新疆准噶尔盆地白家海凸起深部煤层气不同赋存态分配规律  

Distribution patterns of various occurrence states of deep coalbed methane in the Baijiahai Uplift,Junggar Basin,Xinjiang

作　　者：杨兆彪[1] 李存磊 郭巧珍[2] 王彬[2] 刘常青 屈怀林[2] 梁宇辉 王钰强 YANG Zhaobiao;LI Cunlei;GUO Qiaozhen;WANG Bin;LIU Changqing;QU Huailin;LIANG Yuhui;WANG Yuqiang(Key Laboratory of Coalbed Methane Resources&Reservoir Formation on Process,Ministry of Education,China University of Mining and Technology,Xuzhou,Jiangsu 221008,China;Research Institute of Exploration and Development,PetroChina Xinjiang Oilfield Company,Karamay,Xinjiang 834000,China)

机构地区：[1]中国矿业大学煤层气资源与成藏过程教育部重点实验室,江苏徐州221008 [2]中国石油新疆油田分公司勘探开发研究院,新疆克拉玛依834000

出　　处：《中国矿业大学学报》2025年第1期127-137,共11页Journal of China University of Mining & Technology

基　　金：国家自然科学基金项目(42272195,42130802);中国石油天然气股份有限公司攻关性应用性科技项目(2023ZZ18,2023ZZ1804)。

摘　　要：深部煤层气与浅部煤层气相比,其最大区别是煤层气赋存态中游离气的增加,游离态甲烷资源量成为了深部煤层气资源增量的重要贡献者.在煤层气不同赋存态分配规律上,低煤阶储层明显有别于中高煤阶储层.本文以新疆油田在准噶尔盆地白家海凸起西山窑组实施的最新的深部煤层气评价井为分析基础,基于变温压孔渗试验和变温压平衡水等温吸附试验,结合数学建模,研究了低煤阶储层深部煤层气不同相态的分配规律.采用S-DR模型,考虑甲烷吸附态密度在温压场下的变化,结合变温压等温吸附试验测试数据,构建了白家海凸起吸附态含量预测公式;基于构建的温压控制下的孔隙度预测公式,耦合温压场控制下煤层气相态密度变化,形成了不同赋存含气量预测图版.结果显示:白家海凸起低煤阶煤层气储层由于储渗系统相对较好,含气性存在明显的“3个临界深度”,即吸附气、游离气和总含气量均存在临界深度.吸附气临界深度位于900 m左右,其含量可达到11 m^(3)/t.游离气含量临界深度,位于2500~2600 m,其含量可达到9 m^(3)/t.其中,总含气量临界深度,位于1500 m左右,其含量可达到18 m^(3)/t.在2400 m左右,游离气占比达到50%,之后随埋深增加逐渐增大,在埋深达5000 m时,游离气占比可达到80%.这一结果是深部温压控制下,吸附态密度、游离态密度和孔隙度变化耦合的结果,孔隙度随埋深的逐渐衰减,造成赋存空间的缩小,使得游离气同样存在“临界深度”.白家海凸起煤层气具有“低煤阶、高含气量、高游离气占比和高饱和度”的“一低三高”的富集特征.综合考虑资源规模和资源构成,1500~2600 m是本区域最优开发深度范围,在此范围,总含气量高(15~18 m^(3)/t),游离气占比在40%~55%之间,具有良好的可采潜力.Deep coalbed methane(CBM)exhibits significant quantities of free gas,distinguishing it from shallow CBM and rendering it a crucial component of reservoir gas resources.The distribution patterns of different occurrence states of CBM vary notably between low and medium-high coal rank reservoirs.This study investigates the distribution law of various phase states of deep CBM in low coal rank reservoirs,focusing on the Xishanyao Formation of the Baijiahai Uplift in the Junggar Basin,utilizing porosity and permeability experiments under variable temperature and pressure conditions,alongside isothermal adsorption tests under equilibrium water conditions.Incorporating mathematical modeling,the S-DR model considers changes in methane adsorption state density in temperature and pressure fields,establishing a prediction formula for adsorption state content in the Baijiahai uplift.Prediction charts of different gas content are developed based on the porosity prediction formula,integrated with temperature-pressure-dependent phase density of CBM.Results reveal three critical depths of gas content:adsorbed gas(about 900 m,11 m^(3)/t),free gas(2500~2600 m,9 m^(3)/t),and total gas(about 1500 m,18 m^(3)/t).The proportion of free gas increases with depth,reaching 50%at 2400 m and up to 80%at 5000 m,influenced by adsorbed state density,free state density,and porosity changes under deep temperature and pressure.The Baijiahai uplift's CBM demonstrates enrichment characteristics of‘one low and three high':Low coal rank,high gas content,high free gas proportion,and high saturation.Considering resource scale and composition,the optimal development depth range in this region is found to be 1500~2600 m,with high total gas content(15~18 m^(3)/t)and free gas proportion(40%~55%),indicating significant recoverable potential.

关 键 词：低煤阶 深部煤层气 相态分配 准噶尔盆地 白家海凸起 

分 类 号：TE132[石油与天然气工程—油气勘探] P168.11[天文地球—天文学]