Geostatistical Modeling of the Third Upper and Third Lower Sands of the Burgan Formation, Greater Burgan Field, Kuwait

By

 W. Scott Meddaugh¹, Jamal Al-Hamoud², R. H. Kirby³

(1) ChevronTexaco Exploration and Production Technology Co, Houston, TX (2) Kuwait Oil Company, Kuwait, Kuwait (3) ChevronTexaco Overseas Petroleum Co, San Ramon, CA

 A geostatistical modeling study of the Burgan Third Upper (3U) and Third Lower (3L) sands was used to examine reservoir geology uncertainty issues prior to a finite difference flow simulation study. Separate models for the 3U and 3L units were generated for two representative portions of the Greater Burgan field. A variety of approaches including Gaussian Sequential Simulation (GSS), Sequential Indicator Simulation (SIS), Collocated Cokriging with GSS, and Boolean Modeling were evaluated. The following final workflow was used to model the 3U and 3L units: (1) Multi-binary SIS to distribute two facies (“sand” and “shale”); (2) GSS to distribute effective porosity within each facies using appropriate facies and geological interval-specific data; and, (3) facies-dependent transform to add permeability to the reservoir models. The “sand” facies represents higher quality reservoir rock (shale volume less than 40%, effective porosity greater than 10% and permeability greater than 100 md). Sand volume ranges from zero at the top of the 3U and 3L to over 50% at the bottom of the units.

Multiple realizations of the data-driven models and a set of models for which the semivariogram parameters were altered to generate models with varying connectivity were evaluated using a 3D streamline-based flow simulator to establish the appropriate cases for finite-difference fluid-flow simulation. Water breakthrough times were 1300 +/- 130 days for the data-driven base case, 1100 +/- 37 days for the enhanced connectivity case, and 1450 +/- 80 days for the lower connectivity case.