Successful Horizontal Well Program
in Wilmington Field

Donald D. Clarke, City of Long Beach Department of Oil Properties, CA, and Christopher C. Phillips, Tidelands Oil Production Company, Long Beach, CA

Note: This article is a partial excerpt from a talk presented by Don Clarke at the EAGE/AAPG 3rd Joint Research Symposium on Developing and Managing Turbidite Reservoirs, Almeria, Spain.

Figure 1

The Wilmington oil field of Los Angeles County California (Figure 1) is the third largest in the United States. It was discovered in 1932 and has been on continuous production ever since. Cumulative oil production, from Pliocene and Miocene Age basinal turbidite sands, has exceeded 2.5 billion barrels. The asymmetrical anticline is highly faulted and development has proceeded from west to east through each of the ten fault blocks. In areas with the longer production history (65+ years), water cuts exceed 96% and the reservoirs are near the economic limit. Several new technologies, including EarthVision, have been applied to specific areas with the ultimate aim to improve the production efficiencies and prolong the field life. Tertiary and secondary recovery techniques utilizing steam have proved successful in lower Pliocene and upper Miocene heavy oil reservoirs in the oldest section of the field. Field redevelopment has been aided by participation in two United States Department of Energy (DOE) cost share projects. One of these projects involves detailed reservoir characterization and optimization of a steam flood in the Tar Zone, Fault Block V. This article examines the project's tremendous success, highlighted by production rates that increased by an order of magnitude.

The steam flood performance in the Fault Block V Tar Zone exceeded all expectations. Three 30-year old active water flood wells remained in the steam project boundary as of March 1996. The wells initially averaged 16 barrels of oil per day and 200 barrels per day gross with an average water cut of 95%. This area had approximately five years of remaining economic life under water flood with recoverable reserves estimated at about 75,000 barrels. Five horizontal wells were drilled based on the careful characterization and 3D geological modeling using EarthVision. The wells underwent cyclic steam stimulations prior to conversion to steam drive operations. The two steam injectors and three producers now average over 200 barrels of oil per day at 70% cut. The other wells in the area have also realized an increase from 20 barrels of oil per day to 200 barrels of oil per day while the cut dropped from 95% to 70%. This is a ten-fold increase in production rate!

Figure 2

The EarthVision 3D geological model of this region (Figure 2) highlights the five horizontal wells and their perforations. The goal was to keep the wells parallel to the top of the "T" shale to maximize recoverable reserves from the superjacent "S4" sand. The EarthVision maps, cross sections, and geological model were all used to place the horizontal wells accurately. The 3D model helped the drilling team plan and drill with confidence. Drilling time was also reduced by spreading out survey lengths, using less time for correctional sets, and rotating the tool string while drilling a large percentage of the horizontal section. As a result, time and money were saved. Because of the monetary savings and the drilling team's confidence in the 3D geologic model, all of the laterals were extended an extra 12%, on average, effectively increasing the producible area by adding 60,734 stock tank cubic meters (382,000 barrels) of oil.

Figure 3

Several valuable lessons were learned during the project and EarthVision was used to solve a number of the problems encountered. For example, the old well data were potentially difficult to work with because it had to be adjusted for subsidence before accurate modeling could be performed. These adjustments were calculated to yield a time specific and consistent data set. EarthVision enabled very quick and accurate mapping, and when need be, the remapping of models that were updated on the fly while drilling. In addition, the 3D Viewer proved to be excellent for finding data busts. The final EarthVision 3D geological model was highly accurate, and the cross sections derived from the 3D model were constructed down the proposed well course. The cross sections were then used to geosteer the well at the rig with very high precision. All combined, target windows of four and one half meters (15 feet) in thickness at depths of 700 meters (2300 feet) were attainable to place horizontal wells. Figure 3 shows a cross section along the well course of well FJ202 with the Logging While Drilling (LWD) log superimposed. The five horizontal wells were laid out on cross sections similar to this section. These cross sections proved to be highly accurate and were used for geosteering the horizontal wells.

This project shows how innovative use of technology can bring continued life to an old oil field. Thanks to recent innovations like EarthVision, the confidence factor was very high for planning and drilling, and the wells were less expensive to drill and complete. Most importantly, significant amounts of recoverable reserves were added. And, finally, an unexpected benefit of the project was the improved communication between the geologist, reservoir engineer and drilling personnel.

 
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Last updated: March 22, 2007