摘要
大庆外围扶杨油层不仅具有储层薄、砂体窄小、渗透率特低的特点，而且纵向上非均质性较强，水驱开发过程中层间矛盾严重，认清纵向非均质储层的渗流规律对于有效开发特低渗透油田是十分必要的。应用油藏数值模拟方法，根据流体在特低渗透储层中遵循的非线性渗流规律，建立了基于该区块地质特征的纵向正韵律非均质数学模型，模型引入渗透率修正系数对渗透率进行修正，采用五点法进行数值模拟计算，并与常规的达西渗流模型进行对比。结果表明：非线性渗流规律增强了储层纵向非均质性，相对高渗储层吸水能力增强，相对低渗储层吸水能力减弱；非线性渗流规律下注水压力升高，含水上升速度加快，区块整体开发效果差于达西渗流规律情况；相对低渗储层渗透率修正系数普遍分布在0．2—0．4，动用程度低；相对高渗储层渗透率修正系数普遍分布在0．6—0．8，动用程度高；在纵向非均质储层中，毛管力作用可减缓层间非均匀吸水量，故适当降低注水速度不仅可以降低注水压力，而且可以缓解层间吸水矛盾，从而改善开发效果。
The reservoirs in Daqing peripheral oilfield are characterized not only by thin thickness, small-narrow sandbody and ultra-low permeability, but also by strong vertical heterogeneity and serious interlayer interference in the course of waterflooding. It is very necessary to clearly recognize the flow laws＇influences of the heterogeneity on the effective development of this kind of oil reservoirs. With the help of oil-reservoir numerical simulation and the nonlinear flow laws of the fluids in the uhra-low permeability reservoirs, the positive-rhythm vertical heterogeneous mathmetical model is established based on the geological features of the block. Permeability correcting factors are introduced to modify the ultra-low permeabilities, five-point well pattern is adopted to conduct numerical simulation, and moreover the comparison is made with the conventional model of Darcy flow. The simulation results show that the nonlinear flow laws further intensify the vertical heterogeneity of the reservoirs. The water absorption eapac- ity of relatively higher permeability reservoirs is increased, while that of relatively lower permeability ones is just on the eontrary; under the condition of nonlinear flow laws, the water injection pressure rises high, the aeceleration speed of the water eut is propelled, the overall developed effeets of the bloek is poor than those in the laws of Darcy flow. The distribution of permeability eorreeting faetors in the relatively low permeability reservoirs ranges from 0.2 to 0. 4, the developed degree is rather low; while that in the relatively high permeability ones distributes from 0. 6 to 0. 8, signifying greatly higher developed degree. In the reservoirs with vertical heterogeneity, the eapillary force can mitigate the heterogeneous water-intake rates among the reservoirs, so proper reducing the water injection speed ean not only decrease the injection pressure, but also relieve the interlayered eontradiction of water absorption, thus the developed effeets can fully improved.
出处
《大庆石油地质与开发》
CAS
CSCD
北大核心
2012年第6期73-78,共6页
Petroleum Geology & Oilfield Development in Daqing
基金
国家油气重大专项“特低渗透油藏有效开发技术”（2011ZX05013-005）资助.
关键词
特低渗透
纵向非均质
非线性渗流
数值模拟
毛管力
ultra-low permeability
vertical heterogeneity
nonlinear flow
numerical simulation
capillary force
