Key Drilling and Completion Technologies and Application of the First Parametric Well in Dailekh, Nepal

The parametric well Nidaican-1 is the first parametric well drilled in Dailekh, Nepal. Through comprehensive application of geological well logging technology, the identification of the formation lithology, the evaluation of the formation pressure while drilling, the description of reservoir physical properties, and the interpretation and evaluation of the oil/gas/water zones, have been completed, identifying the oil and gas exploration potential of this area. To tackle the difficulties in drilling the high-silica metamorphic quartz sandstones with high hardness and abrasiveness, the assembly of “MWD + single-bend PDM + turbodrill” was adopted to optimize well-path control. Coupled with the strategy of reinforcing the bit materials and bit structure, the rate of penetration was increased by at least 50%, and the footage drilled by a single bit exceeded 300 m. Using the novel potassium calcium based polymer drilling fluid, wellbore instability encountered in drilling the thrust nappe zone was successfully solved, with a rate of hole enlargement of only 6.1%. Using well cementing technology combined contamination-/lost circulation-preventive cement slurry and rigid-elastic centralizer combinations, the casing string was successfully set at a depth of 4,011 m. The integrated geological evaluation-drilling engineering technology established includes (1) drilling assembly and parameter optimization method for drilling in thrust nappe zones aimed at “preventing deviated drilling and drilling fast”; (2) strongly inhibited drilling fluid composition with high plugging capacity; and (3) standard practice for well cementing in complex structural zones. The achievements made not only fill the technical gap in deep hydrocarbon drilling in Nepal, but also bear important practical significance for promoting energy cooperation around the Himalayas.