Shale gas horizontal well geosteering technologies and countermeasures research in narrow and steep syncline formations of northern Guizhou area

Northern Guizhou area is located at the edge of the Sichuan Basin, and its structure belongs to Wuling fold area. Wufeng Longmaxi shale stratum is in a series of narrow and steep residual synclines, and the main developed shale stratum is within five meters of the bottom of the Longmaxi Formation, with a thin thickness. Due to the complex surface and underground geological conditions, the seismic velocity changes in this area, and the horizontal and vertical changes in various geological factors, such as the stratum dip angle and thickness, are large, so the drilling rate of horizontal wells in this area is relatively low. In this paper, the difficulties encountered in horizontal well geosteering in the narrow and steep residual syncline are sorted, and the modelling of velocity, structure, thickness, dip angle and curve was carried out. Combined with the element change law and element imaging technology, the track while drilling horizon was identified step by step to improve the hit target rate and drilling