致密气藏动态启动压力梯度实验研究

发布时间：2018-12-30 16:35

【摘要】：针对目前启动压力梯度测试不能准确表征储层真实启动压力梯度的现状,通过引入高精度回压控制系统,建立致密气藏储层条件下的启动压力梯度测试方法。与常压下测试结果相比,在渗透率相同的条件下,新方法得到的启动压力梯度更小,且岩心渗透率越低,2种方法测定结果相差越大。研究结果表明,启动压力梯度在开发过程中并不是定值,而是随着孔隙流体压力的下降而不断变化,呈现动态启动压力梯度。为此,提出并定义启动压力梯度敏感性和启动压力梯度敏感系数的概念,用其描述致密气藏动态启动压力梯度特征,并通过实验对动态启动压力梯度的影响因素进行分析。结果表明,启动压力梯度随孔隙流体压力的下降而线性增大。岩心渗透率越低、含水饱和度越大,在储层条件下的启动压力梯度越大,在开发过程中启动压力梯度的变化幅度也越大,启动压力梯度敏感性越强,动态启动压力梯度现象越明显。
[Abstract]:In view of the fact that startup pressure gradient testing can not accurately characterize the true starting pressure gradient of reservoir at present, the starting pressure gradient testing method under tight gas reservoir conditions is established by introducing a high precision backpressure control system. Compared with the test results under normal pressure, the starting pressure gradient obtained by the new method is smaller than that under the same permeability, and the lower the core permeability, the greater the difference between the two methods. The results show that the starting pressure gradient is not a constant value in the development process, but changes continuously with the decrease of pore fluid pressure, showing a dynamic starting pressure gradient. For this reason, the concepts of starting pressure gradient sensitivity and starting pressure gradient sensitivity coefficient are proposed and defined. The characteristics of dynamic starting pressure gradient of tight gas reservoirs are described by using them, and the influencing factors of dynamic starting pressure gradient are analyzed through experiments. The results show that the starting pressure gradient increases linearly with the decrease of pore fluid pressure. The lower the core permeability, the greater the water saturation, the greater the starting pressure gradient under reservoir conditions, the greater the change of starting pressure gradient in the development process, and the stronger the sensitivity of starting pressure gradient. The phenomenon of dynamic starting pressure gradient is more obvious.
【作者单位】：中国石化华北油气分公司勘探开发研究院;中国石油大学(北京)石油工程教育部重点实验室;中国石化石油勘探开发研究院;
【基金】：国家科技重大专项“低丰度致密低渗油气藏开发关键技术”(2016ZX05048)
【分类号】：TE37

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