Device and method for measuring fluid saturation in nuclear magnetic resonance on-line displacement

Patent metadata

Field	Value
Publication number	US-11965845-B2
Application number	US-202217860570-A
Country	US
Kind code	B2
Filing date	Jul 8, 2022
Priority date	Jul 8, 2021
Publication date	Apr 23, 2024
Grant date	Apr 23, 2024

Abstract

The present invention provides a device and a method for measuring fluid saturation in nuclear magnetic resonance (NMR) on-line displacement, the method comprising: measuring a nuclear magnetic resonance (NMR) T2 spectrum under the dead volume filling of the on-line displacement system as displacing phase fluid and the core to be measured as saturated nuclear magnetic detection phase fluid to generate a calibrated T2 spectrum; measuring a nuclear magnetic resonance (NMR) T2 spectrum of a process in which the core to be measured is converted from a saturated displaced phase fluid into a displacing phase fluid to generate a displacement process T2 spectrum; generating the fluid saturation of the on-line displacement system in real time according to the generated calibrated T2 spectrum and the displacement process T2 spectrum. The present invention achieves the purpose of improving measurement precision of fluid saturation in the on-line displacement process.

First claim

What is claimed is:

1. A method for measuring fluid saturation in on-line displacement applied to a device for measuring fluid saturation in nuclear magnetic resonance (NMR) on-line displacement, characterized in comprising:
measuring a nuclear magnetic resonance (NMR) T2 spectrum under the dead volume filling of the on-line displacement system as displacing phase fluid and the core to be measured as saturated nuclear magnetic detection phase fluid to generate a calibrated T2 spectrum;
measuring a nuclear magnetic resonance (NMR) T2 spectrum of a process in which the core to be measured is converted from a saturated displaced phase fluid into a displacing phase fluid to generate a displacement process T2 spectrum;
generating the fluid saturation of the on-line displacement system in real time according to the calibrated T2 spectrum and the displacement process T2 spectrum, wherein,
the dead volume is the sum of the space of a liquid discharge end evacuation pipe, a liquid discharge end liquid discharge pipe, a liquid inlet end evacuation pipe, a liquid inlet end liquid inlet pipe and the space of the diversion trench of the core holder plug;
the nuclear magnetic detection phase fluid is a phase fluid in which the influence of the nuclear magnetic resonance is difficult to eliminate, among the displacing phase fluid and the displaced phase fluid;
the device for measuring fluid saturation in nuclear magnetic resonance (NMR) on-line displacement, comprising: an injection device, an intermediate container, a core holder, and a nuclear magnetic resonance (NMR) instrument, wherein,
the injection device is connected to one end of the intermediate container through a first pipe, for injecting fluid into the intermediate container;
the other end of the intermediate container is connected to the core holder by a second pipe, for injecting the fluid into the core in the core holder;
the core holder is located in a central area of the magnetic field of the NMR instrument, for monitoring the NMR signal of the core to be measured;
the core holder includes a sleeve, two fixed plugs, a liquid discharge end movable plug and a liquid inlet end movable plug, wherein,
the two fixed plugs are arranged at two ends of the sleeve respectively;
the liquid discharge end movable plug and the liquid inlet end movable plug pass through the fixed plugs and abut against both ends of the core, to fix the core axially;
the liquid discharge end movable plug is provided with an evacuation pipe and a liquid discharge pipe;
the liquid inlet end movable plug is provided with an evacuation pipe and a liquid inlet pipe;
the liquid inlet pipe is connected to the intermediate container through the second pipe.

2. The method for measuring fluid saturation in nuclear magnetic resonance (NMR) on-line displacement according to claim 1 , characterized in that, the measuring a nuclear magnetic resonance (NMR) T2 spectrum under the dead volume filling of the on-line displacement system as displacing phase fluid and the core to be measured as saturated nuclear magnetic detection phase fluid to generate a calibrated T2 spectrum, includes:
saturating the core to be measured with the nuclear magnetic detection phase fluid and filling it into the core holder;
applying a predetermined confining pressure to the core holder by means of a ring pressure pump and a pressure gauge on the third pipe;
opening the valves on the liquid discharge end evacuation pipe and the liquid inlet end evacuation pipe respectively, and filling the displacing phase fluid into the dead volume of the on-line displacement system;
closing the liquid inlet end evacuation pipe and the valves on the liquid discharge end evacuation pipe;
performing nuclear magnetic resonance (NMR) scanning on the displacing phase fluid in the dead volume and the core to be measured to generate the calibrated T2 spectrum.

