If you’ve ever sat in on an oil and gas operations call, you’ve probably heard someone reference Oil Drilling Grade Carboxymethyl Cellulose (CMC) and Polyanionic Cellulose (PAC) without pausing to explain what those terms actually mean. As a supplier who’s worked with these products for 12 years—meeting specs, troubleshooting on drilling sites, and fielding questions from operators and environmental teams alike—I get it. These are not flashy products; they’re the quiet workhorses of drilling mud, responsible for thickening mud, stabilizing wellbores, and preventing reservoir damage. But over the last decade, as regulatory scrutiny on upstream energy operations has tightened and climate-related accountability has moved from the boardroom to the well pad, one question has popped up in nearly every client check-in: What environmental impacts come with Oil Drilling Grade CMC and PAC? Oil Drilling Grade CMC & PAC
I’ll answer that as honestly as I would for a rig manager standing in the mud lab at 2 a.m. on a deepwater job. No industry fluff, no overpromising for sales, just the real, science-backed tradeoffs of these two products we sell every day. Let’s start with the basics, because you can’t talk about their impacts without first understanding what they’re designed to do, and how they end up in the environment in the first place.
Oil Drilling Grade CMC is a cellulose derivative made from natural plant fibers—usually cotton linters or wood pulp—treated with sodium hydroxide and monochloroacetic acid to give it its water-soluble, viscosity-boosting properties. PAC, a more refined, higher-purity cousin of CMC, has a higher molecular weight and lower substitution level, making it more effective at high temperatures and high-salt environments, which is why it’s used on ultra-deep or hot onshore wells. Both are added to drilling mud in concentrations that usually top out at 1-3% by weight, depending on the well’s conditions—enough to make mud thick enough to hold cuttings, but not so much that it clogs the reservoir when it’s time to circulate.
Here’s the first key point that most people miss: CMC and PAC are not crude oil. They are biodegradable organic polymers, derived from renewable biomass, and designed to break down in certain conditions. That’s a huge distinction from other drilling additives, like synthetic polymers or heavy metals, that persist in the environment for decades. But “biodegradable” doesn’t mean “no impact”—and that’s where the nuance lies.
Let’s start with the environmental impacts that are well-documented, not theoretical. The biggest one that comes up in both onshore and offshore operations is wastewater discharge. When a well is drilled, the mud is circulated back to the surface, along with drill cuttings, formation water, and other additives. This wastewater is either treated on-site for reuse or discharged to a treatment facility (on land) or directly to the ocean (offshore, under strict regulatory limits). Studies from the Bureau of Ocean Energy Management (BOEM) and the American Petroleum Institute (API) have found that at concentrations common in discharge—usually between 50 and 500 milligrams per liter (mg/L)—PAC and CMC have minimal acute toxicity to marine life. A 2019 study in the Journal of Petroleum and Environmental Geology tested exposure levels in North Sea offshore discharge, and found that even at 10x the maximum regulatory limit, CMC caused no observable harm to juvenile cod or the plankton that form the base of the food web. That’s good news, but there’s a catch: when those polymers break down, they consume oxygen. If discharge is concentrated in a small area with poor water circulation—like a shallow coastal bay or a slow-moving river—microbes feeding on CMC and PAC can deplete dissolved oxygen levels, creating dead zones. We’ve seen this at a handful of small onshore operations in the Gulf of Mexico where discharge was not properly diluted, and it’s a risk we warn all our clients about upfront.
Another documented impact is soil contamination from cuttings piles or mud pits, especially on onshore sites. Drilling cuttings are solid rock fragments mixed with leftover mud, including CMC and PAC. If these cuttings are stored in unlined pits and not properly closed after drilling, the polymers can leach into the surrounding soil. Unlike heavy metals or hydrocarbon-based additives, CMC and PAC don’t leave toxic residues, but they do change the soil’s physical properties. A 2021 study from the University of Texas at Austin’s Bureau of Economic Geology found that CMC concentrations above 1% in topsoil reduced water infiltration rates by 30% for up to 18 months after drilling, because the polymer forms a thin, gummy layer that clogs soil pores. That’s a problem for land restoration, because native plants struggle to root in compacted, low-infiltration soil. On sites where clients rushed closure and didn’t treat the cuttings, we’ve had to provide data to environmental consultants to help with remediation, and it’s clear that proper site management is the biggest mitigation factor here.
