24 October 2019
Potential for improved produced water disposal
SWD operators in The Texan Permian Basin may be able to gain efficiencies by injecting produced water into underutilized disposal zones
Produced water volumes in the Permian Basin are projected to as much as double by 2022. Faced with this situation, oil & gas producers and water midstream companies will need to overcome the challenges associated with saltwater disposal wells (SWDs), which take most of the region’s produced water.
Transport costs, lengthy permitting processes and increased scrutiny on behalf of regulators due to induced seismicity and overpressurization concerns are just some of the factors weighing on SWD operators. These issues are exacerbated by the fact that SWDs mainly target just a handful of disposal zones.
Casee Lemons, director of geoscience at oilfield water intelligence firm Sourcewater, told Water in Oil that disposal could become more efficient and economical if new SWDs targeted strategic disposal zones rather than typically utilized formations. Through research, she has identified a total of 47 disposal zones with available capacity, the majority of which are underutilized.
Lemons described how Sourcewater is able to identify the zones, saying, “We take the existing wellbores that are used for disposal across the United States and compare the well histories to the permitted intervals along multiple aspects including depths, reported formations, injectivity and production dates. We then utilize advanced data engineering, data science and sequence stratigraphy to fully characterize zones for disposal,” she said.
The additional zones are situated 400-17,000 feet deep and are vertically and laterally adjacent to areas of high water production in the Permian Basin. Of those, the Devonian, Ellenburger, Delaware Mountain Group/San Andres and Silurian are most commonly used. While those zones have experienced induced seismicity and/or overpressurization issues, the other identified zones do not have the same issues, Lemons said.
Bill Godsey, president and CEO of Geo Logical Environmental Services (he is also an ex-regulator for the Texas Railroad Commission’s underground injection well division), told Water in Oil that the existence of additional formations for disposal could have a positive impact on producers.
“If we did have more zones that were able to take water, it would certainly provide more flexibility and would make a difference in operational costs and efficiencies,” he said.
According to Lemons, SWD operators continue to pump produced water into the more commonly used zones despite the existence of other suitable formations because disposal zones are generally chosen according to popular practice and word of mouth.
Godsey noted that another reason might be that production is taking place in the underutilized disposal zones. “If you have production in a zone in which you’re intending to dispose of water, then there are likely to be protests from operators who are producing,” he said. Godsey went on to explain that oil & gas drilling activities could face difficulties in situations where wells must be drilled through overpressured formations containing disposed produced water.
The underutilized zones are options for the SWD operators in the Texas side of the Permian Basin, but not on the New Mexico side. That state’s regulators are currently only issuing permits for new SWDs targeting the Silurian and Devonian formations.