In the U.S, more than 50 barrels of produced wastewater are generated every single day. It’s a by-product of the oil and gas extraction process. Produced wastewater comes out of the ground along with oil and gas. The amount depends on the formation involved and the age of the well. As a result, the physical and chemical properties of produced wastewater vary considerably from location to location.
Some oil and gas-bearing rock formations also contain water, adding to the amount of produced wastewater.
Fracking is the biggest source of produced wastewater. The process involves injecting large quantities of water, sand and some chemicals at very high pressure into a target rock formation. The mix causes fractures and fissures in the rock formation that allows trapped oil and gas to escape.
Produced water plays a significant factor in the profitability of oil and gas production. Dealing with large volumes of produced is, in some cases, the largest single expense associated with operating wells in several shale plays.
The expenses include:
- Acquiring/Constructing a treatment/disposal facility
- Operating treatment/disposal facility
- Hauling produced water from the production site to the treatment/disposal facility
Oil and gas producers manage produced wastewater through various mechanisms, including underground injection, treatment and discharge, and recycling.
State, local governments and oil and gas producers are making deliberate efforts, using both traditional and innovative approaches, to manage produced wastewater. The main aim is to protect surface and groundwater resources.
Most produced wastewater is managed through underground injection. It’s a process that involves directly injecting it into wells specifically designed for that purpose. Direct injection is the cheapest form of disposal.
Produced wastewater has the potential to harm the environment and human health. Oil and gas producers must treat it before releasing it into the environment to meet regulations on toxic material disposal.
The treatment process removes as much of the suspended solids as possible. It also involves aerating the produced wastewater to put oxygen back in.
The treatment process depends on the local water chemistry and chemical characteristics of the produced wastewater.
Treated produced wastewater can be recycled and used in other processes like irrigation, fracking and even as a source of drinking water for livestock, depending on its chemistry. Recycling replaces or supplements natural sources of water in the area and conserves the resource.
Many of the big oil and gas producers are in the semiarid states of the western U.S. Water scarcity is a critical issue in this area and officials see the millions of gallons of water produced as an opportunity to address the problem. The interest in beneficial uses of large volumes of produced wastewater with oil and gas extraction is becoming an important topic
Currently, a very small percentage of produced wastewater is recycled, mainly in oilfield operations. Most of it is disposed of through direct injection. Many people consider this a waste of resources. It takes produced water from water circulation.
This is about to change though, as produced wastewater is receiving a lot of attention. With the expansion of oil and gas production, producers and lawmakers are looking for ways to recycle the produced wastewater to reduce increasing stresses on the limited water resources in these areas. They are treating produced wastewater as more of an asset than waste.