Development of Bypassed Oil Reserves Using Behind Casing Resistivity Measurements

DE-FG26-03NT15435

Program
The project was selected under the Research with Independents solicitation, DE-PS26-02NT15377. The program is intended to assist small independent oil producers in testing higher-risk technologies that could keep oil flowing from thousands of U.S. fields.

Project Goal
Many productive zones of the Santa Fe Springs oil field in Los Angeles County, CA, have been waterflooded, and more permeable sand layers have preferentially watered out. It is suspected that flood fronts have bypassed lower permeable oil saturated sand intervals. This project used cased-hole resistivity measurements to identify higher oil saturated sands. Four wells were perforated and placed on production to develop behind-flood-front oil sands in marginal stripper production wells. If lower-sand potential exists, one well may be deepened.

Performer
Terra Exploration and Production Co.
Signal Hill, CA

Project Results
The project has demonstrated the cased-hole resistivity measurement technology in four wells in Santa Fe Strings oilfield in southern California.

Benefits
Cased-hole resistivity measurements to identify unswept low permeability sands will allow operators to more effectively produce zones in previously waterflooded oilfields.

Background
Potential oil reserves remain in selected turbidite sand sequences of Santa Fe Springs oilfield. Many productive zones of the field have been waterflooded where more permeable sand layers have preferentially watered out. It is suspected the flood fronts have bypassed lower permeable oil saturated sand intervals. The project used cased-hole resistivity measurements to identify higher oil saturated sands. The successful application of this new, behind-pipe logging tool has widespread application in the US and internationally.

Project Summary
There are five active producing wells on the Pedro-Nepple and Fulton leases in Santa Fe Springs field. Four of the five wells range in depth from 3,841 feet to 4,505 feet. The deeper well, S.P. Pedro-Nepple #1, has a total depth of 10,152 feet, thereby penetrating all of the sand intervals of the four offsetting shallow production wells.

Tubing and rods of the S.P. Pedro-Nepple #1 well were pulled, and Schlumberger's Cased Hole Formation Resistivity Tool (CHFR) was run in selected intervals. The CHFR formation resistivity readings were compared with original open-hole resistivity measurements. Separation between the original and CHFR resistivity curves indicated swept sands. Both watered-out sand intervals and those with high remaining oil saturations were identified. Logs were correlated to the four nearby offset shallow wells. Up to four well workover projects were identified, selectively perforated, and placed on production to develop potential new oil reserves and increase overall well productivity. Deepening a shallow well was considered.

Current Status (August 2005)
A no-cost extension was given the project, from February 14, 2005, to August 14, 2005, due to unforeseen delays caused by the unavailability of subcontract rig services and unseasonably wet weather.

Project Start: June 30, 2003
Project End: August 14, 2005

Anticipated DOE Contribution: $100,000
Performer Contribution: $125,718 (55% of total)

Contact Information
NETL - Jim Barnes (jim.barnes@netl.doe.gov or 918-699-2076 )
Terra Exploration - Michael Conner (acterra@concentric.net or 562-427-3733)