页岩气水平井动态评价方法

Horizontal well dynamic evaluation method in shale gas reservoirs

页岩气在储层特征、渗流机理、完井工艺和动态特征等方面有别于常规气藏。我国页岩气开发处于探索阶段,总结国外页岩气井动态规律和评价方法,对国内页岩气井动态评价和工艺措施的制定具有借鉴和参考作用。根据国外页岩气水平井生产实践和研究成果,总结了页岩气水平井流动机理和生产特征,并重点剖析了目前页岩气水平井动态评价方法,包括流动特征的识别、有效裂缝参数的计算和改造范围内动态储量确定。从气井流动特征来看,不稳定线性流是页岩气水平井常表现出的流动特征,利用这一阶段的动态数据就能评价水平井压裂后形成的有效裂缝参数;有些井在线性流之后会出现边界流,表示整个改造范围内总体处于衰竭状态,利用这一特征可以评价改造范围内的动态储量。

Shale gas reservoirs are different from conventional gas reservoirs in reservoir characteristics, percolation mechanism, completion technique, and dynamic performance. Since the development of shale gas in China is still at the stage of exploration, dynamic regulation and evaluation method of overseas shale gas well were summarized to provide some models and the reference for establishing domestic shale gas well dynamic evaluation and process measures. Based on the field case study and literature review on overseas＇ shale gas wells, the flowing mechanics and production performance of horizontal wells were summarized. The current dynamic performance evaluation methods for shale gas horizontal wells were described in detail, which includes flow region identification, effective fracture parameters calculation and gas reserves determination in SRV. From the point view of gas well flow characteristics, unstable linear flow is the mainly flow characteristics for horizontal wells in shale gas, and the effective fracture parameters formed after horizontal well fracturing can be evaluated according to the dynamic data in this stage. On the other hand, some wells appear boundary flow after linear flow, which means the whole stimulation range generally in a state of exhaustion, and the dynamic reserves within the stimulation region can be evaluated using this feature.