Prediction method and system for pressure coefficient of marine shale formation

Abstract

The invention discloses a pressure coefficient prediction method and system of a marine mud shale formation. The pressure coefficient prediction method of a marine mud shale formation includes the steps: preparing the drilling data, the logging data and the seismic data; for an overpressure shale formation, selecting a sensitive logging curve, and acquiring the longitudinal wave speed and the transverse wave speed; based on the drilling data, analyzing the relation between drilling density and the longitudinal wave speed, acquiring a Gardner formula, optimizing a Fillippone formula, obtainingan optimized Fillippone formula, and performing fitting on the coefficients in the optimized Fillippone formula; based on the transverse wave speed, performing re-optimization on the optimized Fillippone formula, obtaining a re-optimized Fillippone formula, and performing fitting on the coefficients in the re-optimized Fillippone formula; and based on the re-optimized Fillippone formula, predicting the formation pressure coefficient. The pressure coefficient prediction method of a marine mud shale formation performs quantitative evaluation research on the shale gas preservation conditions, cancomplete and deepen the shale gas dessert prediction technique sequence, and can realize optimization of the shale gas high-yield enrichment region.

Description

technical field [0001] The invention relates to the field of shale gas exploration, and more specifically, to a method and system for predicting the pressure coefficient of a marine mud shale formation. Background technique [0002] The practice of shale gas exploration and development in recent years has shown that good preservation conditions are the key to high yield and enrichment of shale gas, and the pressure coefficient is a comprehensive discrimination index of preservation conditions. There is a positive correlation between shale gas production and pressure coefficient, so the pressure coefficient Prediction and research are critical to the success of shale gas exploration. At present, there are mainly two methods for pressure prediction using seismic information, which can be roughly divided into graphic method and formula calculation method. Depth formula calculation method, Eaton method, Fillippone method, Liu Zhenyun method, Stone method, Martinez method and ef...

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Problems solved by technology

[0003] (1) The Silurian marine strata in the southeastern Sichuan Basin are dominated by mudstone deposits, and the velocity decreases from top to bottom, which does not conform to the normal compaction theory. It is often difficult to accurately establish the normal compaction trend line in practical applications, so et al. The prediction accuracy of the effective depth method and Eaton method are both low;

[0004] (2) The principle of the effective stress method is to deduce the effective stress of the formation through elastic parameters, and the magnitude of the strain ΔH / H needs to be known, but the magnitude of the strain cannot be obtained accurately, and is controlled by the burial depth of the formation, especially for structures with large structural fluctuations In complex areas, the prediction accuracy of pressure coefficient is low

[0005] (3) The Fillippone method and its improved method are based on the principle that disequilibrium compaction and organic hydrocarbon generation generate high pore pressure, resulting in undercompaction, the seismic wave velocity is smaller than that of normal compaction, and the implementation is relatively simple. Chen Chao and Qu Dapeng In the articles "Discussion on Prediction Method of Marine Shale Gas Content in Jiaoshiba Area in Southeast Sichuan" and "Prediction of Pressure Coefficient Based on Marine Shale Formation in Southeast Sichuan-Taking Dingshan Block as an Example", a method based on The improved Fillippone method for predicting the pressure coefficient of marine shale formations, but only considering the P-wave velocity, has achieved certain results in structurally stable areas, but when applied to structurally complex areas, the prediction accuracy of the pressure coefficient is low. This prediction method is universal Poor sex

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