Long-Term Field Development Opportunity Assessment using Horizontal Wells in a Thin, Carbonate Reservoir of the Greater Burgan Field, Kuwait

Abstract

The Mauddud reservoir in the Greater Burgan field is a thin, carbonate reservoir containing light oil in a 10 to 20-feet (ft) target zone with "good" porosity. Matrix permeability is low, and natural fracture density can be variable in this reservoir. Thus, this reservoir must be exploited using horizontal wells. In the early 1990s, 16 horizontal wells were drilled in this reservoir. Five more horizontal wells have been drilled in 2005 and 2006 in an effort to scope out the long-term potential of this reservoir. However, only three of these five new wells had a production history of a few months that could be used in our history-matching effort. Thus, the history-matching effort concentrated on 19 wells (16 old plus 3 new wells).In conjunction with the drilling of recent horizontal wells, a comprehensive reservoir characterization program culminating into a full-field reservoir simulation model has been completed. The 24-million cell geological model was scaled up to a 9-million cell model at a 164-ft by 164-ft areal grid level to properly incorporate flow characteristics of horizontal wells into the simulation model. Matrix permeability of the scaled-up model was enhanced by using a unique process based on analytical solutions for short fractures and fracture density/orientation mapping for the entire field. This reservoir simulation model has been historymatched for the 13-year production history of 16 1990s horizontal wells along with a production history of a few months for 3 new wells using only a global-permeability multiplier and water relativepermeability curve shape modification. This model has been used in the forecast mode to assess long-term field development opportunity for the Mauddud reservoir. Primary depletion results show that horizontal wells drilled in an intelligent manner in this difficult reservoir hold the key to economic development of this reservoir.