Who we are

Trusted Consulting

Experienced Professionals

Strategy Development

OGS has been a trusted consulting and services company to energy companies. The firm has rapidly grown and found its place in the market as a trustworthy and reliable firm.

Strategy Development

Experienced Professionals

Strategy Development

We provide in-depth analysis and future projections that form the basis for strategy development, action & operations plans, investment evaluation and commercial decisions on the regional scale. We also offer our clients a combination of advisory, tailored consulting and operations services to meet their needs. First we listen, and then we act decisively on time.

Experienced Professionals

OGS Team is made up of experienced professionals dedicated to providing superior value to our clients. OGS combines deep regional knowledge with a broad understanding of industry interactions, providing clients with a comprehensive analysis of environments and risks. We are committed to excellence – high quality professional services, ethical working relationships and continuous improvement. We are quite aware to make the best decision to ensure our client’s best interests.

Management

Ömür Özavcı | Founder & CEO

Ömür Özavcı is the Founder and Chief Executive Officer of OGS.

He is a Petroleum and Natural Gas Engineering graduate of Middle East Technical University (METU) with more than 30 years of global petroleum engineering and executive leadership experience.

His areas of expertise include reservoir engineering, integrated field development, drilling and workover operations, production optimization, reservoir management and reserves evaluation, enhanced oil recovery, economic evaluations, international project management, and strategic business development.

Under his leadership, OGS has delivered more than 60 field development and operational support projects worldwide, including turnkey drilling and workover campaigns, integrated field development projects, surface facility development projects, production enhancement programs, reservoir studies, and large-scale project management assignments for leading national and international operators including SOCAR, BP, Chevron, TPAO, PDVSA, Genel Energy, Dubai World, BGN Energy, and Petoil.

Prior to establishing OGS, Mr. Özavcı held various leadership positions with international operators and service companies across Türkiye, Azerbaijan, Iraq, Kazakhstan, Libya, Turkmenistan, Ukraine, and the UAE. His career spans both offshore and onshore environments, where he played a key role in increasing production from mature fields through waterflooding and enhanced recovery initiatives, managing multi-million-dollar development programs, conducting reserves evaluations, and improving asset values through technical optimization.

Guided by OGS's philosophy, "What we promise, we do", Mr. Özavcı is committed to safe, reliable, and value-driven delivery by combining technical excellence, operational discipline, and long-term partnership to support clients in complex energy environments.

Bülent Irkkan | CFO

With more than 40 years of experience in finance and corporate leadership, Bulent Irkkan brings deep expertise in supporting complex, capital-intensive businesses.

Throughout his career, he has developed finance organizations and advised on strategic initiatives, joint ventures, due diligence, taxation and cross-border tax matters, economic modelling, risk analysis, and procurement processes.

As CFO, he leads OGS’s financial strategy, cash-flow management, planning, reporting, and investment evaluation, helping the company allocate capital with discipline and pursue sustainable growth across the oil and gas value chain.

He works closely with the executive team and operational leaders to align financial priorities with business strategy, project delivery, and long-term value creation. As a strategic partner to the business, he contributes to corporate planning and helps shape OGS’s future direction by integrating financial insight with operational and commercial decision-making.

Hayati Sezgin | COO

Bülent Irkkan | CFO

Hayati Sezgin serves as the Chief Operating Officer of OGS, bringing over three decades of distinguished experience in the oil and gas industry.

A graduate of the Middle East Technical University (METU) with a degree in Petroleum and Natural Gas Engineering, Mr. Sezgin has held senior technical and leadership roles at international multicultural organizations across Azerbaijan, Iraq, Syria, and Türkiye.

His expertise lies in reservoir and production engineering, supported by extensive hands-on experience in oilfield operations and asset management. Throughout his career, he has led initiatives in production optimization, field development, reservoir management, brownfield rehabilitation, completion design and operations, feasibility studies, and economic analysis, consistently driving efficiency and value creation.

As COO, Mr. Sezgin manages OGS’s day-to-day operations, monitors key performance indicators (KPIs), ensures timely delivery meeting the quality and safety standards. With his cross-functional leadership, he aligns engineering, geoscience, finance and supply chain departments toward shared objectives. His leadership is marked by a commitment to operational excellence, strategic alignment, and sustainable growth.

Sezai Tanyolu | Head of Contracts & Procurement

Sezai Tanyolu, holding a B.Sc. degree in Business Administration from Hacettepe University, has around 35 years of experience in contract management for petroleum, environmental, water supply, wastewater treatment, and solid waste disposal projects, with extensive legal and tender department experience.

As the Head of Procurement and Contracts, Mr. Tanyolu leads OGS's strategic sourcing, vendor management, purchasing operations, and contract management operations. He manages company spending, optimizes supply chain efficiency, mitigates supplier risks, and drives cost-saving initiatives while aligning procurement policies with overall business goals. He oversees all contractual aspects of the project to ensure legal clarity, effective risk management, and alignment with project and financial objectives.

Nilsu Kıstak | Head of Subsurface

Sezai Tanyolu | Head of Contracts & Procurement

Nilsu Kıstak serves as the Head of Subsurface and brings more than 15 years of academic and industry experience. She holds a B.Sc. degree in Geological Engineering from Middle East Technical University (METU) and M.Sc. degree in Petroleum and Natural Gas Engineering from the Pennsylvania State University. Her expertise includes core data interpretation, well log analysis, reservoir structure definition, geological mapping, geomodelling, reservoir characterization and simulation, hydrocarbon reserves estimation, drilling target identification, field development planning, enhanced oil recovery, and production monitoring and optimization for oil and gas wells.

She directs OGS’s subsurface activities, providing technical oversight for well planning, subsurface modelling, asset evaluation, production enhancement, and development planning, in close coordination with geology, geophysics, reservoir engineering, and drilling teams.

Uğur Özavcı | Head of Operations

Sezai Tanyolu | Head of Contracts & Procurement

Uğur Özavcı | Head of Operations

Uğur Özavcı, a graduate of Middle East Technical University (METU) in Petroleum and Natural Gas Engineering, serves as Head of Operations, bringing over 15 years of extensive experiencein field drilling, workover operations, and operational planning using the latest technological advances.

He has worked as drilling, completion, and workover engineer in offshore and onshore fields across Azerbaijan, Türkiye, and Iraq, combining technical and contractual expertise with strengths in leadership, management, finance, and business development. He is strongly committed to high standards of health, safety, and environmental standards, as demonstrated by the Rumaila Field drilling record of zero HSE accidents. He leads OGS’s end-to-end well delivery programs and rig activities, coordinating with subsurface and drilling teams, as well as contractors, to ensure safe, efficient, and cost-effective operations.