Key drilling technologies for large-displacement horizontal wells in shallow shale gas reservoirs of Wulong

Abstract:

Shallow shale gas resources in Wulong are poorly endowed and difficult to develop efficiently. Increasing the length of the horizontal section and drilling large-displacement horizontal wells are important means to increase the production of single well. In view of the technical difficulties faced by shallow shale gas large-displacement horizontal wells， such as difficulty in optimizing the casing program， high safety risk of drilling tools， high requirements for drilling fluid performance， difficulty in lowering casing， and high risk of well completion loss， we have carried out wellbore structure optimization based on accurate prediction of four pressure profiles， analysis of drilling tool safety extension capacity， optimization of water-based drilling fluid system suitable for shallow shale， optimization of casing lowering methods， and optimization of completion cement slurry column structure， forming key technologies for drilling large-displacement horizontal wells for shallow shale gas. The research results were applied on site in 6 wells of the PY1 platform， with an average well depth of 3188m， a vertical depth of 1000~1200m， a horizontal section length of 1532~2250m， a horizontal-to-vertical ratio of 1.59~2.64， and an average mechanical drilling speed of 17.82m/h. This achieved fast drilling and safe well completion， and provided technical support for the efficient development of the Wulong shallow shale gas block.