Constructing a Flowing Well

Published On: February 19, 2024By Categories: Drilling, Guest Editorial

The math and science behind maintaining the beast’s slumber is fairly simple.

By Rob Watson

As drillers, we all have a love/hate relationship with Mother Nature and the geology we experience inside our territory. The flowing well can be the pinnacle of that relationship, or the biggest nightmare.

Though there are factors that are well beyond the control of any water well contractor, the preparation and execution of the drilling and science are the defining moments in the experience you have in constructing a flowing well.

Flowing wells have often been viewed as this unpredictable beast waiting for someone to disturb its slumber so it can unleash its wrath. As true as that can be, the math and science behind maintaining the beast’s slumber is fairly simple.

Have a Game Plan

When preparing your game plan for constructing a flowing well, it revolves around two numbers:

  1. At what depths will I encounter my first water-bearing formation?
  2. What is my positive static level?

These two numbers are what is used in determining drilling fluid weight needed to maintain an idle flow throughout the process.

For example, if the borehole is 50 feet in depth to the first water-bearing formation with a predicted static of plus 10 feet, static divided by depth × 100 = 20% weight increase above weight of water (8.34 pounds/gallon), or 10 pounds/gallons drilling fluid minimum to maintain no flow.

Typically, we as a company like to maintain a level of half-pound to one pound per gallon over minimum weight. This is a safety factor throughout the pipe setting and gravel packing (if applies). Mud weights like to separate and can be problematic if you have multiple water-bearing zones.

Once you have achieved the proper weight needed through natural mud weight or by use of a mud weight additive and drilled to the needed depth, you will set casing and screen if it applies. This is where most of the wrath will be experienced.

On screened wells, a gravel pack is needed, and drillers don’t have the patience to take the extra 10 to 20 minutes to slowly pour in the gravel pack through the weighted mud. They will either pour too fast and bridge their gravel pack or thin their mud before installing the gravel pack. By thinning mud to install gravel pack, it eliminates your ability to maintain the hydraulic weight needed to stay idle, so then the flow
starts, and you’ve lost control of your hole and things are heading south fast.

Accept the fact that installing gravel pack through your weighted fluid requires patience and some extra needed time for development. The benefits far outweigh the consequences of thinning fluids. In bedrock situations, you are ready to cement the annular space. Note I said cement! Bentonite is a great product for sealing, but it does not possess the weight needed in most artesian well applications.

Cementing is not much fun, but neither is doing it again after the fact when you try cutting a corner. Ideally, you’re looking to achieve 15 to 16 pounds/gallon cement, pumping it in place from bottom to top, displacing weighted drilling fluid with the heavier cement. Ideally, the cement is left to cure for 12 to 24 hours before developing the screen or drilling farther into the bedrock to encounter water.

That is a simple explanation of the basic process of drilling a flowing well.

Geology and Regulations

Now we will address the more advanced aspects of flowing wells, which are the geological and the regulatory sides.

Geologically, the factors are site specific and regionally specific.

For example, in northwest Ohio where we are located, flowing wells are the downgradient boundaries of the local aquifer. Others are solely due to elevation change, and in the case of the 2023 Ohio Water Well Association Flowing Well Outdoor Action Well Conference, was man-made due to damming a large river to create a lake with interconnections to lower layers of gravel. Surprises happen every day, but most of the time problems can be predictable.

Regulations can be the thorn in all our sides but can also be your best friend.

“You’ve got to think of it all and be prepared for the worst, and if it goes better than that you’ll be okay!”

In the case in Ohio, there are regulations set forth by the Department of Health stating any well drilled with an anticipated flow of more than 5 gallons per minute shall be double cased. This requires the driller to drill a 14¾-inch borehole into a stable formation such as gray clay and a minimal depth of 25 feet and install and cement 10-inch casing. Once installed and proper curing time is achieved, you can continue drilling standard hole size to casing depth followed by said process earlier here.

Many mutter at this process and gamble by not double casing because of the cost and added time. First, you’re in violation of code, and secondly, this is in place to avoid any negative impact on the aquifer and surrounding environment. It’s also in place as a level of protection for the driller in case that thing goes awry during the process. All that aside, labor and material used is labor and material billed. Go make money!

As the third generation in our family business, my father, Jim Watson, taught me that risk and unique jobs aren’t something you walk away from. They just require more planning, patience, and attention to detail.

“You’ve got to think of it all and be prepared for the worst,” Jim says, “and if it goes better than that you’ll be okay!”

I’ve been blessed to have one of the best in the business be my teacher and co-worker and can say he’s promised out a few flowing wells that I was not thrilled to do, and at the age of 24, would have definitely not have done on my own. But knowing he’s going to let me learn some of it the hard way, he also taught me the right way to think, solve, and execute these flowing monsters. To honestly stand here today at 41 years
old, and say I respect every flowing well and the potential monster it can be, I’m not afraid to go take one on!

Whenever taking on a project or unique job such as a flowing well, remember you don’t have to be the best or know it all, but have the resources and confidence you trust to execute anything and don’t be afraid to ask questions to those with experience!

Flowing Well Resources

Rob Watson of Watson Well Drilling Inc. in Bryan, Ohio, is a third-generation member of the family business. Watson is president of the Ohio Water Well Association. He can be reached at watsonwelldrilling@outlook.com.

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