Drilling is a disruptive process in which most of the damage is created subsurface and is never seen. The challenge for 2016 is to become a drill site surgeon. Create a site management plan that leaves the jobsite with as little impact as possible. A good site management plan will cover the following:
- Drill Site Footprint and Equipment Impact
- Drill Fluid and Cutting Containment
- Disposal of Drill Fluid and Cuttings
A jobsite that is properly managed and laid out has many advantages, like increasing employee and environmental safety. It also acts as your best advertisement. We want our customer’s neighbors to say, “You had a new well installed?”
Drill Site Footprint and Equipment Impact
Drill rigs are big and water trucks are heavy. There, I said it, and we can move on. A site management plan allows your customer to understand what the jobsite will look like before the rig leaves the shop. If you ask the average consumer what it takes to drill a well, they think about the well they have at home neatly surrounded by landscaping, or covered with a fake rock. They do not imagine a couple 30-ton trucks parked on their lawn for a day, let alone a week. Showing a diagram of the jobsite and outlining where every component will be parked or laid out is invaluable. It also opens up the discussion of subsurface hazards like utilities, septic, sewer and other manmade substructures. The goal with a footprint diagram is to align the customers’ expectations with the actual setup and drilling process. If the client understands the impact of large equipment and the drilling process, they will start to see why trees will have to be trimmed or that the extra labor expense is needed because of the rubber mats that need to be used to protect the lawn. The last thing you need is an irate homeowner because the water truck sank into their prized lawn.
Drill Fluid and Cutting Containment
The volume requirement to drill a 250-foot hole with a 10-inch bit is 1019.58 gallons. Although 1019.58 is the total hole volume, we understand that it will take at least one and a half times that amount, or 1529.36 gallons, to complete the hole. On a shallow hole, like our hypothetical 250-foot well, it is common practice to use a mud pan or the combination of a mud pan and solids control system. Regardless of the method chosen, drill fluid and cuttings should be contained. Drilling is a dirty job and to minimize site impact, it is important to contain cuttings and fluids to a particular area. This is as simple as a tarp with a silt fence or the use of a backhoe bucket. Fluid and cuttings flowing over to the neighbor’s yard or on the road is not good site management practice. It is our environmental responsibility to prevent fluids and cuttings from entering any freshwater areas, runoff drains or wildlife habitats. If the site footprint will allow a solids control unit or mud cleaner, containment becomes much more manageable.
Disposal of Drill Fluid and Cuttings
At the end of the drilling process on our 250-foot hole we will have roughly 1,000 gallons of fluid to dispose of, and on the surface we will have 200 to 500 gallons of fluid and cuttings. If a solids control unit was used then, the disposal process is much easier. Utilizing solids control generally allows for less fluid to be used, therefore less liquid to be disposed of. An efficient solids control unit will generate semi-dry cuttings that turn to dry a solids and are easily removed. Sometimes constraints do not allow for a solids control unit to be used. At the end of the job, there are 1,500 gallons of solids laden slurry and it has to be properly disposed of. The two major options for slurry disposal are mechanical and chemical.
Mechanical disposal relies on vacuum trucks, filter bags and filter containers to remove the solids from the drilling fluid. Generally, vac trucks move a fluid to an offsite solids control unit, large filter press or a slurry pit to facilitate solids separation. Filter bags are easy to set up and use, but can be incredibly difficult to remove. Filter bags perform best when allowed to stay in one place and given time to dehydrate. Filter containers work the same way as a filter bag, but allow for easy transport. It’s the difference between moving a gallon of water in a balloon versus a bucket. One last note on filter bags and filter trailers: A good drilling fluid program will utilize sodium bentonite and filtration control polymers. The primary job of bentonite and filtrations control polymers is to create a dense filter cake. The properties required downhole to maintain good borehole stability and to build a filter cake prevent filter bags and filter boxes from quickly removing the fluid phase from the solids.
Chemical removal such as flocculants, coagulants, superabsorbents and “magic dust” can take solids-laden slurry and change its composition. Flocculants and coagulants take slurry and separate the liquid phase from the solids, creating a liquid phase to reuse and solids waste material to dispose of. Superabsorbents make sludge and bind up the liquid phase, forming a large membrane-like material tying everything together. And yes, “magic dust,” a combination or cocktail of chemicals and polymers, can separate, bind and turn slurries into a dry material to dispose of. Contact your local mud engineer and discuss all options and products they offer. The oil field has an entire group of engineers dedicated to fluid disposal that create different solutions for each project they encounter. The key to all chemical reactions is proper mixing and implementation. The solids content of the slurry will determine the right chemical combination required for slurry disposal.
Once the slurry has been separated into solids, fluid, or combined into one, disposal is dependent on your state or local regulations. Many disposal plans depend on a containment pit or area where the material can desiccate over time. Other regulations require the material to be moved to a hazardous waste site with added expense for disposal. NSF-approved drilling fluids are not a hazardous waste but when drill solids are mixed into the fluid, other unknowns such as heavy metals are incorporated and create a possible hazardous material.
The Best Site Management Plan
Create a site management plan that works for your company. Do your math and maintain low solids drilling fluid, utilizing the correct amount of fluid required to drill the hole. Contain all fluids and cuttings to a particular area for easy removal. Consider using both mechanical and chemical removal methods. Mechanical disposal works more efficiently with flocculants or coagulants. They complement each other by facilitating the fluid phase separation. Breaking down the slurry’s filter cake inside a filter bag or container speeds up the separation process. Regardless of the method, it is our responsibility to dispose of it properly. Drilling fluids, no matter how similar to clear water they look, should never be released into a waste water drain or ditch. The principles outlined use water well drilling as an example, but a good site management plan should be used for every drilling application. Drilling, in general, gets a bad reputation because of poor planning and lack of consumer education. If we start to think as a drill site surgeon and align our customers’ expectations with the given project, we will continue to promote our industry in a positive way.
Master Drilling Fluids Management
Learn more from National Driller columnist Brock Yordy with our Drilling Fluids Management web course. Sign up now, because it starts soon. Early signups get a discount. Visit www.nationaldriller.com/DFMcourse for more information.