eMAI PBR Non-oxidizing Polymer Blockage Removal Agent: Degradation of Polymer Solutions, Phenolic Resin Gels and Chromium Gels without Strong Oxidation

• Non-oxidative Degradation
• Polymer Blockage Removal
• Phenolic Resin Gels
• Chromium Gels
• Room-Temperature Degradation
• Low Residue

Extensive use of polymer materials in oilfield waterflooding, polymer flooding, profile control and water shutoff has significantly improved reservoir development efficiency. However, the resulting polymer blockage in the near-wellbore region has also become an unavoidable engineering challenge for injection and production wells. These blockages are often not simple mechanical particles, but highly viscous systems formed by retained polymer solutions, phenolic resin gels, chromium gels, and composite blockages formed by these materials together with formation minerals, crude oil and inorganic salts. Focusing on our eMAI PBR polymer blockage removal agent, this article explains why the "non-oxidative degradation" route merits attention. We aim for scientific rigor and welcome corrections from industry colleagues.

Polymer blockage: the difficulty lies in the "structure"

Under many field conditions, polymer blockage cannot be resolved simply by "flushing and diluting the polymer." In a polymer-flooding system, for example, high-molecular-weight polymers form macromolecular chains with spatial structure in water. The resulting flow resistance depends not only on concentration but also on molecular weight, molecular conformation, shear conditions, temperature, salinity and pore structure. When large amounts of polymer are retained in the near-wellbore region and pore throats, they create a substantial barrier to flow.

Gel systems are more complex. Profile-control and water-shutoff materials such as phenolic resin gels and chromium gels are essentially polymer systems with three-dimensional networks formed by crosslinking. The difficulty is not just "viscosity," but "network formation."

This is also why ordinary water flushing, dilution or conventional acid washing often has limited effectiveness against these blockages.

Oxidative treatment is a common answer, but not the only one

When polymer degradation is discussed in the field, oxidation is often the first approach that comes to mind: strong oxidants use free-radical reactions and oxidative chain scission to "cut" macromolecular chains and reduce molecular weight.

This approach is chemically sound, and oxidative systems such as peroxides and persulfates have established applications in many fields. A reservoir, however, is not a clean laboratory reactor: crude oil, surfactants, metal ions, minerals and various organic substances coexist in the formation. While attacking the target polymer, a strongly oxidizing system may also undergo side reactions with other components, creating concerns about tubing corrosion, secondary reservoir damage and safety during transport and storage.

Evaluating a blockage-removal method therefore requires more than asking "can it degrade the polymer?" Two further questions are essential: how does it degrade the polymer, and what remains afterward? The following table compares the main differences between the two technical routes.

Table · Main differences between two blockage-removal routes

Note: This comparison summarizes general characteristics of the two technical routes; it is not a performance ranking of any specific products. Actual effectiveness must be established through experimental evaluation under the target operating conditions.

The core of eMAI PBR: separating "degradation" from "strong oxidation"

eMAI PBR is a brown to reddish-brown liquid. Its principal technical feature is a non-oxidative approach to degradation.

A straightforward verification method is testing with starch–potassium iodide paper: eMAI PBR does not cause the paper to change color through oxidation. This is more than a test observation; it indicates that the product's polymer-degrading action does not rely on strong oxidation in the conventional sense.

In the field, this means that "disrupting polymer molecular chains" and "creating a strongly oxidizing environment" can be separated. Without typical oxidizing components, the safety-management burden during transport, storage and treatment is lower. The risk of oxidative corrosion to downhole tubing and equipment is also lower, and nonselective attack on other organic components in the formation is reduced, allowing greater flexibility in system compatibility design.

It should be noted that the specific degradation reaction pathway depends on the product's chemical composition, active functional groups and target polymer type. Chemical stability varies substantially among polymer systems, so suitability still needs experimental evaluation in actual applications. It must not be assumed that every polymer degrades by the same mechanism. Maintaining a cautious approach to the treatment method is itself part of taking responsibility for the product.

Rapid degradation: acting on molecular chains, not simply "thinning the liquid"

During field treatment, time itself is a cost. If a chemical only temporarily reduces a system's apparent viscosity without actually disrupting the macromolecular structure, flow resistance may remain after its action ends and the system re-equilibrates. Truly effective blockage removal should act on the polymer molecular chains themselves as far as possible.

