LWD thin-bed analysis identifies 60% more deepwater reserves

Location

Africa, Offshore

Summary

An operator required a detailed evaluation of laminated sand-shale sequences in a complex reservoir offshore Africa. SLB recommended proVISION Plus™ magnetic resonance-while-drilling service to provide a thin-bed analysis. This technology logged high-quality petrophysical data in a single run, characterizing two laminated sand-shale sequences. The operator achieved a 60% increase in calculated reserves by identifying two new pay zones.

Objective

Analyze complex sandstone reservoir in deep water

An operator drilling a deepwater well offshore Africa needed to evaluate potential pay zones in a thinly bedded sandstone reservoir. Because of good vertical connectivity, thinly bedded sandstone reservoirs can contribute to increased well production. However, evaluating potential pay zones within individual sandstone layers is challenging in such complex reservoirs.

Results

Evaluate porosity using thin-bed analysis

Using the proVISION Plus magnetic resonance-while-drilling service, a thin-bed analysis was performed to interpret the porosity directly relating to well performance. This analysis would help in evaluating the well's reservoir volumes and capturing the contribution of each pore system.

Increase calculated reserves 60% offshore Africa

The thin-bed analysis provided advanced interpretation of the deepwater reservoir's porosity. The relaxation T2 distribution information provided by proVISION Plus service enabled characterizing the two laminated sand - shale sequences, resulting in a 60% increase in calculated reserves. Net to gross and continuous permeability were also estimated for perforation interval selection and completion design optimization.

The proVISION Plus service, which is a 2D set of information sensitive to the fluid volume in the antenna aperture, was used to provide a thin-bed analysis in a deepwater sandstone reservoir.

The log shows the petrophysical evaluation while drilling an offshore well in Africa with EcoScope multifunction-while-drilling and proVISION Plus magnetic resonance-while-drilling services. The conventional log shows two distinct pay zones while the proVISION Plus MR thin-bed analysis helps characterize two additional laminated sand–shale sequences, contributing to the identification of 60% more reserves in place. The complete volumetric analysis was performed to provide a comprehensive and accurate view of the reservoir.