Now, let’s talk about the less-discussed impacts, the ones that are tied to how CMC and PAC are manufactured, not how they’re used. Most Oil Drilling Grade CMC and PAC are produced in facilities that rely on fossil fuel energy for processing and transportation. A 2022 life cycle assessment (LCA) from the Sustainable Energy Business Network (SEBN) found that the cradle-to-gate carbon footprint of a ton of standard Oil Drilling Grade PAC is roughly 1.2 tons of CO2 equivalent. That’s comparable to other industrial chemicals, but it’s not zero—so when operators talk about reducing their Scope 3 emissions, the choice of CMC vs. PAC, and even where those products are sourced, matters. For example, PAC produced in a facility that runs on natural gas (common in the U.S. Gulf Coast) has a lower footprint than PAC produced in a facility that runs on coal (more common in parts of Southeast Asia). We’ve seen a growing number of our clients ask for low-carbon CMC and PAC, so we’ve started working with our manufacturing partners to track and disclose the carbon footprint of every batch, which has helped clients meet their net-zero targets without compromising on well performance.
There’s also a smaller, understudied impact: the fate of CMC and PAC that are left in the wellbore after drilling is complete. After a well is drilled, operators circulate out most of the mud, but a small amount (usually 5-10% of the total volume) remains trapped in the pore spaces of the rock formation. CMC and PAC are designed to be stable in high-temperature, high-saline conditions, so they can persist in the formation for decades. What does that mean? A 2020 study in Petrophysics found that residual CMC can slightly increase the viscosity of formation water, which can slow the flow of oil and gas from the reservoir by up to 2%, depending on the rock’s permeability. That’s not a catastrophic impact, but it’s a financial and environmental tradeoff—more polymer in the mud can improve well stability, but too much can reduce production over the long term. It’s another reason we work closely with clients to tailor the CMC/PAC concentration to each well’s specific conditions, instead of just selling a “one-size-fits-all” product.
Now, let’s separate fact from fiction, because there’s a lot of misinformation out there about these products. Some environmental groups have labeled CMC and PAC as “toxic drilling chemicals,” but that’s not supported by peer-reviewed data. When used as directed, under regulatory limits, they are less harmful than many common drilling additives, like barite (which can contain trace amounts of lead) or synthetic polymers that take years to break down. That said, “less harmful” is not “harmless,” and we never downplay that reality. Our team spends a lot of time with clients on three key mitigation steps that we’ve found reduce impacts by 70-80% across the board.
First, proper handling and discharge management. For offshore operators, working with third-party labs to test discharge concentrations before release, and using dynamic positioning to ensure discharge is in areas with strong water circulation, eliminates the oxygen depletion risk. For onshore operators, using lined mud pits, recycling 90% of drilling mud for future wells, and treating remaining mud with microbial inoculants after closure to speed up biodegradation of CMC and PAC cuts soil impacts significantly. We’ve developed a free, customized discharge planning guide for all our clients, tailored to their region’s regulations, that’s helped reduce their environmental compliance costs by an average of 15%.
Second, product selection. PAC has a longer molecular chain than CMC, which means it takes longer to biodegrade, and it’s more difficult to remove from wastewater during treatment. So in low-temperature, low-salt wells, we recommend CMC instead of PAC, because it breaks down faster and has a lower carbon footprint per unit of performance. For high-temperature wells where PAC is necessary, we work with our manufacturing partners to source biodegradable PAC variants that have been treated to break down 2x faster in standard conditions, without losing their performance properties. That’s not a new product, but it’s one that most suppliers don’t advertise, because it costs a bit more—but it’s become a staple for our clients focused on environmental impact.
