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3D waterflood monitoring at Lost Hills with crosshole EM

Schlumberger, Richmond, California, U.S.

Michael Morea

ChevronTexaco Exploration & Production Company, Bakersfield, California, U.S.

Corresponding author: mwilt@slb.com

The first 20% of the full text of this article appears below.

Producing oil and gas at the Lost Hills Field in central California has always been a challenge. Although the reserves are significant, production is hampered by low matrix permeability and unusual mechanical properties in the diatomite (marine mudstone/siltstone) reservoir. Since 1911 operators have struggled with methods to improve production, control local subsidence and well failure, and improve recovery that presently is projected to be less than 10%.

ChevronTexaco is pilot testing a variety of technologies to improve both production and overall recovery at Lost Hills. In the enhanced recovery pilot a new well spacing is being tested in addition to changes in the water injection design and some new hydraulic-fracture designs. To monitor the effects of these new strategies, ChevronTexaco and Schlumberger have employed a number of technologies, one of which is crosswell electromagnetics (EM). The crosswell EM technology is attractive because of its capability to map the interwell resistivity distribution, which thus allows for convenient tracking of ongoing flooding operations as well as improved reservoir characterization.

In this article we describe the application of crosswell EM to monitoring waterflood operations at this pilot. We first look at the field problem, briefly describe the technology and finally show how it is used to characterize the water flood and track the ongoing saturation changes.

	Field setting and background

 
The Lost Hills Field is along the western margin of the San Joaquin Basin, approximately 45 miles northwest of Bakersfield, California, U.S. The field, approximately 8 miles long and 1 mile wide, is situated on a NW-SE trending asymmetric anticline that is oriented nearly parallel to the trend of the San Andreas Fault 25 miles to the west (Figure 1).

View larger version (32K): [in this window] [in a new window]   Figure 1. Location map for San Joaquin Valley Fields.