Integrated BHA System Drills Curve/Lateral in One Run at Record ROP Saving Seven Days Rig Time

Abstract

Rodrigo MartinApache Energia Argentina recently commenced horizontal drilling activity to develop shale gas reserves in Neuquén basin, Argentina. On the first well, the curve was drilled with a 12¼-in PDC bit on a positive displacement motor (PDM) bottom hole assembly. The lateral was drilled with an 8½" PDC on a point-the-bit rotary steerable system. A motor BHA was used in the curve because a standard RSS could not deliver the required dogleg severity (DLS). To optimize operations, the operator wanted to complete the curve and lateral with a single 8½" PDC bit. However, the lack of a high-build rate RSS tool required the curve to be drilled with a motor building to 50° of inclination then tripping for a point-the-bit RSS to TD the lateral. The single diameter strategy was successfully executed but further NPT reduction was still possible.The challenge was to drill the curve and lateral with a high build-rate RSS and a single 8½" PDC in one run to eliminate a trip to change the directional drilling system. The introduction of an inclination hold and azimuth software system would enable the hybrid RSS tool, created to build the aggressive curve angle, to continue efficiently drilling in the lateral saving an additional trip. An engineering analysis was then launched to design an application specific PDC bit for the hybrid RSS. An FEA-based system was employed to analyze offset BHAs, directional profiles, bit technologies and mud properties. The study revealed that the baseline PDC was delivering excellent ROP in both the curve and lateral sections, but t modifications would be required to improve the bit's dynamic stability. A modified 8½-in SDi513bit was proposed that featured a customized cutting structure and gauge for improved stability.Next, a rock strength analysis system was used to determine characteristics of lithologies encountered in the field. The study determined that Quintuco (curve) and Vaca Muerta (lateral) formations have relatively low unconfined compressive strengths (3-15 kpsi) but vibration potential in Quintuco formation is moderate. Computer simulations were run to map lateral/axial acceleration and bit torque on the hybrid RSS. The results showed that the new PDC design displayed a significant increase in dynamic stability compared to the baseline bit with similar high rate of penetration (ROP) potential.The shale optimized BHA was run and it drilled 1289m of curve and lateral in one run at a record ROP of 9.64 m/hr, 35% faster than the offset average. The high build-rate hybrid RSS landed the wellbore at 96° inclination with a maximum turning radius of 11.8°/30m increasing reservoir exposure within the allotted acreage unit. The increased ROP enabled Apache to reach total depth (TD) seven days ahead of plan with savings of $595,000USD.