OSCAR ARENAS MANTILLA

Highlighted Achievements — HPHT Offshore Completions & WO | Gulf of Mexico

• Led HPHT offshore completions & workovers (6,000–7,500 m) for development and exploratory wells.
• Designed and executed complex completion and Workover programs, DST & well testing operations, Wellbore cleanout, CT N₂ kick-off & Milling.
• Ensured well integrity via rigorous barrier verification and compliance with API / ISO / NORSOK / PEMEX standards.
• Delivered process optimization through structured lookbacks, risk assessments & lessons learned.
• Performed QA/QC across services, tools & engineering studies; conducted audits and technical investigations.
• Onsite offshore Supervision and leadership ensuring safe, efficient and high-performance operations.

• Led planning, execution, and lookback for integrity assurance and technical P&A of high-risk exploratory wells under National Oil Company (NOC) standards and national regulations.
• Executed well integrity restoration and secure abandonment programs with strong process safety and operational discipline focus.
• Applied advanced technologies for wellhead conditioning (hot tap), fluid control, remedial cementing, controlled perforating (PAC), sand jetting, and casing section milling to restore annulus integrity and ensure barrier compliance.
• Coordinated multidisciplinary interface with HSE, environmental, civil works, and security teams to guarantee compliant and incident-free operations.
• Achieved 100% Operational and ZERO HSE&SQ

• Led planning, execution, and lookback for high-complexity exploratory well integrity assurance and technical abandonment under NOC standards and Colombia regulations.
• Implemented advanced integrity and abandonment technologies: hot-tap wellhead recovery, fluid control systems, remedial cementing, PAC perforating, sand-jetting and casing section milling to re-establish annulus integrity.
• Directed engineering of Well Intervention Guides (WIG) for rigless interventions (CT & well testing) on two exploratory wells (Putumayo & Piedemonte), ensuring containment of sustained annulus pressures up to 2,000 psi and successful permanent P&A within HSE, time & cost targets.
• Led WIG engineering for workover-based technical abandonment of one exploratory well and two legacy wells (>50 years old) in the Middle Magdalena Basin.
• Successful execution with zero HSE incidents, full regulatory compliance and technical objectives achieved.

• Led of D&C Completion Well Delivery Process for Ecopetrol new field development projects.
• Coordinated the execution of the completion stage of nine wells in the development phase of heavy oil Castilla field and ten wells in the Chichimene field development project with following Well Development Process (WDP).
• Led the Apiay-Suria Field appraisal wells project managed under the Well Delivery Process framework, with which development plans for these fields were leveraged.
• Led four contracts as technical advisor in Liner Hanger services.
• Instructor at the University of Ecopetrol (NOC)

• Wellsite supervisor in completion and intervention of exploration and development wells with Rig and Rigless technologies in environments with a high concentration of H2S (up to 40%) and HPHT.
• Designed the procedure for recording and lookback of lessons learned and good practices from the Technical and Well Services section of the drilling department.
• Performed and reviewed drilling, completion and intervention programs (Coiled Tubing, Wireline, Slickline, specialized well testing, fluid sampling, fishing, wellhead maintenance, acid pumping, N2 and cement, perforating and logging).
• Participated in the Well Integrity area with the implementation of operational schemes for the control of H2S corrosion based on NACE standards.

• Coordinated projects and daily activities of production operations in Casabe field wells (Stimulation, sand control and implementation of new technologies such as clean perforating, digital Slickline, sand logs and selective strings for water injection).
• Achieved the implementation of a methodology to improve safety based on the communication characteristics of people (e-colors).

• Led the design and planning of drilling and completion for three ERD horizontal wells (two at Ballena field and one at Riohacha field).
• Led three ERD horizontal wells in the field during the execution and lookback phases (lessons learned and best practices).
• Led the completion phase (design-planning, execution and lookback) for three wells with technology for real-time data acquisition and running of pre-drilled and slotted liner technologies.
• Lead and executed as representative of the company in office and wellsite important projects like the temporary suspension of critical wells in the Ballena Field, reconditioning (Workover) in gas wells and abandonment with Rigless units.
• Achieved internal certification as a subject matter expert in the processes of risk management and management of change.

• Led the implementation from Chevron headquarter standards processes for the systematic optimization of existing offshore and onshore (wells, surface facilities and plants) facilities through the definition, modeling, analysis and identifying and executing optimization opportunities to achieve a more profitable and energy efficient operation in support of future business.
• Achieved of IPM (Prosper and Gap) and Hysys (Process Modeling) construction of integrated models (reservoir, wells, flow lines, separation, compression, dehydration and distribution of natural gas in the fields of Ballenas and Chuchupa).
• Wellsite supervisor with Wireline for the maintenance of sub surface safety valves and bottomhole pressure and temperature surveys.

• Operations Engineer in the Production Enhancement (Stimulation) service line. From the design phase of the jobs to the execution of the job and evaluation of quality and performance in HSE (Frac-Acid-Coiled Tubing-Nitrogen).
• Participated in the design of programs and leadership in well stimulation jobs from planning to execution and feedback.
• MVP recognition for optimization initiatives.