The introduction of New Rotary Steerable Technology and Automation Drive Performance Drilling in Los Monos Formation in the Subandean Region of Bolivia
Authors: Bertarelli Mario , Barrón Jorge , Orellana Grover , Votruba Juan , Dias Rafael 
Published: June 2023

Abstract
Repsol's drilling campaign in the Caipipendi Block in Bolivia faced a unique challenge to reduce well construction time while drilling through Los Monos formation. This is a challenging environment due to its instability, high rock strength and abrasiveness, while building a minimum required 3.5°/30m curve from 12 to 55 degrees while maintaining a good wellbore quality for post drilling operations.
Two primary goals were targeted to accomplish this objective: reduce the planned runs to one shoe to shoe run and an come up with an engineered bottom-hole-assembly (BHA) design to tackle dogleg severity demand and wellbore quality. A multidisciplinary group from the Latin America region conducted a detailed analysis to understand the performance limiters and to better define the drilling strategy. This comprised of, first, providing a robust Rotary Steerable System (RSS) with an abrasive resistant set of pads and a fit for purpose PDC bit design for Los Monos formation; and second, an engineered BHA design to deliver required directional response and to reduce vibration levels while introducing automation technology in the process.
Three paths-of-action were developed for this objective: reduce the planned runs from two to one, an engineered BHA design to meet dogleg severity demand and wellbore quality, and a dedicated roadmap compiling lessons learned along the campaign.
A team of experts conducted a detailed analysis to understand performance limiters, defining a drilling strategy around a fit for purpose PDC bit with a robust Rotary Steerable System, both with abrasion resistance features designed for Los Monos formation, a BHA design to deliver the required directional response and engineered guidelines implemented with innovative automation technology to reduce vibration levels
The objective was successfully achieved delivering the longest run for the field inside Los Monos formation while setting a new benchmark for the Caipipendi Block with 673 m drilled in 250.5 circulating hours and 181.2 drilling hours with and effective Rate Of Penetration (ROP) of 3.71 m/hr. This represented a 24% improvement in time over plan and allowed the client to saved more than 93 operational hours in the well. While following automated software recommendations, a maximum build-up rate of 5.43°/30m was achieved while drilling the curve with an average of 3.95°/30m allowing the team to optimize wellbore positioning as required by the geology department. Excellent borehole condition at the end of the run allowed the operator to execute two wireline log runs and the 9-5/8" Casing run to bottom successfully with no conditioning trips.
The paper presents important data that quantifies the beneficial impact of implementing new RSS technologies and automated drilling in a very challenging environment where benchmarks are not easily achieved. It also demonstrates how proper and focused engineering approaches in conjunction with custom designed solutions generate significant improvement to wellbore trajectory management and large benefits for the operation in time savings, wellbore positioning and hole quality. The study presented provides the foundation for future performance improvements with the use of new technologies available in the market.