Coal bed gas horizontal well track control method

Abstract

The invention provides a coal bed gas horizontal well track control method, which belongs to the field of coal bed gas exploitation. According to earthquake data and drilled logging well logging data, the coal bed top surface depth and the coal bed occurrence are determined, and a single-inclination region is selected for well position deployment; the initial end of a multi-branch horizontal well hole track is designed to be positioned at a lower position of the structure, the tail end of the multi-branch horizontal well hole track is positioned at the higher position of the structure, a main branch well hole is positioned at a coal bed top layer rock layer, and a branch well hole is positioned at the coal bed; main and branch well hole track control target points are determined according to the coal bed top surface depth and the coal bed occurrence, geometric orientation is used as the main measure for controlling the well hole tracks in the top plate rock layer, the well hole and the coal bed top maintain a proper vertical distance, meanwhile, and the well inclination angle is maintained to be always greater than 90.5 degrees; the coal bed gas multi-branch horizontal well branch well hole track is completed by adopting a dropping lateral extending mode. The method provided by the invention effectively solves the problems that the coal bed drilling encountering rate is excessively pursued, the well hole tracks are in wave-shaped fluctuation along with the coal bed local inclination angle change, and the water blockage and ash blockage are caused in the later-stage discharge and exploitation process.

Description

technical field [0001] The invention relates to a trajectory control method for multi-branched horizontal wells of coal bed gas, which belongs to the field of coal bed gas exploitation. Background technique [0002] At present, the drilling technology of multi-branch horizontal wells for coalbed methane still follows the drilling method of conventional oil and gas horizontal wells, adopts directional control technologies such as measurement while drilling (MWD) and logging while drilling (LWD), and takes geosteering as the core Carry out control to realize the accurate tracking of the coal seam by the wellbore trajectory, obtain a high coal seam encounter rate, and achieve the purpose of increasing the leaking area of ​​the coal seam and increasing the production capacity. [0003] This trajectory control method aimed at pursuing the coal seam penetration rate, in order to ensure a high coal seam penetration rate, it is usually necessary to adjust the wellbore trajectory up ...

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Problems solved by technology

These inflection points not only increase the wear resistance of the drilling tool and make construction difficult in the subsequen

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