Direction determining device in drilling hole for crustal stress testing according to hydrofracturing method

Abstract

The invention discloses a direction determining device in a drilling hole for crustal stress testing according to a hydrofracturing method. The device comprises a top base and an outer sleeve. The upper end of the top base is connected with the lower end of a packer through threaded connection. The lower end of the top base is connected with the upper end of the outer sleeve through threaded connection. The lower end of the top base is connected with an inner support and a pressure switch. The inner support and the pressure switch are arranged in the outer sleeve. The outer sleeve is internally provided with a battery, an ultraviolet lamp and a geological compass in which liquid UV glue is packaged. The geological compass is fixed to the lower end of the inner bracket. The battery and theultraviolet lamp are fixed to the middle part of the inner support through a middle separating board. The ultraviolet lamp right faces the dial of the geological compass. The pressure switch is communicated with a pressure hole in the top base. The pressure hole is communicated with the inner chamber of the packer. The battery is connected with the input contact of the pressure switch through a first lead harness. The ultraviolet lamp is connected with the output contact of the pressure switch through a second lead harness. The direction determining device in the drilling hole can resist a measurement error caused by loosening and deflection of a compass pointer because of any vibration interference.

Description

technical field [0001] The invention relates to the technical field of in-situ testing of rock masses, in particular to an in-drilling orienting device for in-situ stress testing by hydraulic fracturing. Background technique [0002] The main stress direction of the hydraulic fracturing ground stress test is obtained by the impression method. The basic working principle is: use the asphaltene colloid on the outer layer of the packer to print the cracks in the drilled rock mass, and use the orientation device at the bottom of the equipment Acquire the azimuth data synchronously, and then determine the specific azimuth of the crack in the rock mass. At present, the orientation devices used for hydraulic fracturing testing mainly adopt several technical solutions such as borehole inclinometer, borehole photography technology and geological compass with locking function. [0003] Among them, the solution using borehole inclinometer and borehole camera technology needs to arrang...

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Problems solved by technology

[0005] However, for the geological compass scheme with locking function, since its orientation device adopts a rigid shrapnel to press the compass pointer to achieve locking, the rigid shrapnel and the compass pointer are in rigid plane contact with a small area, and the rigid shrapnel is thinner and compressed. The force is not high, so the locked geological compass pointer is very easy to loosen and deflect under vibrations such as handling, disassembly, and knocking, resulting in large positioning deviations or even positioning errors

Vibration factors such as handling, dismantling, and knocking are all unavoidable objective factors in the process of hydraulic fracturing stress testing using on-site drilling rigs, which lead to great directional accuracy and actual use effect of the geological compass technology with locking function. discount

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