Formation pore pressure prediction precision improving method

Abstract

The invention discloses a formation pore pressure prediction precision improving method comprising the following steps: (A) a single path common midpoint stacking path is subjected to geological strata partitioning operation, and a distribution interval of maximum compacting speed and minimum compacting speed in each geological strata is determined; (B) maximum compacting speed and minimum compacting speed corresponding to each time sample point in each geological strata are corrected via a compacting speed trend fitting algorithm; (C) the corrected maximum compacting speed and minimum compacting speed corresponding to each time sample point in each geological strata are used for determining a pressure factor corresponding to each time sample point in each geological strata; (D) a shallow-layer pressure coefficient is corrected via a shallow-layer pressure coefficient correction formula; (E) the corrected shallow-layer pressure coefficient is used for determining a pressure value corresponding to each time sample point in a shallow layer. The method provided in the invention can help enable formation pore pressure prediction results to be in line with geophysical significance and actual geological condition.

Description

technical field [0001] The invention relates to the field of digital signal processing of seismic data, in particular to a method for improving the prediction accuracy of formation pore pressure. Background technique [0002] In the process of oil and gas field development, seismic formation pressure prediction methods can be used to describe the distribution characteristics of vertical and horizontal formation pressure; systematic research on the distribution of oil and gas layer pressure can not only help us understand and discover new oil and gas layers, but also help us understand the underground It is of great significance to study the energy of oil and gas layers, control the change of pressure of oil and gas layers, and rationally use the energy of oil and gas layers to maximize the recovery of underground oil and gas. [0003] At present, formation pressure prediction methods are mainly divided into three types: pre-drilling prediction method, monitoring-while-drilli...

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Problems solved by technology

[0007] First, when using seismic data to predict pressure from shallow to deep, it is found that in the process of calculating the compaction velocity using the root mean square velocity, the compaction velocity reverses, which violates the characteristic that the compaction velocity increases linearly with depth , leading to the phenomenon that the layer velocity is greater than the maximum compaction velocity, and the pressure prediction value is abnormal. Therefore, based on this phenomenon, the current method is mainly applied to the target horizon interval, and rarely calculates the pressure value from shallow to deep;

[0008] Second, when calculating the pressure coefficient from shallow to deep, because the pressure coefficient is inversely proportional to the layer velocity, that is, low velocity corresponds to high pressure, therefore, according to the characteristics of the algorithm, when the shallow layer velocity is small, the calculated pressure coefficient Too high, not in line with the actual situation

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