Case Study: Interwell Resistivity Images Monitor Cyclic Steam Injection

DeepLook-EM service’s reservoir-scale surveys image steam fronts, San Joaquin Valley

Challenge: Determine the steam-saturated volume around cyclic injector wells in relation to the local geology.

Solution: Conduct reservoir-scale resistivity imaging with the DeepLook-EM crosswell electromagnetic imaging service to identify the steam front based on changes in fluid saturation and temperature.

Result: Successfully identified the steam-saturated volume associated with the cyclic steam injection within the tomographic section.

Tracking cyclic steam injection

An operator is using steam drive to produce from several reservoirs in a field in the San Joaquin Valley, California, USA. Encompassing approximately 20 square miles [52 km2], the field is known to have complex, steeply dipping geology and a variety of reservoirs. This challenging environment makes it difficult to determine the affected volume around each cyclic injector and the vertical and radial distribution of the steam distribution from the well.

Imaging interwell resistivity responses to injection

DeepLook-EM crosswell electromagnetic imaging service performs resistivity surveys on a reservoir scale between boreholes up to 3,280 ft [1,000 m] apart. The sensitivity of resistivity to changes in fluid saturation and temperature makes DeepLook-EM service ideal for tracking the distribution of injected steam volumes and the resulting swept zone. Being able to map the effect of steam saturation guides field development planning and improves reserves estimates.

Clearly profiling extraction boundaries

DeepLook-EM service’s transmitter and receiver tools were deployed in Wells A and B for mapping the steam-affected zone between the wells. A baseline model for data inversion was constructed from conventional wireline resistivity measurements made in the two wells prior to injection and the survey by DeepLook-EM service.

In the resistivity profile, the blue colors denote the lower resistivity characteristic of shale layers and steam-swept zones; the orange and red colors are characteristic of unswept oil sands. The contrast between the preinjection resistivity logs from injector Well C and nearby observation Well A is extremely well defined. The abrupt boundary located 75 ft [23 m] from Well A in the DeepLook-EM service’s profile marks a resistivity change from 2 ohm.m to more than 50 ohm.m over a short interval. The lower resistivity identifies the depleted zone resulting from the replacement of oil by formation water and steam condensate, which matches the log in Well A. From this accurate boundary placement, the steam-saturated volume could be appropriately positioned in the tomographic section for optimizing extraction.

Download: Interwell Monitoring of Cyclic Steam Injection (0.43 MB PDF)

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Tracking Steam Injection Reveals Bypassed Pay

The DeepLook-EM transmitter and receiver tools surveyed between Wells A and B relative to injector Well C.The resistivity profile between the two observation wells images an abrupt boundary midway between the wells in which the resistivity changes from 2 ohm.m in the depleted zone to more than 50 ohm.m in the unswept zone. The low resistivity potentially results from the replacement of oil by formation water and steam condensate.
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Interwell Resistivity Accurately Images Fluid Flow

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