020-07-15 |
Cutoff of Free Gas and Porosity in Shale Gas Industrial Production Area of Longmaxi Formation in Southern Sichuan Basin |
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| RAO Quan,KANG Yongshang,HUANG Yi,ZHAO Qun,WANG Hongyan.Cutoff of Free Gas and Porosity in Shale Gas Industrial Production Area of Longmaxi Formation in Southern Sichuan Basin[J].Geoscience——Journal of Graduate School,China University of Geosciences,2021,35(4):1054-1064. |
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| Authors: | RAO Quan KANG Yongshang HUANG Yi ZHAO Qun WANG Hongyan |
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| Institution: | 1. College of Geosciences, China University of Petroleum, Beijing 102249, China2. State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum,Beijing 102249, China3. Southwest Branch, CNPC Logging Company Limited, Chongqing 400021, China4. Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China |
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| Abstract: | As an important form of shale gas, free gas determines the development potential and economic benefit of shale gas. Taking the Longmaxi Formation shale in southern Sichuan Basin as an example, and combining with X-ray diffraction (XRD), rock organic carbon, reservoir physical property, log interpretation and production test, we compared and correlated between free gas content and test daily gas production in Sichuan Basin and its periphery. We proposed the free gas content cutoff in industrial production area, and discussed the major controlling factors of shale free gas content from the aspects of hydrocarbon source, reservoir and preservation. Porosity cutoff was also discussed accordingly. The results show that it is easier to obtain industrial gas flow when the shale free gas content is above 2.5 m3/t. Free gas content of the Longmaxi Formation shale in southern Sichuan Basin is clearly positively correlated with TOC, porosity, siliceous mineral content, formation pressure coefficient, and fracture development, but negatively correlated with water saturation and carbonate mineral content. Fracture development, water saturation, siliceous minerals and carbonate can indirectly affect free gas content by correlating porosity, which are unlikely to be its major controlling factors. Major controlling factors of free gas content are TOC, porosity and formation pressure coefficient. The Monte Carlo simulation of free gas content indicates over 50% probability for 2.5 m3/t above free gas content when the shale porosity is > 4%. It is recommended to set porosity cutoff at 4% in shale gas industrial production area selection to control geological risk. Shale gas content should be evaluated systematically from three important aspects (i.e.TOC, porosity and formation pressure coefficient) with focus on free gas evaluation. |
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| Keywords: | shale gas Longmaxi Formation free gas major controlling factor TOC porosity formation pressure gradient |
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