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Geoscience Conference & Exhibition
Innovative Geoscience Solutions – Meeting Hydrocarbon Demand in Changing Times
March 7-10, 2010 – Manama, Bahrain
Horizontal Wells Optimize Production in a Super K Sandstone Reservoir Minagish Field, West Kuwait
(1) KOC, Ahmadi, Kuwait.
(2) KOC, Ahmadi, Kuwait.
Burgan reservoirs of Minagish Field are clastic sandstone reservoirs with super-K permeability. The upper reservoir layer consists of fluvial sandstones with grain sizes ranging between medium to coarse sands. The average porosity is about 28% to 35% and the average permeability varies between 0.7 to 10 Darcy. This reservoir has been a challenge due to early water breakthrough resulting from coning effect. This paper presents a case study where horizontal well technology has been used to mitigate risk of water coning besides enhancing productivity. At the early stages 6 vertical wells are completed in Burgan with low production rates. Water coning was a major problem because of the homogeneous massive nature of the sand bodies that probably have Kv/Kh ratio close to 1. The high ratio between the oil viscosity and the water viscosity is also a major reason of coning.
Although the first horizontal well drilled in 2005 with 950 feet of net pay achieved unprecedented production rates, production life was short due to several factors where low stand-off with OWC and high off-take rates resulted in water coning accentuated by the presence of a fault acting as a conduit for early water breakthrough.
The second horizontal well was completed at the upper most part of the reservoir where rock quality has shown a gradation of facies from marine silts and shales to fluvial clean sand package. Only 300ft of the heel out of 1000ft horizontal section has been penetrated.
Taking into account control on production rates, standoff from the overlying marine shale above and the oil water contact with no significant faulting to be encountered at the sweet spot, five horizontal wells were drilled and completed very much successfully, achieving a dry oil production and minimized the possibility of water conning.