铜城断裂带阜二段储层应力场数值模拟及开发建议

Numerical simulation of stress field of Fu-2 Member in Tongcheng fault zone and development suggestions

关键词:  裂缝性储层  应力场  数值模拟  储层破裂压力  裂缝开启压力  铜城断裂带

Key words:  fractured reservoir  stress field  numerical simulation  reservoir breakdown pressure  fracture open pressure  Tongcheng fault zone

摘要:

通过裂缝形成时期古应力场数值模拟,预测铜城断裂带阜二段储层裂缝的产状;利用岩心声速实验以及微地震监测技术确定井点现今地应力方位;结合压裂资料计算井点现今地应力;通过确定岩石力学参数并建立有限元模型进行现今应力场数值模拟;借助于裂缝产状以及现今应力场数值模拟结果,预测储层中天然裂缝的开启压力和开启次序。结果表明,铜城断裂带阜二段现今水平最大主应力为北东东向;在注水过程开发中,北东东向裂缝优先开启,南东东向裂缝后开启;裂缝的开启压力随裂缝走向与水平最大主应力之间的夹角增大而增大;裂缝埋深与开启压力同样具有较好正相关性,在构造高部位(1850～2350 m)裂缝的开启压力在25～50 MPa之间,在构造低部位(3300～4000 m)裂缝的开启压力在45～75 MPa之间;通过计算储层的实际破裂压力,提出在不同区块采用不同的注水压力,以保证油气井的高产与稳产。

Abstract:

Based on numerical simulations of the ancient stress field of the fracture formation, the fracture occurrence of Fu-2 Member in Tongcheng fault zone was predicted. Present-time in-situ stress orientations for wells were determined using the core velocity experiment and micro seismic monitoring technology. The size of present-time in-situ stress for wells was determined by the combination of the fracturing data. Numerical simulations of the present-time stress field were carried out by ascertaining the rock mechanical parameters and establishing the finite element model. The reservoir natural fracture opening pressure and the opening sequence were predicted on the basis of fracture occurrence and present-time stress field simulation state. The results are as follows:the present-time horizontal maximum stress is NEE. Fractures with the NEE maximum stress direction open first and fractures with the SEE direction open afterwards in the process of waterflooding. Fracture opening pressure increases when the angle between the fracture direction and the maximum horizontal stress direction increases. Fracture depth and opening pressure also have positive correlation. Fracture opening pressure is between 25-45 MPa in the structural high part(1850-2350 m) and 45-75 MPa in the low part (3300-4000 m). It is proposed that different blocks use different injection pressures by calculating the actual reservoir breakdown pressures to ensure the high and stable production of oil and gas wells.