基于储层“三品质”的煤层气产能主控地质因素分析

煤层气资源性、可改造性和可采性是影响产能的3个关键储层品质。通过对比DJC区块67口排采时间3年以上的直井生产数据，详细剖析了储层三品质与煤层气井产能之间的关系，进而分析了影响储层三品质的关键地质因素。结果显示：①当资源丰度大于1.2×10⁸m/km²时，平均日产气量大于1 000m/d；开采煤层厚度稳定且变化较小，含气量是决定资源丰度大小的关键参数；②划分出5种压裂曲线类型，其中下降稳定型和下降波动型产气效果最佳；断层、煤体结构和地应力共同控制储层改造效果；③影响煤层气可采性的地质参数主要为临储比和渗透率，当临储比大于0.6，米产水指数大于0.8m/(d·m·MPa)时，煤储层整体排水降压相对容易，产气效果较好。

Analysis of main controlling geological factors of production based on “three qualities” of CBM reservoir

The resources,reconstruction and recoverability of coal seams are the three key reservoir qualities (TKRQ) that affect the capacity of coalbed methane (CBM).By comparing the production data of 67 wells produced over three years in DJC area,the relationship between TKRQ and well productivity is analyzed in detail.Then,the main geological factors affecting TKRQ are analyzed as well.As the results showed,in this area:（1）The main controlling factor on CBM resources is gas content when the abundance of resources is greater than 1.2×10⁸m/km²,the average daily gas production of CBM well is greater than 1 000m/d,and the thickness of No.3 coal seams is stable.（2）There are five fracturing curve types,where the decline-stable type and decline-wave type are better on gas production.The properties of fault,coal structure and crustal stress have combined influence on the reconstruction of coal seams.（3）The recoverability of CBM is due to the ratio of critical desorption pressure to reservoir pressure and permeability.The CBM well is easier to drainage and high production when the ratio is greater than 0.6 and the water production index per meter is greater than 0.8 m/(d·m·MPa).