Coal reservoir structure testing while-drilling bit based on nuclear magnetic resonance and testing method

Abstract

The invention discloses a coal reservoir structure testing while-drilling bit based on nuclear magnetic resonance and a testing method, nuclear magnetic detection is carried out on coal around a drilled hole in real time through a nuclear magnetic probe in the drilling process, a nuclear magnetic detection process is achieved after drilling construction is completed, then the drilled hole can be used for subsequent gas extraction, and the drilling efficiency is improved. According to the mode that one-time drilling has multiple functions, on one hand, additional drilling of a plurality of drill holes is reduced; on the other hand, nuclear magnetic detection can be conducted in the drilling process and the drilling retreating process through a nuclear magnetic testing means, real-time in-situ coal seam nondestructive monitoring is achieved, and data validity and credibility are greatly improved; and finally, a plurality of pieces of nuclear magnetic relaxation information obtained during drilling and a plurality of pieces of nuclear magnetic relaxation information obtained during drilling retreating form a set, judgment is carried out according to a set standard, whether the coal seam pore structure around the drill hole changes due to drill hole pressure relief or not can be finally determined, and then corresponding measures are taken in time according to the change conditions. And the safety of subsequent coal seam mining is ensured.

Description

technical field [0001] The invention relates to the technical field of coal seam detection, in particular to a nuclear magnetic resonance-based coal reservoir structure test-while-drilling probe and a test method. Background technique [0002] High-precision testing of coal seam structure is one of the important means to evaluate coal resources and gas distribution in coal seams. Affected directly by in-situ stress and mining stress, the structure and distribution of multi-scale pores and fractures in the coal matrix are in a dynamic process. When the pressure relief borehole is formed, from the perspective of stress release, it is easy to form three zones around the borehole: "broken zone - stress concentration zone - original rock stress zone"; from the perspective of pore evolution, the complexity of fracture structure distribution along the The drilling distance is radial around. At present, the existing detection methods for basic properties of coal seams mainly inclu...

AI Technical Summary

Problems solved by technology

However, the current nuclear magnetic resonance method is limited to the test of a single coal sample in the laboratory under the saturated and centrifuged state. The space volume ratio of the free pores of the coal sample is determined by examining the amplitude difference between the two states. Does not take into account the real-time influence of the in-situ stress on the coal structure

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