Method for recognizing lithological characters while drilling

Abstract

The invention discloses a method for recognizing lithological characters while drilling, which mainly solves the problems of unclear horizontal boundary and serious rock debris collection time delay of the conventional cutting logging method. The method is characterized in that: actually drilling different rock samples on the ground, recording vibration signal generated under a condition of the combination of a plurality of groups of typical drilling parameters, acquiring different drilling parameters and a standard frequency spectrum under the condition of the combination of lithological characters by using quick Fourier transform, and storing the different drilling parameters and the standard frequency spectrum in a database; setting an orthogonal three-axis acceleration sensor, a two-axis strain transducer and a gyroscope in the drill collar of a near drill bit; and string the data collected by the three-axis acceleration sensor, the two-axis strain transducer and the gyroscope during the drilling of the drill bit, comparing the spectrum of data with the standard frequency spectrum for analysis, extracting data on vibration type, main frequency, frequency doubling and the like to form lithological feature codes, vibration characteristic codes and drill bit health code, and determining the lithological characters. The method can realize while-drilling recognition and has high recognition effect.

Description

Technical field: [0001] The invention relates to a method applied in the field of measurement-while-drilling in oil and natural gas drilling operations, in particular to a method for identifying lithology while drilling in a geosteering drilling system. Background technique: [0002] At present, the commonly used method to identify lithology in the process of oil and gas drilling is the cuttings logging method, that is, after manually collecting sand samples at fixed points, the lithology is identified by physical and chemical methods such as visual inspection and microscope observation. However, this method of identifying lithology has the following defects: Since the sand sample collection process is inevitably disturbed by factors such as drilling fluid density, viscosity, and displacement, the depth of the collection cannot be accurately measured, and horizon boundaries often appear to be inaccurate. In addition, due to the hysteresis of cuttings collection, for a well w...

AI Technical Summary

Problems solved by technology

[0003] In order to solve the technical problems raised in the background technology, the present invention provides a new method for identifying lithology while drilling. This method uses the law that the main frequency of the rock when the drill bit is broken causes the rock to change with the lithology to identify different rocks. Lithology, so as to solve the problems of unclear horizon boundary and severe lag in cuttings collection time in the prior art, and provide a reliable guarantee for identifying lithology, optimizing drilling parameters, and avoiding drilling risks

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