TITLE
Recommendation to receive and file the report, “Elevation Changes in the City of Long Beach, November 2017 through October 2018.” (Citywide)
DISCUSSION
The City of Long Beach, through the Energy Resources Department (ER), supervises oil production and subsidence control operations in the Wilmington Oil Field. ER conducts elevation surveys every six months to monitor elevation changes in the oil fields and adjacent city areas. This report focuses on elevation changes that have occurred from November 2017 through October 2018. The ER survey includes the following areas: Civic Center, Central City, Alamitos Bay, Naples, Harbor District, and the offshore area encompassing the four oil islands.
The results of the last two six-month surveys indicate that elevations were stable in the Civic Center, Central City, Naples, Alamitos Bay, and the offshore area. During the first half of the year, the Harbor District was stable, except for a portion of Pier H and a small area northwest of Pier A West. Pier H experienced an elevation decline of up to 0.06 foot (0.7 inch). Water injection and fluid production requirements were adjusted and the decline did not continue into the second half of the year. The area northwest of Pier A West experienced an elevation decline of up to 0.06 foot (0.7 inch). The elevation decrease was within normal limits and did not continue into the second half of the year. All of the Harbor District was stable during the second half of the year.
The ER survey uses a series of benchmarks to determine 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 up in elevation) or pessimistic (slightly down in elevation). These changes in elevations may be associated with tidal cycles, drought, temperature changes, deep earth tectonic changes, dewatering activities, and/or re-pressuring operations in the oil field. Surfac...
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