Schlumberger

Case Study: Reservoir-Scale Imaging Survey Maps Interwell Resistivity

DeepLook-EM service monitors between wells 845 m apart to reveal sweep efficiency, Middle East

Challenge: Accurately map interwell resistivity in mature waterflooded field to optimize recovery.

Solution: Image resistivity between wells with DeepLook-EM crosswell electromagnetic imaging service.

Result: Discovered variability in sweep efficiency across the reservoir between the wells.

Irregular waterflood distribution

For 30 years, Saudi Aramco has been continuously pumping seawater into peripheral water injectors to maintain pressure in a giant oil field. However, the distribution of the injected water is irregular as a result of the complexity of the reservoir, which is not fully understood. Resistivity measurements obtained by conventional wireline logging indicated that two producing wells were watered out, but the resistivity distribution between the wells was unknown. Without that data, the fluid saturations in the reservoir could not be inferred.

Interwell resistivity imaging

DeepLook-EM crosswell electromagnetic imaging service uses a transmitter and receiver pair in wells up to 1,000 m [3,280 ft] apart to measure resistivity on a reservoir scale. From a baseline model constructed with conventional resistivity logs as the endpoints, the data from DeepLook-EM service are inverted for interpretation. The result is an image of reservoir resistivity that provides greater coverage than individualwell monitoring and improved resolution over seismic surveys.

Reservoir flood optimization

Crosswell measurements were collected by DeepLook-EM service between producing wells 845 m [2,772 ft] apart on the west flank of the reservoir. Although conventional resistivity logs in the wells indicated that the interwell section was watered out, DeepLook-EM service’s survey revealed variable sweep efficiency, potentially leaving hydrocarbons in place.

DeepLook-EM Service Survey Design
Well A Well B Well C
Casing Open hole Open hole 100 m [328 ft]: Open hole
200 m [656 ft]: Chromium casing
Interval logged 250 m [802 ft] 260 m [853 ft] 300 m [984 ft]
Well pair: frequency A–C: 177 Hz B–C: 177 Hz B–A: 105 Hz

 


Download: Reservoir-Scale Survey Maps Interwell Resistivity (0.58 MB PDF)

Related Products and Services

 
Request More Information

Discovering Variability in Sweep Efficiency

The DeepLook-EM crosswell survey involved three wells on the west flank of the reservoir. Wells A and B are watered-out producers; Well C was drilled offset by 120 m [394 ft] between the two existing wells.In the top panel, the baseline model inferred from conventional resistivity logs indicates that the reservoir between the wells is watered out, with conductive injected fluid (blue area at the top of the section) sweeping the reservoir. The inverted DeepLook-EM resistivity survey in the middle panel indicates otherwise, with a higher resistivity range (green to yellow) in the same section of the reservoir. The resistivity difference between the baseline and inverted data in the bottom panel shows that the efficiency of the waterflood is variable in the area of the reservoir with higher porosity.
PrevNextZoom1 of 2

Interwell Resistivity Accurately Images Fluid Flow

DeepLook-EM
Expand resistivity logging to the reservoir scale for optimizing sweep efficiency and identifying bypassed reserves. Visit DeepLook-EM Crosswell Electromagnetic Imaging page