As carbon capture, utilization, and storage (CCUS) becomes central to credible net-zero pathways, well design and well control are emerging as critical risk areas.

In this interview, Lei Zhou, principal well control engineer at SLB, discusses how CCUS wells differ fundamentally from traditional oil and gas wells, why well control demands must be reevaluated, and how industry collaboration and advanced simulation technology are enabling safer, scalable CCUS deployment.

SLB: CCUS is increasingly cited as essential to meeting global climate targets. From your perspective, why is it such a critical part of the decarbonization puzzle today?

Lei Zhou: All credible emissions pathways that limit global warming to below 2°C require engineered carbon capture and storage. Even with aggressive emissions reductions, we are likely to overshoot our remaining carbon budget by mid-century, which means CCUS and carbon negative technologies become essential to returning to net zero.

This is particularly true for hard-to-abate industries such as cement, steel, chemicals, and fertilizers, where emissions are inherent to the process chemistry and alternatives are limited. In those sectors, CCUS is not optional—it is foundational.
 

SLB: Scaling CCUS clearly introduces new complexities. What are the key operational risks, particularly from a well control standpoint?

LZ: One of the biggest risks is that well control incidents in CCUS operations can have consequences that extend well beyond a single asset. Any loss of control could jeopardize decarbonized product supply, undermine regulatory approvals, and threaten legally binding net‑zero commitments.

Unlike hydrocarbons, CO₂ is not flammable, but it is a noxious gas, so releases carry serious safety risks, including asphyxiation. From an operational perspective, maintaining control is essential not only for safety, but also for long‑term business resilience and market credibility.
 

SLB: How does well control in CCUS wells differ fundamentally from what the industry is used to in oil and gas?

LZ: Historically, well control methodologies have been developed around hydrocarbon systems. CO₂ behaves very differently. The pressure, volume, and temperature relationships are fundamentally distinct from methane, which means traditional assumptions no longer hold. CO₂ can exist as a gas, liquid, or supercritical fluid depending on conditions, and these phase changes significantly affect compressibility and volume expansion. As a result, both well design and mitigation procedures must be reassessed rather than reused from oil and gas practice.
 

SLB: Beyond basic behavior differences, what additional technical factors complicate well control in CCUS wells?

LZ: There are several interacting factors. High flow rates combined with extreme expansion and Joule‑Thomson cooling can result in hydrate formation or even dry ice, which complicates flow assurance and control. Impurities in the CO₂ stream can accelerate corrosion, and when low temperatures increase steel brittleness, the risk to well integrity rises significantly.

Supercritical CO₂ introduces further complexity: it is highly compressible, and that compressibility increases as pressure and temperature decrease, amplifying volume expansion during pressure drops. All of these effects must be considered dynamically, not statically.
 

SLB: Given this complexity, how is the industry addressing the gap between traditional well control practices and the needs of CCUS?

LZ: There is a clear need for both deeper technical competence and fit‑for‑purpose digital tools. To that end, SLB has partnered with Equinor, Chevron, and GASSNOVA in a joint industry partnership to develop dedicated CCUS well‑control workflows.

These workflows are built in Drillbench XD™ dynamic drilling simulation software and leverage the Olga™ dynamic multiphase flow simulator, drawing on more than 15 years of CO₂ modeling experience. The solution is cloud‑based, supports high‑performance parallel simulations, and automates key workflows, which makes it scalable and practical for real‑world operations.
 

SLB: What practical decisions can these tools help operators evaluate more effectively?

LZ: They enable operators to rigorously assess questions that are central to safe CCUS operations: whether temperature conditions may trigger hydrates or dry ice, how supercritical‑to‑gas phase transitions affect volume expansion, and how varying compressibility influences dynamic kick tolerance.

They also support decision‑making around circulation versus bullheading, early kick detection, the need for managed pressure drilling, surface gas handling volumes, and blowout containment strategies, including the feasibility of capping stacks versus relief wells. These are not theoretical questions—they directly inform well design and emergency response planning.
 

SLB: Looking ahead, what does mastering well control in CCUS wells ultimately enable?

LZ: At a fundamental level, it enables confidence. Confidence that CCUS wells can be designed and operated safely, that risks are understood and mitigated, and that projects can scale without compromising integrity or credibility.

By combining technical expertise, advanced simulation technology, and industry collaboration, we can reduce uncertainty, improve efficiency, and make CCUS a reliable pillar of the energy transition. Ultimately, this is not just about managing risk—it is about enabling a sustainable, resilient path to net zero.