煤储层流体特征、聚气主控因素及富气模式--以鄂尔多斯盆地中东部上古生界为例  

Fluid characteristics,gas accumulation controlling factors and gas enrichment modes in coal reservoirs:A case study of the Upper Paleozoic in the central-eastern Ordos Basin,NW China

作　　者：陈世达[1,2] 汤达祯 侯伟[3,4] 黄道军 李永洲 虎建玲[5] 许浩 陶树 李松[1,2] 唐淑玲 CHEN Shida;TANG Dazhen;HOU Wei;HUANG Daojun;LI Yongzhou;HU Jianling;XU Hao;TAO Shu;LI Song;TANG Shuling(School of Energy Resources,China University of Geosciences(Beijing),Beijing 100083,China;Coal Reservoir Laboratory of National Engineering Research Center of CBM Development&Utilization,Beijing 100083,China;National Engineering Research Center of China United Coalbed Methane Co.,Ltd.,Beijing 100095,China;PetroChina Coalbed Methane Company Limited,Beijing 100028,China;Research Institute of Exploration and Development,PetroChina Changqing Oilfield Company,Xi’an 710018,China)

机构地区：[1]中国地质大学(北京)能源学院,北京100083 [2]国家煤层气工程中心煤储层物性实验室,北京100083 [3]中联煤层气国家工程研究中心有限责任公司,北京100095 [4]中石油煤层气有限责任公司,北京100028 [5]中国石油长庆油田公司勘探开发研究院,西安710018

出　　处：《石油勘探与开发》2025年第2期385-394,共10页Petroleum Exploration and Development

基　　金：国家自然科学基金项目(42130802、42272200);中国石油天然气集团有限公司攻关性应用性科技专项(2023ZZ18);中国石油长庆油田公司科技重大专项(2023DZZ01);中石油煤层气有限责任公司科技项目(2023-KJ-18)。

摘　　要：基于鄂尔多斯盆地中东部探井上古生界岩心的测试化验资料,结合构造、埋深及流体地球化学分析,揭示煤储层流体特征、聚气主控因素及富气模式。研究表明:①1500~1800 m深度段为中浅层开放型流体系统和深层封闭型流体系统的转换深度带,1500 m以浅水侵改造强度大,储层压力梯度分布离散,甲烷气存在不同程度的次生生物成因气混入,整体呈富含水、吸附气欠饱和特征;1800 m以深呈现出极低渗储层自封闭特征,水动力侧向封堵和致密盖层围限共同作用形成封闭型流体系统,系统内地表径流入渗微弱,流体次生改造程度低,压力梯度相对统一,大部分层段吸附气含气饱和度超过100%,游离气含量主要为1~8 m^(3)/t,个别层段可超过10 m^(3)/t;②在深部地层温压环境约束下,煤储层聚气能力受控于煤岩煤质、储盖组合和构造位置主导的储集性、润湿性和封闭性,高变质程度、低灰分产率煤和灰岩、泥岩盖层等多因素叠合区聚气优势明显,正向构造高点和宽缓负向构造低点是有利的富气场所,两翼陡坡含气量相对较低。研究成果有助于深化煤储层聚气机理认识,可为深部资源精准选区评价和适应性增产技术创新发展提供有效参数依据。Based on the test and experimental data from exploration well cores of the Upper Paleozoic in the central-eastern Ordos Basin,combined with structural,burial depth and fluid geochemistry analyses,this study reveals the fluid characteristics,gas accumulation control factors and accumulation modes in coal reservoirs.The study indicates findings in two aspects.First,the 1500–1800 m interval represents the transition zone between shallow–medium open fluid system and deep closed fluid system.Reservoirs above 1500 m reflect intense water invasion,with discrete pressure gradient distribution,and the presence of methane mixed with varying degrees of secondary biogenic gas,and they generally exhibit high water content and adsorbed gas undersaturation.Reservoirs deeper than 1800 m,with extremely low permeability,are self-sealed,and contains closed fluid systems formed jointly by the hydrodynamic lateral blocking and tight caprock confinement.Within these systems,surface runoff infiltration is weak,the degree of secondary fluid transformation is minimal,and the pressure gradient is relatively uniform.The adsorbed gas saturation exceeds 100%in most seams,and the free gas content primarily ranges from 1 m^(3)/t to 8 m^(3)/t(greater than 10 m^(3)/t in some seams).Second,the gas accumulation in deep coals is primarily controlled by coal quality,reservoir-caprock assemblage,and structural position governed storage,wettability and sealing properties,under the constraints of the underground temperature and pressure conditions.High-rank,low-ash yield coals with limestone and mudstone caprocks show superior gas accumulation potential.Positive structural highs and wide and gentle negative structural lows are favorable sites for gas enrichment,while slope belts of fold limbs exhibit relatively lower gas content.This research enhances understanding of gas accumulation mechanisms in coal reservoirs and provides effective parameter reference for precise zone evaluation and innovation of adaptive stimulation technologies for deep reso

关 键 词：煤岩气 煤层气 流体系统 封闭性 吸附气 游离气 上古生界 鄂尔多斯盆地 

分 类 号：TE122.1[石油与天然气工程—油气勘探]