The Design and Application of Horizontal Well Drilling with High Dep/TVD Ratio in the Weibei Oilfield

To solve drilling difficulties in the Chang-3 Reservoir of the Weibei Oilfield that displayed high friction and difficult well trajectory control caused by shallow burial depth and high ratio of horizontal departure and true vertical depth(Dep/TVD), the research on horizontal drilling technology with high ratio of Dep/TVD in shallow reservoir was conducted. Based on an analysis of the primary drilling technology difficulties in the oilfield, a numerical simulation for friction and torque was made in different hole sizes. Three spudding well sections were adopted, and φ215.9 mm drill bits were used to drill the last horizontal section. In order to ensure accurate landing and targeting, a double build hole profile was adopted according to the geological characteristics of the Chang-3 Reservoir. According to characteristics and drilling requirements of the formations drilled in the three sections, the first section adopted a tapered bottomhole assembly, the second and the third spudding sections adopted inverted BHA that the heavy weight drill pipe was applied in the hole section with a deviation angle of 45° to 60°, a potassium ammonium-based polymer drilling fluid was used and the fluid loss less than 5 mL in the horizontal section. To reduce drilling cost, the existing drilling rig ZJ30 without a top drive was selected. Field practice shows that, the conventional drilling equipment and drilling technology mentioned above can be used to solve the drilling difficulties of shallow horizontal wells, so as to achieve the effective the development for the Chang-3 Reservoir of the Weibei Oilfield.