摘要
通过对鄂尔多斯盆地深部煤层的沉积环境、分布特征、煤岩性质、储层特征、含气性特征以及聚散组合等方面开展系统研究,以揭示该盆地煤岩气富集条件,评价其资源潜力。研究表明:①鄂尔多斯盆地石炭系—二叠系广泛发育厚层煤层,主力煤层二叠系山西组5^(#)、石炭系本溪组8^(#)煤生烃能力强,热演化程度高,为煤岩气形成奠定了丰富的资源基础;②深部煤岩储集物性好,孔渗条件佳,5^(#)、8^(#)煤平均孔隙度为4.1%和6.4%,平均渗透率分别为8.7×10^(-3)μm^(2)和15.7×10^(-3)μm^(2);煤岩中割理和裂隙发育,与微孔共同构成主要的储集空间,且随着演化程度增高,微孔体积呈增大趋势;割理和裂隙的发育程度对渗透率影响较大;③煤岩储层与工业分析的成分在纵向上存在较为明显的非均质性分布,与下段相比,中上段受灰分充填影响较小的光亮煤,其孔隙和裂隙更为发育,为优质储层发育层段;④鄂尔多斯盆地深部煤岩含气性好,含气量为7.5×20.0 m^(3)/t,煤岩气中游离气占比明显高于浅层煤层气,游离气占比为11.0%~55.1%,超过10%;深部煤岩中游离气富集程度主要受控于宏孔和微裂缝的数量;⑤煤岩压力测试分析表明,煤灰、煤泥聚散组合封盖性好,泥岩/灰岩(顶板)-煤层-泥岩(底板)的成藏组合条件下,煤岩气测值总体较高;⑥通过体积法对鄂尔多斯盆地煤岩气资源量进行了初步评价,估算结果为22.38´1012 m3,并优选了鄂尔多斯盆地煤岩气主要有利区。研究认为,鄂尔多斯盆地中东部的乌审旗、横山—绥德、延安、子长以及宜川地区是8^(#)煤层煤岩气有利勘探区,盆地中东部的临县西、米脂、宜川—黄陵、榆林以及乌审旗—横山地区是5^(#)煤层煤岩气有利勘探区,有望形成新的天然气规模储量、产量增长区。
To reveal the enrichment conditions and resource potential of coal-rock gas in the Ordos Basin,this paper presents a systematic research on the sedimentary environment,distribution,physical properties,reservoir characteristics,gas-bearing characteristics and gas accumulation play of deep coals.The results show that thick coals are widely distributed in the Carboniferous–Permian of the Ordos Basin.The main coal seams 5^(#)and 8^(#)in the Carboniferous–Permian have strong hydrocarbon generation capacity and high thermal evolution degree,which provide abundant materials for the formation of coal-rock gas.Deep coal reservoirs have good physical properties,especially porosity and permeability.Coal seams 5^(#)and 8^(#)exhibit the average porosity of 4.1%and 6.4%,and the average permeability of 8.7×10^(-3)μm^(2) and 15.7×10^(-3)μm^(2,)respectively.Cleats and fissures are developed in the coals,and together with the micropores,constitute the main storage space.With the increase of evolution degree,the micropore volume tends to increase.The development degree of cleats and fissures has a great impact on permeability.The coal reservoirs and their industrial compositions exhibit significantly heterogeneous distribution in the vertical direction.The bright coal seam,which is in the middle and upper section,less affected by ash filling compared with the lower section,and contains well-developed pores and fissures,is a high-quality reservoir interval.The deep coals present good gas-bearing characteristics in Ordos Basin,with the gas content of 7.5–20.0 m^(3)/t,and the proportion of free gas(greater than 10%,mostly 11.0%–55.1%)in coal-rock gas significantly higher than that in shallow coals.The enrichment degree of free gas in deep coals is controlled by the number of macropores and microfractures.The coal rock pressure testing shows that the coal-limestone and coal-mudstone combinations for gas accumulation have good sealing capacity,and the mudstone/limestone(roof)-coal-mudstone(floor)combination generally indicat
作者
牛小兵
范立勇
闫小雄
周国晓
张辉
荆雪媛
张盟勃
NIU Xiaobing;FAN Liyong;YAN Xiaoxiong;ZHOU Guoxiao;ZHANG Hui;JING Xueyuan;ZHANG Mengbo(National Engineering Laboratory for Exploration and Development of Low Permeability Oil and Gas Fields,Xi’an 710018,China;PetroChina Changqing Oilfield Company,Xi’an 710018,China;Research Institute of Exploration and Development,PetroChina Changqing Oilfield Company,Xi’an 710018,China)
出处
《石油勘探与开发》
EI
CAS
CSCD
北大核心
2024年第5期972-985,共14页
Petroleum Exploration and Development
基金
中国石油攻关性应用性科技专项“深地煤岩气成藏理论与效益开发技术研究”(2023ZZ18)
中国石油长庆油田公司“揭榜挂帅”项目“鄂尔多斯盆地中东部上古生界煤系气甜点评价及增产机理研究”(2022D-JB01)。
关键词
煤岩气
煤层气
临界深度
煤岩特征
富集条件
聚散组合
资源潜力
勘探方向
鄂尔多斯盆地
coal-rock gas
coalbed methane
critical depth
coal characteristics
enrichment conditions
gas accumulation play
resource potential
exploration direction
Ordos Basin
