致密油储层应力敏感性评价研究

Study on the Stress Sensitivity of Tight Oil Reservoir

针对致密油藏应力敏感性问题,采用非稳态和稳态渗透率测试方法,研究在围压一定,流压逐渐降低的过程中致密岩石气测渗透率的变化情况。研究结果表明:在流压降低的过程中,致密岩石渗透率损失率达到90%,存在强应力敏感性;对于同一岩样,不同流压下的非稳态渗透率比稳态渗透率小;有效围压小于20 MPa时,渗透率快速下降,当有效围压大于20 MPa时,渗透率下降速度逐渐减缓。

As for the stress sensitivity of tight oil reservoir, the unsteady method to measure permeability change is adopted under the condition of constant confining pressure and decreasing flow pressure. The result indicates that as the flowing pressure decreases, the permeability damage can achieve as high as 90%, showing that tight rock exists tense stress sensitivity. For the same sample, the unsteady permeability is smaller than steady permeability. When the effective confining pressure is less than 20 MPa, the permeability decreases sharply, while the decreasing rate slows down as the effective pressure exceeds 20 MPa.