Key techniques for far connection of fan U1 test well group U-shaped well - Fanshi U1 well group

The Fan U1 test well group was the first U-shaped horizontally connected well drilled by Bohai Drilling Engineering Company Limited in Qinshui, Shanxi Province. Its designed horizontal displacement is nearly 1 000 m, much longer than the connected wells drilled previously. Coalbed methane development practices show that the U-shaped connected well can effectively connect the fissure system in the coal reservoir, increase the gas and water conductivity. Compared with vertical wells and ordinary directional wells, the U-shaped wells have greatly increased the single-well production and recovery rate, compared with multi-branch horizontal wells, the investment is greatly reduced. So this U-shaped well is a top option in the development of coalbed methane. This paper introduces the design and drilling philosophy of U-shaped well and the completion technology with ?50.8 mm PVC screen pipe. By analyzing the geological characteristics of #15 Coal Reservoir, this paper presents a method to calculate the vertical depth of landing point in #15 Coal Reservoir through 2D seismic graph. By building a mathematical model for error accumulation of instrument system, the magnetic declination correction coefficient is presented in this paper, and far-end connection was realized successfully at one time.