Gas Utilization – The KOC Approach

Abstract Kuwait Oil Company (KOC), an upstream subsidiary of Kuwait Petroleum Corporation (KPC), ranks amongst the major oil companies of the world. However, due to an inherently low GOR of its flagship oil fields, Kuwait has not been very gas-rich and has been compelled to practically utilize all of its produced gas in order to meet its needs. The gas utilization presently ranges in excess of 97%, produced at the grass-root level (flaring < 3% of produced gas). The plan is to increase the gas utilization to over 99%, predominantly by reducing the flaring further down to < 1% by 2011-12. Utilization of WK (sour) rich gas is KOC's biggest challenge. This paper intends to bring out KOC's approach in meeting the gas challenge and maximizing the utilization of its gas. KOC's total gas business is managed by two separate groups. While one manages the associated gas from its three legendary primary producing assets viz. South & East Kuwait (S&EK), North Kuwait (NK) and West Kuwait (WK), the other group manages the non-associated gas from the newly exploited ‘Jurassic’ fields. The asset facilities of the former are owned and operated by KOC while those of the latter are leased under build, operate & maintain contracts. WK & Jurassic gas are significantly sour. Upstream gas handling & processing is restricted to gas compression & dehydration, metering and transportation. Gas sweetening, sulfur recovery and extraction of LPG and other lighter / heavier value added are carried out in KPC's downstream subsidiary Kuwait National Petroleum Corporation (KNPC). However, Jurassic non-associated gas is sweetened down to 4 ppm H2S in-situ, using amine sweetening and Claus sulfur recovery units. NK & Jurassic fields are logistically farthest from KNPC facilities. The gases evolved from separators at the gathering centers (GCs) are handled depending upon their operating pressure and molecular weight. These gases become progressively richer as the pressure drops (HP gas at about 260-270 PSIG is leanest, LP gas at about 50-65 PSIG is richer and Tank Vapor at about 4" water column is richest in heavier fractions / value added components). In most locations, the tank vapor is compressed in condensate recovery units (CRUs) to a pressure sufficient to recover the bulk heaviers (condensate); at a few locations, it is compressed in vapor compressors to a pressure sufficient to export it alongwith LP rich gases. The LP & HP rich gases are then sent to the booster stations for compression & dehydration and onward export to KNPC's gas handling plants. The hot desert climate, especially during summers, does not favor gas dehydration down to 7 lb/MMSCF; in certain locations, a propane gas chilling plant reduces the feed gas temperature of the gas dehydration unit to about 45 °C. NK utilizes gas-lift as one of its artificial lift modes and comprises of a high-pressure lift gas grid and a significant fraction of its gas handling facilities is consumed by ‘recycle gas’. In principle, KOC bulk flaring, if any, is done at gathering centers. The condensate generated as a consequence of compression in the condensate recovery units is pumped to the LPG plant. S&EK & NK gases and condensate being similar, largely share inter-field gas transfer / handling facilities for the purpose of operational flexibility and avoiding over-redundancy. West Kuwait (WK) gas and condensate being significantly sour, are handled separately altogether; sweetening and sulfur recovery are carried out at refinery end in KNPC's Acid Gas Removal Plants (AGRPs) and the sweetened gas and condensate then join the S&EK & NK gas and condensate streams to be collectively processed in KNPC's Gas Plant for extraction of C2, C3-C4 (LPG), C5+, etc.