Drilling pads are the heart of the oilfield operation and they deserve plenty of attention to ensure they’re meeting all local and state regulations on environmental protection. Since drilling pads concentrate the majority of the rig equipment in one area, they also accumulate all the worst leak and spill risks in the same spot. This makes it easy to add secondary containment to the pad simply by surrounding it with an appropriately sized basin with an impermeable liner. Find out how to properly line an oilfield drilling pad, right down to the right material to use.
What is the Drill Pad?
Each well site generally includes at least three, and up to six, individual well heads. These heads are clustered together to make them easier to install with the large rig, in addition to concentrating the costly equipment needed to support and operate them. Pipes to route the flow of process water and mud connect to the well heads at the pad before leading away to other tanks, ponds, and pipelines. The drill pad is a complex and crowded spot, making it essential to keep it lined from below to catch every drip and spill when they occur. Trying to clean up after a spill occurs is nearly impossible with all the well heads and other equipment packed onto the pad.
Specific Leak Risks
There are a few risks specific to the drilling pad that necessitate a double layer of lining for most designs. First, the concentration of multiple well heads in one area means there is the potential for a massive leak of highly concentrated process water at any given time. Second, the number of connections to pipes and pipelines further increases the chances of a massive leak. A single freestanding reserve pit may only have a few thousand gallons of wastewater in it at one time, but a drilling pad in full operation could possibly spew out millions of gallons of process water before its leak is discovered. A containment basin built around the pad is the most convenient way to capture leaks before they can go anywhere, and it allows you to reclaim the spilled oil or wastewater with minimal effort.
Secondary Containment
Secondary containment is generally mandated by the EPA, but oilfields are exempt from their regulations under the Clean Water Act. State laws and regulations likely still mandate it for the majority of new oil developments that are being built today. Secondary containment follows the concept of spill protection and is designed to trap any leaked wastewater before it can escape. A frac pit or reserve pit may serve as primary containment for waste until it’s processed, but secondary containment liners, for drilling pads and more, serve a slightly different purpose. They should remain empty most of the time but should remain intact and leak free so they’re ready to hold liquid whenever necessary.
Basins and Trenches
Even with proper sizing to contain the largest potential spill or leak, it’s possible for the containment basin on a drilling pad to overflow. This defeats the purpose of secondary containment. So, it should be avoided whenever possible by building trenches to drain excess overflow to other holding pits and ponds. These trenches must be lined as well, or they’ll become a contamination hazard in case of a large-scale leak. Make sure they’re graded properly so gravity encourages a steady flow of even the thickest mud and sludge mixtures away from the overflowing basin.
Don’t install drilling pads, no matter how temporary or limited in scale, without some kind of reliable secondary containment option. A double lined basin is the best choice, but even a single layer of RPE from BTL Liners will do a great job of containing process water and spilled oil. Keep drilling pads clean, productive, and easy to repair in case of an emergency with the help of good containment practices.
