大倾角地质耦合条件下煤层气开发效果与地质评价

Coalbed methane development effect and geological evaluation under large inclination angle geological coupling condition

准噶尔盆地南缘是我国中低煤阶煤层气资源产能建设的重要攻坚地区,根据其大倾角、多煤层、低热演化以及厚煤层等典型特征进行地质评价,是进一步勘探开发的关键。针对大倾角复杂地质条件制约下选区评价参数优选问题,通过对准南乌鲁木齐河东-大黄山地区产能建设示范区进行剖析,探讨大倾角地质耦合条件下中低煤阶煤层气井的产能影响因素,分析发现影响大倾角煤层产能的单因素作用效果往往有限,地质耦合条件制约下,各项地质参数匹配关系以及工程开发对策的合理实施是决定煤层气井高产、稳产的关键。因此,总结出了控制煤层气产能效果的三大综合因素:资源赋存条件、气藏关键要素以及开发技术对策,并结合勘探开发现状,优选出了适应性较强的评价参数。此外,针对现阶段选区评价过程中,低煤阶煤层气资源选区评价指标标准尚未明确的问题,采用模糊数学聚类分析方法,深入分析不同区域煤层同一指标属性值之间的逻辑关系,对研究区煤层含气量、热演化程度以及多煤层组合系数进行系统聚类,最终建立适用于本次选区定量指标参数的评价标准。最后利用多层次模糊数学综合评判(AHP),进行乌鲁木齐河以西地区煤层气资源潜力评价,结果表明,开发潜力由大到小排序依次为:乌鲁木齐河西地区、呼图壁地区、硫磺沟地区。

The southern margin of Junggar Basin is an important area for the production of medium and low-rank CBM resources in China.Typical characteristics,such as multiple coal seams,large dip angle(LDA),low thermal evolution and thick coal seams,are the key considerations for further exploration and development.Aiming at the problem of optimizing the selection parameters of the selected area under the constraints of high dip angle complex geological conditions,this paper analyzes the productivity construction demonstration area in the southern Urumqi River East-Dahuangshan area,and discusses the factors affecting the productivity of medium and low coal rank coalbed methane wells under large dip angle geological coupling conditions.It is found that the effect of single factors affecting the productivity of high-inclination coal seamsis often limited.Under the constraints of geological coupling,the matching relationship of various geological parameters and the reasonable implementation of engineering countermeasures are the keys to determine the high and stable production of coalbed methane wells.Therefore,three comprehensive factors that control the productivity of CBM were summarized:resource occurrence conditions,key elements of gas reservoirs,and development technical countermeasures,and combined the status quo of exploration and development,evaluation parameters with strong adaptability were determined.In addition,in view of the problem that the evaluation criteria of low-rank CBM resource selection were not clarified in the current selection evaluation process,fuzzy mathematical clustering analysis method was used to deeply analyze the logical relationship between the attribute values of the same index of coal seams in different regions and quantitatively establish standards applicable to this evaluation,such as gas content,thermal evolution,multi-coal combination coefficient.Finally,analytic hierarchy process(AHP)was used to evaluate the potential of CBM resources in the west of Urumqi river.The results showed that the development potential was ranked in order from large to small:western area of Urumqi river,Hutubi area and Liuhuanggou area.