CASING DESIGN FOR EXTENDED REACH DRILLING (ERD) NAW-68 WELL

Abstract

This study addresses the critical challenges in designing a robust casing for the NAW-68 Extended Reach Drilling (ERD) well, with a True Vertical Depth (TVD) of 9,000 ft and a planned Horizontal Displacement of 18,000 ft (2:1 ratio). The objective was to develop a fit-for-purpose casing design, evaluate mechanical loads, and optimize configurations for safe and cost-effective operations. Using existing well data, detailed analyses were performed with Landmark software, including casing point selection based on geological hazards, kick tolerance verification in accordance with Pertamina Drilling Way (PDW) standards, and comprehensive burst, collapse, and axial load simulations. Rig sizing was assessed against maximum operational loads, while sensitivity studies compared NAW-68 SCN-01 and NAW-68-SCN-02 across lateral-to-TVD ratios from 1:1 to 3:1. Results confirmed that all selected casing depths met kick tolerance requirements, and both scenarios maintained structural integrity under all simulated loads, with a 1,500 HP drawworks rig capable of accommodating maximum running loads (958,849.51 lbs for SCN-01 and 879,082.37 lbs for SCN-02). Economically, SCN-02 offered the lowest total cost at USD 1,248,978, representing a more cost efficient solution compared to SCN-01 while retaining operational integrity. However, neither scenario met the ERD 2:1 classification threshold due to insufficient push force and the risk of 7” casing buckling in extended laterals, with maximum safe lateral lengths determined to be 15,300 ft (1.70:1) for SCN-01 and 15,600 ft (1.73:1) for SCN-02, classifying both as horizontal wells. These findings emphasize the need for integrating mechanical load capacity, casing grade optimization, cost-efficiency analysis, and rig capability verification into NAW 68 ERD well planning to enhance feasibility and performance.