气体渗流启动压力实验测试及应用

对于致密储层气体渗流是否存在启动压力或启动压力梯度以及对气藏开发有何指导作用等问题，目前还存在较大争议。为此，采用逐级增压气驱实验和仿真物理模拟技术两种实验方法对上述问题进行了研究。结果表明：气体在致密岩心中渗流时存在启动压力，而且是岩心长度的函数；利用启动压力梯度可以计算单井最大控制泄流半径，启动压力与启动压力梯度两者结合可以计算定容气藏不同井控范围内的理论最大可采程度。采用该理论对苏里格气田进行了计算，其结果为：覆压40 MPa下渗透率为0.12～0.312 mD（平均值0.24 mD）的不含水储层最大井控半径约为474 m，理论最大采出程度在15％以上；覆压40 MPa下渗透率为0.015 mD的不含水储层最大井控半径约为193 m，理论最大采出程度在7％以上。

Experimental test analysis of the threshold pressure in tight sandstone gas flow: A case study of the Sulige Gas Field

It is still in hot dispute whether threshold pressure or threshold pressure gradient exists in gas seepage in tight sand gas reservoirs and what guiding roles they play in the development of tight sand gas reservoirs. Therefore, two experimental methods including progressive supercharged gas drive test and constant volume depleted exploitation simulation are adopted to study the above problem. The results show that threshold pressure exists when gas flows in tight core samples and it is a function of the core size; the maximum well control radius can be calculated by using the threshold pressure and the theoretical exploitable degree of a constant volume reservoir within different range of well control can be obtained by the threshold pressure in combination with threshold pressure gradient. These two experimental test methods were applied in the Sulige Gas Field. When the initial formation pressure is 25 MPa for the water free gas reservoirs in this field, the results show that the maximum well control radius is 474 m under a burden pressure of 40 MPa with the permeability ranging from 0.12~ 0.312 mD (averaged at 0.24 mD) and the theoretical exploitable degree is above 15%; the maximum well control radius is 193 m under a burden pressure of 40 MPa with the permeability of 0.015 mD and the theoretical exploitable degree being above 7%. This proves that the presented experimental test methods play a guiding role in the rational development of similar gas fields.