| Popis: |
The carbonate reservoirs lithofacies discussed in this paper contain heterogeneous pore types and properties. The challenge in predicting the distribution of the pores properties is through the technique used to construct a representative model to effectively describe the lithofacies distribution in 3D.The studied reservoirs are part of the Lekhwair and Kharaib Formations that were deposited in carbonate platform environment varied from lagoon, shoal, to ramp settings during Valanginian-Barremian age. Core and well-log data from an onshore oil field of Abu Dhabi were used to establish lithofacies distribution schemes and high resolution sequence stratigraphy (HRSS) frameworks. Twenty four lithofacies were identified based on faunal content, texture, sedimentary structures, and lithologic composition. HRSS interpretation indicated twenty one fourth-order parasequences that displayed aggradational, progradational, and retrogradational stacking cycles.A novel stochastic multirealizations modeling of lithofacies and their property distribution has been developed to characterize the subsurface complexity. The method combined depositional environment, HRSS, and diagenesis trend, and then integrated them with dynamic data to generate a holistic reservoirs characterization and representative simulation model.The workflow is as follows: Detailed core, thin section and lithofacies description;Paleoenvironmental interpretation;HRSS interpretation;Field scale stochastic modeling;Flow simulation and history match validation.Field wide reservoirs lithofacies and property distributions were modeled and constrained by the identified HRSS framework. Hybrid combination of Truncated Gaussian Simulation (TGS) and Sequential Indicator Simulation (SIS) algorithms were used. This allows generating equiprobable multirealizations of realistic lithofacies cycles and properties trend in the area. The use of lithofacies distribution provided flexibility in the modeling workflow as it offers the outline for rock properties distribution such as rock types, porosity, permeability, and water saturation. The resulting multirealizations demonstrated consistency with the conceptual scheme, outcrop analogs, and geostatistical trend.This innovative approach has recently been implemented successfully in the studied field reservoirs. The resulting dynamic model depicted a good production history match; hence it will provide reliable production forecast and reservoirs development plan. |
