Reservoir Engineer

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Compensation Grade

ONS-USD-35

Who We Are

INEOS was founded in 1998 by Sir Jim Ratcliffe with a single site and has grown into one of the world's largest privately owned manufacturing groups. We have grown by buying good assets and running them better with small, empowered teams, minimal bureaucracy and a relentless focus on performance.

INEOS Energy is building a global energy business, and our US Onshore team in Denver currently operates approximately 2,000 wells in the Eagle Ford shale play of South Texas. We are a small team with a big mandate: grow the business through disciplined development and acquisitions.

About the job

Job Title: Subsurface Manager

Department: Development

Summary of Position

We are seeking a skilled and motivated Subsurface Manager to play a pivotal role in shaping and scaling our US onshore development program. This is a hands‑on role for a strong reservoir engineer who wants real ownership. This high-impact position will lead and develop a small team while owning critical development tracking, capital budgeting, and reserves processes. You will drive accountability across active development pads, lead the capital forecast and capital budget submission process, oversee corporate reserves, and provide essential insight for lender, capital markets, and executive reporting. With significant visibility across the business and direct influence on investment decisions, you will help translate subsurface expertise into disciplined, value‑creating development plans.

What We Look For

• Uncompromising on safety.
• An owner's mindset. You treat company capital like it's your own money.
• A bias for action. You make sound decisions quickly with imperfect information, and you don't wait for permission.
• Commercial instinct. You connect subsurface work to value: dollars, barrels and returns.
• Hands‑on and unpretentious. You're happy to build the model yourself and to be in the field when it matters.
• Drive and resilience. You thrive in a lean team where everyone carries real responsibility.

Primary Job Responsibilities

• Manage, coach, and develop a Reservoir Engineer and Senior Development Geoscientist, setting clear priorities and ensuring high-quality technical analysis across development planning, capital allocation, and reserves.
• Own development tracking and project accountability across active development pads, including permitting status, land clearance, and engineering milestones. Maintain the Pad Readiness tracking process, proactively identify risks and dependencies, and partner across functions to support on‑time execution.
• Lead the monthly capital forecasting process, tracking actual spend against budget, identifying opportunities to reallocate or repurpose capital, and preparing and refining capital budget submissions for Finance.
• Lead and perform economic evaluations and reservoir analyses, including decline curve analysis and type‑curve development, to inform development decisions, capital budgeting, and reserves.
• Lead the corporate reserves process, including database management, Lease Operating Statement models, economic model runs, and documentation sufficient to support internal and external audits.
• Support reserve‑based lending redeterminations and other capital markets activities by responding to lender and bank‑engineering inquiries, preparing Lease Operating Statement updates, and coordinating with third‑party reserve auditors and legal counsel to ensure reserve values and technical disclosures are accurate and well‑supported.
• Develop clear, decision‑ready technical materials for ExCo approval packages, post‑investment pad lookbacks, and other internal and external stakeholder updates.
• Champion compliance with safety and environmental requirements while promoting a strong culture of safety across all activities.

Education & Experience

• Bachelor’s or master’s degree in Petroleum Engineering, Chemical Engineering, or a related technical field.
• Minimum of eight years of upstream oil and gas experience with an operator