Research on precise directional drilling technology for multi-branch horizontal wells in coal mine water hazard control

Abstract:

Multi-branch horizontal well grouting technology has been widely used in coal mine water hazard control due to its low construction cost， low environmental pollution and good water isolation effect. However， the coal seam floor generally is featured of complex conditions such as fracture development， thin target layers， and aggregation of fracture zones， often leading to problems such as mud leakage， difficulty in in-seam drilling， and easy sticking through the fractures during drilling operations and affecting the effect of grouting treatment seriously. In view of these problems， taking a coal mine in Anhui as an example， based on the analysis of its geological features， this paper studies directional wellbore trajectory design， selection of directional equipment and control of wellbore trajectory. Directional drilling and geo-steering technology were combined and successfully applied to the advance grouting treatment project with multi-branch horizontal wells. The field application showed that the technology improved the accuracy of wellbore trajectory control， ensured the target layer intersection rate， and had good application effect.

Key words:multi-lateral horizontal well;control of water hazards in coal mines;directional drilling technology;well trajectory control;grouting treatment