白云凹陷烃源岩生烃特征及天然气成因  

Characteristics of hydrocarbon generation and genesis of natural gas from source rocks in Baiyun Sag

作　　者：陈聪 龙祖烈 石创 黄玉平 明承栋 黄文宇 CHEN Cong;LONG Zulie;SHI Chuang;HUANG Yuping;MING Chengdong;HUANG Wenyu(CNOOC China Limited,Shenzhen Branch,Shenzhen,Guangdong 518054,China;CNOOC Deepwater Development Limited,Shenzhen,Guangdong 518054,China)

机构地区：[1]中海石油(中国)有限公司深圳分公司,广东深圳518054 [2]中海石油深海开发有限公司,广东深圳518054

出　　处：《中国海上油气》2025年第2期70-81,共12页China Offshore Oil and Gas

基　　金：“十三五”国家科技重大专项“珠江口盆地深水区古温压演化与油气生排聚过程(编号:2016ZX05026-003-006)”;中国海洋石油集团有限公司“十四五”重大科技项目“南海北部深水区勘探关键技术(编号:JGG2022-0103-03)”部分研究成果。

摘　　要：烃源岩生烃机制及天然气成因的有效界定直接制约白云凹陷天然气勘探潜力评价及有利勘探区带优选。白云凹陷钻遇古近系烃源岩探井少且发育多种类型烃源岩,但对于该区复杂多样的烃源岩产烃特征研究较少,且缺乏气岩对比,致使该区天然气成因类型以及主力气源岩层系长期存在争议。通过对白云凹陷已钻遇不同类型烃源岩开展封闭体系生烃模拟实验,揭示各类型烃源岩生烃机制及生烃模拟实验产物中天然气组分与稳定碳同位素演化特征,对番禺低隆起及白云主洼东部商业性气藏进行气源对比研究。结果表明:(1)文昌组半深湖相及恩平组海侵/海相烃源岩整体以生油为主,具有快速生油的特征,但产干酪根裂解气的能力偏弱;(2)白云凹陷文昌组及恩平组浅湖相烃源岩产油能力相对一般,但具有较好的生干酪根裂解气能力,EasyRo达到2.1%之后仍可具备持续快速生气能力,整体呈现生气窗口较宽且持续生气特征,并具有较高产气率,且文昌组浅湖相烃源岩产气率高于恩平组;(3)白云凹陷已发现煤岩均为富氢煤,具有早期窄窗生油,晚期持续生气特征,但产干酪根裂解气潜力相对偏弱;(4)已发现天然气碳同位素组成特征与文昌组浅湖相烃源岩高成熟阶段所生天然气具有极好的对应关系,推测该区天然气主体为文昌组浅湖相烃源岩混合型生烃母质所生高成熟混合成因气,文昌组浅湖相烃源岩为白云凹陷主力气源岩。该成果为白云凹陷天然气资源潜力的客观评价及油气成藏研究提供相关数据支撑与成果借鉴。The effective definition of the mechanism of hydrocarbon generation and genesis of natural gas from source rocks directly influence the evaluation of natural gas exploration potential and the selection of favorable exploration zones in Baiyun Sag.There are few exploration wells for the Paleogene source rocks encountered during drilling in the Baiyun Sag,and multiple types of source rocks are developed.However,there is little research on the characteristics of hydrocarbon generation from the complex and diverse source rocks in the area,and there is a lack of gas-source rock correlation,which results in long-term disputes over the genesis types of natural gas and main gas source rock formations in the area.By conducting high-temperature and high-pressure hydrocarbon generation simulation experiments in a closed system of a gold pipe on different types of source rocks encountered during drilling in the Baiyun Sag,this study revealed the mechanism of hydrocarbon generation,natural gas components,and carbon isotope evolution characteristics of different types of source rocks.A study of gas-source correlation was conducted on commercial gas reservoirs in the eastern part of the Panyu low uplift and Baiyun Sag.The results indicate the following:①The semi-deep lacustrine source rocks of the Wenchang Formation and the marine-invasion/marine source rocks of the Enping Formation are mainly oil-generating,with the characteristics of rapid oil generation,but their ability to generate kerogen pyrolysis gas is relatively weak.②The shallow lacustrine source rocks of the Wenchang Formation and the Enping Formation in the Baiyun Sag have relatively general oil generation capacity,but they have good ability to generate kerogen pyrolysis gas.When the EasyRo reaches 2.1%,they still have the ability to generate gas rapidly and continuously,showing the characteristics of a wide gas generation window and continuous gas generation,and have a relatively high gas generation rate.The gas generation rate of the shallow lacustrine source

关 键 词：白云凹陷 烃源岩类型 生烃模拟实验 生烃机制 天然气成因 

分 类 号：TE122.1[石油与天然气工程—油气勘探] P744.4[天文地球—海洋科学]