Decomposing and synthetic method of quasi-saturated water nuclear magnetic resonance spin echo signals

A nuclear magnetic resonance and signal technology, which is applied in the field of petroleum exploration, can solve the problems that the separation and inversion of pore fluid information and pore structure information cannot be realized, and the accuracy of identifying pore fluid and analyzing pore structure cannot be fundamentally improved, so as to improve accuracy, The effect of improving accuracy and reliability

Inactive Publication Date: 2014-01-01
TONGJI UNIV
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Problems solved by technology

Although the accuracy and stability of the relaxation spectrum distribution can be improved by improving the inversion algorithm, it is impossible to fundamentally improve the identificat

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  • Decomposing and synthetic method of quasi-saturated water nuclear magnetic resonance spin echo signals
  • Decomposing and synthetic method of quasi-saturated water nuclear magnetic resonance spin echo signals
  • Decomposing and synthetic method of quasi-saturated water nuclear magnetic resonance spin echo signals

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Embodiment 1

[0035] Embodiment 1 (theoretical basis)

[0036] The relaxation process of hydrogen nuclei in rock pores is the process of energy transfer and transformation that occurs due to the interaction between hydrogen nuclei and pore walls under the action of an external magnetic field. The relaxation process of hydrogen nuclei in pores is related to the boundary conditions of hydrogen nuclei relaxation, and this boundary condition is composed of the inner wall of pores. Therefore, the relaxation process of hydrogen nuclei is related to the pore structure of rocks. This is the nuclear magnetic resonance relaxation process. Signals are the basis for evaluating rock pore structure. On the other hand, the rock relaxation signal is significantly affected by all fluids in the rock, including brines and hydrocarbons. The relaxation signal that can reflect the pore structure of the rock mainly comes from the fluid near the pore wall. The actual calculation results show that when there are ...

Embodiment 2

[0058] Embodiment 2 (specific operation)

[0059] First, the pattern to obtain experimental data:

[0060] In the first step, three experimental rock cores are taken and pretreated respectively, such as oil washing, salt washing, drying, vacuuming, etc., all of which belong to conventional techniques in the art.

[0061] The second step is to configure brine with a certain salinity. The salinity of the brine used this time is 80000ppm.

[0062] Step 3, for the prepared brine and experimental oil samples, measure the free transverse relaxation times of the brine and oil samples, respectively. In this experiment, the free transverse relaxation times of brine and oil samples (transformer oil) were 773ms (T 2w ) and 875ms (T 20 )

[0063] In step 4, the pretreated core is saturated with brine. After vacuuming the core, the influence of air bubbles is eliminated, and the core is completely saturated with brine.

[0064] The fifth step is to measure the transverse relaxation e...

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Abstract

The invention provides a decomposing and synthetic method of quasi-saturated water nuclear magnetic resonance spin echo signals. According to known saturation data and corresponding relaxation signals, influence coefficients of different oil sample saturation on the relaxation process are fixed in an optimizing and fitting mode. In terms of the relaxation signals with different oil saturation, salt water of the same size replaces oil samples, the influence coefficients are led in so as to represent influences of the oil samples with different oil saturation on the relaxation signals, and accordingly quasi-saturated water nuclear magnetic resonance relaxation signals under different oil saturation are written. Spin echo relaxation signals of a quasi-saturated water rock core are inverted, influences of different fluid types and different saturation can be removed in a certain degree, and the identification capacity of the nuclear magnetic resonance signals for a rock pore structure and fluids can be improved. According to the method, synthesis and decomposing of the quasi-saturated water rock core nuclear magnetic resonance spin echo signals are achieved, and accuracy and reliability of nuclear magnetic resonance data for assessment of the rock pore structure and fluid identification are improved.

Description

technical field [0001] The invention belongs to the technical field of petroleum exploration and is applied to the identification of pore fluids in formation rocks and the analysis of pore structures. technical background [0002] The NMR spin echo signal is the basic data of the NMR relaxation spectrum inversion, and the NMR relaxation spectrum can be used to identify the pore fluid of formation rocks and analyze the pore structure. In practical applications, the effects of formation pore fluid and pore structure on spin echo signals are superimposed on each other. Therefore, the relaxation spectrum distribution obtained by direct inversion of spin echo signals actually includes the mutual superposition of rock pore fluid and pore structure. information, leading to difficulties in pore fluid identification and pore structure analysis with relaxation spectrum data. [0003] The existing spin echo signal inversion methods indiscriminately invert the total echo signal includi...

Claims

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Application Information

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IPC IPC(8): G01V3/14G01V3/38
Inventor 刘堂晏邬龙薛苗苗王红涛潘豪杰王飞飞
Owner TONGJI UNIV
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