考虑井间干扰的煤层气井动态预测方法

Dynamic prediction method of coalbed methane well under consideration of inter-well interference

为了简便准确地计算多井开采条件下的煤层气井单井动态参数,考虑煤岩基质自调节效应时的裂缝孔隙度变化,建立了用于求取平均地层压力的煤层气藏气水两相物质平衡方程.在封闭煤层气藏中,引入形状因子,根据等产量两汇原理,应用汇源反映法得到了考虑井间干扰条件下的煤层气井产气量与产水量的计算式.通过与物质平衡方程结合,形成气井动态预测方法,能够快速有效地预测煤层气井的平均地层压力及产量的动态变化.将此方法应用于陕西某煤层气藏,对比不同井距条件下的生产参数.结果表明:一口井生产10a左右产量达到最大值,约为3 000m3/d;两口井在200m最优井距条件下,单口气井在7a左右产量达到最大值,约为4 180m3/d.

In order to accurately calculate the dynamic parameters of single well under the condition of multi-well exploitation, gas-water two-phase material balance equations of coalbed methane reservoir, which were used to calculate the average pressure, were established by con sidering the change of fracture porosity in self-regulation effect. The shape factor was introduced in airtight coalbed methane reservoir. According to the two-sink principle of equal production, the calculation equations for gas and water production were obtained, with consideration of inter-well interference of coalbed methane. Combining those equations and the material balance equation was to generate the dynamic prediction method which could quickly predict the dynamic change of average pressure and production. Using this method for coalbed methane reservoir in Shaanxi province as well as the comparison of the manufacturing parameters of dif- ferent well intervals was to conclude the following results, the production of single well reaches the maximum value 3 000 m3/d in the tenth year; the maximum production of single well under the condition of 200m optimal well interval is 4 180 m3/d in the seventh year.