Application of New Techniques in First Successful Coring Operation in Challenging Unconventional Heavily Vuggy and Severely Loss Prone Reservoir, in North Kuwait Field to Recover High Quality of Core

Abstract Importance of having core samples for entire Shuaiba Formation in North Kuwait fields plays a crucial role in enhancing the understanding of geological and petrophysical characteristics of the formation and allowing for detailed analysis. KOC drilled SA-1105 well and for the first time successfully cored Shuaiba Reservoir with high recovery and good quality core samples. A total of ten cores runs were conducted to complete the 337ft of core from Shuaiba Reservoir with 98.5% recovery, which is considered the First Ever Successful coring operations in Shuaiba reservoir in North Field, Kuwait As Shuaiba Formation is an unconventional oil and gas bearing reservoir with low pressures and high permeability, the main objective for well SA-1105 was to obtain high quality of core samples with minimal damage, with smooth and regular core surface handling to help in evaluating the Shuaiba Reservoir. The coring was incredibly challenging due to the high jamming frequency in previous offset wells due to the nature of the low compressive strength, vuggy and fragile lithology, core milling and severe mud losses to complete losses. The coring program was carefully designed by KOC and CORPRO considering using fully stabilized Double Bearing Core Barrel (every 10 & 20ft) at the beginning of the job until passing over Burgan / Shuaiba marker and increased its length based on the achieved performance on run-by-run basis. The implemented coring methodologies were optimized to minimize the risk of core jamming and core milling by utilizing the combination of TSP Core head – Thermal Stable Polycrystalline (low aggressive design), Easy Entry Shoe (low friction shoe assembly to minimize the jamming risk related to friction between the core and steel shoe assembly), Sealed Bearing (to mitigate the core jamming related to bearing failure) and Jam Show (to detect the coring jamming as soon as it happen and avoid core milling and enhance the core recovery and quality) and Full Closure Catcher to maximize core recovery.