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.

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.

"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