One design priority of eMAI PBR is to promote relatively rapid degradation of polymer molecular chains. Once macromolecular chains are cleaved and molecular weight decreases, interchain entanglement is reduced, the spatial network weakens and flow resistance falls, ultimately lowering viscosity and improving fluidity. Its non-oxidative degradation pathway does not depend on the initiation and propagation of free-radical chain reactions, so observing changes during treatment does not require relying solely on prolonged soaking.

Of course, "rapid" cannot be discussed independently of the conditions of use. Actual degradation rates are still affected by polymer type and concentration, degree of crosslinking, chemical concentration, contact time, salinity and other factors. A more accurate statement is that, under suitable concentration and contact conditions, eMAI PBR can rapidly reduce the molecular weight and flow resistance of the corresponding polymer system. This is more consistent with oilfield-chemical evaluation principles than a blanket claim of "complete decomposition within minutes."

Room-temperature degradation: a broader operating window without relying on formation temperature

Temperature is an important variable in many chemical reaction systems. Some conventional blockage-removal systems react much faster at higher temperatures, while their activity falls substantially in low-temperature environments. Some even depend on reservoir temperature for "activation" before they can work.

Actual oilfields are not all high-temperature environments. Room-temperature surface pretreatment, low-temperature water-injection systems, cool reservoirs and winter operations are all relevant scenarios. In these settings, "whether a blockage-removal agent must rely on high temperature to work" directly determines its range of application.

An important application feature of eMAI PBR is that it can degrade the corresponding polymer systems at room temperature without relying on very high formation temperatures. This broadens the product's operating window and is particularly relevant to low-temperature reservoirs and injection-well operations.

It must likewise be emphasized that room-temperature degradation does not mean all polymers react at exactly the same rate at room temperature. Chemical stability differs substantially between polymer types and crosslinked systems. Field suitability should still be verified through bottle tests, viscosity measurements and core experiments where necessary.

Low residue: treatment must not leave a new blockage behind

This is one of the most easily overlooked aspects of polymer blockage removal. When evaluating an agent, many people first ask "can it degrade the original blockage?" They should also ask what is produced afterward.

If a system lowers viscosity but simultaneously generates large amounts of poorly soluble material, precipitates or macromolecular fragments, these substances may still remain in the pore throats. The original polymer blockage may decrease while a new residual blockage appears.

"Low residue" is therefore a key technical indicator for a blockage-removal agent. The application approach of eMAI PBR is to promote degradation of polymer molecular chains into lower-molecular-weight products. Under appropriate reaction conditions, this reduces the persistence of macromolecular structures and makes the degradation products easier to carry out with flowback fluid instead of retaining them again in the formation.

From a field perspective, evaluation should not focus only on "how much the viscosity decreased." It should also ask whether significant residue remains after degradation, whether new insoluble material appears, what macromolecular residues remain in the flowback fluid, and whether there are new effects on subsequent water injection and flow through the formation. Together, these indicators determine whether a treatment "truly solves the problem" or merely achieves "an apparent viscosity reduction."

Which field conditions are suitable?

eMAI PBR is not a "universal blockage-removal agent," but a non-oxidative degradation solution targeting polymer and organic-gel blockages. The following scenarios merit focused experimental evaluation.

Table · Field conditions that merit priority experimental evaluation for eMAI PBR

Final suitability should be verified by considering the blockage composition, well temperature, salinity, chemical concentration and treatment method together. First identify the blocking material, then match the agent to it, and determine the optimum concentration and treatment time through experiments.

From "strong oxidation" toward "targeted degradation"

As oilfield development becomes more precisely managed, increasing attention will be paid to blockages associated with polymer flooding, profile control, water shutoff and gel systems. For complex blockages formed by polymer solutions, phenolic resin gels and chromium gels, "strong oxidation and aggressive reaction" is no longer the only choice. Non-oxidative polymer degradation is emerging as another technical route worth considering.

The product features of eMAI PBR can be summarized in four points:

Table · The four main product features of eMAI PBR at a glance

For specific well conditions, we recommend laboratory evaluation before determining chemical concentration, treatment-slug design and contact time. If you are seeking a solution to polymer blockage while wishing to avoid concerns associated with strongly oxidizing systems, eMAI PBR can be included among your options.