河流相致密砂岩气地质甜点评价——以四川盆地川中地区侏罗系沙溪庙组二段1亚段为例
Evaluation of geological sweet spots in fluvial tight sandstone gas:A case study of the first submember of the second member of the Jurassic Shaximiao Formation,central Sichuan Basin
潘辉 1蒋裕强 1朱讯 2邓海波 3宋林珂 3王占磊 1李杪 1周亚东 1冯林杰 1袁永亮 1王猛4
作者信息
- 1. 西南石油大学 地球科学与技术学院,四川 成都 610500
- 2. 中国石油 西南油气田分公司 气田开发管理部,四川 成都 610051
- 3. 中国石油 西南油气田分公司 致密油气项目部,四川 成都 610051
- 4. 成都西南石油大学科技园发展有限公司,四川 成都 610500
- 折叠
摘要
四川盆地侏罗系沙溪庙组储层具有孔隙度和渗透率低、非均质性强、砂体叠置关系复杂的特点,导致地质甜点判别困难、预测精度较低.为实现气藏的高效开发,通过分析、研究沉积作用、成岩作用和源-储配置关系对天然气聚集成藏的影响,建立了研究区沙溪庙组二段1亚段致密砂岩气地质甜点评价标准.研究结果表明:①沉积微相和河道类型控制了砂体规模及储层的物性,顺直河或低弯度曲流河边滩砂体厚度大、物性好,是优质储层发育区.②岩浆岩岩屑含量和成岩相不同是导致储层质量差异的主要原因.其中绿泥石胶结相物性最好.③源-储配置关系控制储层中天然气的充注程度,与烃源断层直接相接或距离烃源断层较近的砂体含气性最好.④储层质量和含气性共同控制单井天然气产量.根据研究提出的地质甜点评价标准,将研究区地质甜点分为3类.Ⅰ类甜点主要为顺直河或低弯度曲流河边滩砂体,孔隙度大于12%,渗透率大于0.30×10-3 μm2,以绿泥石胶结为主,且距烃源断层近,含气性好,含水饱和度小于30%,泊松比小于0.24,单井产气强度大于0.10×104 m3/(d∙m).Ⅱ类甜点主要为中弯度曲流河砂体,孔隙度10%～12%,渗透率为0.15×10-3～0.30×10-3 μm2,以伊利石或伊/蒙混层胶结为主,距烃源断层相对较远,含水饱和度为30%～40%,泊松比为0.24～0.25,单井产气强度为0.05×104～0.10×104 m3/(d∙m).Ⅲ类甜点主要为小型中弯度曲流河边滩,孔渗性差,主要发育伊利石或伊/蒙混层胶结,且远离烃源断层,含气性较差.
Abstract
Reservoirs of the Jurassic Shaximiao Formation in the Sichuan Basin feature low porosity and permeability,strong heterogeneity,and complex sand body superposition.These characteristics complicate the identification and accurate prediction of geological sweet spots.To achieve efficient exploitation of the gas reservoirs,we establish the criteria for evaluating geological sweet spots in tight sandstone gas in the 1st submember of the 2nd member of the Shaximiao Formation(the Sha 21 submember)in the study area by delving into the effects of the sedimentation,diagenesis,and source rock-reservoir configuration on the formation and hydrocarbon accumulation of these gas reservoirs.Key findings are as follows.(1)The sand body scale and reservoir physical properties are governed by sedimentary microfacies and channel types.Notably,sand bodies located within the point bars of straight or low-sinuosity meandering rivers exhibit large thicknesses and favorable physical properties,standing as high-quality reservoirs.(2)Reservoir quality discrepancy primarily results from differences in lithic content in magmatic rocks and diagenetic facies.Specifically,the chlorite-cemented facies exhibits the most favorable physical properties.(3)Natural gas charging in the reservoirs is dictated by the source rock-reservoir configuration.Most especially,sand bodies in contact with or in proximity to source rock-rooted faults boast the most favorable gas-bearing properties.(4)The single-well natural gas production is jointly determined by reservoir quality and gas-bearing properties.Based on the evaluation criteria established in this study,the geological sweet spots in the study area are categorized into three types:types Ⅰ,Ⅱ,and Ⅲ.Type Ⅰ sweet spots primarily encompass sand bodies in the point bars of straight or low-sinuosity meandering rivers,with porosity exceeding 12%and permeability surpassing 0.30×10-3 μm2,and chlorite-cemented facies dominating.They are situated near source rock-rooted faults,exhibiting favorable gas-bearing properties with water saturation below 30%,Poisson's ratio less than 0.24,and single-well gas production rate over 0.10×104 m3/(d∙m).Type Ⅱ sweet spots are dominated by sand bodies in middle-sinuosity meandering rivers,with porosity ranging from 10%to 12%and permeability from 0.15×10-3 to 0.30×10-3 μm2.Their diagenetic facies are dominated by illite-or mixed-layer montmorillonite-illite-cemented facies.They are positioned comparatively far from source rock-rooted faults,with water saturation ranging from 30%to 40%,Poisson's ratio from 0.24 to 0.25,and single-well gas production rate from 0.05×104 to 0.10×104 m3/(d∙m).Type Ⅲ sweet spots primarily comprise sand bodies in the point bars of small-scale,medium-sinuosity meandering rivers,characterized by low porosity and permeability.Their diagenetic facies mainly include illite-or mixed-layer montmorillonite-illite-cemented facies sitting far from source rock-rooted faults and with poor gas-bearing properties.
关键词
顺直河/曲流河/甜点主控因素/甜点评价标准/致密砂岩气/沙溪庙组/侏罗系/四川盆地Key words
straight river/meandering river/primary factor controlling sweet spot formation/criteria for evaluating sweet spot/tight sandstone gas/Shaximiao Formation/Jurassic/Sichuan Basin引用本文复制引用
基金项目
重庆市自然科学基金面上项目(CSTC2021JCYJ-MSXMX0897)
中国石油西南油气田分公司重大专项(2022ZD01)
出版年
2024
国家科技期刊平台
NSTL
万方数据