改进压裂压降曲线分析方法在海上低渗气田的应用

Application of improved pressure decline analysis for fracturing in offshore low permeability gas field

 刘书杰 蔡久杰 王飞 吕欣润 王伟

中海油研究总院，北京100027 中国石油大学（北京）石油工程教育部重点实验室，北京 102249

CNOOC Research Institute, Beijing 100027, China MOE Key Lab of Petroleum Engineering,
China University of Petroleum, Beijing 102249, China

 水力压裂已成为海上低渗透气藏最为有效的增产措施。然而，低渗气田中较少进行压力恢复试井，且压裂压降过程中，压力波传播速度很慢，常规测试时间内常出现几乎无压降的情况，导致无法用FracproPT软件对施工进行特征曲线分析；部分低渗气藏（东海）储层断层较多，微裂缝发育，容易导致FracproPT软件分析得到的闭合时间偏早，闭合压力过大。文中针对实际压裂过程中微裂缝发育导致初滤失严重及滤失系数随压力变化的情况，对传统的Nolte压降分析方法进行了改进，使之能更有效地适应海上气田的压裂井。通过东海低渗气田2口压裂井的实例应用，证明了改进的压降曲线分析方法评价结果可靠，现场实用性强。

 Fracturing technology becomes a main method to improve the production of offshore low permeability gas fields. However, traditional pressure buildup test is merely used after fracturing because it takes long time to reach infinite-acting radial flow in such low permeability formation. Moreover, the very slight variations in pressure during the fracture closure period make the pressure decline analysis difficult with FracproPT software. In some fields, natural fractures develop since many faults exist there, as a consequence we may get a shorter closed-time of hydraulic fractures and a bigger closed-pressure with FracproPT. This paper provides an improved Nolte method to achieve key fracture parameters in low permeability gas fields. The proposed method was applied to two field cases in East Sea, China. The results prove that the method is reliable and practical in field application.

10.6056/dkyqt201503022