煤层气直井产气曲线特征及其与储层条件匹配性

煤层气产气曲线类型与地质条件的匹配与否直接影响产气效果。以沁水盆地柿庄南区块排采4 a以上的直井为研究对象，在产气曲线类型划分基础上，分析不同产气曲线特征，进一步分析产气曲线与储层参数的匹配性。结果表明:研究区产气曲线可划分为单峰快速上升、单峰稳定上升、双峰后低和双峰后高4种类型。产气曲线所表现出的特征受控于储层原始渗透率，储层动力及压裂效果。单峰快速上升型适用于含气量大于12 m3/d、临储比大于0.4和渗透率大于0.1×10-3 μm2的储层，该种曲线容易造成产气量的骤降；单峰稳定上升型适用的储层条件广泛，与储层参数匹配性较高；双峰后低型产气效果整体不佳，与储层参数的匹配性差；双峰后高型适用于压裂效果较好的井、对储层原始参数要求较低，其后峰产气量的增加速率影响整体的排采效果。基于上述分析，将储层划分为七种类型，对研究区及其相邻区块实施"一井一策"的排采制度具有重要的指导意义。 

The matching of gas production curve characteristic and reservoir conditions in vertical coalbed methane wells

The matching of coalbed methane(CBM) production curve type and geological conditions directly affects the gas production. Based on dividing gas production curves types of vertical CBM wells in the southern block of Shizhuang in Qinshui basin over 4 years, the characteristics of gas production curve were analyzed. The matching of gas production curve with reservoir parameters was further analyzed. The paper discovered and divided the gas production curve into four types:type of fast rising of single peak, type of stable rising of single peak, bimodal type of being low later and bimodal type of being high later. The original permeability, dynamic condition, and fracturing effect control the characteristics of gas production curve. The reservoir parameters of the type of fast rising of single peak has high gas content(>12 m3/d), high permeability(>0.1×10-3 μm2), high specific value of critical desorption pressure and reservoir pressure(>0.4). This kind of curve is easy to cause sharp drop of gas production in the peak period. The type of stable rising of single peak is applicable in a wide range of reservoir conditions. Gas production of bimodal type of being low of is usually lower than other types. The gas production curve is poorly matched to the reservoir characteristics. The bimodal type of being high later is suitable for wells with better fracturing effect and have lower requirements for reservoir parameters. Gas production growth rate of the back peak determines the gas production effect. On the basis of above analysis, the reservoir is divided into seven types, which has important guiding significance for the implementation of the "one well and one scheme" drainage system in the study area and its adjacent blocks.