Reservoir evaluation of tight sandstone involves the determination of reservoir properties from samples and logs. In the calculation of water saturation, Archie formula is an important fundamental and connection between log evaluation and petrophysics. Highly accurate parameters of Archie formula are the key to the log evaluation of gas-bearing tight sandstone. At present, there are two methods of the rock-electric experiment to measure parameters of Archie formula: water increment (imbibition) and water decrement (centrifugation). In this paper the experimental measurement of a group of tight sandstone has been designed and the results of the two experimental ways are quite different. In the experiment, the distribution of brine is a main factor affecting the electrical properties of rocks. Fluid distribution model during imbibition and drainage is used to explain the results of rock electrical experiments, and the results are verified by nuclear magnetic resonance measurement. In the end, the Pickett chart method of actual data is used to compute the ranges of the saturation exponent n approximately, then to verify the correctness of the theoretical analysis. The results demonstrate that the centrifugal method is more applicable. In the log evaluation of tight sandstone, the appropriate choice of the method which can get accurate rock electrical parameters is important. Reliable evaluation will provide support for future development of gas-bearing tight sandstone.

中文翻译：

---

饱和方法对饱和指数n的影响的实验与分析

致密砂岩储层评价涉及从样品和测井中确定储层性质。在计算含水饱和度时，阿奇公式是测井评估与岩石物理学之间的重要基础和联系。阿尔奇公式的高精度参数是含气致密砂岩测井评估的关键。目前，岩电实验测量阿奇公式参数的方法有两种：加水量（吸水）和减水量（离心）。本文设计了一组致密砂岩的实验测量方法，两种实验方法的结果相差很大。在实验中，盐水的分布是影响岩石电性能的主要因素。用吸水排水过程中的流体分布模型来解释岩石电实验的结果，并通过核磁共振测量对结果进行验证。最后，利用实际数据的皮克特图法近似计算饱和指数n的范围，进而验证理论分析的正确性。结果表明，离心法更适用。在致密砂岩的测井评价，可以得到准确的岩电参数的方法的适当选择是很重要的。可靠的评估将为含气致密砂岩的未来开发提供支持。实际数据的Pickett图表方法用于近似计算饱和指数n的范围，然后验证理论分析的正确性。结果表明，离心法更适用。在致密砂岩的测井评价，可以得到准确的岩电参数的方法的适当选择是很重要的。可靠的评估将为含气致密砂岩的未来开发提供支持。实际数据的Pickett图表方法用于近似计算饱和指数n的范围，然后验证理论分析的正确性。结果表明，离心法更适用。在致密砂岩的测井评价，可以得到准确的岩电参数的方法的适当选择是很重要的。可靠的评估将为含气致密砂岩的未来开发提供支持。