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The current market climate has forced industry players to focus on reducing their operating costs in an effort to remain competitive during this prolonged downturn. Across the value chain companies have been forced to evaluate the costs of their products and services while simultaneously striving for efficiencies to bring down breakeven extraction costs. The effective dewatering of water-based drilling muds allows operators and service providers to reduce drilling waste while increasing drilling footage, positioning them to remain successful in this competitive industry.

Dewatering of drilling muds is an essential component of upstream drilling operations. The process involves the separation of solids from the mud system, allowing the water to be recycled and the solids to be effectively treated. An adept dewatering operation can facilitate a number of operational efficiencies for fluid companies and oil and gas operators. The process of dewatering water-based drilling muds can produce large amounts of waste that must be treated either in open pits or in a closed loop. When this process is performed in a closed-loop system, it reduces the production of drilling waste and corresponding disposal costs. This system continually treats cuttings in the mud system, the efficiency of which allows wells to be drilled faster and deeper with the same resources. Furthermore, the reduced footprint of these operations can allow oilfield service providers to better comply with state and local environmental regulations. Dewatering the mud can improve penetration rates, improve filter cake integrity and reduce water and drilling fluid chemical use, thus contributing to a reduction in overall well costs.

Dewatering chemicals

In short, the dewatering process involves separating solids from the drilling mud system.Often it is necessary to use chemicals to enhance the overall performance of the dewatering equipment. The chemicals used are both coagulant- and flocculant- type polymers that are able to physically alter the properties to allow small particles from drilling cuttings to agglomerate or “flocculate” together so they are large enough to be removed by a centrifuge. For optimum and efficient solids removal onsite, experimentation is needed to determine the appropriate amount and type of polymer. These polymers are based on polyacrylamide (PAM) that are either positive, negative or neutrally charged. Flocculation is based on the interaction of the drilling mud particles and the PAM polymer. The particles have an electrical charge that repels the like-charged particles surrounding it. These particles are difficult to remove with solids control equipment alone as they are extremely small and are surrounded by their own charge radius, which can vary depending on the type and amount of the solids or the characteristics of the water phase. This charge radius must be reduced to allow the particles to flocculate.

The addition of a polymer-type chemistry allows charged particles to come in contact with each other, forming larger particles that are able to have a higher density and thus are able to be separated.

For a polymer to help flocculate the small particles effectively, the PAM polymer has to have the right charge density and molecular weight. As these aspects are more optimized, the polymer will interact more robustly with the solid small particles in the drilling mud. Alcomer 24 from BASF’s Oilfield Solutions Business has been designed to offer a large, robust performance over several mud systems.

Polymer forms

When selecting polymer for use in dewatering, along with evaluating optimized performance and compatibility with the muds it is important to also use products that are easy for an operator to use. There are two main types of polymer form that are used in dewatering applications: standard powder and microbeads. Powder products tend to be jagged with nonuniform particles. This nonuniform nature leads to clumping, incomplete dissolution and handling concerns related to dust particles. Powders are therefore often considered hard to handle in applications. Alternatively, the innovative microbeads have a uniform structure with no jagged edges, which can allow better dissolution, better solubility and better handling. Microbead technology offers improvement over powder forms in solubility, pourability, ease of handling with low dust and avoidance of freeze/thaw issues.

There is a wide range of bead products available for use in water-based drilling operations. A leading chemistry in the field, Alcomer 24 has become an industry mainstay. A low-anionic polyacrylamide-based product in microbead form, Alcomer 24 has been specifically designed to flocculate water-based drilling muds and provide better performance in closed-loop systems. As a result of its microbead form, the product offers more solubility than many powder competitors, which makes it more effective in dewatering operations. The product is more easily poured, allowing it to be more effectively dosed than powders, where clumping can cause handling challenges. As a result of its physical form, the selection of Alcomer 24 in dewatering applications can reduce overall chemical usage and expenditure. The product solubility and hydration time leads to superior performance in application, which can allow fluids companies to reduce flocculant chemical volumes. Through effective handling, customers can achieve proper chemical dosing and reduce potential wasted polymer from product clumping. When a mud system is optimized with Alcomer 24, some customers report a usage rate of half vs. the competitive powder offerings.

The additive can allow a longer well to be drilled with less product, thereby improving operational efficiency and reducing drilling costs. One customer saw impressive results in field conditions when comparing the BASF product against a competitor’s powder offering. Using 14 bags of a competitor’s anionic powder along with six bags of calcium carbonate (CaCO3), the customer drilled 564 m (1,850 ft), or 35 m/bag (115 ft/bag). Using 12 bags of Alcomer 24 and eight bags of CaCO3, this same customer was able to drill 792 m (2,600 ft), or 56 m/bag (185 ft/bag). Alcomer 24 permitted this customer to drill a 40% longer well with a 14% decrease in polymer volume. This increase in operational efficiency, coupled with a decrease in chemical dosage, allowed the customer to decrease costs on a dollar-per-foot basis. In addition to these application improvements, the customer noted the product’s ease of handling and improved solubility, with Alcomer 24 taking 10 minutes to 15 minutes vs. the powder product, which took about one hour.

Through the use of high-performance PAM products such as Alcomer 24, oilfield service providers can achieve operational efficiencies and reduce costs, helping them to compete in the current market climate.