TITLE
Recommendation to receive and file the attached report, “Elevation Changes in the City of Long Beach, November 2019 through October 2020.” (Citywide)
DISCUSSION
The City of Long Beach (City), through its Energy Resources Department (ER), supervises oil production and subsidence control operations in the Wilmington Oil Field. ER conducts ground elevation surveys every six months to monitor ground elevation changes in the oil fields and adjacent city areas. This report focuses on ground elevation changes that have occurred from November 2019 through October 2020. The ER survey includes the following areas: Civic Center, Central City, Alamitos Bay, Naples, Harbor District, and the offshore area encompassing the existing four oil islands.
The results of the last two six-month surveys indicate that ground elevations were stable in the Civic Center, Central City, Naples, and Alamitos Bay. During the first half of the year, the offshore Islands Grissom and Freeman were stable. The elevations of Islands White and Chaffee declined by 0.06 foot (0.7 inch) during the period. The ground elevation decrease was within normal limits for field operations. Water injection and fluid production requirements were adjusted, and the ground elevation loss did not continue in the second half of the year. In the Harbor District, the western portion was stable during the twelve-month period while much of the central portion rose in ground elevation. Ground elevations on Piers B, C, D, E, S, and T increased by as much as 0.11 foot (1.3 inches). The increase is on the high end of normal limits, but still considered minor and will be closely monitored. Changes to waterflood requirements will minimize future ground elevation gains.
The ER survey uses a series of benchmarks to determine ground elevation changes. Studies by the Department’s engineers and geologists show the benchmarks may rise and fall in such a manner as to make a survey either optimistic (slightly ...
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