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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractKnowledge of permeability is critical to developing an effective reservoir description. Permeability data can be obtained from well tests, cores or logs. Normally, using well log data to derive estimates of permeability is the lowest cost method. To estimate permeability, we can use values of porosity, pore size distribution, and water saturation from logging data and established correlations. One benefit of using wireline log data to estimate permeability is that it can provide a continuous permeability profile throughout a particular interval. This paper will focus on the evaluation of formation permeability for a sandstone reservoir in Central Arabia from well log data using the concept of Hydraulic Flow Units (HFU). Cluster analysis is used to identify the hydraulic flow units. We have developed a new clustering technique that is unbiased and easy to apply. Moreover, a procedure for determining the optimal number of clusters that should be used in the HFU technique will be introduced. In this procedure, the sum of errors squared method was used as criterion for determining the required number of HFU's to describe the reservoir.In our work, the statistically derived

Chemical EOR (CEOR) can be economic in a low-price environment, but it requires economic insights be integrated into the initial reservoir screening, laboratory and numerical simulation evaluations, and continued review through field implementation. The CEOR economic evaluation for the Sabriyah Lower Burgan (SALB) using this integrated process found that surfactant-polymer and alkaline-surfactant-polymer flood had different economic potentials due to different oil recoveries, facility costs, and operating costs. Initial reservoir screening of the SLAB indicated that LoSal and CO2, flooding might also have economic potential. Laboratory corefloods injecting field proportioned volumes of chemical solutions using dead oil and reservoir rock resulted in chemical cost average $3.12 per incremental barrel of oil for alkaline-surfactant-polymer formulations and $18.61 for surfactant-polymer formulations. Live oil corefloods for corresponding chemical formulations cost per incremental barrel estimates were $3.70 and $7.83. LoSal process provided no incremental oil based on laboratory coreflood results. Numerical simulation forecast economics included chemical costs, estimated operating costs, facilities cost, drilling of wells, and other capital costs. 2.2, 5.4, and 60 MMbbl pilots forecast by numerical simulation indicated that alkaline-surfactant-polymer cost per incremental barrel of oil was $28.63, $10.42, and $10.95 for the respective pilot sizes. Smaller pilots show a greater impact of fixed costs such a facilities and new wells. 5.4 and 60 MMbbl pilots paid out at 3.4 years or less. Corresponding discounted rates of return were up to 14%. Sensitivity analysis indicated that crude oil price has the greatest effect on chemical enhanced oil recovery economics, regardless of pilot size. This paper summarizes how economic applications at each phase of a chemical flood evaluation are performed and how those evaluations can be understood and applied to prevent adverse project selection. Economic parameters should be evaluated at various phases of project evaluation, influencing decisions to move forward. Methods of evaluation at each phase are documented and discussed using the Sabriyah, Lower Burgan study as a basis.

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