What's new in production: When everything is going wrong at the same time

LEONARD KALFAYAN, CONTRIBUTING EDITOR  

Few experiences are as familiar to us as suddenly facing multiple problems all at once. There is no single term that perfectly captures this unfortunate phenomenon. Instead, it is described in different ways, depending on the context. When issues converge at the same time, the resulting complexity can become overwhelming, challenging the ability to cope. What begins as ordinary stress escalates into something far more daunting—a burden that is multiplicative or amplified, rather than one that is merely additive.  

While we face such situations in life, this is also a situation that can, in effect, confront a production engineer responsible for high-value deepwater oil and gas wells. Such wells may, and often do, suffer at the same time and all at once from several independent problems that cannot be addressed through conventional treatment strategies. 

A realistic and not entirely uncommon example in the deepwater environment involves wells plagued by multiple formation damage mechanisms occurring at the same time. These can include combinations of:  

• Naturally occurring or induced barium sulfate and calcium carbonate scale buildup in the production tubing 
• Wax and/or asphaltene deposition 
• Clay swelling and migration, leading to near-wellbore permeability reduction 
• Non-clay siliceous fines migration and near-wellbore plugging 
• Residual drilling mud damage 
• Unbroken frac-pack gel. 

In such a case, or even a less complex one, operators typically either leave the well untreated, because the situation is overwhelming, or they address only one, or at most, just a few of the damage mechanisms for practical and economic reasons. There is often an assumption that treatments for different damage types are chemically incompatible and cannot safely be combined in a single operation. In reality, with thoughtful, creative treatment designs, multiple steps that might normally be considered unthinkable in one job can be executed successfully together. 

Representative example. Consider an offshore deepwater oil well where everything seems to be going wrong at once. After thorough laboratory testing and well diagnostics, the well is found to be suffering, to varying and unknown degrees, from the following issues that are severely restricting production: 

• Very high water cut 
• Barium sulfate and calcium carbonate scale build-up 
• Wax and asphaltene deposition 
• Clay sensitivity and fines migration 
• Lingering drilling fluid damage (including barite weighting material and oil-wetting of the formation). 

The natural question. How can such a well be effectively treated and restored? Should the operator focus only on what appears to be the most significant damage mechanism, hoping it will deliver sufficient improvement? Unfortunately, it is rarely possible to know with certainty which issue is the most significant culprit.  

Concerns about attempting a comprehensive solution are understandable: combining multiple treatment steps may seem impractical, excessively costly (unless oil prices are strong), or risky if fluid stages are incompatible and potentially make the situation worse. 

However, a practical, integrated single-operation treatment design—built entirely from proven, long-established methods—can effectively address all of these issues simultaneously. It represents a “new” way of thinking while relying on “old,” field-tested chemistry. A generalized approach might look like this:  

1. Organic Deposition Removal Stage

• Xylene or other aromatic solvent combined with a water-wetting surfactant for wax removal. 
• The same or a separate terpene-based treatment for asphaltene dissolution. 

2. Barite Scale and Barite Mud Damage Removal Stage

• High-pH barite scale dissolver (note: currently available options are only partially effective; none are fully effective on all barite damage). 

3. Innocuous Spacer Fluid Stage

• Ammonium chloride (NH₄Cl) brine, which also helps control clay swelling near the wellbore while providing effective separation between high-pH and low-pH fluids in subsequent stages. 

4. Carbonate Scale Removal and HF Acid Preflush Stage

• HCl acid (or a derivative acid that generates HCl at temperature) plus appropriate additives, including a water-wetting surfactant. 

5. Clay and Fines Damage Removal Stage

• HCl–HF, organic acid–HF, or carboxylic acid–HF formulations tailored to the specific mineralogy. 

6. Acid Treatment Overflush Stage

• Ammonium chloride (NH₄Cl) brine containing fines-stabilizing additives and a water-wetting surfactant to establish favorable wettability. 

7. Diversion and Water Control Treatment

• Relative permeability modifier (RPM) or an RPM/viscoelastic surfactant combination. This provides diversion during the acid stages (4–6) and helps reduce water production relative to oil after treatment. 

8. Final Displacement and Scale Inhibition Treatment

• Wellbore displacement followed by a large volume of NH₄Cl brine containing an appropriate scale inhibitor (or combination of inhibitors) to help prevent future sulfate and carbonate scale buildup. 

Such a treatment is undeniably expensive—but it is typically far less costly than performing multiple separate operations (each requiring its own vessel mobilization). Oil prices and project economics will ultimately determine whether it makes sense, but at least operators can know that a comprehensive solution is technically feasible and has been applied successfully in the field. 

When the economic environment supports investment in remedial well stimulation, it becomes possible to think more creatively, rather than defaulting to the same familiar treatments that address only the most obvious or easiest problems—often delivering only partial or temporary gains. 

Readers are encouraged to explore the technical literature for examples of creative, multi-step, single-operation well stimulation treatments that have delivered success both offshore and onshore.