Formation resistivity combined inversion method based on while-drilling electromagnetic wave resistivity logging

A technology of resistivity logging and formation resistivity, which is applied in earthwork drilling, wellbore/well components, electrical digital data processing, etc. It can solve the problem of poor vertical resolution, shallow radial depth, and inability to respond well to resistivity Information and other issues, achieve good vertical resolution and reduce the workload of inversion

Active Publication Date: 2018-01-26
YANGTZE UNIVERSITY
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Problems solved by technology

Theoretical research and practical application results show that the amplitude ratio resistivity has a deeper detection depth, but its longitudinal resolution is poor and only has good accuracy in low-resistivity formations, while the phase difference resistivity has a better vertical resolution, but its radial depth relatively shallow
[0005] Therefore, neither the amplitude ratio resistivity nor the phase difference resistivity alone can reflect the true formation resistivity information well, and the combination of amplitude ratio resistivity and phase difference resistivity has the problem of mismatching longitudinal resolution and radial detection depth. , these problems have seriously restricted the application effect of electromagnetic wave resistivity logging while drilling

Method used

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  • Formation resistivity combined inversion method based on while-drilling electromagnetic wave resistivity logging
  • Formation resistivity combined inversion method based on while-drilling electromagnetic wave resistivity logging
  • Formation resistivity combined inversion method based on while-drilling electromagnetic wave resistivity logging

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Embodiment 1

[0055] Model 1 is the invasion formation model, which divides the formation into invasion zones and undisturbed formations from the tool axis along the radial direction. In order to calculate the LWD tool response under different invasion conditions, the model invasion zone resistivity R in and undisturbed formation resistivity R t They are 2.5Ω.m and 10Ω.m respectively, and the calculation range of invasion depth is 0.1 to 6m. In order to invert to obtain the resistivity value of the intruded formation model, such as Figure 1~2 Shown: The specific formation resistivity inversion steps are as follows:

[0056] S1) The response value of the LWD electromagnetic wave resistivity logging tool in the above-mentioned intrusive formation model is used as the actual measurement data, and the response value of the tool in the uniform formation model is used as the forward modeling data.

[0057] S2) carry out weighted summation according to amplitude ratio and phase difference data,...

Embodiment 2

[0081] Example 2: Longitudinal Resolution Analysis

[0082] The method of this embodiment is basically the same as the method of embodiment 1, the difference is:

[0083] Model 2 is a vertically layered stratigraphic model. The resistivity of the background stratum and the interlayer are 10Ω.m and 1Ω.m respectively. In the model, the background stratum and the interlayer appear alternately. The obtained amplitude ratio and phase difference resistivity curves and the apparent resistivity curve obtained by the joint inversion method in the present invention are shown in FIG. 5 . As shown in the figure, according to the method of dividing the formation thickness by the half-amplitude point of the traditional curve, it is found that the smaller the source distance of the coil and the higher the transmission frequency, the better the longitudinal resolution of the apparent conductivity curve; under the fixed source distance of the coil system and the transmission frequency , the v...

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Abstract

The invention discloses a formation resistivity combined inversion method based on while-drilling electromagnetic wave resistivity logging. The formation resistivity combined inversion method comprises the steps that firstly, the amplitude ratio and phase difference data of while-drilling electromagnetic wave resistivity logging are obtained; then, weighted summation is conducted according to theamplitude ratio and the phase difference data, and the combined constraint inversion objective function is built; and finally, based on the combined constraint inversion objective function, the particle swarm algorithm is used for inversion, and thus the formation resistivity is obtained. A formation resistivity curve obtained through the formation resistivity inversion method combines the advantages of the good radial investigation depth of a traditional amplitude ratio resistivity curve and the good longitudinal resolution of a phase difference resistivity curve, while-drilling electromagnetic wave resistivity logging information is utilized more fully, and compared with a traditional inversion method, the inversion workload is reduced by a half.

Description

technical field [0001] The invention relates to the technical field of oil and gas reservoir development, and specifically refers to a joint inversion method of formation resistivity based on electromagnetic wave resistivity logging while drilling, which uses the phase difference signal and amplitude measured by the electromagnetic wave resistivity logging instrument while drilling A method for jointly inverting formation resistivity by ratio signal. Background technique [0002] As one of the main logging-while-drilling technologies, electromagnetic wave resistivity logging while drilling plays a vital role in geosteering while drilling and reservoir oil saturation evaluation. Compared with other logging tools that directly measure formation resistivity, the actual measurement and recording of electromagnetic wave resistivity logging while drilling are two signals of amplitude ratio and phase difference. Inverted into formation resistivity. [0003] At present, algorithms...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21B49/00G06F17/50
Inventor 许巍朱小露刘迪仁
Owner YANGTZE UNIVERSITY
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