Petrophysical properties of tight sandstone reservoirs are complex which brings difficulties to fluid discrimination. Rock physics makes it possible to obtain petrophysical properties from elastic parameters. However, both deterministic rock physics and statistical rock physics have corresponding limitations. By combining deterministic rock physics and statistical rock physics, a joint posterior probability is proposed for fluid discrimination. To consider the effect of complex pore structure and permeability in tight sandstone reservoirs, a new deterministic rock physics model is built. In this model, soft porosity and connected porosity are quite important parameters to describe the above-mentioned reservoir characteristics. Assuming the noise follows a Gaussian distribution, we can obtain the posterior probability of gas saturation from the deterministic rock physics. Bayes discriminant is an effective method for statistical rock physics to estimate the prior, condition and posterior probabilities of petrophysical properties from well-logging data. Thus, the posterior probability of gas saturation belonging to the statistical rock physics is obtained. To guarantee the accuracy of fluid discrimination, the reflectivity method is used to achieve high-precision elastic parameters from seismic data. Application examples of well-logging data and seismic data confirm the validity of the proposed joint probabilistic fluid discrimination.

致密砂岩储层的岩石物理性质很复杂，给流体判别带来了困难。岩石物理学使从弹性参数获得岩石物性成为可能。但是，确定性岩石物理学和统计岩石物理学都有相应的局限性。通过结合确定性岩石物理学和统计岩石物理学，提出了联合后验概率进行流体判别。考虑到致密砂岩储层中复杂的孔隙结构和渗透率的影响，建立了新的确定性岩石物理模型。在该模型中，软孔隙度和连通孔隙度是描述上述储层特征的重要参数。假设噪声遵循高斯分布，我们可以从确定性岩石物理学获得气体饱和度的后验概率。贝叶斯判别法是一种用于统计岩石物理学的有效方法，可以根据测井数据估算岩石物理特性的先验，条件和后验概率。因此，获得了属于统计岩石物理学的气体饱和度的后验概率。为了保证流体判别的准确性，使用反射率法从地震数据中获得高精度的弹性参数。测井数据和地震数据的应用实例证实了提出的联合概率流体判别方法的有效性。测井数据得出岩石物理特性的状况和后验概率。因此，获得了属于统计岩石物理学的气体饱和度的后验概率。为了保证流体判别的准确性，使用反射率法从地震数据中获得高精度的弹性参数。测井数据和地震数据的应用实例证实了提出的联合概率流体判别方法的有效性。测井数据得出岩石物理特性的状况和后验概率。因此，获得了属于统计岩石物理学的气体饱和度的后验概率。为了保证流体判别的准确性，使用反射率法从地震数据中获得高精度的弹性参数。测井数据和地震数据的应用实例证实了提出的联合概率流体判别方法的有效性。