Water Well Journal
Issue link: http://read.dmtmag.com/i/715953
A fluid is defined as anything flowing and tending to take the size and shape of its container. When we talk about drilling fluids, we are talking about whatever your circulating medium is. Sometimes it is air; sometimes it is air with additives; and sometimes it is water with additives as needed. It can be more exotic in other drilling disciplines on occasion. The physical properties of both air and water can be modi- fied to facilitate our needs and enhance our drilling project. It should be designed to improve our performance, minimize our problems, and improve our profitability. Drilling fluid additives are anything altering the chemical or physical properties and characteristics of the fluid. Products will only function for us and perform as they should if they are properly mixed. Proper mixing will: • Activate the products' functions. We need to make sure the desirable properties of each additive are fully activated. • Enhance the ability to achieve the desired fluid properties. By activating the function of the products we will be able to achieve and maintain the desirable properties of the drilling fluid. • Ensure full performance of the drilling fluid additives. We need to have adequate shear in the mixing equipment and time for the additive to mix. This will maximize the prod- uct's yield and performance. This will also reduce the potential for any unintentional un-yielded product to be introduced to the borehole. We need to make sure we achieve the maximum potential of each additive so we get the full value of the drilling fluid and its impact on our drilling operation. We do not want un- yielded additives to cause us to waste money and reduce our profitability. We have spent a lot of time researching the project and making sure we know what we need to maximize our overall performance and minimize any potential problems. Now we should make sure that time and effort were well spent. The Requirements Drilling fluids require: • Planning of the project, which we have already done as the first step. • A well-designed drilling fluids system with adequate ca- pacity, solids control equipment, and baffling. The drilling fluid needs to be designed based on the available drilling fluid equipment as well as the anticipated lithology and challenges in the borehole. • A good source of product-friendly make-up water. The water needs to be low in calcium—less than 100 mg/L, low in chlorides—less than 500 mg/L, low in chlorine—less than 100 mg/L, and preferably have a pH of ±9.0. We may need to add soda ash in order to achieve those parameters. The average tap water across the U.S. is more than 200 mg/L calcium with a pH of ±7.0. Products need to be added in the correct order: • If a product is used to adjust the chemical properties of the water, then it needs to be added first to ensure those prop- erties are adjusted before any additives which would be impacted by the properties of the water are introduced. • Bentonite products need to be added next and must be given adequate shear and time to hydrate before any other additives are introduced. • Polymer products can be added next. One of the inherent properties of polymers is they will inhibit the hydration and yield of other products as well as activate sections of the borehole. • Dry products must be added before liquid products. Poly- mers need to have adequate shear to assure hydration, but not so much as to break down the individual polymer chains, which can change their properties. Always mix dry polymers first since they require less initial shear and more time to fully hydrate. Allow them enough time to fully hy- drate before you add any liquid polymers. Liquid polymers require more shear but less time to hydrate. • All drilling fluid additives mix best when mixed slowly. This provides them enough time to fully hydrate. Have Time We're always in a hurry to get things done, but one of the most critical things in any mixing operation is adequate time to allow the products to shear and mix. RONALD B. PETERSON WATER WELLS AND COMMON CENT$ MIXING AND HANDLING OF DRILLING FLUIDS Products function as they should, so be sure you know how to properly do things. We need to make sure we achieve the maximum potential of each additive so we get the full value of the drilling fluid and its impact on our drilling operation. waterwelljournal.com 54 September 2016 WWJ