Hith and Gotnia Formations: Emerging Frontier Tight Oil Exploration Targets in Kuwait

Abstract

Late Jurassic Hith and Gotnia Formations in Kuwait comprises of evaporitic facies that were traditionally considered as regional seals for the early to middle Jurassic hydrocarbon bearing reservoirs. However, recent discovery and flow of hydrocarbons from low porosity and permeability thin carbonate mudstone-wackestone units embedded within these formations have attested their potential as reservoir facies opening up new frontiers for exploration. The Formations have been synergistically evaluated in terms of their depositional environments, carbonate facies development and distribution, porosity, natural fractures and pore pressures to locate potential thrust areas for exploration and exploitation. Hith Formation of Tithonian age is deposited in a broad supratidal sabkha setting and comprises mainly Anhydrite with thin carbonate mudstone-wackestone units. The Formation is divisible into two regionally correlatable packages. The lower pack is clean anhydrite while the upper one comprises anhydrite and carbonates. The gross thickness varies from 200–650 feet with carbonate thickness ranging from 50–130 feet from north to south. The underlying Gotnia Formation of Kimmeridgian age is deposited in a protected lagoon to supratidal setting whose gross thickness ranges from 200–1600 feet. It consists of cyclic alternations of four salts and anhydrite packs with the latter hosting the carbonate facies. The first anhydrite pack flowed commercial quantities of oil on testing. The gross thickness of this pack varies from 50–200 feet with a carbonate thickness of 25–60 feet. Carbonate to anhydrite facies ratio maps suggest better development of carbonate facies in the south. An average porosity of 7–10% with hydrocarbon saturations of 70–80% have been interpreted. Seismic attributes indicated better carbonate facies development in the south. The formations are over pressured at 0.94–1.04 psi/ft and fractured with dominant fracture trends being NE-SW and NW-SE. Fractures oriented NE-SW aligned with the present day maximum stress are open contributing to production. Preliminary estimates suggest substantial hydrocarbon reserves to exist in these reservoirs The study has indicated that the southern part of Kuwait has better potential for exploration and exploitation of these reservoirs. High resolution sequence stratigraphy and depositional modeling, horizontal well drilling, innovative testing and well completions are key to unlock the potential of these reservoirs.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015