Overview of the coring program for the JAPEX/JNOC/GSC et al. Mallik 5L-38 gas hydrate production research well

Abstract

Forty-eight wireline coreswere taken from depths of 885 to 1151min the JAPEX/JNOC/GSCet al. Mallik 5L-38 gas hydrate production research well. Approximately 192.6 m of core were retrieved, with 90% recovery in gas-hydrate-bearing sand and conglomerate, andmore variable recovery in gas-hydrate-free silt, organic silt, and sand below the gas hydrate stability zone at 1108 m. Cores were carefully described at the drill site within minutes of recovery to document gas hydrate character and abundance. An extensive sampling program supported time-sensitive core studies and a wide variety of physical property, geochemical, and microbiology studies. A miniature data logger installed within each core barrel provided a continuous record of core temperature and depth during coring operations. For gas-hydrate-bearing core, a substantial increase in the rate of core coolingwas observed upon exiting the gas hydrate stability field during transit. This additional core cooling was attributed to the endothermic dissociation of a small portion of the gas hydrate.