3D technology maps path to avoid waterflooding and target optimal production of mature reservoir

Published: 02/18/2022

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The challenge

A carbonate reservoir onshore in Middle East has been producing water, hampering production. High-permeability streaks, peripheral water injection, and changes in reservoir pressure were behind the onset of unpredictable waterfronts detrimental to oil output, resulting in fluid traveling horizontally to unidentified areas above and within the reservoir itself. Negative capillary pressure resulted in reverse water coning, leading to water production from the horizontal well.

The solution

SLB recommended integrating GeoSphere 360 service data with LWD logs and images from MicroScope HD™ resistivity- and high-definition imaging-while-drilling service to characterize the reservoir structure. GeoSphere 360 service was used in the 6-in horizontal section with one transmitter and two receiver subs with a 100+ft radial depth of detection. The 1D-longitudinal and 2D-transverse resistivity inversions were used to generate a resistivity map tied directly to the seismic data. To accurately characterize the reservoir structure, the GeoSphere 360 service 3D reservoir map result was integrated with LWD logs and images from MicroScope HD service.

GeoSphere 360 3D reservoir mapping-while-drilling service plotted against the 1D-longitudinal resistivity inversion.
GeoSphere 360 3D reservoir mapping-while-drilling service plotted against the 1D-longitudinal resistivity inversion. (A) Full 3D resistivity volume. (B) Filtered (resistivity <2 ohm.m) 3D resistivity volume highlighting the lateral extension of the reverse coning. (C) Filtered (resistivity >2 ohm.m) 3D resistivity volume highlighting the lateral extension of the reverse coning.

The results

Capturing the reservoir fluid dynamics led to optimizing the placement and completion of the wellbore. Integrating information from the reservoir and the borehole enabled the mapping of the reservoir layers, waterflooding, reverse coning, connecting open fractures, and overall image to identify water flow patterns.

The GeoSphere 360 service accurately delineated the onset of a high-conductivity zone. This water slump occurred about the depth of a fracture or fault zone with subseismic displacement nearing 8-ft TVD, which indicated a connection between the two layers. Slices of the pixel-based inversion of the 2D transverse resistivity along the well azimuth orthogonal plane showed the direction of the water movement.

The GeoSphere 360 service provided water volumes, faults, and pockets of oil at reservoir scale in 3D. This technology illuminated the reservoir, resulting in a redesign of the directional drilling path that avoided the water coning intervals and targeted the leftover pockets of oil. This type of data visualization extends the production life in brownfields.

MicroScope HD resistivity- and high-definition imaging-while-drilling service imaging of the fracture zone.
MicroScope HD resistivity- and high-definition imaging-while-drilling service imaging of the fracture zone. (A) MicroScope HD service dip and fracture analysis. (B) GeoSphere 360 service 2D-transverse resistivity inversion mapping the fractures, picked on MicroScopeHD service high-resolution images, controlling resistivity lateral variation.

"A full understanding of the reservoir fluid dynamics gave way to optimizing placement and completion of a single wellbore. Integrating information from reservoir-to-borehole scale allowed the mapping of the reservoir layers, water flooding, and reverse coning along with connecting fractures and overall image interpretation to the understanding of water flow patterns. Lower completion was redesigned to isolate high water saturation zones, and new wells will be planned based on the novel 3D field information.”

Drilling Engineer

Location
Middle East, Asia, Onshore
Background
A mature carbonate reservoir in onshore in the Middle East has been producing injected water unexpectedly, leading to water production. The GeoSphere 360™ 3D reservoir mapping-while-drilling service was applied to locate the waterfloods and potential leftover oil pockets. With 3D visualization using EM pulses of 100+ft in radius, an accurate volumetric map of the formation was captured in real time, enabling completion design optimization to defer early water production.
Products Used