3. The method for measuring fluid saturation in nuclear magnetic resonance (NMR) on-line displacement according to claim 1 , characterized in that, the measuring a nuclear magnetic resonance (NMR) T2 spectrum of a process in which the core to be measured is converted from a saturated displaced phase fluid into a displacing phase fluid to generate a displacement process T2 spectrum, includes:
saturating the core to be measured with the displaced phase fluid and filling it into the core holder;
applying a predetermined confining pressure to the core holder by means of a ring pressure pump and a pressure gauge on the third pipe;
opening the valves on the liquid discharge end evacuation pipe and the liquid inlet end evacuation pipe respectively, and filling the displacing phase fluid into the dead volume of the on-line displacement system;
closing the valves on the liquid discharge end evacuation pipe and the liquid inlet end evacuation pipe;
injecting the displacing phase fluid in the intermediate container into the core to be measured by an injection device;
performing NMR scanning on the displacement process of the core to be measured to generate the displacement process T2 spectrum.

4. The method for measuring fluid saturation in nuclear magnetic resonance (NMR) on-line displacement according to claim 1 , characterized in that, the generating the fluid saturation of the on-line displacement system in real time according to the calibrated T2 spectrum and the displacement process T2 spectrum, includes:
determining a boundary relaxation time according to the displacement process T2 spectrum, wherein the boundary relaxation time is a time boundary point in the displacement process T2 spectrum that represents the fluid in the core to be measured and represents the dead volume fluid;
determining a true T2 spectrum in the displacement process of the core to be measured according to the boundary relaxation time;
calculating fluid saturation in the displacement process of the core to be measured according to the true T2 spectrum and the calibrated T2 spectrum.

5. The method for measuring fluid saturation in nuclear magnetic resonance (NMR) on-line displacement according to claim 4 , characterized in that, the determining a boundary relaxation time according to the displacement process T2 spectrum, includes:
obtaining a long relaxation time spectrum thereof according to the displacement process T2 spectrum;
determining an intersection point of increase and decrease of the long relaxation time spectrum;
determining the calibrated T2 spectrum to determine the boundary relaxation time according to a time corresponding to the intersection point.

6. The method for measuring fluid saturation in nuclear magnetic resonance (NMR) on-line displacement according to claim 1 , characterized in further comprising: correcting the fluid saturation of the on-line displacement system, including:
measuring a nuclear magnetic resonance (NMR) T2 spectrum under the dead volume filling of the on-line displacement system as displacing phase fluid and the core to be measured that is saturated with the displaced phase fluid, to generate an initial T2 spectrum;
correcting the fluid saturation of the on-line displacement system according to the initial T2 spectrum, the calibrated T2 spectrum and the displacement process T2 spectrum.

7. The method for measuring fluid saturation in nuclear magnetic resonance (NMR) on-line displacement according to claim 6 , characterized in that, the measuring a nuclear magnetic resonance (NMR) T2 spectrum under the dead volume filling of the on-line displacement system as displacing phase fluid and the core to be measured that is saturated with the displaced phase fluid, to generate an initial T2 spectrum, includes:
saturating the core to be measured with the displaced phase fluid and filling it into a core holder;
applying a

Assignees

• Inst Geology & Geophysics Cas
• Univ Northeast Petroleum

Inventors

• Zhang Likuan
• Luo Xiaorong
• Yan Jianzhao
• Lei Yuhong
• Cheng Ming
• Liu Naigui

Classifications

• G01N24/081 Primary

  Making measurements of geologic samples, e.g. measurements of moisture, pH, porosity, permeability, tortuosity or viscosity · CPC title

• G01N15/088

  Investigating volume, surface area, size or distribution of pores; Porosimetry · CPC title

• G01N24/082 Primary

  Measurement of solid, liquid or gas content · CPC title

• G01R33/448

  Relaxometry, i.e. quantification of relaxation times or spin density (G01R33/50 takes precedence) · CPC title

• G01V3/32

  operating with electron or nuclear magnetic resonance · CPC title