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Method for forecasting formation pore pressure by utilizing propagation time of seismic longitudinal waves

A technology of formation pore pressure and propagation time, which is used in the field of predicting formation pore pressure and using seismic longitudinal wave propagation time to predict formation pore pressure, which can solve problems such as inaccuracy and influence of formation pore pressure.

Active Publication Date: 2015-08-26
CHINA UNIV OF PETROLEUM (BEIJING)
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Problems solved by technology

[0005] Usually the methods for predicting pore pressure are based on the rock properties of shale. The pore pressure obtained by these methods is the pressure in shale, but for the pore pressure in sandstone formation, carbonate formation and other permeable formations , either assuming that the pressure in the shale is equal to the pressure in the sandstone, or using a fluid flow model to calculate, however these methods are not accurate
In addition, due to the redistribution of pressure near the wellbore due to drilling disturbance, this also affects the formation pore pressure

Method used

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  • Method for forecasting formation pore pressure by utilizing propagation time of seismic longitudinal waves
  • Method for forecasting formation pore pressure by utilizing propagation time of seismic longitudinal waves
  • Method for forecasting formation pore pressure by utilizing propagation time of seismic longitudinal waves

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Embodiment 1

[0129] Such as figure 1 As shown, according to an embodiment of the method for predicting formation pore pressure using seismic longitudinal wave propagation time of the present invention, it comprises the following steps in sequence:

[0130] Step 1: Select the target well and the drilled well in the same block;

[0131] Step 2: Using formation density logging test to measure the rock volume density of the drilled well at different formation depths, and combining the formation logging data to calculate the overlying formation pressure;

[0132] Step 3: Measure the propagation time of the seismic compressional wave in the formation of the target well by using the seismic data acquisition test, and calculate the compaction constant in combination with the porosity trend line of the normally compacted formation;

[0133] Step 4: Drill cores in the drilled well and measure the clay content of different cores;

[0134] Step 5: Using the porosity stress sensitivity test, measure ...

Embodiment 2

[0193] According to the embodiment of the method for predicting formation pore pressure using seismic longitudinal wave propagation time of the present invention, its steps, laboratory test method, formation logging method, theoretical derivation, beneficial effect and scope of application, etc. are all the same as embodiment one, the difference is : This embodiment selects sandstone formations of different oilfields to verify the feasibility and accuracy of the pore pressure prediction model. Drill 40 cores in the drilled well, and test the clay content and effective pressure coefficient respectively. The following key parameter values ​​are obtained through laboratory tests, formation logging data and theoretical derivation: Δt m =230μs / m, Δt ml =672μs / m, α=0.8-2.5, c=0.00085m -1 . As the clay content increases, the effective pressure coefficient increases gradually, and different clay contents correspond to different effective pressure coefficients. By substituting each...

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Abstract

The invention discloses a method for forecasting formation pore pressure by utilizing the propagation time of seismic longitudinal waves. The method comprises the following steps in sequence: measuring the volume densities of rocks at different formation depths in a drilled well, and combining formation well-log data with the measured volume densities to calculate overlying formation pressure; measuring the propagation time of the seismic longitudinal waves in a target well formation, and combining the porosity trend line of normal compacting formations with the measured propagation time to calculate a compacting constant; measuring the clay contents of different rock cores; measuring the pore pressure and porosities of the different rock cores, and confirming the effective pressure coefficients of the different rock cores; establishing a relationship plate of the effective pressure coefficients and the clay contents of the different rock cores; confirming the effective pressure coefficient of the target well formation according to the established relationship plate, and calculating the pore pressure of the target well formation by utilizing a forecasting model. The method is wide in application range and not impacted by well drilling; the effective pressure coefficients can be quantitatively analyzed through laboratory testing, so that the accuracy of forecasting results can be improved.

Description

technical field [0001] The invention belongs to the technical field of oil and gas exploration engineering, and relates to a method for predicting formation pore pressure, in particular to a method for predicting formation pore pressure by using seismic longitudinal wave propagation time. Background technique [0002] Formation pore pressure changes continuously from normal pore pressure to abnormal high pressure, and abnormal high pressure can sometimes reach twice the normal pore pressure. Abnormal high pressure usually exists in many basins in the world. If the abnormal high pressure cannot be accurately predicted before drilling, various risks and accidents will increase during the drilling process. For example, in the deep water of the Moscow Gulf, accidents caused by pore pressure and bottom hole instability accounted for 5.6% of the drilling time in non-basic rock formations and 12.6% of the drilling time in mafic rock formations. Abnormally high pore pressures can l...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21B49/00E21B47/06
Inventor 于海洋朱常玉程时清
Owner CHINA UNIV OF PETROLEUM (BEIJING)
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