Joint positioning method of anisotropic medium vertical and horizontal waves

Abstract

The invention discloses a joint positioning method of anisotropic medium vertical and horizontal waves. The method comprises the following steps: 1) 1) using the picked perforation micro-seismic signal vertical and horizontal wave travel time as an observation value, establishing a perforation signal relative travel time target equation for inversion and obtaining an anisotropic velocity model andsize relationship of weight coefficients; 2) utilizing micro-seismic event vertical and horizontal wave travel time as the observation value, inputting an initial positioning velocity model and carrying out inversion on a micro-seismic event spatial position according to the micro-seismic event anisotropic vertical and horizontal wave joint positioning target equation; 3) inverting the micro-seismic event spatial position again and obtaining a repositioned micro-seismic event spatial position and a corresponding corrected velocity model. The joint positioning method of anisotropic medium vertical and horizontal waves satisfies unconventional micro-seismic monitoring requirements of coal bed gas, shale gas and the like; a novel weighted positioning formula is set, so that the radial and depth positioning errors are further reduced, and a higher-precision positioning result is obtained.

Description

technical field [0001] The invention relates to the field of micro-seismic signal processing in wells, and more particularly relates to a method for joint positioning of longitudinal and transverse waves in anisotropic media. Background technique [0002] Microseismic monitoring in the well is one of the microseismic observation methods. It is characterized in that the downhole three-component geophone receives the full wave field signal of the microseismic. There are many types of geophones, but the disadvantage is that the location of the downhole geophone is unknown, which leads to disorder and disorder of the X component and Y component microseismic data of the geophone, which affects the subsequent positioning processing. At the same time, due to the short microseismic observation distance in wells (generally in the range of 200-1000 meters) and the limited number of geophones (generally 12-32 three-component well geophones), some microseismic positioning in wells is pr...

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Problems solved by technology

[0002] Microseismic monitoring in the well is one of the microseismic observation methods. It is characterized in that the downhole three-component geophone receives the full wave field signal of the microseismic. There are many types of geophones, but the disadvantage is that the location of the downhole geophone is unknown, which leads to disordered and disordered microseismic data of the geophone X component and Y component, which affects the subsequent positioning processing

At the same time, due to the short microseismic observation distance in wells (generally in the range of 200-1000 meters) and the limited number of geophones (generally 12-32 three-component well geophones), some microseismic positioning in wells is prone to instability, Phenomena such as low precision

[0003] At present, there are two main ideas for microseismic location technology in wells: one is based on travel time forward modeling of P-wave and S-wave events, representative algorithms include network search method, simulated annealing method, geiger method, etc. Weak first-arrival phase signals make it difficult to accurately pick up P-wave and S-wave events during travel, which affects positioning results; the second positioning idea is based on wave equation convolution, and representative algorithms include interferometry, reverse time migration, and passive source imaging. , the advantage is that there is no need to pick up the first arrival of the event, and the disadvantage is that the data signal-to-noise ratio and velocity model are high, and the calculation cost is high

[0004] The above methods are suitable for isotropic homogeneous media, but in the microseismic development of unconventional tight sandstone gas and shale gas reservoirs, the strata are heterogeneous and belong to anisotropic media. And the propagation path is different from isotropy, using the current positioning method leads to inaccurate positioning of microseismic events

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