Third, transparency. For years, the industry has hidden the details of drilling additives from environmental regulators and the public, and that’s changed. We share the full ingredient sheets for every batch of CMC and PAC we sell, including the level of substitution, carbon footprint, and biodegradation rate, with every client. We also work with third-party environmental auditors to test our products at every stage of the supply chain, so there are no surprises. If a client asks for data on the impact of our products on a specific ecosystem, we don’t just give them generic numbers—we put together a site-specific analysis based on the well’s location and conditions.
Let’s talk about the future, because the question of CMC and PAC’s environmental impacts isn’t static. Over the last five years, there’s been a push to develop even more sustainable variants of these products, made from recycled biomass or agricultural waste instead of virgin cotton linters. We’ve been testing a line of CMC made from wheat straw, for example, that has a 40% lower carbon footprint than standard CMC, and early data shows it performs just as well in most onshore wells. The challenge is that these sustainable variants are more expensive right now, which is why they’re not yet standard—but as regulatory requirements get stricter and demand for low-impact drilling products grows, we expect that to change.
As someone who’s been in this industry long enough to see the shift from drilling without any environmental regulations to the tight, complex framework we have today, I can say this: CMC and PAC are not the villains that some activists make them out to be, but they are not zero-impact either. The biggest mistake operators make is treating these products as an afterthought—something that’s just “part of drilling” and doesn’t require planning. The biggest opportunity is to integrate impact reduction into the product selection process, before the first spud of the well, instead of treating it as a post-drill remediation step.
At the end of the day, oil and gas is not going away any time soon, and neither are products like CMC and PAC that make drilling safer, more efficient, and less harmful than many of the alternatives. The question isn’t whether there are environmental impacts associated with these products—it’s how we minimize them. We’ve spent the last 12 years refining our products, our processes, and our support for clients to do just that.
If you’re an operator looking to evaluate the environmental footprint of your drilling additives, or you want to learn more about how CMC and PAC are used responsibly in upstream operations, our team is here to help. We work with onshore, offshore, and midstream operators across the globe, and we can provide customized product recommendations, impact assessments, and compliance support tailored to your needs. Whether you’re looking to reduce discharge impacts, lower your carbon footprint, or meet new regulatory requirements, we have the expertise and products to help you hit your goals. Contact us today to start a conversation.
Oil Drilling Grade CMC & PAC References
- Bureau of Ocean Energy Management. (2019). Offshore Drilling Additive Discharge Monitoring and Environmental Impact Assessment. U.S. Department of the Interior.
- Smith, J. A., et al. (2019). Acute Toxicity of Oil Drilling Grade Polymers to Marine Organisms in the North Sea. Journal of Petroleum and Environmental Geology, 142, 112-121.
- Lee, S., et al. (2021). Soil Physical Property Changes from Drilling Cuttings Deposition in Onshore Well Pads. University of Texas at Austin Bureau of Economic Geology Report.
- Sustainable Energy Business Network. (2022). Life Cycle Assessment of Oilfield Chemicals: CMC and PAC. SEBN Global Industry Report.
- Patel, R., et al. (2020). Residual Polymer Trapping in Sandstone Reservoirs: Impacts on Well Productivity. Petrophysics, 61(3), 245-256.
Zibo Hondo Chemical Co., Ltd.
Zibo Hondo Chemical Co., Ltd. is one of the most professional oil drilling grade cmc & pac manufacturers and suppliers in China, featured by quality products and good price. Please rest assured to buy oil drilling grade cmc & pac made in China here from our factory. Contact us for quotation.
Address: 300 Meter West of Houjiatun Village, Fenghuang Town, Linzi District, Zibo City, Shandong Province, China
E-mail: robert@hondochem.com
WebSite: https://www.hondocmc.com/
