摘要
滇黔北探区赋煤向斜众多,多薄煤层发育,含气量较高,煤层气资源丰富,是筠连外围重要的拓展区块。基于大量煤田孔及煤层气试验井,分析煤层气地质条件,建立多层合采有利区优选评价方法:多层次模糊数学+关键指标法。首先,基于层次递阶优选构建评价模型并确定关键指标,明确关键指标为合采系数、煤体结构、含气量,其中,合采系数由最优合采跨度及合采累计煤厚构成,并给出关键指标的定量评价表,然后,运用模糊数学计算公式,得到储层评分结果,最终获得多层合采有利区优选结果。结果显示:研究区晚二叠世龙潭组/宣威组煤层最多可达到20层以上,可采煤层一般3层左右,煤层总厚度一般在6 m以上,煤层层数及煤层厚度由东南向西北逐渐减少或减薄。大部分区域主力煤层为C5(M11)煤层,厚度一般在2 m以上,其灰分质量分数平均为27.73%,为中灰煤,煤级主要为贫煤–无烟煤。各向斜主力煤层含气性差异性较大,含气量最大可达到30.53 m^(3)/t。研究区煤体结构以原生结构煤和碎裂结构煤为主。以C5(M11)煤层分别向上或向下合采计算合采系数,由此形成了两个合采层段,多层合采Ⅰ类有利区主要位于研究区可乐向斜中西部,牛场–以古向斜南部,镇雄向斜南部,庙坝向斜东南部,洛旺向斜中西部,石坎向斜中西部。
Due to the abundance of coal-bearing synclines,multiple seams and high gas content,the exploration area in North Yunnan and Guizhou Provinces is an important expansion block in the periphery of Junlian County.Based on a large number of coalfield holes and test wells,the geological conditions of CBM are analyzed,and the optimization and evaluation method of multi-layer favorable area is established,i.e.multi-level fuzzy mathematics plus key indicators.Firstly,the evaluation model is constructed based on hierarchical optimization,and the key indicators are determined as co-mining coefficient,coal structure and gas content.The co-mining coefficient is composed of the optimal co-mining span and the cumulative coal thickness,and the quantitative evaluation table of the key indicators is given.Then,the fuzzy mathematics calculation formula is used to obtain the reservoir score results,guiding the optimization of multi-layer co-mining favorable areas.The results show that the coal seam of Longtan Formation/Xuanwei Formation in Late Permian in the study area can reach up to more than 20 layers,and the recoverable coal seam is generally about 3 layers with the total thickness of more than 6 m.From southeast to northwest,coal seams pinch out and the number of layers gradually decreases.In most areas,the main coal seam is C5(M11),with a thickness of more than 2 m and an average ash content of 27.73%,belonging to medium ash coal,and the coal rank is mainly lean coal–anthracite.The gas content of main coal seams in each syncline varies significantly,and the maximum gas content can reach 30.53 m^(3)/t.The coal structure in the study area is dominated by primary structure coal and fractured structure coal.The co-mining coefficient is calculated by the upward or downward co-mining of seam C5(M11),thus forming two co-mining layers.The multilayer co-mining type I favorable area is mainly located in the central and western Kele syncline,the south of NiuchangYigu syncline,the south of Zhenxiong syncline,the southeast of Miaoba syncline,the central and western Luowang syncline,and the central and western Shikan syncline.
作者
孙斌
田文广
杨兆彪
杨敏芳
李存磊
SUN Bin;TIAN Wenguang;YANG Zhaobiao;YANG Minfang;LI Cunlei(PetroChina Research Institute of Petroleum Exploration and Development,Langfang 065007,China;Key Laboratory of CBM Resources and Dynamic Accumulation Process,Ministry of Education of China,China University of Mining and Technology,Xuzhou 221008,China)
出处
《煤田地质与勘探》
CAS
CSCD
北大核心
2022年第9期86-95,共10页
Coal Geology & Exploration
基金
中国石油天然气股份有限公司超前基础研究项目(2019B-4910)
中国石油天然气股份有限公司前瞻性基础性技术攻关项目(2021DJ2303)
国家自然科学基金项目(42130802)。
关键词
有利区优选
储层特征
多煤层
合采系数
模糊数学
滇黔北探区
favorable area optimization
reservior characteristic
multiple seam
co-mining coefficient
fuzzy mathematic
north Yunnan and Guizhou exploration area