关键词: 碳酸盐岩, 异常地层孔隙压力, 预测方法, 成因机制, 岩石物理模型

Abstract: Accurate prediction of pore pressure in carbonate formations is a critical prerequisite for maintaining wellbore stability and ensuring the efficient exploration and development of carbonate oil and gas reservoirs. However, carbonate formations are characterized with complex geological conditions, strong heterogeneity, and significant regional variation, which leads to great difficulty in achieving accurate pore pressure prediction, as well as the low applicability of prediction models. There are still significant challenges in enhancing prediction accuracy and expanding model applicability. To deepen the scientific understanding of pore pressure prediction methods for carbonate formations, this paper explores the formation mechanisms of abnormal pressure, classifies and compares the main prediction methods for the current pressure in carbonate formations, and systematically summarizes the principles, advantages, and disadvantages of each method. Using the marine carbonate formations in the southern Sichuan Basin as a case study, the adaptability of different prediction methods were comparatively evaluated. Key findings include:(1)The prediction methods such as the equivalent depth method and Eaton method, which are built based on undercompaction theory, rely on establishing reasonable compaction trend lines. These methods exhibit low accuracy and poor applicability for carbonate formations. (2)Numerical simulation-based methods can accurately describe formation geometry and obtain high-precision numerical solutions through fine grid division and high-order finite element parameters. However, their stringent parameter requirements and high computational complexity limit practical implementation. (3)As for the methods established based on statistical analysis and artificial intelligence algorithms, prediction models are obtained by analyzing large volumes of regional data. However, model variability across different blocks limits their applicability. (4)The rock physics-based prediction methods for pore pressure include flow-solid coupling models and wavelet transform-based models, in which rock physics models are constructed to determine the response relationship between pore pressure and elastic wave parameters of carbonate formations. However, their high complexity and parameter-processing difficulties hinder widespread application. Finally, based on the comprehensive understanding, the paper outlines future research direction for pore pressure prediction in carbonate formations, providing theoretical guidance and technical support for the safe and efficient exploration and development of oil and gas resources in carbonate reservoirs.

Key words: carbonate rock, abnormal formation pore pressure, prediction methods, formation mechanism, rock physics model