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Method for judging tight sandstone gas reservoir based on compressibility factor of pore fluid

A technology of compressibility and pore fluid, applied in geophysical measurements, instruments, etc., can solve the problem of low recognition accuracy, and achieve the effect of improving comprehensiveness, highlighting the difference between gas and water, and broadening the application field.

Inactive Publication Date: 2016-05-18
CHINA NAT PETROLEUM CORP CHUANQING DRILLING ENG CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] However, the existing technologies represented by the above-mentioned periodical documents still have the following disadvantages: the recognition accuracy is not high for formations with complex pore structures, tight gas layers, difficult gas layers and other gas-water characteristics.

Method used

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  • Method for judging tight sandstone gas reservoir based on compressibility factor of pore fluid
  • Method for judging tight sandstone gas reservoir based on compressibility factor of pore fluid

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Embodiment 1

[0042] As the best implementation mode of the present invention, it discloses a method for discriminating tight sandstone gas layers by pore fluid compressibility, which is characterized in that: the compressional wave time difference and shear wave time difference provided by array acoustic logging data, and the density logging data provide The formation density is the input information, and the formation bulk modulus is calculated to derive the formation compressibility coefficient. Combined with the formation volume model, the pore fluid compressibility coefficient is derived, and finally the fluid compressibility coefficient is used to judge whether it is a tight sandstone gas layer.

[0043] The specific steps are as follows:

[0044] a. Determine the compressibility factor of the formation

[0045] Assume that the formation bulk modulus is K b , the formula for calculating the bulk modulus of the formation is:

[0046] (1)

[0047] where ρ b is the formation densit...

Embodiment 2

[0068] Such as figure 1 As shown, it is an example of identifying tight sandstone gas layers in a certain area. The lithology of No. 11 reservoir in the figure is green-gray pebble-bearing medium sandstone B. From the results of conventional logging processing, it can be seen that the average porosity of the formation is 8.3%, and the average permeability The rate is 0.22×10 -3 μm 2 . The second pore fluid compressibility from the right shows that the pore fluid compressibility of this layer is mainly distributed in the range of 1.20-2.25 (1 / mpsi), indicating a gas layer; the third oil test conclusion from the right shows that this Layers produce pure gas 1.94×10 4 m 3 / d, to verify the correctness of the method.

Embodiment 3

[0070] Such as figure 2 As shown, it is an example of identification of tight sandstone gas-water layers in a certain area. The lithology of No. 4 reservoir in the figure is gray-white gas-bearing pebble-bearing coarse sandstone C. From the results of conventional logging processing, it can be seen that the average porosity of the formation is 8.7%. Average permeability 0.14×10 -3 μm 2 . The second pore fluid compressibility coefficient from the right shows that the pore fluid compressibility coefficient of the No. 4 reservoir is mainly distributed in the range of 0.65-1.85 (1 / mpsi), showing the characteristics of "upper gas and lower water", and the identification conclusion is determined as a gas-water layer . The conclusion of the third oil test from the right shows that the gas production in this layer is 1.18×10 4 m 3 / d, water production 12m 3 / d, to verify the correctness of the method.

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Abstract

The invention discloses a method for judging a tight sandstone gas reservoir based on the compressibility factor of the pore fluid. According to the technical scheme of the invention, the time difference of longitudinal waves and the time difference of transverse waves are provided based on the array sonic logging information. Meanwhile, the formation density of the density logging information is adopted as the input information to calculate a formation bulk modulus, so that the compressibility factor of reservoir rocks is derived. In combination with a formation bulk model, the compressibility factor of the pore fluid can be further derived. Finally, based on the compressibility factor of the pore fluid, whether the fluid is a tight sandstone gas reservoir or not can be judged. The acoustic information is deeply excavated in the method, and the difference between the compressibility factor of reservoir rocks and the compressibility factor of the pore fluid is utilized for the judgment of the fluid property. Therefore, the application range of the array sonic information for the judgment of the fluid property is broadened. Meanwhile, the judgment accuracy of the fluid property is improved.

Description

technical field [0001] The invention relates to the technical field of a method for identifying tight sandstone gas layers in the process of oil and gas exploration and development. Background technique [0002] The methods of determining fluid properties mainly include crossplot method, porosity overlapping method, nuclear magnetic shift spectrum method and difference spectrum method, elastic modulus difference ratio method of array acoustic waves, longitudinal and transverse wave time difference ratio method, and the combination of longitudinal wave time difference and theoretical calculation of longitudinal wave time difference. Difference method, mathematical methods of comprehensive utilization of various logging curves such as fuzzy recognition, neural network, etc. [0003] The authors are Zhang Yinhai, Hu Xuehong, Li Changwen, etc., and published a paper titled "Research on Sandstone Gas Reservoirs Using Compressibility Coefficients" in the journal "Jianghan Petroleu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01V11/00
CPCG01V11/00
Inventor 罗利刘海军毛英雄
Owner CHINA NAT PETROLEUM CORP CHUANQING DRILLING ENG CO LTD
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