超低渗油藏超前注水区油井压裂时机探讨

Study on the best fracturing opportunity of the oil wells in the advanced water flooding zone of super-low permeability reservoirs

针对部分超低渗油藏超前注水后,油井压裂缝高度控制难度大的问题,通过声发射测试及有限元模拟方法分别对超前注水前、后的地应力特征进行了研究,认为超前注水后,储、隔层应力差更低,不利于控制压裂缝高.在对该类岩石物理性质研究的基础上,通过物理模拟实验方法对该类油藏油井压裂时机进行了研究,认为油井在未注水前压裂,有利于控制缝高,压裂试油结束后注水,待地层压力达到超前注水设计压力水平后投产,可提高开发效果.

The height of the fractures of the oil wells in super-low permeability reservoirs becomes difficult to control after the advanced water flooding.For this reason,the characteristics of the earth stress before and after the advanced water injection are studied by acoustic emission testing and finite element simulation.It is held that the stress difference between reservoir and barrier becomes lower after the advanced water flooding,which is just the cause why the height is difficult to control.The laboratory simulation experiments for determining the best fracturing opportunity of the oil wells in the low-permeability reservoirs are carried out based on the study on the physical properties of tight rocks,and it is shown that the best fracturing opportunity is before water injection,when the height of the fractures is easy to control.The production is put on after formation pressure reaches to the designed advanced water flooding pressure,which can improve the development result.