Underground Science
The Wilmington Oil Field sits atop a large geological dome, called an anticline, beneath the Los Angeles Basin. The oil-bearing rock layers were deposited over millions of years and are organized into dozens of distinct zones separated by shale barriers and geological faults. Managing production across this complex underground landscape is a continuous technical challenge.
The Geology
The field’s primary oil-producing formations are the Puente Formation, deposited during the Upper Miocene Epoch roughly 10 to 12 million years ago, and the overlying Repetto Formation, from the Pliocene Epoch, 3 to 5 million years ago. Together they comprise thousands of feet of alternating sandstone and shale layers. A series of transform faults divides the field into distinct fault blocks, which is why the City’s operations are organized around those boundaries.
How Wells Work
The Wilmington Field is served by an extensive network of producing wells and injection wells. Most are vertical or slant wells that cross multiple reservoir zones. Starting in the 1990s, horizontal wells were added in areas where oil concentrated in specific zones; these allow a longer open interval and significantly higher production rates.
Because the field has been producing for decades, all producing wells today require artificial lift: pumping systems that bring oil and water to the surface. Most use electric submersible pumps (ESPs) installed inside the wellbore. The West Wilmington area also uses rod pumps, the familiar surface pump systems visible at older oilfields.
Reservoir Management
Managing the Wilmington reservoir involves monitoring each well regularly, tracking injection volumes, and running pressure surveys to assess underground conditions. Engineers analyze which areas of the field are producing well and which need attention, then plan new wells, interventions, and rate adjustments to maximize recovery while maintaining ground stability.
As a mature waterflooded field, Wilmington produces a substantial volume of water alongside each barrel of oil, a natural result of decades of injection. That produced water is separated at the surface and recycled back into the injection system.
3D Visualization
The sheer complexity of the Wilmington Field, with its intricate faulting and thousands of wells drilled over nearly a century, requires sophisticated tools to navigate. Raw data from well logs, wellbores, and seismic surveys is assembled into detailed three-dimensional geological models. These models allow engineers to plan new well locations, forecast fluid movement, and identify opportunities for additional production.
