With so many lining materials commonly sold for pond use today, it’s easy to assume that the majority of them might work well for pits on the oilfield. However, the many challenges of the oilfield make it harder than some expect when attempting to keep in-ground features properly lined for containment purposes. A pit may look like it’s holding water correctly and not losing any liquid, but it’s easy for makeup water running over the surface to give this appearance. The pit may be leaking steadily from below and causing a contamination issue while it looks intact from the surface. Even if a liner is installed, there’s no guarantee against leaking unless the right material is selected. So, what is the best liner material to choose for an oilfield pit?
Reinforced Polyethylene (RPE)
Reinforced polyethylene, or RPE, is the best flexible liner material for use on oilfield pits of all types and designs. It offers the best combination of hydrocarbon compatibility and UV resistance, making it ideal for the exposed installation preferred for these kinds of pits and ponds. RPE is also a very leak resistant liner due to its reinforced design. The addition of heavy loads of sediment and sharp abrasive drill cuttings is less likely to tear this kind of flexible liner than any other material. Flame resistant RPE formulas are also available to help reduce the spread of a fire if one begins on the oilfield. Thanks to its thinner design with higher strength when compared to other polyethylene liners, it’s a better choice for unusually shaped trenches and square-edged basins as well.
Polyvinyl Chloride (PVC)
PVC, or polyvinyl chloride, is one of the most widely used liner materials for ponds of all kinds. While it was one of the first materials used for pit lining on oilfields, it’s far from the ideal material. First, it’s far less durable and tears more easily than RPE liners. Even reinforced PVC doesn’t compare in strength to RPE. Since oilfield reserve and waste pits are often filled with heavy loads of sludge in addition to the weight of the wastewater, the extra strength and tear resistance of RPE is enough of a reason to choose it over PVC. Not all PVC formulations are as hydrocarbon resistant as RPE either. PVC is generally only recommended for the lightest levels of chemical contamination and non-abrasive sludges, limiting its value heavily at the oilfield.
High Density Polyethylene (HDPE)
High density polyethylene, or HDPE, is a flexible liner material related to RPE. Yet it still doesn’t quite stack up to RPE when compared on all the essential features for oilfield use. First, it’s a dense material with high strength, but it only gains that strength through stiffness and thickness. RPE manages to be just as strong and tear-resistant while being thinner, lighter, and much more flexible. HDPE is also more likely to tear if the ground isn’t perfectly prepared, while RPE is more forgiving of rocky or uneven soil. Finally, RPE has better lay flat ability than HDPE in particular. HDPE tends to hold creases and folds and create gaps that allow leaks to form over time.
Low Density Polyethylene (LDPE)
For ease of installation and flexibility, LDPE is sometimes recommended for oilfield pit lining. It does have relatively good hydrocarbon compatibility, just like the rest of the polyethylene group. It’s not as resistant to hydrocarbons as RPE though, and that is obviously a major issue on the oilfield. It’s also not as tough as either HDPE or RPE. Even reinforced LDPE tends to be weaker than a true multi layer RPE product; such as the ones from BTL Liners. LDPE can work well for limited containment areas that aren’t constantly exposed to wastewater that is rich in hydrocarbons, but it shouldn’t be used for any constant or long-term use like storage ponds or frac pits.
Chlorosulfinated Polyethylene (CSPE)
Chlorosulfinated polyethylene (CSPE) is technically a part of the polyethylene group, but it doesn’t have the hydrocarbon or oil resistance of other materials like RPE. It’s particularly weak against most oils, making it a poor choice for an oilfield. It’s also very expensive when compared to RPE and similar materials.
Reinforced Polypropylene (RPP)
Reinforced polypropylene, RPP, may sound very similar to RPE. It does share a reinforced design that adds strength, but the polypropylene polymer is not the most durable or hydrocarbon compatible choice. It’s generally a better fit for oilfield use than PVC, but not by much. If you want the extra strength of a reinforced liner design, stick with RPE instead. The polyethylene materials used to manufacture it offer a much better UV and hydrocarbon resistance combination for enhanced longevity on even the most challenging oilfield sites. RPP is an acceptable choice for covers and floating tarps, but it doesn’t perform under thousands of pounds of pressure as an oilfield liner.
Concrete
Concrete is rarely used for oil drilling jobs because the rigs simply aren’t in place long enough to make it worth pouring and curing such a permanent material. With most rigs being removed just months, or possibly even weeks after being erected, concrete adds too many delays to the process. If concrete is needed for reinforcement, or to stabilize an area that will be used for years, make sure it’s paired with an impermeable and flexible liner material like RPE. Flexible liners back up any concrete liner material to ensure it remains leak free as it ages and inevitably develops small stress fractures. It’s hard to detect leaks in concrete, so just assume the material will begin leaking within the first few years of use and install a flexible liner to protect the soil and water.
It’s clear that only RPE liners offer the best combination of easy installation, cost effectiveness, and durability when installed on the oilfield. Find the RPE liners you need, that can handle mechanical damage, abrasive soils, and constant oil exposure, here at BTL Liners.
