Lower cretaceous unconventional play in Kuwait comprised of majority of Carbonate with a maximum of 15% clay content. Kerogen-rich intervals present in the formation has hydrocarbon potential. However, the rock has very low matrix porosity and permeability and may not flow by itself. This paper discusses the pilot project of this play including formation evaluation and data integration to characterize the geomechanical sweet spots.
Highly deviated well in minimum horizontal stress direction was drilled through this unconventional target formation. No major wellbore instability was noticed while drilling this well. Comprehensive log data acquisition plan was made which included basic logs, image logs, formation pressure measurements, advanced acoustic and deep shear wave imaging. 1D geomechanical model was built by integrating information from drilling, geology, petrophysics and reservoir engineering. This model was calibrated against failure from Image and Caliper logs. Furthermore, wellbore instability events were also calibrated with the model produced failure. Natural fractures were interpreted not only from image logs (on wellbore wall) but also from ‘deep shear wave imaging (away from the wellbore)’. Critically stressed fractures (CSF) analysis was carried out using the fracture interpretations from image logs and geomechanical modeling.
It has been observed that at present day in-situ stresses and pore-pressure profile, some of the optimally oriented natural fractures are critically-stressed (which are hydraulically conductive). Production logging was carried out in an open hole and flow of hydrocarbon was recorded naturally. Hydrocarbon production from production logging matched very well with zones of critically stressed fractures, thereby establishing the role of stress-sensitive natural fractures on production optimization in such low permeable reservoirs.
Using integrated Sub-surface and Geomechanical characterization, hydrocarbon was unlocked from unconventional reservoir in a pilot well. Natural fractures interpretations from deep-shear wave imaging has added significant value and played key role to maximize the production from such low permeability unconventional reservoir. This finding has developed insights on field development strategy that has to include the natural fractures and geomechanics for enhanced production.