Please Pass the Salt: Using Oil Fields for the Disposal of
Concentrate From Desalination Plants

Jean-Philippe Nicot, principal investigator, Ali D. Chowdhury (Texas Water Development Board), Robert E. Mace (Texas Water Development Board), and Alan R. Dutton (now at The University of Texas at San Antonio)

The Texas Water Development Board (TWDB) and BEG, funded by the Bureau of Reclamation, investigated the feasibility of injecting concentrates from desalination plants into depleted oil or gas fields. The objective of this study was twofold: (1) to evaluate the use of depleted fields as sites for injection wells to dispose of desalination concentrates and (2) to demonstrate to the regulatory community that deep-well disposal of concentrates in oil and gas fields is safe and reliable. The State of Texas is interested in diversifying its water resources in the face of a growing demand. Large volumes of practically untapped brackish water relatively well distributed across the state are available. However, communities interested in desalination are concerned about what to do with their (nontoxic) concentrate that is chemically enriched relative to initial brackish water composition and that accounts for one-third to one-tenth of the input water stream. One possibility is to inject it into oil fields, along with produced waters. To show through physical and chemical modeling that oil fields can readily accept the waste, fields within specific basins were investigated. Basins were chosen so that their characteristics would cover the range of variability in the state: Permian, East Texas, Gulf Coast, Anadarko, Dallas-Fort Worth, and Maverick Basins.

Despite some differences, the six analysis areas show a consistent picture. All areas have a history of fresh waterflooding, especially during early production in the first half of the twentieth century, suggesting a favorable outlook for concentrate injection. Achievable injection rates are not on average historically high, which is confirmed by low permeability values of Paleozoic formations. The East Texas and Gulf Coast reservoirs have higher permeability and subsequent maximum potential injection rates. Multiple wells will be needed to accommodate the desalination concentrate stream of a typical plant. Scaling tendency by calcite and gypsum is not outside that typically encountered and dealt with by the oil and gas industry. The greatest risk for formation damage may be changing the ionic ratio of formation water or the selectivity of ion exchange between water and clay minerals, although water sensitivity of the clayey material can be accommodated using operational solutions such as pretreatments with appropriate chemicals or buffer solutions. Technical challenges of injecting desalination concentrates into oil-producing formations are not unlike those of injecting water from a source different from that of formation water. The oil industry has a long history of dealing with such issues. This work suggests that injection of desalination concentrates in formation water will likely not be a problem if the injection water and the formation are appropriately pretreated, as is done routinely in the oil industry.

Presentations and Reports

Please Pass the Salt: Using Oil Fields for the Disposal of Concentrate from Desalination Plants

 

National Ground Water Association’s 2005 Ground Water Summit, San Antonio, April 19, 2005
[Abstract] [PDF]

 

Final Report, June 2005 [PDF, 5 MB]

 

Nicot, J. P., and Chowdhury, A. H., 2005, Disposal of brackish water concentrate into depleted oil and gas fields: a Texas study: Desalination, 181, 61-74 [PDF]

   

Please Pass the Salt: Using Oil Fields for the Disposal of Concentrate

 

Presentation of final report to the U.S. Bureau of Reclamation, September 29, 2004 [PDF, 3.9 MB]

   

Please Pass the Salt: Can the Oil Industry Benefit from Desalination Wastes?

 

Presented at the TIPRO mid-winter policy meeting, January 13, 2004, Fort Worth, Texas
[ Powerpoint 8.2 MB] [PDF] [Notes, Word]

 

For more infomation, please contact Jean-Philippe Nicot.
Telephone 512-471-6246; e-mail jp.nicot@beg.utexas.edu.

July 2005