As a technical sales manager for a company that makes drilling-related products, such as drilling fluids, polymers and additives, grouts and sealants, and well rehabilitation products, I spend a lot of time answering questions about the many products I work with. One topic that comes up frequently is the use and application of well rehabilitation products. This article will address the most frequently asked questions regarding determining which well rehabilitation product (or products) to use for specific applications, and clearly define a well rehabilitation treatment program (what products to use when) for wells with multiple problems.
A question I receive often relates to mud thinners used to thin drilling fluid during the drilling process and to enhance well development, and mud removers designed to break down clay that has deposited around the gravel pack or well screen. Are they interchangeable, which one works better and how does one determine which product to use?
Mud thinners (or dispersants) are designed to thin bentonite drilling fluids and help speed up the well development process, but do not effectively break down caked up bentonite or native clays built up through time. Therefore, thinners are a drilling and well development product. Well rehabilitation mud removers are specifically designed for well rehabilitation, and do not work as an effective dispersant. Well rehabilitation mud removers commonly use acidic salts and surfactants to break down native clays, and even residual bentonite that has caked up around the well screen and gravel pack and can even permeate scale. In a rehabilitation program for a well with multiple problems including clay, utilizing a mud remover should be the first step.
Well rehabilitation surfactants or wetting agents are designed to be used before adding chemicals to treat iron bacteria/biofilm or mineral incrustation (or both). Surfactants are relatively inexpensive in comparison to other well rehabilitation chemicals, but can dramatically improve the performance of other well rehabilitation products by opening up the pores and cracks in biofilm and/or mineral encrustation and enhancing the dispersion efficiency of other well rehabilitation products. This speeds up the well rehabilitation process and, ultimately, helps to improve the overall results. Some manufacturers recommend purging surfactants from the well before using other well rehabilitation products.
Biofouling agents come in both liquid and dry versions, and are designed to clean screens, gravel packs, casing and all other well components affected by biofouling or iron bacteria. Biofouling agents can also be used for debris fouling of environmental monitoring and recovery wells, oil/water separators, air strippers, and other types of equipment used in groundwater remediation. These products penetrate and disperse debris layers, allowing dissolved minerals and debris to be pumped to waste. Chlorinating a well with biofouling or iron bacteria is a temporary solution at best, and is not recommended. Well rehabilitation treatment for biofouling/iron bacteria (if present) should be conducted before treating for mineral incrustation.
Mineral incrustation removers designed specifically for well rehabilitation are most often dry penetrating acidic products that are much safer to use than hydrochloric or muriatic acids. These products have the ability to penetrate and dissolve carbonates and hydroxides of calcium, iron and manganese on the well casing, screen, gravel pack and pumps, and are much less corrosive on well materials (screen, pumps) than traditional chemicals such as hydrochloric acid. Mineral incrustation removers can be used immediately after treating for biofouling.
The above-mentioned well rehabilitation products are only as good as the way that they are used. The effectiveness of these products depends on good agitation that can include brushing, jetting, surging, air-bursting, pumping and contact time. It is also important to make sure that products used in well rehabilitation are phosphate free. Adequate flushing and sanitation of a well after rehabilitation is also important to ensure safe, good quality drinking water. Use good reputable products designed specifically for well rehabilitation, and follow the manufacturer’s instructions and recommendations. Many makers of well rehabilitation products now have online calculators that can take the guesswork out of developing a well rehabilitation treatment program.