Casing Design in Directional Drilling Well with The Biaxial Effect Consideration

Abstract

Casing design in directional drilling well has its challenges compared to vertical wells due to additional load caused by increased angles. Set casing depth and kick tolerance calculations are needed to do casing design. The casing grade that will be used in the directional well is obtained from burst load calculations, collapse load with true vertical depth (TVD) depth parameters as well as vertical wells. Next, the calculation of the tension load on the directional well is added to the bending load and friction drag with the measurement depth (MD) parameter. Besides, the biaxial effect of the tension load created will affect the burst rating and collapse rating of the casing grade we chose previously, so we need to re-check whether the selected casing grade is appropriate or not. The result turns out that the highest tension load is in the curved section between the kick-off point (KOP) to the end of build (EOB), then in the vertical/before KOP, and the last is at the slant section/after EOB. With the influence of the biaxial effect, there are changes such as reducing and increasing the rating efficiency of the selected grade. After calculating the biaxial effect, the chosen casing grades are K55 133ppf for section 20inch, K55 68ppf for section 13.375inch, L80 53.5ppf for section 9,625inch, and L80 26ppf for section 7inch.