A kind of helicopter pre-polarization field magnetic resonance oil and gas detection device and detection method

Abstract

The invention discloses a helicopter pre-polarization field magnetic resonance oil and gas detection device and a detection method thereof. The device comprises a pre-polarization coil suspended below a helicopter and an emission / receiving coil. A current is guided into the pre-polarization coil so as to generate a direct-current electric field. Pre-polarization is performed on hydrogen nucleuses in oil so as to enhance an magnetization intensity of the hydrogen nucleuses. After a pre-polarization process is completed, through emitting an alternating current whose frequency is a local Larmor frequency to the ground, the hydrogen nucleuses in underground oil are excited to form a macroscopic magnetic moment. The macroscopic magnetic moment carries out precession motion in a geomagnetic field. When excitation stops, the hydrogen nucleuses spin so as to generate a relaxation phenomenon. The receiving coil senses a nuclear magnetic resonance signal generated by macroscopic magnetic moment precession and finally the signal is transmitted to an upper computer so as to carry out data interpretation. In the invention, a pre-polarization field is used to increase the magnetization intensity so that a purpose of in-situ non-invasive detection can be realized; advantages of a high speed, high efficiency, low cost, good trafficability and large-area coverage are possessed; detection time can be saved and a detection result with a high signal to noise ratio and high precision can be acquired; and a foundation is laid for improving an oil and gas exploration capability of our country.

Description

technical field [0001] The invention relates to an underground oil and gas resource detection device, in particular to a device and a detection method for rapidly detecting underground oil and gas resources by using a helicopter prepolarization field. Background technique [0002] Petroleum is a non-renewable energy source and an indispensable strategic resource for the survival and development of a country. It plays an inestimable role in national economic, social development and national defense security. With the rapid growth of my country's economy, the continuous improvement of urbanization speed and the substantial increase of population, petroleum is widely used in transportation, industrial manufacturing, chemical textiles, agricultural production and other fields. At present, there are many oil exploration methods, but there are problems such as high cost, poor anti-interference ability, low detection efficiency, and weak awareness of safety and environmental protec...

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Problems solved by technology

[0004] The magnet structure of the petroleum downhole nuclear magnetic resonance logging while drilling tool of the above invention adopts a centered gradient magnetic field design, and multiple formation nuclear magnetic information at different depths can be obtained at the same time in one trip, but the detection range is limited, and it is difficult to realize extensive detection of underground oil leakage. For detection, if multiple drilling methods are used, it will increase the cost and reduce the detection efficiency; the magnetic resonance detection device of hydrocarbon pollution shallow groundwater uses permanent magnets to increase the magnetic field strength to detect hydrocarbons in shallow groundwater, which is suitable for small-scale and small-scale The detection of the target body is powerless for large-scale detection; the underground full-space NMR prepolarization detection device mainly detects disaster water bodies in the full-space geological environment such as mines and tunnels, and operates in a narrow underground space, and the detection distance is limited. It is moved to the ground for two-dimensional detection, which needs to lay multiple coils and choose a reasonable combination of coils, so the wiring is complicated, the detection efficiency is low, and the flexibility is poor. Moreover, it is not suitable for use on the ground for working areas where personnel and instruments are difficult to enter. Detection by way of laying coils

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